New Even Horizon Telescope Results Trace M87 Jet Back to Its Black Hole

A Hubble Space Telescope image of the giant elliptical galaxy M87 with its blowtorch-like jet. The visible part of this giant stream of particles spans around 3000 light-years. © NASA, ESA, A. Lessing (Stanford University), E. Baltz (Stanford University), M. Shara (AMNH), J. DePasquale (STScI)

At 230 GHz (bottom), data from the EHT reveal the fine structure of the ring surrounding the supermassive black. © Bottom: Saurabh et al.: “Probing jet base emission of M87* with the 2021 Event Horizon Telescope observations”, Astronomy & Astrophysics 705 (2026), Figure 6. Upper Right: Lu, R.-S. et al.: “A ring-like accretion structure in M87 connecting its black hole and jet”. Nature 616 (2023), Figure 1

Selected sites from the 2021 EHT observing campaign, highlighting additional stations: the 12−m Kitt Peak (KP) Telescope, USA and the NOrthern Extended Millimeter Array (NOEMA), France. This introduces two critical intermediate-length baselines to the Submillimeter Telescope (SMT), USA and IRAM 30−m, Spain, providing sensitivity to emission structures close to the base of the jet. © Saurabh/MPIfR

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To the point:

• Recently published data from the Event Horizon Telescope (EHT) of the galaxy Messier 87 facilitate new insights into the direct environment of the central supermassive black hole.

• Measured differences in the radio light on different spatial scales can be explained by the presence of an as of yet undetected jet at frequencies of 230 Gigahertz at spatial scales comparable to the size of the black hole.

• The most likely location of the jet base is determined through detailed modeling.

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Observations with the Event Horizon Telescope enable researchers to localize the likely base of the central outflow in a massive galaxy

Some galaxies eject powerful streams of charged particles—jets—from their centers into space. The prominent jet of Messier 87 (M87) in the constellation Virgo is visible over distances of 3000 light-years and can be observed over the full electromagnetic spectrum. It is powered by the central engine, the supermassive black hole at the heart of the galaxy with a mass of around six billion times that of our Sun. The exact location around the black hole where the jets originate is still unknown. Using observations from the Event Horizon Telescope (EHT) from 2021, an international research team led by Saurabh (Max Planck Institute for Radio Astronomy, MPIfR), Hendrik Müller (National Radio Astronomy Observatory, NRAO) and Sebastiano von Fellenberg (formerly at MPIfR, currently at the Canadian Institute for Theoretical Astrophysics, CITA) has found first hints of the jet base in M87. The results are published in the current issue of the journal Astronomy & Astrophysics.

Observing different scales

M87*, the supermassive black hole at the center of the galaxy M87, is about 55 million light years (5 × 10²⁰ kilometers) away from Earth. In 2019, the first images of its shadow and the glowing ring of hot gas around it went around the world. In order to resolve these structures, radio telescopes around the world must be combined into a single virtual telescope such as the EHT. This technique is called Very Long Baseline Interferometry (VLBI). The images produced in this way are sensitive to emission on different scales, depending on the distances between telescopes (baselines): With long baselines of several thousand kilometers, the smallest structures—such as the luminous ring—around M87* can be depicted. Short baselines of a few hundred meters, on the other hand, reveal emission emanating from much larger spatial scales in M87 (the extended jet), but are blind to details near the black hole. Intermediate baselines of a few hundred to a few thousand kilometers are the important link. They can be used to establish a connection between the material around the black hole and the jet. Precisely these intermediate baselines enabled the research team to determine the probable position of the jet base. "This study represents an early step toward connecting theoretical ideas about jet launching with direct observations. Identifying where the jet may originate and how it connects to the black hole’s shadow, adds a key piece to the puzzle and points toward a better understanding of how the central engine operates", explains Saurabh.

The decisive difference

The researchers find hints to the base of the jet by comparing the measured radio intensity on different spatial scales: On short to intermediate baselines, the measured intensity is higher compared to that on long baselines. This indicates that what is observed with long baselines—the luminous ring of hot gas around the black hole—is not solely responsible for the detected radio emission. Instead, the current data show that part of the missing emission is captured on intermediate baselines. One possibility is the jet, which has not yet been observed at a radio frequency of 230 gigahertz (GHz) with the EHT.

EHT observations from 2017 and 2018 lacked the intermediate baselines to detect it. However, with the recently published data, Saurabh's team was able to show with numerous model calculations that part of the missing emission can be best explained by an additional compact region. From our perspective, this region is about 0.09 light-years away from M87* and associated with the base of the jet. The position of the region appears to coincide with the southern arm of a radio jet discovered at a different frequency (86 GHz) in 2018. "We have observed the inner part of the jet of M87 with global VLBI experiments for many years, with ever increasing resolution, and finally managed to resolve the black hole shadow in 2019. It is amazing to see that we are gradually moving towards combining these breakthrough observations across multiple frequencies and complete the picture of the jet launching region", says Hendrik Müller.

What’s next?

The current study shows that these interesting structures around M87* become visible at radio frequencies of 230 GHz with intermediate baselines. However, further observations with the EHT will be necessary to further constrain the morphology of the jet. These observations will then make it possible to not only deduce structures such as the jet base, but to image them. This opens up new possibilities for probing the direct environment of supermassive black holes and for testing theories of black hole physics. "Newly observed data—now being correlated and calibrated with support from MPIfR—will soon add back the Large Millimetre Telescope in Mexico. This will bring an even sharper view of the jet‑launching region within reach", says Sebastiano von Fellenberg.

Source: Max Planck for Radio Astronomy/Press Releases

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Additional Information

The following scientists affiliated to the MPIfR are coauthors of this publication: Saurabh, Sebastiano D. von Fellenberg, Michael Janssen, Thomas P. Krichbaum, Dhanya G. Nair, Walter Alef, Rebecca Azulay, Uwe Bach, Anne-Kathrin Baczko, Silke Britzen, Gregory Desvignes, Sergio A. Dzib, Ralph P. Eatough, Christian M. Fromm, Ramesh Karuppusamy, Joana A. Kramer, Michael Kramer, Jun Liu, Andrei P. Lobanov, Ru-Sen Lu, Nicholas R. MacDonald, Nicola Marchili, Karl M. Menten, Cornelia Müller, Georgios Filippos Paraschos, Alexander Plavin, Eduardo Ros, Helge Rottmann, Alan L. Roy, Tuomas Savolainen, Lijing Shao, Pablo Torne, Efthalia Traianou, Jan Wagner, Robert Wharton, Gunther Witzel, Jompoj Wongphexhauxsorn, J. Anton Zensus, and Guang-Yao Zhao.

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Contacts:

Mr. Saurabh
Tel: +49 228 525-366
saurabh@mpifr-bonn.mpg.de
Max Planck Institute for Radio Astronomy, Bonn

Dr. Hendrick Müller
Tel: +1 626 781-0043
hmuller@nrao.edu
National Radio Astronomy Observatory (NRAO), USA

Dr. Sebastiano von Fellenberg
Tel: +1 437 328-5547
sfellenberg@utoronto.ca
Canadian Institute for Theoretical Astrophysics (CITA), University of Toronto, Canada

Dr. Nina Brinkmann
Press and Public Relations
Tel: +49 228 525-399
brinkmann@mpifr-bonn.mpg.de
Max Planck Institute for Radio Astronomy, Bonn

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Original publication

Saurabh et al.
Probing jet base emission of M87* with the 2021 Event Horizon Telescope observations
Astronomy & Astrophysics 705 (2026)
[doi.org/10.1051/0004-6361/202557022]

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Parallel Press Release

CITA Press Release
From the Canadian Institute for Theoretical Astrophysics

Saurabh/MPIfR

Animation (open in full screen)

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Images

• eht_closure_phase_triangles 1.56 MB


• m87_possible_jet_base 1.13 MB


• m87_possible_jet_base_blank 1.11 MB

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Distant galaxy A1689-zD1 found to have unusually low dust-to-gas ratio

False-color JWST/NIRCam RGB image cutout (blue: F150W; green: F277W; red: F444W), overlaid with [C ii]-158µm emission contours showing 3, 5, 7, 10σ (white solid lines). A scalebar is shown in the image plane. Credit: arXiv (2025). DOI: 10.48550/arxiv.2510.07936

Using the James Webb Space Telescope (JWST) and the Atacama Large Millimeter/sub-millimeter Array (ALMA), an international team of astronomers has carried out comprehensive multiwavelength observations of a distant massive galaxy known as A1689-zD1.

The new observations, detailed in a paper published October 9 on the pre-print server arXiv, yield important insights into the properties of the galaxy, especially regarding dust production in this system.

A1689-zD1 is a bright highly-lensed massive galaxy at a redshift of approximately 7.13. It has a diameter of about 3,000 light years and its stellar mass is estimated to be some 2.6 billion solar masses.

Previous observations of A1689-zD1 have found that it has a metallicity close to the solar value and that it contains a substantial amount of dust—with an estimated mass of 15 million solar masses. Due to this, A1689-zD1 is an excellent place to study the existence of interstellar dust at early cosmic epochs.

That is why a group of astronomers led by Kasper E. Heintz of the University of Copenhagen, Denmark, decided to explore the dust content with JWST and ALMA.

"We revisited this galaxy to gauge the baryonic matter components in the ISM [interstellar medium], with particular focus on constraining the build up of cosmic dust," the researchers explained.

Hintz's team performed the rest-frame ultraviolet to far-infrared modeling of the spectral energy distribution (SED) of A1689-zD1 to determine its stellar mass, dust mass, visual attenuation, and star-formation rate. The ALMA observations were also used to constrain the total dynamical mass of the source, and infer the gas mass using common gas tracers but bounded by the overall dynamics of the system.

The study found that although A1689-zD1 has a substantial dust mass, its dust-to-gas (DTG) and dust-to-metal (DTM) mass ratios are remarkably low—at a level of 0.00051 and 0.061, respectively. The astronomers note that this is due to the high metallicity of A1689-zD1 and its substantial gas mass, which was calculated to be 28 billion solar masses.

Therefore, the DTG and DTM mass ratios for A1689-zD1 are an order of magnitude lower than that found in the Milky Way and the Large Magellanic Cloud (LMC) or the Small Magellanic Cloud (SMC). These ratios also suggest that the bulk neutral atomic hydrogen (HI) gas in the line-of-sight to A1689-zD1 is relatively dust-poor compared to its chemical enrichment.

The authors of the paper conclude that the obtained results point to a potential change in the relative dust abundance or composition of early galaxies.

"We find that this deviation in the DTG and DTM mass ratios appears to be ubiquitous in other metal-rich galaxies at similar redshifts, z ≳ 6. This suggests that the processes that form and destroy dust at later times, or the dust emissivity itself, are drastically different for galaxies in the early universe," the scientists conclude.

by Tomasz Nowakowski, Phys.org
edited by Sadie Harley, reviewed by Robert Egan

Source: Phys.org/News

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Written for you by our author Tomasz Nowakowski, edited by Sadie Harley, and fact-checked and reviewed by Robert Egan—this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive. If this reporting matters to you, please consider a donation (especially monthly). You'll get an ad-free account as a thank-you.

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More information: Kasper E. Heintz et al, Inefficient dust production in a massive, metal-rich galaxy at z=7.13 uncovered by JWST and ALMA, arXiv (2025). DOI: 10.48550/arxiv.2510.07936

Journal information: arXiv

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Explore further

• Astronomers discover ultra-luminous infrared galaxy lurking behind quasar

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Nuclear star clusters boost the growth of intermediate mass black holes

The low-mass galaxy NGC 300 (left) hosts a compact nuclear star cluster at its centre that can be resolved using an image from the Hubble Space Telescope (middle). A similar nuclear star cluster is included in the simulations (right). Credit: left: Adam Block/Mount Lemmon SkyCenter/University of Arizona; middle: Carson et al. (2015); right: MPA/Partmann et al. (2025).

Growth of IMBHs of different initial mass in the center of a simulated galaxy. Solid lines show growth without a nuclear star cluster, while dashed lines show growth with one. Low-mass black holes (red, blue and orange lines) only grow when embedded in a nuclear star cluster, whereas more massive black holes, which are comparable in mass to the nuclear star cluster itself, show little additional growth (green line). The nuclear star cluster contains 500,000 solar masses of stars, representing a few percent of the galaxy’s total stellar mass. Credit: MPA/Partmann

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Black holes with masses between the stellar and supermassive regime are among the most elusive objects in the Universe. These intermediate-mass black holes are believed to reside in many dwarf galaxies. Using new, high-resolution supercomputer simulations, MPA scientists discovered that nuclear star clusters — compact, massive clusters of stars at the centres of galaxies — may be key to enabling these black holes to grow, thus shedding light on the origins of supermassive black holes.

All massive galaxies, including our own Milky Way, contain supermassive black holes at their centres, with masses ranging from millions to billions of solar masses. However, the formation and growth of these giants remains a mystery. Low-mass galaxies may hold the answer: some of them contain these elusive intermediate-mass black holes (IMBHs), which have masses ranging from hundreds to hundreds of thousands of times that of the Sun. These are more massive than stellar black holes, but have never reached the supermassive stage. IMBHs exert influence only in a tiny region around them. This makes it difficult for them to capture gas and stars, affect their host galaxies, or even be detected in the first place.

Many low-mass galaxies host nuclear star clusters: extremely dense systems of stars spanning only a few light years, yet containing a few percent of the entire galaxy’s stellar mass. Nuclear star clusters form an extremely compact and deep potential well at the centre of the galaxy. Recent observations suggest a strong correlation between nuclear star clusters and the existence of IMBHs at their centres. The nuclear star clusters in low-mass galaxies tend to be more massive than their IMBHs, and may play a crucial role in the evolution of galactic centres. The MPA team set out to study how such an environment affects IMBH growth.

Simulating black hole growth is complex as it requires tracking how interstellar gas flows from galactic scales down to the tiny sphere of influence of the black hole. The team of researchers used high-resolution simulations that resolve the black hole's sphere of influence and capture many relevant physical processes in the interstellar gas. The simulations also follow millions of individual stars, including the radiation they emit and the supernovae of the most massive ones. By heating and stirring the gas, these processes strongly influence whether black holes can feed and grow.

The team tested low-mass galaxies with IMBHs of different initial masses. They found that light IMBHs (those below 10,000 solar masses) are barely able to capture gas and grow unless a nuclear star cluster is present. If the IMBH is embedded in a cluster, its additional gravitational potential enables rapid gas accretion and swift black hole growth. More massive IMBHs accrete efficiently even without a nuclear star cluster, but the additional growth is small compared to their initial mass. This demonstrates that nuclear star clusters are particularly significant for the smallest black holes, where the cluster's mass far exceeds that of the black hole itselfas is typical in low-mass galaxies.

Even with a nuclear star cluster, growth can be easily disrupted by stellar feedback. Some of the gas captured by the nuclear star cluster forms stars, including massive stars. When these massive stars end their lives as supernovae, they can expel gas from the galaxy’s centre, temporarily starving the black hole. Consequently, IMBHs undergo cycles of activity and quiet phases. This means that many are likely to be missed in current surveys, which typically detect only actively feeding black holes through the radiation produced by the accretion process.

The study shows that nuclear star clusters are essential for the growth of intermediate-mass black holes in low-mass galaxies, which would otherwise remain stagnant. This is particularly exciting because many theories suggest that the first black hole seeds in the early Universe formed through stellar collisions inside such clusters. Therefore, the new results point not only to nuclear star clusters as the birthplace of intermediate-mass black holes, but also as the sites where they grow most efficiently.

Simulation of an IMBH at the centre of a dwarf galaxy.

Interstellar gas (top left) is stirred by radiation and supernova explosions from massive stars, creating hot, low-density regions (top middle). Occasionally, the IMBH captures gas (bottom left), fuelling growth and star formation in the galactic centre. In the IMBH’s immediate surroundings (bottom middle and right), supernovae clear gas from the galaxy’s core, temporarily stopping black hole feeding. Once most massive stars have exploded, new gas can be captured by the black hole. Stars with masses greater than 8 solar masses (and their potential massive remnants) are depicted as red, orange, and yellow star symbols, with colour indicating increasing mass.

Source: Max Planck Institute for Astrophysics/Research Highlights

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Author:

Christian Partmann
partmann@mpa-Garching.mgp.de

Thorsten Naab
Scientific Staff
tnaab@mpa-garching.mpg.de

Original publication

Christian Partmann, Thorsten Naab, Natalia Lahén, Antti Rantala, Michaela Hirschmann, Jessica M Hislop, Jonathan Petersson, Peter H Johansson

The importance of nuclear star clusters for massive black hole growth and nuclear star formation in simulated low-mass galaxies

Monthly Notices of the Royal Astronomical Society, Volume 537, Issue 2, February 2025, Pages 956–977

Source

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‘Beyond what’s possible’: new JWST observations unearth mysterious ancient galaxies

Spectral analysis of its light with JWST revealed this red disk galaxy’s anomalous nature – it formed around 13 billion years ago even though it contains ~4x more mass in stars than our Milky Way does today. (This Webb image shows ZF-UDS-7329, a rare massive galaxy that formed very early in the Universe. Image credit: Glazebrook et al., doi: 10.1038/s41586-024-07191-9)

Associate Professo Lagos developed the theoretical modelling used in the study.

Our understanding of how galaxies form and the nature of dark matter could be completely upended, after new observations of a stellar population bigger than the Milky Way from more than 11 billion years ago that should not exist.

A paper published today in Nature details findings using new data from the James Webb Space Telescope (JWST). The results finds that a massive galaxy in the early universe – observed 11.5 billion years ago (a cosmic redshift of 3.2) – has an extremely old population of stars formed much earlier – 1.5 billion years earlier in time (a red shift of around 11). The observation upends current modelling, as not enough dark matter has built up in sufficient concentrations to seed their formation.

Swinburne University of Technology’s Distinguished Professor Karl Glazebrook led the study and the international team who used the JWST for spectroscopic observations of this massive quiescent galaxy.

“We’ve been chasing this particular galaxy for seven years and spent hours observing it with the two largest telescopes on earth to figure out how old it was. But it was too red and too faint, and we couldn’t measure it. In the end, we had to go off earth and use the JWST to confirm its nature.”

The formation of galaxies is a fundamental paradigm underpinning modern astrophysics and predicts a strong decline in the number of massive galaxies in early cosmic times. Extremely massive quiescent galaxies have now been observed as early as one to two billion years after the Big Bang which challenges previous theoretical models.

Distinguished Professor Glazebrook worked with leading researchers all over the world, including Dr Themiya Nanayakkara, Dr Lalitwadee Kawinwanichakij, Dr Colin Jacobs, Dr Harry Chittenden, Associate Professor Glenn G Kacprzak and Associate Professor Ivo Labbe from Swinburne’s Centre for Astrophysics and Supercomputing.

“This was very much a team effort, from the infrared sky surveys we started in 2010 that led to us identifying this galaxy as unusual, to our many hours on the Keck and Very Large Telescope where we tried, but failed to confirm it, until finally the last year where we spent enormous effort figuring out how to process the JWST data and analyse this spectrum.”

Dr Themiya Nanayakkara, who led the spectral analysis of the JWST data, says, “we are now going beyond what was possible to confirm the oldest massive quiescent monsters that exist deep in the Universe.”

“This pushes the boundaries of our current understanding of how galaxies form and evolve. The key question now is how they form so fast very early in the Universe and what mysterious mechanisms leads to stopping them forming stars abruptly when the rest of the Universe doing so.”

Associate Professor Claudia Lagos from the University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR) was crucial in developing the theoretical modelling of the evolution of dark matter concentrations for the study.

“Galaxy formation is in large part dictated by how dark matter concentrates,” she says. “Having these extremely massive galaxies so early in the Universe is posing significant challenges to our standard model of cosmology. This is because we don’t think such massive dark matter structures as to host these massive galaxies have had time yet to form. More observations are needed to understand how common these galaxies may be and to help us understand how truly massive these galaxies are.”

Distinguished Professor Glazebrook hopes this could be a new opening for our understanding of the physics of dark matter.

“JWST has been finding increasing evidence for massive galaxies forming early in time. This result sets a new record for this phenomenon. Although it is very striking, it is only one object. But we hope to find more; and if we do this will really upset our ideas of galaxy formation.”

Source: International Center for Radio Astronomy Research (ICRAR)/News

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Astronomers Discover a Massive Galaxy 'Shipyard' in the Distant Universe

Several instruments joined forces to produce this image of the G237 protocluster, identifying its galaxies in different colors representing different wavelengths of observations. The image on the right zooms in on the central region of this massive galaxy “shipyard.” Credits: ESA/Herschel and XMM-Newton; NASA/Spitzer; NAOJ/Subaru; Large Binocular Telescope; ESO/VISTA. Polletta, M. et al. 2021; Koyama, Y. et al. 2021. Credits: ESA/Herschel and XMM-Newton; NASA/Spitzer; NAOJ/Subaru; Large Binocular Telescope; ESO/VISTA

Several instruments joined forces to produce this image of the G237 protocluster, identifying its galaxies in different colors representing different wavelengths of observations. The image on the right zooms in on the central region of this massive galaxy “shipyard.” Credits: ESA/Herschel and XMM-Newton; NASA/Spitzer; NAOJ/Subaru; Large Binocular Telescope; ESO/VISTA. Polletta, M. et al. 2021; Koyama, Y. et al. 2021. Credits: ESA/Herschel and XMM-Newton; NASA/Spitzer; NAOJ/Subaru; Large Binocular Telescope; ESO/VISTA

Even galaxies don't like to be alone. While astronomers have known for a while that galaxies tend to congregate in groups and in clusters, the process of going from formation to friend groups has remained an open question in cosmology.

In a paper published in the Astronomy & Astrophysics Journal, an international team of astronomers reports the discovery of objects that appear to be an emerging accumulation of galaxies in the making – known as a protocluster.

"This discovery is an important step toward reaching our ultimate goal: understanding the assembly of galaxy clusters, the most massive structures that exist in the universe," said Brenda Frye, an associate professor of astronomy at the University of Arizona's Steward Observatory and a co-author of the study.

To cite a local analog, the Milky Way, the galaxy that is home to our solar system, belongs to a galaxy cluster known as the Local Group, which in turn is a part of the Virgo supercluster. But what did a supercluster such as Virgo look like 11 billion years ago?

“We still know very little about protoclusters, in part because they are so faint, too faint to be detected by optical light,” Frye said. At the same time, they are known to radiate brightly in other wavelengths such as the sub-millimeter.”

Initially discovered by the European Space Agency’s Planck telescope as part of an all-sky survey, this protocluster showed up prominently in the far-infrared region of the electromagnetic spectrum. Sifting through a sample of more than 2000 candidate objects – structures that could be in the process of becoming clusters – the researchers came across a protocluster designated as PHz G237.01+42.50, or G237 for short. The observations looked promising, but to confirm its identity required follow-up observations with other telescopes.

Led by Mari Polletta at the National Institute for Astrophysics, or INAF in Milan, Italy, the team conducted the observations using the combined power of the Large Binocular Telescope in Arizona, which is managed by UArizona, and the Subaru Telescope in Japan. As a result of this combined study, the team identified 63 galaxies belonging to the G237 protocluster. The original discovery was published in a paper (https://ui.adsabs.harvard.edu/abs/2021MNRAS.503L...1K/abstract), and follow-up observations were also obtained using archival data, the Herschel Space Observatory, and the Spitzer Space Telescope.

"You can think of galaxy protoclusters such as G237 as a galaxy shipyard in which massive galaxies are being assembled, only this structure existed at a time when the universe was 3 billion years old," Frye said. "At the same time, the genealogy may be closer than you think. Because the universe is homogeneous and the same in all directions, we think that the Milky Way may have docked at a protocluster node similar to G237 when it was very young.”

At first, the observations of G237 implied a total star formation rate that was unrealistically high, and the team struggled to make sense of the data. The G237 protocluster seemed to be forming stars at a rate of 10,000 times that of the Milky Way, the authors note. At that rate, the protocluster is expected to rapidly use up its stellar fuel and subsequently settle down into a complex system similar to the Virgo supercluster.

"Each of the 63 galaxies discovered so far in G237 was like a star factory in overdrive," Frye said. "It's as if the galaxies were working on overtime to the assemble stars. The rate of production was unsustainable. As such a pace, the supply chains are expected to break in the near future, and in a way that permanently shuts down the galaxy shipyard.”

Such high yields can only be maintained by a continuous injection of fuel, which for stars is hydrogen gas. Frye said the result required an efficient and unbroken supply chain that drew in unreasonably-large amounts of fresh gas to fuel the star-forming factories.

"We don't know where that gas was coming from," she said.

Later, the team discovered that some of the light was coming from galaxies unrelated to the protocluster, but even after the irrelevant light was removed, the total star formation rate remained high, at least a thousand solar masses per year, according to Poletta. For comparison, the Milky Way produces about one solar mass each year.
“The picture we have pieced together now is that of a successful galaxy shipyard which is working at high efficiency to assemble galaxies and the stars within them and and has an energy supply that is more sustainable,” Frye said.

All galaxies in the universe are part of a giant structure that resembles a three-dimensional spider web shape called the cosmic web. The filaments of the cosmic web intersect at the nodes, which equate to the galaxy shipyards in the analogy used here.

“We believe that the filaments mediate the transfer of hydrogen gas from the diffuse medium of intergalactic space onto these hungry, newly forming protocluster structures in the nodes,” Frye said.

Pointing to future research, Polletta said: “We are in the process of analyzing more observations on this and other Planck protoclusters with the goal of tracing the gas that gives birth to these newly-forming stars and feeds the supermassive black holes, to determine its origin and explain the observed extraordinary activity.”

Frye said she is looking forward to combining data from the Large Binocular Telescope with planned observations using the James Webb Space Telescope, to be launched in December.

“Protoclusters offer an opportunity to investigate key questions in astronomy that only this new observatory can answer,” she said, “such as what mechanisms drive the prodigious star formation, and when will the hydrogen supply run out, forcing this galaxy shipyard to close its doors and turn into a supercluster similar to the one our Milky Way is in?”

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The two research papers are:

“A Planck-selected dusty protocluster at z=2.16 associated with a strong over-density of massive Hα emitting galaxies”, authored by Yusei Koyama, Maria del Carmen Polletta, Ichi Tanaka, Tadayuki Kodama, Hervé Dole, Geneviève Soucail, Brenda Frye, Matt Lehnert, Marco Scodeggio, 2021, MNRAS, 501, L1, Abstract here and publication here.

"Spectroscopic observations of PHz G237.01+42.50 : a galaxy protocluster at z=2.16 in the Cosmos field”, authored by M. Polletta, G. Soucail, H. Dole, M. D. Lehnert, E. Pointecouteau, G. Vietri, M. Scodeggio, L. Montier, Y. Koyama, G. Lagache, B. L. Frye, F. Cusano, and M. Fumana, 2021, A&A, Volume 654, A121.

The work reported here used different facilities around the world and in space:

• Subaru Telescope in Hawaii. MOIRCS: Multi-Object Infrared Camera and Spectrograph.
• Large Binocular Telescope in Arizona. Operated by different universities and research institutions in the USA, Germany, Italy. LUCI spectrograph — Large Binocular Telescope Near-infrared Spectroscopic Utility with Camera and Integral Field Unit for Extragalactic Research.
• Planck, an ESA mission dedicated to cosmology and the cosmic microwave background, observing the whole sky in the radio and sub-millimeter light
• ​Herschel, an ESA observatory dedicated to the cold and far-away universe, observing the far-infrared and sub-millimeter light
• ​Spitzer, a NASA great observatory observing in the infrared.

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Other links:

UA/LBTO pdf version of this PR here
UA News Release here
INAF Press Release (Italian) here​
CNRS Press Release (French) here
Subaru Press Release (Japanese - English)​

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About LBT

​The largest optical telescope in operation, the Large Binocular Telescope uses two 8.4-meter primary meters which offer the light gathering power of an 11.7m mirror and, when used in interferometric mode, the resolving power of an 22.7m telescope. A sophisticated Adaptive Optics System correcting for atmospheric disturbances enables LBT to generate crisp and clear images of the universe. Operated by the University of Arizona (UA) in Tucson, Arizona, USA, the LBT is an international collaboration of the UA, Italy (INAF: Istituto Nazionale di Astrofisica), Germany (LBTB: LBT Beteiligungsgesellschaft), and The Ohio State University (OSU) representing OSU, the University of Minnesota, the University of Virginia, and the University of Notre Dame. 

More information: http://www.lbto.org/

Source: Large Binocular Telescope Observatory (LBTO)

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Hubble Finds Early, Massive Galaxies Running on Empty

These images are composites from NASA's Hubble Space Telescope and the Atacama Large Millimeter/submillimeter Array (ALMA). The boxed and pullout images show two of the six, distant, massive galaxies where scientists found star formation has ceased due to the depletion of a fuel source – cold hydrogen gas. Hubble, together with ALMA, found these odd galaxies when they combined forces with the "natural lens" in space created by foreground massive galaxy clusters. The clusters' gravity stretches and amplifies the light of the background galaxies in an effect called gravitational lensing. This phenomenon allows astronomers to use massive galaxy clusters as natural magnifying glasses to study details in the distant galaxies that would otherwise be impossible to see. The yellow traces the glow of starlight. The artificial purple color traces cold dust from ALMA observations. This cold dust is used as a proxy for the cold hydrogen gas needed for star formation. Even with ALMA's sensitivity, scientists do not detect dust in most of the six galaxies sampled. One example is MRG-M1341, at upper right. It looks distorted by the "funhouse mirror" optical effects of lensing. In contrast, the purple blob to the left of the galaxy is an example of a dust-and-gas-rich galaxy. One example of the detection of cold dust ALMA did make is galaxy MRG-M2129 at bottom right. The galaxy only has dust and gas in the very center. This suggests that star formation may have shut down from the outskirts inward. Annotated image on the left, unannotated image on the right. Credits: Image Processing: Joseph DePasquale (STScI).  Hi-res image

When the universe was about 3 billion years old, just 20% of its current age, it experienced the most prolific period of star birth in its history. But when NASA's Hubble Space Telescope and the Atacama Large Millimeter/submillimeter Array (ALMA) in northern Chile gazed toward cosmic objects in this period, they found something odd: six early, massive, "dead" galaxies that had run out of the cold hydrogen gas needed to make stars.

Without more fuel for star formation, these galaxies were literally running on empty. The findings are published in the journal Nature.

"At this point in our universe, all galaxies should be forming lots of stars. It's the peak epoch of star formation," explained lead author Kate Whitaker, assistant professor of astronomy at the University of Massachusetts, Amherst. Whitaker is also associate faculty at the Cosmic Dawn Center in Copenhagen, Denmark. "So what happened to all the cold gas in these galaxies so early on?"

This study is a classic example of the harmony between Hubble and ALMA observations. Hubble pinpointed where in the galaxies the stars exist, showing where they formed in the past. By detecting the cold dust that serves as a proxy for the cold hydrogen gas, ALMA showed astronomers where stars could form in the future if enough fuel were present.

Using Nature's Own Telescopes

The study of these early, distant, dead galaxies was part of the appropriately named REQUIEM program, which stands for Resolving QUIEscent Magnified Galaxies At High Redshift. (Redshift happens when light is stretched by the expansion of space and appears shifted toward the red part of the spectrum. The farther away a galaxy is with respect to the observer, the redder it appears.)

The REQUIEM team uses extremely massive foreground galaxy clusters as natural telescopes. The immense gravity of a galaxy cluster warps space, bending and magnifying light from background objects. When an early, massive, and very distant galaxy is positioned behind such a cluster, it appears greatly stretched and magnified, allowing astronomers to study details that would otherwise be impossible to see. This is called "strong gravitational lensing."

Only by combining the exquisite resolution of Hubble and ALMA with this strong lensing was the REQUIEM team able to able to understand the formation of these six galaxies, which appear as they did only a few billion years after the big bang.

"By using strong gravitational lensing as a natural telescope, we can find the distant, most massive, and first galaxies to shut down their star formation," said Whitaker. "I like to think about it like doing science of the 2030s or 40s – with powerful next-generation space telescopes – but today instead by combining the capabilities of Hubble and ALMA, which are boosted by strong lensing." 

"REQUIEM pulled together the largest sample to date of these rare, strong-lensed, dead galaxies in the early universe, and strong lensing is the key here," said Mohammad Akhshik, principal investigator of the Hubble observing program. "It amplifies the light across all wavelengths so that it's easier to detect, and you also get higher spatial resolution when you have these galaxies stretched across the sky. You can essentially see inside of them at much finer physical scales to figure out what's happening."

Live Fast, Die Young

These sorts of dead galaxies don't appear to rejuvenate, even through later minor mergers and accretions of nearby, small galaxies and gas. Gobbling up things around them mostly just "puffs up" the galaxies. If star formation does turn back on, Whitaker described it as "a kind of a frosting." About 11 billion years later in the present-day universe, these formerly compact galaxies are thought to have evolved to be larger but are still dead in terms of any new star formation.

These six galaxies lived fast and furious lives, creating their stars in a remarkably short time. Why they shut down star formation so early is still a puzzle.

Whitaker proposes several possible explanations: "Did a supermassive black hole in the galaxy's center turn on and heat up all the gas? If so, the gas could still be there, but now it's hot. Or it could have been expelled and now it's being prevented from accreting back onto the galaxy. Or did the galaxy just use it all up, and the supply is cut off? These are some of the open questions that we'll continue to explore with new observations down the road."

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington, D.C.

Media Contacts:

Claire Andreoli
NASA's Goddard Space Flight Center
301-286-1940

​Ann Jenkins
Space Telescope Science Institute, Baltimore, Maryland

Ray Villard
Space Telescope Science Institute, Baltimore, Maryland

Science Contact:

Katherine E. Whitaker
University of Massachusetts, Amherst, Massachusetts

Editor: Lynn Jenner

Source: NASA/Hubble

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At cosmic noon, puffy galaxies make stars for longer

An ensemble of twenty-five disk galaxies. The view on the left shows light emitted in the H-alpha line from interstellar gas as a result of ongoing star-formation, while the panels on the right shows the optical light emitted by a mix of young (bluer) and old (redder) stars. Each galaxy can be seen rotated edge-on below its face-on view. Image Credit: TNG Collaboration. Hi-res imagem

Galaxies with extended disks maintain productivity, research reveals

Massive galaxies with extra-large extended “puffy” disks produced stars for longer than their more compact cousins, new modelling reveals.

In a paper published in the Astrophysical Journal, researchers led by Dr Anshu Gupta and Associate Professor Kim-Vy Tran from Australia’s ARC Centre of Excellence in All Sky Astrophysics in 3 Dimensions (ASTRO 3D), show that the sheer size of a galaxy influences when it stops making new stars.

“There’s a period in the life of the Universe known as the ‘cosmic noon’, which occurred about 10 billion years ago,” said Dr Gupta.

“That was when star formation in massive galaxies was at its peak. After that, gas in most of these galaxies grew hot – in part because of the black holes in the middle of them – and they stopped forming stars.

“In galaxies that are really, really stretched out, however, we found that things didn’t heat up as much and the black holes didn’t exert such a great influence, so stars kept getting made over a longer period.”

Dr Gupta and Dr Tran, both of whom are based at the University of NSW, Sydney, found that they could predict the end of star formation based on the size of a galaxy’s disk – the flat, circular region surrounding its centre, comprising stars, hydrogen gas and dust.

“Where the stars in the disk are widely distributed – you could call it ‘puffy’ – the gas stays cooler, so continues to coalesce under gravity and form new stars,” said Dr Gupta.

“In galaxies with more compact disks, the gas heats up quite quickly and is soon too energetic to mash together, so the formation of stars finishes by just after cosmic noon. Puffy disks keep going much longer, say as far as cosmic afternoon tea.”

To make their findings, the researchers, with colleagues from Melbourne, Germany, Mexico and the United States, used cosmological galaxy formation simulations from an international collaboration known as the IllustrisTNG project.

This was integrated with deep observations from an Australian-led project known as the Multi-Object Spectroscopic Emission Line (MOSEL) Survey.

“The IllustrisTNG simulations required millions of hours of supercomputer time,” said Dr Tran.

“And the MOSEL survey needs both the WM Keck Observatory in Hawai’i and the Hubble Space Telescope.

“The results mean that for the first time we’ve been able to establish a relationship between disk size and star-making. So now astronomers will be able to look at any galaxy in the Universe and accurately predict when it will stop making stars – just after lunch, or later in the cosmic afternoon.”

The Milky Way, incidentally, is a massive galaxy that is still making stars. That’s because it was something of a cosmic late-starter. When cosmic noon arrived it was very small – containing only one-tenth of the star mass it hosts today – and did not attain ‘massive’ status until much, much later.

As a result, the gas and dust within it has not yet warmed up enough to quench the star-making process.

It is not, however, an extended puffy galaxy, so it will quench, relatively speaking, sooner rather than later.

“Cosmic noon was a long time ago,” said Dr Gupta. “I’d say that by now the Universe has reached cosmic evening. It’s not night-time yet, but things have definitely slowed down.”

As well as UNSW, team members hailed from Swinburne University, the Max-Planck-Institut fur Astronomie, the Universidad Nacional Autonoma de Mexico, and the Flatiron Institute and Columbia University, both in New York.

About the Author: Andrew Masterton

Andrew Masterton is Science in Public’s editor-in-chief and an award-winning writer. He writes media releases in conjunction with the researchers for ASTRO 3D. Before joining Science in Public as editor-in-chief, was editor of both the quarterly print and daily online iterations of Cosmos. Prior to that, he was a specialist science feature contributor to a wide range of newspapers and magazines, primarily the former Fairfax titles The Age, Sydney Morning Herald and Australian Financial Review. He also edited the Livewire technology section that appears in the Melbourne and Sydney mastheads, as well as sometimes filling in as acting editor of the television guides for both papers.

Source: Astro 3D

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ALMA captures distant colliding galaxy dying out as it loses the ability to form stars

This artist’s impression of ID2299 shows the galaxy, the product of a galactic collision, and some of its gas being ejected by a “tidal tail” as a result of the merger. New observations made with ALMA  have captured the earliest stages of this ejection, before the gas reached the very large scales depicted in this artist’s impression.  Credit: ESO/M. Kornmesser

Galaxies begin to “die” when they stop forming stars, but until now astronomers had never clearly glimpsed the start of this process in a far-away galaxy. Using the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers have seen a galaxy ejecting nearly half of its star-forming gas. This ejection is happening at a startling rate, equivalent to 10 000 Suns-worth of gas a year — the galaxy is rapidly losing its fuel to make new stars. The team believes that this spectacular event was triggered by a collision with another galaxy, which could lead astronomers to rethink how galaxies stop bringing new stars to life.

“This is the first time we have observed a typical massive star-forming galaxy in the distant Universe about to ‘die’ because of a massive cold gas ejection,” says Annagrazia Puglisi, lead researcher on the new study, from the Durham University, UK, and the Saclay Nuclear Research Centre (CEA-Saclay), France. The galaxy, ID2299, is distant enough that its light takes some 9 billion years to reach us; we see it when the Universe was just 4.5 billion years old.

The gas ejection is happening at a rate equivalent to 10 000 Suns per year, and is removing an astonishing 46% of the total cold gas from ID2299. Because the galaxy is also forming stars very rapidly, hundreds of times faster than our Milky Way, the remaining gas will be quickly consumed, shutting down ID2299 in just a few tens of million years.

The event responsible for the spectacular gas loss, the team believes, is a collision between two galaxies, which eventually merged to form ID2299. The elusive clue that pointed the scientists towards this scenario was the association of the ejected gas with a “tidal tail”. Tidal tails are elongated streams of stars and gas extending into interstellar space that result when two galaxies merge, and they are usually too faint to see in distant galaxies. However, the team managed to observe the relatively bright feature just as it was launching into space, and were able to identify it as a tidal tail.

Most astronomers believe that winds caused by star formation and the activity of black holes at the centres of massive galaxies are responsible for launching star-forming material into space, thus ending galaxies’ ability to make new stars. However, the new study published today in Nature Astronomy suggests that galactic mergers can also be responsible for ejecting star-forming fuel into space.

“Our study suggests that gas ejections can be produced by mergers and that winds and tidal tails can appear very similar,” says study co-author Emanuele Daddi of CEA-Saclay. Because of this, some of the teams that previously identified winds from distant galaxies could in fact have been observing tidal tails ejecting gas from them. “This might lead us to revise our understanding of how galaxies ‘die’,” Daddi adds.

Puglisi agrees about the significance of the team’s finding, saying: “I was thrilled to discover such an exceptional galaxy! I was eager to learn more about this weird object because I was convinced that there was some important lesson to be learned about how distant galaxies evolve.“

This surprising discovery was made by chance, while the team were inspecting a survey of galaxies made with ALMA, designed to study the properties of cold gas in more than 100 far-away galaxies. ID2299 had been observed by ALMA for only a few minutes, but the powerful observatory, located in northern Chile, allowed the team to collect enough data to detect the galaxy and its ejection tail. 

“ALMA has shed new light on the mechanisms that can halt the formation of stars in distant galaxies. Witnessing such a massive disruption event adds an important piece to the complex puzzle of galaxy evolution,” says Chiara Circosta, a researcher at the University College London, UK, who also contributed to the research.

In the future, the team could use ALMA to make higher-resolution and deeper observations of this galaxy, enabling them to better understand the dynamics of the ejected gas. Observations with the future ESO’s Extremely Large Telescope could allow the team to explore the connections between the stars and gas in ID2299, shedding new light on how galaxies evolve.

More Information

This research was presented in the paper “A titanic interstellar medium ejection from a massive starburst galaxy at z=1.4” to appear in Nature Astronomy (doi: 10.1038/s41550-020-01268-x).

The team is composed of A. Puglisi (Centre for Extragalactic Astronomy, Durham University, UK and CEA, IRFU, DAp, AIM, Université Paris-Saclay, Université Paris Diderot, Sorbonne Paris Cité, CNRS, France [CEA]), E. Daddi (CEA), M. Brusa (Dipartimento di Fisica e Astronomia, Università di Bologna, Italy and INAF-Osservatorio Astronomico di Bologna, Italy), F. Bournaud (CEA), J. Fensch (Univ. Lyon, ENS de Lyon, Univ. Lyon 1, CNRS, Centre de Recherche Astrophysique de Lyon, France), D. Liu (Max Planck Institute for Astronomy, Germany), I. Delvecchio (CEA), A. Calabrò (INAF-Osservatorio Astronomico di Roma, Italy), C. Circosta (Department of Physics & Astronomy, University College London, UK), F. Valentino (Cosmic Dawn Center at the Niels Bohr Institute, University of Copenhagen and DTU-Space, Technical University of Denmark, Denmark), M. Perna (Centro de Astrobiología (CAB, CSIC–INTA), Departamento de Astrofísica, Spain and INAF-Osservatorio Astrofisico di Arcetri, Italy), S. Jin (Instituto de Astrofísica de Canarias and Universidad de La Laguna, Dpto. Astrofísica, Spain), A. Enia (Dipartimento di Fisica e Astronomia, Università di Padova, Italy [Padova]), C. Mancini (Padova) and G. Rodighiero (Padova and INAF-Osservatorio Astronomico di Padova, Italy).

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Organisation for Astronomical Research in the Southern Hemisphere (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

The original press release was published by the European Southern Observatory (ESO), an ALMA partner on behalf of Europe.

Source: Atacama Large Millimeter/submillimeter Array (ALMA)/Press Releases

 Contacts

Valeria Foncea
Education and Public Outreach Manager
Joint ALMA Observatory Santiago - Chile
Phone: +56 2 2467 6258
Cell phone: +56 9 7587 1963
Email: valeria.foncea@alma.cl

Bárbara Ferreira
ESO Public Information Officer
Garching bei München, Germany
Phone: +49 89 3200 6670
Email: pio@eso.org

Iris Nijman
News and Public Information Manager
National Radio Astronomy Observatory Charlottesville, Virginia - USA
Cell phone: +1 (434) 249 3423
Email: inijman@nrao.edu

Masaaki Hiramatsu

 Education and Public Outreach Officer, NAOJ Chile
Observatory, Tokyo - Japan
Phone: +81 422 34 3630
Email: hiramatsu.masaaki@nao.ac.jp

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Galaxy Survives Black Hole’s Feast – For Now

Illustration of the galaxy called CQ4479. The extremely active black hole at the galaxy’s center is consuming material so fast that the material is glowing as it spins into the black hole’s center, forming a luminous quasar. Quasars create intense energy that was thought to halt all star birth and drive a lethal blow to a galaxy’s growth. But SOFIA found that the galaxy CQ4479 is surviving these monstrous forces, holding on to enough cold gas, shown around the edges in brown, to birth about 100 Sun-sized stars a year, shown in blue. The discovery is causing scientists to re-think their theories of galactic evolution. Credits: NASA/ Daniel Rutter.Hi-res image

The hungriest of black holes are thought to gobble up so much surrounding material they put an end to the life of their host galaxy. This feasting process is so intense that it creates a highly energetic object called a quasar – one of the brightest objects in the universe – as the spinning matter is sucked into the black hole’s belly. Now, researchers have found a galaxy that is surviving the black hole’s ravenous forces by continuing to birth new stars – about 100 Sun-sized stars a year.   

The discovery from NASA’s telescope on an airplane, the Stratospheric Observatory for Infrared Astronomy, can help explain how massive galaxies came to be, even though the universe today is dominated by galaxies that no longer form stars. The results are published in the Astrophysical Journal. 

“This shows us that the growth of active black holes doesn’t stop star birth instantaneously, which goes against all the current scientific predictions,” said Allison Kirkpatrick, assistant professor at the University of Kansas in Lawrence Kansas and co-author on the study. “It’s causing us to re-think our theories on how galaxies evolve.” 

SOFIA, a joint project of NASA and the German Aerospace Center, DLR, studied an extremely distant galaxy, located more than 5.25 billion light years away called CQ4479. At its core is a special type of quasar that was recently discovered by Kirkpatrick called a “cold quasar.” In this kind of quasar, the active black hole is still feasting on material from its host galaxy, but the quasar’s intense energy has not ravaged all of the cold gas, so stars can keep forming and the galaxy lives on. This is the first time researchers have a detailed look at a cold quasar, directly measuring the black hole’s growth, star birth rate, and how much cold gas remains to fuel the galaxy. 

“We were surprised to see another oddball galaxy that defies current theories,” said Kevin Cooke, postdoctoral researcher at the University of Kansas in Lawrence, Kansas, and lead author of this study. “If this tandem growth continues both the black hole and the stars surrounding it would triple in mass before the galaxy reaches the end of its life.” 

As one of the brightest and most distant objects in the universe, quasars, or “quasi-stellar radio sources,” are notoriously difficult to observe because they often outshine everything around them. They form when an especially active black hole consumes huge amounts of material from its surrounding galaxy, creating strong gravitational forces. As more and more material spins faster and faster toward the center of the black hole, the material heats up and glows brightly. A quasar produces so much energy that it often outshines everything around it, blinding attempts to observe its host galaxy. Current theories predict that this energy heats up or expels the cold gas needed to create stars, stopping star birth and driving a lethal blow to a galaxy’s growth. But SOFIA reveals there is a relatively short period  when the galaxy’s star birth can continue while the black hole’s feast goes on powering the quasar’s powerful forces.  

Rather than directly observing the newborn stars, SOFIA used its 9-foot telescope to detect the infrared light radiating from the dust heated by the process of star formation.  Using data collected by SOFIA's High-resolution Airborne Wideband Camera-Plus, or HAWC+ instrument, scientists were able to estimate the amount of star formation over the past 100 million years. 

“SOFIA lets us see into this brief window of time where the two processes can co-exist,” said Cooke. “It’s the only telescope capable of studying star birth in this galaxy without being overwhelmed by the intensely luminous quasar.” 

The short window of joint black hole and star growth represents an early phase in the death of a galaxy, wherein the galaxy has not yet succumbed to the devastating effects of the quasar. Continued research with SOFIA is needed to learn if many other galaxies go through a similar stage with joint black hole and star growth before ultimately reaching the end of life. Future observations with the James Webb Space Telescope, which is scheduled to launch in 2021, could uncover how quasars affect the overall shape of their host galaxies. 

SOFIA is a joint project of NASA and the German Aerospace Center. NASA’s Ames Research Center in California’s Silicon Valley manages the SOFIA program, science, and mission operations in cooperation with the Universities Space Research Association, headquartered in Columbia, Maryland, and the German SOFIA Institute at the University of Stuttgart. The aircraft is maintained and operated by NASA’s Armstrong Flight Research Center Building 703, in Palmdale, California. The HAWC+ instrument was developed and delivered to NASA by a multi-institution team led by NASA’s Jet Propulsion Laboratory (JPL). 

Members of the news media interested in covering this topic should reach out to the NASA Ames newsroom.

Felicia Chou
NASA Headquarters, Washington 
202-358-0257
felicia.chou@nasa.gov

Alison Hawkes 
Ames Research Center, Silicon Valley, Calif.
650-604-4789
alison.hawkes@nasa.gov

Editor: Kassandra Bell

 

Source: NASA/SOFIA

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Galactic Census Reveals Origin of Most "Extreme" Galaxies

A wide field view of the central region of the Virgo Cluster, measuring 4.4 million light years on each side, from the Sloan Digital Sky Survey. Some of Virgo's brightest member galaxies are labeled, including Messier 87, or M87, which is located close to the cluster center. Insets show deep images of two structurally extreme galaxies, taken with the MegaCam instrument on CFHT as part of the Next Generation Virgo Cluster Survey. An ultra-compact dwarf is within the crosshairs in the lower inset, while an ultra-diffuse galaxy is featured in the upper inset. These galaxies are nearly a thousand times fainter than the bright galaxies visible on this image. Although the compact and diffuse galaxies contain roughly the same number of stars, and their total brightness is similar, they differ in area by a factor of more than 20,000. The scale bars in each inset represent a distance of 10,000 light years. Image credits: Sloan Digital Sky Survey, Canada-France-Hawaii Telescope and the NGVS team.

Astronomers have found that the key to understanding galaxies with "extreme" sizes, either small or large, may lie in their surroundings. In two related studies, an international team found that galaxies that are either "ultra-compact" or "ultra-diffuse" relative to normal galaxies of comparable brightness appear to reside in dense environments, i.e., regions that contain large numbers of galaxies. This has led the team to speculate that these "extreme" objects could have started out resembling normal galaxies, but then evolved to have unusual sizes through interactions with other galaxies.

The team identified both ultra-compact and ultra-diffuse galaxies as part of an unprecedented census of galaxies residing in the nearby Virgo cluster. The investigation used data from the Next Generation Virgo Cluster Survey (NGVS) obtained at the Canada-France-Hawaii Telescope (CFHT) using MegaCam, a wide-field, optical camera. At a distance of 50 million light years, Virgo is the galaxy cluster nearest to the Milky Way, and contains several thousand member galaxies, the majority of which are revealed, for the first time, in the NGVS data.

Astronomers discovered ultra-compact dwarf galaxies (UCDs) a quarter century ago, and they are the densest known galaxies in the Universe. Competing theories describe UCDs as either large star clusters, or as the remnants of larger galaxies that have been stripped of their stellar envelopes.

"We found hundreds of UCDs in the nearby Virgo galaxy cluster, and at least some of them appear to have started their lives as larger galaxies," said Dr. Chengze Liu of Shanghai Jiao Tong University, lead author of the first study.

While UCDs are similar in appearance to a large star cluster, a number of UCDs in this study were found with faint stellar envelopes surrounding the central, compact core. These envelopes could be the last remnants of a galaxy that has gradually been stripped away by gravitational tidal forces from neighboring galaxies. Additionally, UCDs were found to inhabit preferentially the regions of the Virgo cluster with the highest galaxy densities. Together, these pieces of evidence point to an environmentally-induced transformation as being responsible for producing some UCDs.

Ultra-diffuse galaxies (UDGs) are a mystery at the other end of the size spectrum. They are much larger, and more diffuse, than typical galaxies with similar brightness. Some theories suggest that UDGs are massive galaxies whose gas --- the fuel for their star formation --- was removed before many stars could form. Others suggest that they were once normal galaxies that have been made more diffuse through mergers and interactions.

"We found that the ultra-diffuse galaxies in the Virgo cluster are more concentrated toward the dense cluster core, indicating that a dense environment may be important for their formation," said Dr. Sungsoon Lim of the University of Tampa, and the lead author of the second study. "The diversity in their properties indicate that while no single process has given rise to all objects within the UDG class, at least some UDGs have appearances suggesting their diffuse nature is due to tidal interactions or to the merger of low-mass galaxies."

Another mystery is that some ultra-diffuse galaxies were found to contain significant populations of globular star clusters. "The intense star-forming events needed to make globular clusters generally make a galaxy less, rather than more diffuse, so understanding how we get globular clusters in ultra-diffuse galaxies is an interesting challenge," said Prof. Eric Peng of Peking University's Kavli Institute for Astronomy and Astrophysics, and co-author on both studies.

"To find galaxies that are truly unusual, you first need to understand the properties of so-called normal galaxies," said Dr. Patrick Côté of the National Research Council of Canada’s Herzberg Astronomy and Astrophysics Research Center, and an author on both studies. "NGVS provides the deepest, most complete look at the entirety of the Virgo cluster galaxy population, allowing us to find the most compact and most diffuse galaxies, advancing our understanding of how they fit into the general picture of galaxy formation."

These research results have been presented in two papers that were published recently in the Astrophysical Journal ( Lim et al. 2020; Liu et al. 2020).

NGVS is based on observations obtained with MegaPrime/MegaCam, a joint project of the Canada-France-Hawaii Telescope and CEA/DAPNIA, and on data produced and hosted at the Canadian Astronomy Data Centre. CFHT is operated by the National Research Council of Canada, the Institute National des Sciences de l'Universe of the Centre National de la Recherche Scientifique of France, and the University of Hawai’i.laychak@cfht.hawaii.edu

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Contacts

Dr. Eric Peng
Department of Astronomy
Kavli Institute for Astronomy and Astrophysics
Peking University, Beijing, China
peng@pku.edu.cn

Dr. Patrick Côté
Herzberg Astronomy and Astrophysics Research Center
National Research Council of Canada
Victoria, BC, Canada
patrick.cote@nrc-cnrc.gc.ca

Dr. Chengze Liu
Department of Astronomy
School of Physics and Astronomy
Shanghai Jiao Tong University
Shanghai, China
czliu@sjtu.edu.cn

Dr. Sungsoon Lim
University of Tampa
Tampa, FL, USA
slim@ut.edu

Media Contact

Mary Beth Laychak
Canada-France-Hawaii Telescope
laychak@cfht.hawaii.edu

Source: Canada-France-Hawaii Telescope (CFHT)/News

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Hungry galaxies grow fat on the flesh of their neighbours

Simulation showing distribution of dark matter particles around the galaxy.

Credit: Gupta et al/ASTRO 3D/ IllustrisTNG collaboration

Hi-res Image

Simulation showing distribution of dark matter density overlayed with the gas density. This image cleanly shows the gas channels connecting the central galaxy with its neighbours. Credit: Gupta et al/ASTRO 3D/ IllustrisTNG collaboration. Hi-res Image

Modelling shows big galaxies get bigger by merging with smaller ones

Galaxies grow large by eating their smaller neighbours, new research reveals.

Exactly how massive galaxies attain their size is poorly understood, not least because they swell over billions of years. But now a combination of observation and modelling from researchers led by Dr Anshu Gupta from Australia’s ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) has provided a vital clue.

In a paper published in The Astrophysical Journal, the scientists combine data from an Australian project called the Multi-Object Spectroscopic Emission Line (MOSEL) survey with a cosmological modelling program running on some of the world’s largest supercomputers in order to glimpse the forces that create these ancient galactic monsters.

By analysing how gases within galaxies move, Dr Gupta said, it is possible to discover the proportion of stars made internally – and the proportion effectively cannibalised from elsewhere.

“We found that in old massive galaxies – those around 10 billion light years away from us – things move around in lots of different directions,” she said.

“That strongly suggests that many of the stars within them have been acquired from outside. In other words, the big galaxies have been eating the smaller ones.”

Because light takes time to travel through the universe, galaxies further away from the Milky Way are seen at an earlier point in their existence. Dr Gupta’s team found that observation and modelling of these very distant galaxies revealed much less variation in their internal movements.

“We then had to work out why ‘older’, closer big galaxies were so much more disordered than the ‘younger’, more distant ones,” said second author ASTRO 3D’s Dr Kim-Vy Tran, who like Dr Gupta, is based at the UNSW Sydney.

“The most likely explanation is that in the intervening billions of years the surviving galaxies have grown fat and disorderly through incorporating smaller ones. I think of it as big galaxies having a constant case of the cosmic munchies.”

The research team – which included scientists from other Australian universities plus institutions in the US, Canada, Mexico, Belgium and the Netherlands – ran their modelling on a specially designed set of simulations known as IllustrisTNG.

This is a multi-year, international project that aims to build a series of large cosmological models of how galaxies form. The program is so big that it has to run simultaneously on several of world’s most powerful supercomputers.

“The modelling showed that younger galaxies have had less time to merge with other ones,” said Dr Gupta.

“This gives a strong clue to what happens during an important stage of their evolution.”

Source: Science in Public/Media Releases

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Paper Details:

Title: MOSEL Survey: Tracking the Growth of Massive Galaxies at 2 < z < 4 Using Kinematics and the IllustrisTNG Simulation

Full Paper

DOI: 10.3847/1538-4357/ab7b6d

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Authors:

Anshu Gupta1,2 , Kim-Vy Tran1,2,3, Jonathan Cohn3 , Leo Y. Alcorn3,4 , Tiantian Yuan2,5 , Vicente Rodriguez-Gomez6, Anishya Harshan1 , Ben Forrest7 , Lisa J. Kewley2,8 , Karl Glazebrook5 , Caroline M. Straatman9 , Glenn G. Kacprzak2,5, Themiya Nanayakkara10 , Ivo Labbé5 , Casey Papovich3,11 , and Michael Cowley12,13

1. School of Physics, University of New South Wales, Sydney, NSW 2052, Australia;
2. ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), Australia
3. George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University, College Station, TX 77843-4242, USA
4. Department of Physics and Astronomy, York University, 4700 Keele Street, Toronto, Ontario, MJ3 1P3, Canada
5. Swinburne University of Technology, Hawthorn, VIC 3122, Australia
6. Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, A.P. 72-3, 58089 Morelia, Mexico
7. Department of Physics & Astronomy, University of California, Riverside, 900 University Avenue, Riverside, CA 92521, USA
8. Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston Creek, ACT 2611, Australia
9. Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, B-9000 Gent, Belgium
10. Leiden Observatory, Leiden University, P.O. Box 9513, NL 2300 RA Leiden, The Netherlands
11. Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843-4242, USA
12. Centre for Astrophysics, University of Southern Queensland, West Street, Toowoomba, QLD 4350, Australia
13. School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD 4001, Australia

Funded by:  ASTRO 3D, Australia Research Council, National Science Foundation, Nederlandse Organisatie voor Wetenschappelijk Onderzoek

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More about ASTRO 3D:

ASTRO 3D is a seven-year $40 million Centre of Excellence project funded by the Australian Government through the Australian Research Council. The Centre began in June 2017 and will end in June 2024. It hosts around 200 investigators and professional staff, mostly based at six nodes: the Australian National University, Curtin University, Swinburne University of Technology, University of Melbourne, University of Sydney, and University of Western Australia. https://astro3d.org.au/ More about IllustrisTNG

The IllustrisTNG project is an ongoing series of large, cosmological magnetohydrodynamical simulations of galaxy formation. TNG aims to illuminate the physical processes that drive galaxy formation: to understand when and how galaxies evolve into the structures that are observed in the night sky, and to make predictions for current and future observational programs. The simulations use a state of the art numerical code which includes a comprehensive physical model and runs on some of the largest supercomputers in the world. TNG is a successor to the original Illustris simulation and builds on several years of effort by many people. The project description page contains an introduction to the motivations, techniques, and early science results of the TNG simulations. Presently, the project includes three primary runs spanning a range of volume and resolution; these are called TNG50, TNG100, and TNG300. https://www.tng-project.org/

More about the Multi-Object Spectroscopic Emission Line (MOSEL) survey

The MOSEL survey is an ongoing survey of star-forming galaxies around 12 billion light years away. The main objective is identify factors affecting the rise and fall of star formation activity in young galaxies.

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