Massive black hole in the early universe spotted taking a ‘nap’ after overeating

Computer-simulated image of a supermassive black hole at the core of a galaxy.
Credit: NASA, ESA, and D. Coe, J. Anderson, and R. van der Marel (STScI)

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Gravitational waves data held clues for high-mass black holes’ violent beginnings

The size and spin of black holes can reveal important information about how and where they formed, according to new research. The study tests the idea that many of the black holes observed by astronomers have merged multiple times within densely populated environments containing millions of stars.

The team, involving researchers from the University of Cambridge, examined the public catalogue of 69 gravitational wave events involving binary black holes detected by The Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo Observatory for clues about these successive mergers, which they believe create black holes with distinctive spin patterns.

They discovered that a black hole’s spin changes when it reaches a certain mass, suggesting it may have been produced through a series of multiple previous mergers.

Their study, published in the journal Physical Review Letters, shows how spin measurements can reveal the formation history of a black hole and offers a step forward in understanding the diverse origins of these astrophysical phenomena.

“As we observe more black hole mergers with gravitational wave detectors like LIGO and Virgo, it becomes ever clearer that black holes exhibit diverse masses and spins, suggesting they may have formed in different ways,” said lead author Dr Fabio Antonini from Cardiff University. “However, identifying which of these formation scenarios is most common has been challenging.”

The team pinpointed a clear mass threshold in the gravitational waves data where black hole spins consistently change.

They say this pattern aligns with existing models which assume black holes are produced through repeat collisions in clusters, rather than other environments where spin distributions are different.

This result supports a robust and relatively model-independent signature for identifying these kinds of black holes, something that has been challenging to confirm until now, according to the team.

“Our study gives us a powerful, data-driven way to identify the origins of a black hole’s formation history, showing that the way it spins is a strong indicator of it belonging to a group of high-mass black holes, which form in densely populated star clusters where small black holes repeatedly collide and merge with one another,” said co-author Dr Isobel Romero-Shaw, from Cambridge’s Department of Applied Mathematics and Theoretical Physics.

Their study will now help astrophysicists further refine computer models which simulate the formation of black holes, helping to shape how future gravitational wave detections are interpreted.

“Collaborating with other researchers and using advanced statistical methods will help to confirm and expand our findings, especially as we move toward next-generation detectors,” said co-author Dr Thomas Callister from the University of Chicago. “The Einstein Telescope, for example, could detect even more massive black holes and provide unprecedented insights into their origins.”

Reference:

Fabio Antonini, Isobel M. Romero-Shaw, and Thomas Callister. 'Star Cluster Population of High Mass Black Hole Mergers in Gravitational Wave Data.' Physical Review Letters (2025). DOI: 10.1103/PhysRevLett.134.011401

Source: University of Cambridge/News

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Most energetic stellar collisions in the Universe

These plots show various parameters of the nearly head-on collision between two red giant stars, shortly before collision (left column), at the collision moment (second column), 1 day and 30 days after collision (two right columns). The top row shows the density, the middle row shows the temperature and the bottom row the speed of the gas with the arrows indicating the direction of gas motion. The red dots in each panel indicate the location of the cores. Initially the two stars start to move towards each other with 10 000 km/s. At collision, strong shocks are created when the incoming gas collides with the pressure barrier. The gas bounces off and expands quasi-spherically at supersonic speeds. © MPA

In dense stellar environments, stars can collide. If there is a massive black hole nearby – at the centre of galaxies – these collisions can be so energetic that the two stars are completely destroyed upon collision, leaving behind an expanding gas cloud. While the collision itself can generate a very luminous flare for several days, there might be an even brighter flare that can last up to many months, as the gas cloud is captured by the nearby black hole. A research team led by MPA has estimated the observables of such powerful events for the first time using the two state-of-the-art codes AREPO and MESA, developed at MPA.

What are the most energetic collisions between stars in the Universe? Such collisions would happen if the stars move at high relative velocities. In the deep potential well of the massive black hole at the centre of a galaxy, stars can reach a few percent of the speed of light (up to 10 000km/s). The collision of two such fast-moving stars would be fascinating to observe, because the resulting flare could be at least as luminous as various types of electromagnetic transients, such as tidal disruption events or supernovae.

Because we did not understand their observational signatures, however, not much effort has been spent searching for these high-velocity collisions. A research team led by an MPA fellow has now made quantitative predictions how such black hole-driven destructive collisions between giant stars could be observed. For their analysis, the team used the state-of-the-art simulation codes AREPO and MESA.

Collision of fast red giants 

This animation shows the collision of two red giant stars with large relative velocity. The time starts about one day before the event and runs until 30 days after. The colour scale shows the density of the material, the two red dots indicate the locations of the cores. Note the changing length scale (depicted as solar radii), which first decreases and then increases.

In particular, the team analysed two red giant stars, colliding at velocities much greater than the escape velocity of the colliding stars. This means that the two stars are entirely destroyed. Very powerful shocks convert a large fraction of the initial kinetic energy into heat, driving the resulting gas cloud to expand quasi-spherically.

The maximum expansion speed of the cloud is larger than the initial relative velocity of the stars, and the parameters of the gas cloud depend rather strongly on the collision velocity. A collision between larger stars colliding at a higher speed tends to result in greater conversion efficiency. As the heat energy escapes from the cloud, a prompt flare with a peak luminosity comparable to that of a supernova explosion (1041 - 1044 erg/s) can be generated. Because of the rapid expansion of the cloud, the prompt flare becomes very faint in days or a week.

However, the expanding gas cloud interacts with the nearby black hole. The accretion of the gravitationally captured gas creates a second flare that could even be brighter and lasting much longer than the first flare. This heightened luminosity can be sustained for up to ten years.

These unique features of the electromagnetic radiation make such events a promising probe for the existence of dormant black holes. In addition, the growth of black holes through the accretion of the collision products would be another venue for the growth mechanism for seed black holes at high redshifts.

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Author:

Taeho Ruy
Postdoc
tel:2358
tryu@mpa-garching.mpg.de

Original publication:

Taeho Ryu et al.
Collisions of red giants in galactic nuclei
Submitted to MNRAS
Source

Source: Max Planck Institute for Astrophysics

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Researchers find the origin and the maximum mass of massive black holes observed by gravitational wave detectors

Figure 1: Schematic diagram of the binary black hole formation path for GW170729. A star below 80 solar mass evolves and develops into a core-collapse supernova. The star does not experience pair-instability, so there is no significant mass ejection by pulsation. After the star forms a massive iron core, it collapses by its own gravity and forms a black hole with a mass below 38 solar mass. A star between 80 and 140 solar mass evolves and develops into a pulsational pair-instability supernova. After the star forms a massive carbon-oxygen core, the core experiences catastrophic electron-positron pair-creation. This excites strong pulsation and partial ejection of the stellar materials. The ejected materials form the circumstellar matter surrounding the star. After that, the star continues to evolve and forms a massive iron core, which collapses in a fashion similar to the ordinary core-collapse supernova, but with a higher final black hole mass between 38 - 52 solar mass. These two paths could explain the origin of the detected binary black hole masses of the gravitational wave event GW170729. (Credit：Shing-Chi Leung et al./Kavli IPMU)

Simulation: Pulsational pair-instability supernova evolutionary process

Credit: Shing-Chi Leung et al.

Figure 2: The red line shows the time evolution of the temperature and density at the center of the initially 120 solar mass star (PPISN: pulsational pair-instability supernova). The arrows show the direction of time. The star pulsates (i.e., contraction and expansion twice) by making bounces at #1 and #2 and finally collapses along a line similar to that of a 25 solar mass star (thin blue line: CCSN (core-collapse supernova)). The thick blue line shows the contraction and final expansion of the 200 solar mass star which is disrupted completely with no black hole left behind (PISN: pair-instability supernova). Top left area enclosed by the black solid line is the region where a star is dynamically unstable. (Credit：Shing-Chi Leung et al.)

Figure 3: The red line (that connects the red simulation points) shows the mass of the black hole left after the pulsational pair-instability supernova (PPISN) against the initial stellar mass. The red and black dashed lines show the mass of the helium core left in the binary system. The red line is lower than the dashed line because some amount of mass is lost from the core by pulsational mass loss. (Pair-instability supernova, PISN, explodes completely with no remnant left.) The peak of the red line gives the maximum mass, 52 solar mass, of the black hole to be observed by gravitational waves. (Credit：Shing-Chi Leung et al.)

Figure 4: The masses of a pair of the black holes (indicated by the same color) whose merging produced gravitational waves (GW) detected by advanced LIGO and VIRGO (merger event names GW150914 to GW170823 indicate year-month-day). The box enclosed by 38 - 52 solar mass is the remnant mass range produced by PPISNe. Black hole masses falling inside this box must have an origin of PPISN before collapse. Below 38 solar mass is the black hole formed by a massive star undergoing CCSN. In addition to GW170729, GW170823 is a candidate of a PPISN in the lower mass limit side. (Credit：Shing-Chi Leung et al.)

Through simulations of a dying star, a team of theoretical physics researchers have found the evolutionary origin and the maximum mass of black holes which are discovered by the detection of gravitational waves as shown in Figure 1.

The exciting detection of gravitational waves with LIGO (laser interferometer gravitational-wave observatory) and VIRGO (Virgo interferometric gravitational-wave antenna) have shown the presence of merging black holes in close binary systems.

The masses of the observed black holes before merging have been measured and turned out to have a much larger than previously expected mass of about 10 times the mass of the Sun (solar mass). In one of such event, GW170729, the observed mass of a black hole before merging is actually as large as about 50 solar mass. But it is not clear which star can form such a massive black hole, or what the maximum of black holes which will be observed by the gravitational wave detectors is.

To answer this question, a research team at the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) consisting of Project Researcher at the time Shing-Chi Leung (currently at the California Institute of Technology), Senior Scientist Ken’ichi Nomoto, and Visiting Senior Scientist Sergei Blinnikov (professor at the Institute for Theoretical and Experimental Physics in Mosow) have investigated the final stage of the evolution of very massive stars, in particular 80 to 130 solar mass stars in close binary systems. Their finding are shown in Illustrations (a - e) and Figures (1 - 4).

In close binary systems, initially 80 to 130 solar mass stars lose their hydrogen-rich envelope and become helium stars of 40 to 65 solar mass. When the initially 80 to 130 solar mass stars form oxygen-rich cores, the stars undergo dynamical pulsation (Illustrations a - b and Figure 2), because the temperature in the stellar interior becomes high enough for photons to be converted into electron-positron pairs. Such “pair-creation” makes the core unstable and accelerates contraction to collapse (Illustration b).

In the over-compressed star, oxygen burns explosively. This triggers a bounce of collapse and then rapid expansion of the star. A part of the stellar outer layer is ejected, while the inner part cools down and collapses again (Illustration c). The pulsation (collapse and expansion) repeats until oxygen is exhausted (Illustration d). This process is called “pulsational pair-instability”(PPI). The star forms an iron core and finally collapses into a black hole, which would trigger the supernova explosion (Illustration e), being called PPI-supernova (PPISN).

By calculating several such pulsations and associated mass ejection until the star collapses to form a black hole, the team found that the maximum mass of the black hole formed from pulsational pair-instability supernova is 52 solar mass (Figure 3).

Stars initially more massive than 130 solar mass (which form helium stars more massive than 65 solar mass) undergo “pair instability supernova” due to explosive oxygen burning, which disrupts the star completely with no black hole remnant. Stars above 300 solar mass collapse and may form a black hole more massive than about 150 solar mass.

The above results predict that there exists a “mass-gap” in the black hole mass between 52 and about 150 solar mass. The results mean that the 50 solar mass black hole in GW170729 is most likely a remnant of a pulsational pair-instability supernova as shown in Figures 3 and 4.

The result also predicts that a massive circumstellar medium is formed by the pulsational mass loss, so that the supernova explosion associated with the black hole formation will induce collision of the ejected material with the circumstellar matter to become a super-luminous supernovae. Future gravitational wave signals will provide a base upon which their theoretical prediction will be tested.

Source: Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU)

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Paper details:

Journal: The Astrophysical Journal

Title: Pulsational Pair-instability Supernovae. I. Pre-collapse Evolution and Pulsational Mass Ejection

Authors: Shing-Chi Leung (1, 2), Ken'ichi Nomoto (1) and Sergei Blinnikov (1, 3, 4)

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Author affiliations:

1. Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, The University of Tokyo, Kashiwa, Chiba 277-8583, Japan.
2. Walter Burke Institute for Theoretical Physics, California Institute of Technology (TAPIR at Caltech), Pasadena, CA 91125, USA.
3. National Research Center, “Kurchatov Institute,” Institute for Theoretical and Experimental Physics (ITEP), B. Cheremushkinkaya 25, 117218 Moscow, Russia.

4. Automatics Research Institute (VNIIA), Suschevskaya 22, 127055 Moscow, Russia.

DOI: https://doi.org/10.3847/1538-4357/ab4fe5 (Published 10 December, 2019)

Images All images can be downloaded from here

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Research contact

Ken'ichi Nomoto
Senior Scientist
Kavli Institute for the Physics and Mathematics for the Universe,
University of Tokyo
E-mail: nomoto@stron.s.u-tokyo.ac.jp
Phone: +81-4-7136-5940

Media Contact

John Amari
Press officer
Kavli Institute for the Physics and Mathematics of the Universe
The University of Tokyo
E-mail: press_at_ipmu.jp
Tel: 080-4056- 2767

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Monster Black Hole Found in the Early Universe

Astronomers discovered this, the second most distant quasar ever found, using the international Gemini Observatory and Cerro Tololo Inter-American Observatory (CTIO), Programs of NSF’s NOIRLab. It is the first quasar to receive an indigenous Hawaiian name. In honor of its discovery from Maunakea, a sacred mountain revered in the Hawaiian culture, the quasar J1007+2115 was given the Hawaiian name Pōniuāʻena, meaning “unseen spinning source of creation, surrounded with brilliance" in the Hawaiian language. Credit: International Gemini Observatory/NOIRLab/NSF/AURA/P. Marenfeld. download TIFF | JPEG

An artist’s impression of the formation of quasar Pōniuāʻena, starting with a seed black hole, 100 million years after the Big Bang. Astronomers discovered this, the second most distant quasar ever found, using the international Gemini Observatory and Cerro Tololo Inter-American Observatory (CTIO), Programs of NSF’s NOIRLab. It is the first quasar to receive an indigenous Hawaiian name. Credit: International Gemini Observatory/NOIRLab/NSF/AURA/P. Marenfeld.  download TIFF | JPEG

An artist’s impression of the quasar Pōniuāʻena. Astronomers discovered this, the second most distant quasar ever found, using the international Gemini Observatory and Cerro Tololo Inter-American Observatory (CTIO), Programs of NSF’s NOIRLab. It is the first quasar to receive an indigenous Hawaiian name. Credit: International Gemini Observatory/NOIRLab/NSF/AURA/P. Marenfeld.  download TIFF | JPEG

Astronomers have discovered the second most distant quasar ever found, using the international Gemini Observatory and Cerro Tololo Inter-American Observatory (CTIO). It is also the first quasar to receive an indigenous Hawaiian name, Pōniuāʻena. Credit: International Gemini Observatory/NOIRLab/NSF/AURA/Pete Marenfeld, ESA/Hubble, NASA, M. Kornmesser. A Special Thanks to A Hua He Inoa and the ‘Imiloa Astronomy Center of Hawaiʻi. Music: zero-project — The Lower Dungeons (zero-project.gr).  Video

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The second most distant quasar ever discovered now has a Hawaiian name

Astronomers have discovered the second most distant quasar ever found, using the international Gemini Observatory and Cerro Tololo Inter-American Observatory (CTIO), Programs of NSF’s NOIRLab. It is also the first quasar to receive an indigenous Hawaiian name, Pōniuāʻena. The quasar contains a monster black hole, twice the mass of the black hole in the only other quasar found at the same epoch, challenging the current theories of supermassive black hole formation and growth in the early Universe.

After more than a decade of searching for the first quasars, a team of astronomers used the NOIRLab’s Gemini Observatory and CTIO to discover the most massive quasar known in the early Universe — detected from a time only 700 million years after the Big Bang [1]. Quasars are the most energetic objects in the Universe, powered by their supermassive black holes, and since their discovery astronomers have been keen to determine when they first appeared in our cosmic history.

Systematic searches for these objects have led to the discovery of the most distant quasar (J1342+0928) in 2018 and now the second most distant, J1007+2115 [2]. The A Hua He Inoa program named J1007+2115 Pōniuāʻena, meaning “unseen spinning source of creation, surrounded with brilliance" in the Hawaiian language [3]. The supermassive black hole powering Pōniuāʻena is 1.5 billion times more massive than our Sun.

“Pōniuāʻena is the most distant object known in the Universe hosting a black hole exceeding one billion solar masses” said Jinyi Yang, a Postdoctoral Research Associate at the Steward Observatory of the University of Arizona.

For a black hole of this size to form this early in the Universe, it would need to start as a 10,000 solar mass “seed” black hole about 100 million years after the Big Bang, rather than growing from a much smaller black hole formed by the collapse of a single star.

“How can the Universe produce such a massive black hole so early in its history?” wondered Xiaohui Fan, Regents’ professor and associate department head of the Department of Astronomy at the University of Arizona. “This discovery presents the biggest challenge yet for the theory of black hole formation and growth in the early Universe.”

Current theory suggests that at the beginning of the Universe following the Big Bang, atoms were too distant from one another to interact and form stars and galaxies. The birth of stars and galaxies as we know them happened during the Epoch of Reionization, beginning about 400 hundred million years after the Big Bang. The discovery of quasars like Pōniuāʻena, deep into the reionization epoch, is a big step towards understanding this process of reionization and the formation of early supermassive black holes and massive galaxies. Pōniuāʻena has placed new and important constraints on the evolution of the matter between galaxies (the intergalactic medium) in the reionization epoch.

The search for distant quasars began with the research team combing through large area surveys such as the DECaLS imaging survey which uses the Dark Energy Camera (DECam) on the Víctor M. Blanco 4-meter Telescope, located at CTIO in Chile. The team uncovered a possible quasar in the data, and in 2019 they observed it with telescopes including the Gemini North telescope and the W. M. Keck Observatory both on Maunakea on Hawai‘i Island. Gemini’s GNIRS instrument confirmed the existence of Pōniuāʻena.

“Observations with Gemini were critical for obtaining high-quality near-infrared spectra which provided us with the measurement of the black hole’s astounding mass,” said Feige Wang, a NASA NHFP fellow at the Steward Observatory of the University of Arizona.

In honor of its discovery from Maunakea, this quasar was given the Hawaiian name Pōniuāʻena. The name was created by thirty Hawaiian immersion school teachers during a workshop led by the A Hua He Inoa group, a Hawaiian naming program led by the ‘Imiloa Astronomy Center of Hawai‘i. Pōniuāʻena is the first quasar to receive an indigenous name.

“In addition to the teamwork of the telescopes of NOIRLab that made this discovery possible, it is exciting to see the collaboration of science and culture in local communities, highlighted by this new name,” said Chris Davis, Program Officer at the National Science Foundation.

“I am extremely grateful to be a part of this educational experience — it is a rare learning opportunity,” said Kauʻi Kaina, a High School Hawaiian Immersion Teacher from Kahuku, Oʻahu who was involved in the naming workshop. “Today it is relevant to apply these cultural values in order to further the wellbeing of the Hawaiian language beyond ordinary contexts, such as in school, but also so that the language lives throughout the Universe.”

Source: Gemini Observatory

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Notes

[1] This corresponds to a redshift of 7.52 or a lookback time of 13.02 billion years.

[2] The full name of the quasar is J100758.264+211529.207.

[3] Pronounced: POH-knee-ew-aah-EH-na.

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More information

This research was presented in a paper to appear in The Astrophysical Journal Letters.

The team is composed of Jinyi Yang (University of Arizona), Feige Wang (University of Arizona), Xiaohui Fan (University of Arizona), Joseph F. Hennawai (University of California, Santa Barbara), Frederick B. Davis (University of California, Santa Barbara), Minghao Yue (University of Arizona), Eduardo Banados (Max Planck Institute for Astronomy), Xue-Bing Wu (Peking University), Bran Venemans (Max Planck Institute for Astronomy), Aaron J. Barth (University of California, Irvine), Fuyan Bian (European Southern Observatory), Roberto Decalari (INAF), Emanuele Paolo Farina (Max Planck Institute for Astrophysics), Richard Green (University of Arizona), Linhua Jiang (Peking University), Jiang-Tao Li (University of Michigan), Chiara Mazzucchelli (European Southern Observatory), and Fabian Walter (Max Planck Institute for Astronomy).

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Links

• Research paper
  
• Interview on the naming process
• Photos of the Gemini Telescope

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Contacts:

Jinyi Yang
University of Arizona
Phone: +1 520 360 3966
Email: jinyiyang@email.arizona.edu

Xiaohui Fan
University of Arizona
Phone: +1 520 626 7558
Email: fan@as.arizona.edu

Peter Michaud
NewsTeam Manager
NSF’s NOIRLab
Gemini Observatory, Hilo HI
Cell: +1 808 936 6643
Email: pmichaud@gemini.edu

Amanda Kocz
Press and Internal Communications Officer
NSF’s NOIRLab
Cell: +1 626 524 5884
Email: akocz@aura-astronomy.org

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Astronomers Find Wandering Massive Black Holes in Dwarf Galaxies

Artist's conception of a dwarf galaxy, its shape distorted, most likely by a past interaction with another galaxy, and a massive black hole in its outskirts (pullout). The black hole is drawing in material that forms a rotating disk and generates jets of material propelled outward. Credit: Sophia Dagnello, NRAO/AUI/NSF. Hi-Res File

Artist's conception of a dwarf galaxy, its shape distorted, most likely by a past interaction with another galaxy, and a massive black hole in its outskirts (bright spot, far right; no pullout). Credit: Sophia Dagnello, NRAO/AUI/NSF. Hi-Res File

Visible-light images of galaxies that VLA observations showed to have massive black holes. Center illustration is artist's conception of the rotating disk of material falling into such a black hole, and the jets of material propelled outward. Credit: Sophia Dagnello, NRAO/AUI/NSF; DECaLS survey; CTIO. Hi-Res File

Roughly half of the newly-discovered black holes are not at the centers of their galaxies

Astronomers seeking to learn about the mechanisms that formed massive black holes in the early history of the Universe have gained important new clues with the discovery of 13 such black holes in dwarf galaxies less than a billion light-years from Earth.

These dwarf galaxies, more than 100 times less massive than our own Milky Way, are among the smallest galaxies known to host massive black holes. The scientists expect that the black holes in these smaller galaxies average about 400,000 times the mass of our Sun.

“We hope that studying them and their galaxies will give us insights into how similar black holes in the early Universe formed and then grew, through galactic mergers over billions of years, producing the supermassive black holes we see in larger galaxies today, with masses of many millions or billions of times that of the Sun,” said Amy Reines of Montana State University.

Reines and her colleagues used the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) to make the discovery, which they are reporting at the American Astronomical Society’s meeting in Honolulu, Hawaii.

Reines and her collaborators used the VLA to discover the first massive black hole in a dwarf starburst galaxy in 2011. That discovery was a surprise to astronomers and spurred a radio search for more.

The scientists started by selecting a sample of galaxies from the NASA-Sloan Atlas, a catalog of galaxies made with visible-light telescopes. They chose galaxies with stars totalling less than 3 billion times the mass of the Sun, about equal to the Large Magellanic Cloud, a small companion of the Milky Way. From this sample, they picked candidates that also appeared in the National Radio Astronomy Observatory’s Faint Images of the Radio Sky at Twenty centimeters (FIRST) survey, made between 1993 and 2011.

They then used the VLA to make new and more sensitive, high-resolution images of 111 of the selected galaxies.

“The new VLA observations revealed that 13 of these galaxies have strong evidence for a massive black hole that is actively consuming surrounding material. We were very surprised to find that, in roughly half of those 13 galaxies, the black hole is not at the center of the galaxy, unlike the case in larger galaxies,” Reines said

The scientists said this indicates that the galaxies likely have merged with others earlier in their history. This is consistent with computer simulations predicting that roughly half of the massive black holes in dwarf galaxies will be found wandering in the outskirts of their galaxies.

“This work has taught us that we must broaden our searches for massive black holes in dwarf galaxies beyond their centers to get a more complete understanding of the population and learn what mechanisms helped form the first massive black holes in the early Universe,” Reines said.

Reines worked with James Condon, of the National Radio Astronomy Observatory; Jeremy Darling, of the University of Colorado, Boulder; and Jenny Greene, of Princeton University. The astronomers are publishing their results in the Astrophysical Journal. (Preprint )

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Media Contact:

Dave Finley, Public Information Officer
(575) 835-7302
dfinley@nrao.edu

Source:  National Radio Astronomy Observatory (NRAO)/News

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NuSTAR Finds Cosmic Clumpy Doughnut Around Black Hole

Galaxy NGC 1068 can be seen in close-up in this view from NASA's Hubble Space Telescope. NuSTAR's high-energy X-rays eyes were able to obtain the best view yet into the hidden lair of the galaxy's central, supermassive black hole. Image credit: NASA/JPL-Caltech.  › Full image and caption 

The most massive black holes in the universe are often encircled by thick, doughnut-shaped disks of gas and dust. This deep-space doughnut material ultimately feeds and nourishes the growing black holes tucked inside.

Until recently, telescopes weren't able to penetrate some of these doughnuts, also known as tori.

"Originally, we thought that some black holes were hidden behind walls or screens of material that could not be seen through," said Andrea Marinucci of the Roma Tre University in Italy, lead author of a new Monthly Notices of the Royal Astronomical Society study describing results from NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, and the European Space Agency's XMM-Newton space observatory.

With its X-ray vision, NuSTAR recently peered inside one of the densest of these doughnuts known to surround a supermassive black hole. This black hole lies at the center of a well-studied spiral galaxy called NGC 1068, located 47 million light-years away in the Cetus constellation.

The observations revealed a clumpy, cosmic doughnut.

"The rotating material is not a simple, rounded doughnut as originally thought, but clumpy," said Marinucci.

Doughnut-shaped disks of gas and dust around supermassive black holes were first proposed in the mid-1980s to explain why some black holes are hidden behind gas and dust, while others are not. The idea is that the orientation of the doughnut relative to Earth affects the way we perceive a black hole and its intense radiation. If the doughnut is viewed edge-on, the black hole is blocked. If the doughnut is viewed face-on, the black hole and its surrounding, blazing materials can be detected. This idea is referred to as the unified model because it neatly joins together the different black hole types, based solely upon orientation.

In the past decade, astronomers have been finding hints that these doughnuts aren't as smoothly shaped as once thought. They are more like defective, lumpy doughnuts that a doughnut shop might throw away.

The new discovery is the first time this clumpiness has been observed in an ultra-thick doughnut, and supports the idea that this phenomenon may be common. The research is important for understanding the growth and evolution of massive black holes and their host galaxies.

"We don't fully understand why some supermassive black holes are so heavily obscured, or why the surrounding material is clumpy," said co-author Poshak Gandhi of the University of Southampton in the United Kingdom. "This is a subject of hot research."

Both NuSTAR and XMM-Newton observed the supermassive black hole in NGC 1068 simultaneously on two occasions between 2014 to 2015. On one of those occasions, in August 2014, NuSTAR observed a spike in brightness. NuSTAR observes X-rays in a higher-energy range than XMM-Newton, and those high-energy X-rays can uniquely pierce thick clouds around the black hole. The scientists say the spike in high-energy X-rays was due to a clearing in the thickness of the material entombing the supermassive black hole.

"It's like a cloudy day, when the clouds partially move away from the sun to let more light shine through," said Marinucci.

NGC 1068 is well known to astronomers as the first black hole to give birth to the unification idea. "But it is only with NuSTAR that we now have a direct glimpse of its black hole through such clouds, albeit fleeting, allowing a better test of the unification concept," said Marinucci.

The team says that future research will address the question of what causes the unevenness in doughnuts. The answer could come in many flavors. It's possible that a black hole generates turbulence as it chomps on nearby material. Or, the energy given off by young stars could stir up turbulence, which would then percolate outward through the doughnut. Another possibility is that the clumps may come from material falling onto the doughnut. As galaxies form, material migrates toward the center, where the density and gravity is greatest. The material tends to fall in clumps, almost like a falling stream of water condensing into droplets as it hits the ground.

"We'd like to figure out if the unevenness of the material is being generated from outside the doughnut, or within it," said Gandhi.

"These coordinated observations with NuSTAR and XMM-Newton show yet again the exciting science possible when these satellites work together," said Daniel Stern, NuSTAR project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California.

For more information on NuSTAR, visit:  http://www.nasa.gov/nustar  - http://www.nustar.caltech.edu/

Media Contact

Whitney Clavin

Jet Propulsion Laboratory, Pasadena, California

818-354-4673

whitney.clavin@jpl.nasa.gov 

Source: JPL-Caltech

Elegant spiral hides a hungry monster

NGC 4639

Credit: ESA/Hubble & NASA

NGC 4639 is a beautiful example of a type of galaxy known as a barred spiral. It lies over 70 million light-years away in the constellation of Virgo and is one of about 1500 galaxies that make up the Virgo Cluster.

In this image, taken by the NASA/ESA Hubble Space Telescope, one can clearly see the bar running through the bright, round core of the galaxy. Bars are found in around two thirds of spiral galaxies, and are thought to be a natural phase in their evolution.

The galaxy’s spiral arms are sprinkled with bright regions of active star formation. Each of these tiny jewels is actually several hundred light-years across and contains hundreds or thousands of newly formed stars. But 

NGC 4639 also conceals a dark secret in its core — a massive black hole that is consuming the surrounding gas.

This is known as an active galactic nucleus (AGN), and is revealed by characteristic features in the spectrum of light from the galaxy and by X-rays produced close to the black hole as the hot gas plunges towards it.

Most galaxies are thought to contain a black hole at the centre. NGC 4639 is in fact a very weak example of an AGN, demonstrating that AGNs exist over a large range of activity, from galaxies like NGC 4639 to distant quasars, where the parent galaxy is almost completely dominated by the emissions from the AGN.

Source: ESA/Hubble - Space Telescope

The Environments of Radio-Bright Active Galaxies

A Chandra X-ray Observatory image of the galaxy cluster Abell 2125, showing its complex of galaxies and very hot gas clouds in the process of merging. Some galaxies in clusters host active black-hole nuclei that are ejecting jets of particles and emitting at radio wavelengths. A new study finds evidence that the cluster environment plays an important role in determining the nature of accretion onto the black hole. Credit: NASA/CXC/UMass/Q.D.Wang et al.

The nucleus of an active galaxy contains a massive black hole that is vigorously accreting material. In the process, the nucleus typically ejects jets of rapidly moving charged particles that radiate brightly at many wavelengths, in particular radio wavelengths. Active galaxies display a range of dramatically different properties and one categorization uses the radio emission, finding one class that is bright in the radio and a second group that is comparatively faint. Astronomers suspect that the reason for the difference is a different rate of accretion onto the central black hole, but there are other activities that also seem to correlate with the radio emission including nearby star formation, for example, or the age of the galaxy. Astronomers are therefore trying to identify the ones that might be causal.

Feedback from the intergalactic medium onto a galaxy's nucleus has recently been identified as an important driver of galaxy evolution, and the question naturally arises about the role of such feedback in a galaxy’s radio activity and the accompanying effects. CfA astronomers Ralph Kraft and Dan Evans and their colleagues used the Chandra X-Ray Telescope in the first systematic X-ray study of the cluster environment of radio galaxies all dating from the same epoch. The X-ray emission is the key to understanding how the gas accretes onto the black hole.

The team observed fifty-five radio emitting sources spanning a factor of a thousand in radio luminosity, twenty-five of them classified as bright. They found that the bright radio sources show evidence of high accretion from a circumnuclear disk. The faint sources, on the other hand, have a more uncertain mechanism, perhaps the chaotic accretion of cool gas clouds; significantly, their radio emission strength is strongly correlated with the cluster richness and central density, while no such correlations were found for the bright sources. The scientists conclude that there are strong environmental differences between these two classes consistent with thinking that the cluster environment supports the fueling of emission. This evidence has prompted the team to study next the relationships between the gas in the intracluster medium and the other phenomena associated with the two classes.

Reference(s):

"The Link between Accretion Mode and Environment in Radio-Loud Active Galaxies," J. Ineson, J. H. Croston, M. J. Hardcastle, R. P. Kraft, D. A. Evans, and M. Jarvis, MNRAS 453, 2682, 2015.

Source: Smithsonian Astrophysical Observatory

Gigantic, Early Black Hole Could Upend Evolutionary Theory

In this illustration a black hole emits part of the accreted matter in the form of energetic radiation (blue), without slowing down star formation within the host galaxy (purple regions). Credit: M. Helfenbein, Yale University / OPAC. Hi-res image

Maunakea, Hawaii – An international team of astrophysicists led by Benny Trakhtenbrot, a researcher at ETH Zurich’s Institute for Astronomy, discovered a gigantic black hole in an otherwise normal galaxy, using W. M. Keck Observatory’s 10-meter, Keck I telescope in Hawaii. The team, conducting a fairly routine hunt for ancient, massive black holes, was surprised to find one with a mass of more than 7 billion times our Sun making it among the most massive black holes ever discovered. And because the galaxy it was discovered in was fairly typical in size, the study calls into question previous assumptions on the development of galaxies. Their findings are being published today in the journal Science.

The data, collected with Keck Observatory’s newest instrument called MOSFIRE, revealed a giant black hole in a galaxy called CID-947 that was 11 billion light years away. The incredible sensitivity of MOSFIRE coupled to the world’s largest optical/infrared telescope meant the scientists were able to observe and characterize this black hole as it was when the Universe was less than two billion years old, just 14 percent of its current age (almost 14 billion years have passed since the Big Bang).

Even more surprising than the black hole’s record mass, was the relatively ordinary mass of the galaxy that contained it.

Most galaxies host black holes with with masses less than one percent of the galaxy. In CID-947, the black hole mass is 10 percent that of its host galaxy. Because of this remarkable disparity, the team deduced this black hole grew so quickly the host galaxy was not able to keep pace, calling into question previous thinking on the co-evolution of galaxies and their central black holes.

“The measurements of CID-947 correspond to the mass of a typical galaxy,” Trakhtenbrot said. “We therefore have a gigantic black hole within a normal size galaxy. The result was so surprising, two of the astronomers had to verify the galaxy mass independently. Both came to the same conclusion.”

“Black holes are objects that possess such a strong gravitational force that nothing – not even light – can escape,” said Professor Meg Urry of Yale University, co-author of the study. ”Einstein’s theory of relativity describes how they bend space-time itself. The existence of black holes can be proven because matter is greatly accelerated by the gravitational force and thus emits particularly high-energy radiation.”

Until now, observations have indicated that the greater the number of stars present in the host galaxy, the bigger the black hole. “This is true for the local Universe, which merely reflects the situation in the Universe’s recent past,” Urry said.

Furthermore, previous studies suggest the radiation emitted during the growth of the black hole controlled, or even stopped, the creation of stars as the released energy heated up the gas. This cumulative evidence led scientists to assume the growth of black holes and the formation of stars go hand-in-hand.

The latest results, however, suggest that these processes work differently, at least in the early Universe.

The distant young black hole observed by Trakhtenbrot, Urry and their colleagues had roughly 10 times less mass than its galaxy. In today’s local Universe, black holes typically reach a mass of 0.2 to 0.5 percent of their host galaxy’s mass. “That means this black hole grew much more efficiently than its galaxy – contradicting the models that predicted a hand-in-hand development,” he said.

The researchers also concluded stars were still forming even though the black hole had reached the end of its growth. Contrary to previous assumptions, the energy and gas flow propelled by the black hole did not stop the creation of stars.

"From the available Chandra data for the source, we also concluded that the black hole has a very low accretion rate, and is therefore reached the end of its growth. On the other had, other data suggests that stars were still forming throughout the host galaxy," Trakhtenbrot said. 

The galaxy could continue to grow in the future, but the relationship between the mass of the black hole and that of the stars would remain unusually large. The researchers believe CID-947 could be a precursor of the most extreme, massive systems that we observe in today’s local Universe, such as the galaxy NGC 1277 in the constellation of Perseus, some 220 million light years away from our Milky Way.

The W. M. Keck Observatory operates the largest, most scientifically productive telescopes on Earth. The two, 10-meter optical/infrared telescopes near the summit of Mauna Kea on the Island of Hawaii feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrographs and world-leading laser guide star adaptive optics systems.

MOSFIRE (Multi-Object Spectrograph for Infrared Exploration) is a highly-efficient instrument that can take images or up to 46 simultaneous spectra. Using a sensitive state-of-the-art detector and electronics system, MOSFIRE obtains observations fainter than any other near infrared spectrograph. MOSFIRE is an excellent tool for studying complex star or galaxy fields, including distant galaxies in the early Universe, as well as star clusters in our own Galaxy. MOSFIRE was made possible by funding provided by the National Science Foundation and astronomy benefactors Gordon and Betty Moore.

Keck Observatory is a private 501(c) 3 non-profit organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

Science Contact

Benny Trakhtenbrot
ETH Zürich
Institute for Astronomy, Switzerland
benny.trakhtenbrot@phys.ethz.ch
+41 (0)44-632-4213

Media Contact

Steve Jefferson
W. M. Keck Observatory
sjefferson@keck.hawaii.edu
808-881-3827

Source: W.M. Keck Observatory

An Over-Massive Black Hole in the Young Universe

An artist's impression of the Chandra X-ray Telescope in Earth orbit. Astronomers have used Chandra to identify an X-ray bright supermassive black hole from an era only two billion years after the big bang. The finding appears to challenge conventional wisdom about how quickly such supermassive black holes can form in galaxies. Credit: NASA/Chandra

Astronomers generally accept the notion that black holes at the centers of galaxies co-evolve with their host galaxies, and that they have done did so during all cosmic epochs, from the early period after the big band until today. This means that as a galaxy grows in mass, which it does by accreting material (and perhaps also consuming other galaxies) from the intergalactic medium, its black hole also accretes matter and grows. Indeed, the black hole is so massive -- perhaps as much as ten percent (!) of the entire stellar mass of the galaxy – that these two growth processes may be related, for example, because the black hole influences accretion onto the galaxy. The black hole accretion process may have other consequences too, like suppressing star formation by heating and/or disrupting nearby molecular clouds.

Testing these ideas is difficult because it requires measuring black hole properties in cosmic epochs when the universe was only a few billion years old and at the correspondingly cosmic distances even ultraluminous galaxies appear faint to us. A few recent studies have indicated that some supermassive black holes actually grew faster than their galaxies in epochs about three billion years after the big bang, but these measurements were made only on exceptionally X-ray luminous objects which are perhaps not representative of most systems and whose galaxy masses are very uncertain. 

CfA astronomers Francesca Civano, Martin Elvis, and Hyewon Suh joined their colleagues in using the Chandra X-Ray Observatory and another X-ray mission, XMM-Newton, to select an X-ray bright black-hole nucleus only two billion years after the big bang, and then to observe it in the infrared with the Keck telescope to study its ionized hydrogen gas, a tracer of black hole growth. The astronomers find that the black hole in this galaxy has apparently grown much more efficiently than the galaxy itself, contrary to conventional models. In fact, it is as much fifty times more massive compared to its galaxy than all but the most extreme local examples – it is a whopping seven billion solar masses. The important implication is that it grew to this size in a very much shorter time than local galaxies, which had thirteen billion years to grow. The galaxy also appears to be making stars without any suppression. The new paper both challenges the conventional theoretical paradigm and steers future research toward examining these distant X-ray monsters.

Reference(s): 

 "An Over-Massive Black Hole in a Typical Star-Forming Galaxy, 2 Billion Years After the Big Bang," Benny Trakhtenbrot, C. Megan Urry, Francesca Civano, David J. Rosario, Martin Elvis, Kevin Schawinski, Hyewon Suh, Angela Bongiorno, Brooke D. Simmons, Science, 2015 (in press).

 

 Source: Smithsonian Astrophysical Observatory (SAO)

Spinning Black Holes in Galactic Nuclei

An image of the galaxy NGC 1365, whose nucleus contains a massive black hole actively accreting material. Astronomers have used a series of X-ray observations to measure time variations in the iron emission line from the nucleus and thereby determine the value of the black hole's spin. Credit & Copyright:  SSRO-South (R. Gilbert, D. Goldman, J. Harvey, D. Verschatse) - PROMPT (D. Reichart) 

The nuclei of most galaxies contain a massive black hole. In our Milky Way, for example, the nuclear black hole contains about four million solar masses of material, and in other galaxies the black holes are estimated to have masses of hundreds of millions of suns, or even more. In dramatic cases, like quasars, these black holes are suspected of driving the observed bipolar jets of particles outward at nearly the speed of light. How they do this is not known, but scientists think that the spin of the black hole somehow plays a pivotal role.

A black hole is so simple (at least in traditional theories) that it can be completely described by just three parameters: its mass, its spin, and its electric charge. Even though it may have formed out of a complex mix of matter and energy, all the other specific details are lost when it collapses to a singular point. Astronomers are working to measure the spins of black hole in active galaxies in order to probe the connections between spin and jet properties.

One method for measuring black hole spin is X-ray spectra, by looking for distortions in the atomic emission line shapes from the very hot gas in the accreting disk of material around the black hole. Effects due to relativity in these extreme environments can broaden and skew intrinsically narrow emission lines into characteristic profiles that depend on the black hole spin value.

CfA astronomers Guido Risaliti, Laura Brenneman, and Martin Elvis, together with their colleagues, used joint observations from the NuSTAR and XMM-NEWTON space missions to examine the time-varying spectral shape of highly excited iron atoms in the nucleus of the galaxy NGC 1365, a well-studied active galaxy about sixty-six million light-years away and known for exhibiting time-variable line profiles. The team obtained four high quality observations of the source, catching it over an unprecedented range of absorption states, including one with very little line-of-sight absorption to the central nucleus. All the observations, despite the range of absorptions, displayed hallmarks of the innermost regions of the accretion flow. There have been disagreements within the community about the reliability of attributing observed line shapes to the black hole spin (rather than to other effects in the nucleus), but this new result not only demonstrates that it is possible, it shows that even single-epoch observations are likely to provide reliable measurements, making the task of studying other such systems more efficient.

Reference(s): 

"NuSTAR AND XMM-NEWTON Observations of NGC 1365: Extreme Absorption Variability and a Constant Inner Accretion Disk," D. J. Walton, G. Risaliti, F. A. Harrison, A. C. Fabian, J. M. Miller, P. Arevalo, D. R. Ballantyne, S. E. Boggs, L. W. Brenneman, F. E. Christensen, W. W. Craig, M. Elvis, F. Fuerst, P. Gandhi, B. W. Grefenstette C. J. Hailey, E. Kara, B. Luo, K. K. Madsen, A. Marinucci, G. Matt, M. L. Parker, C. S. Reynolds, E. Rivers, R. R. Ross, D. Stern, and W. W. Zhang, ApJ, 788,76, 2014

Source: Smithsonian Astrophysical Observatory