Spiral, elliptical or neither?

NGC 2775

A galaxy seen face-on, with a slightly elliptical disc that appears to have a hole in the centre like a doughnut. In the hole, the core is a brightly glowing point that shines light out beyond the edge of the disc. Around the hole is an inner ring of dust, and at the galaxy’s edge is a thicker outer ring of dust, with a swirling web of dust strands in between. Blue stars and red nebulae are visible behind the dust. Credit: ESA/Hubble & NASA, F. Belfiore, J. Lee and the PHANGS-HST Team

Today’s NASA/ESA Hubble Space Telescope Picture of the Week features a galaxy that’s hard to categorise. The galaxy in question is NGC 2775, which lies 67 million light-years away in the constellation Cancer (The Crab). NGC 2775 sports a smooth, featureless centre that is devoid of gas, resembling an elliptical galaxy. It also has a dusty ring with patchy star clusters, like a spiral galaxy. Which is it, then: spiral or elliptical — or neither?

Because we can only view NGC 2775 from one angle, it’s difficult to say for sure. Some researchers have classified NGC 2775 as a spiral galaxy because of its feathery ring of stars and dust, while others have classified it as a lenticular galaxy. Lenticular galaxies have features common to both spiral and elliptical galaxies.

It’s not yet known exactly how lenticular galaxies come to be, and they might form in a variety of ways. Lenticular galaxies might be spiral galaxies that have merged with other galaxies, or that have mostly run out of star-forming gas and lost their prominent spiral arms. They also might have started out more similar to elliptical galaxies, then collected gas into a disk around them.

Some evidence suggests that NGC 2775 has merged with other galaxies in the past. Invisible in this Hubble image, NGC 2775 has a tail of hydrogen gas that stretches almost 100 000 light-years around the galaxy. This faint tail could be the remnant of one or more galaxies that wandered too close to NGC 2775 before being stretched apart and absorbed. If NGC 2775 merged with other galaxies in the past, it could explain the galaxy’s strange appearance today.

A Hubble image of NGC 2775 was previously released in 2020. The new version adds observations of a specific wavelength of red light that is emitted by clouds of hydrogen gas surrounding massive young stars.

Source: ESA/Hubble/potw

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Hubble provides a new view of a galactic favourite

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Sombrero Galaxy

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Pan video: Sombrero Galaxy

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In anticipation of the upcoming 35th anniversary of the NASA/ESA Hubble Space Telescope, ESA/Hubble is continuing the celebrations with a new image of the Sombrero Galaxy, also known as Messier 104. An eye-catching target for Hubble and a favourite of amateur astronomers, the enigmatic Sombrero Galaxy has features of both spiral and elliptical galaxies. This image incorporates new processing techniques that highlight the unique structure of this galaxy.

As part of ESA/Hubble’s 35th anniversary celebrations, a new image series is being shared to revisit stunning Hubble targets that were previously released. First, a new image of NGC 346 was published. Now, ESA/Hubble is revisiting a fan-favourite galaxy with new image processing techniques.The new image reveals finer detail in the galaxy’s disc, as well as more background stars and galaxies.

Several Hubble images of the Sombrero Galaxy have been released over the past two decades, including this well-known Hubble image from October 2003. In November 2024, the NASA/ESA/CSA James Webb Space Telescope also gave an entirely new perspective on this striking galaxy.

Located around 30 million light-years away in the constellation Virgo, the Sombrero Galaxy is instantly recognisable. Viewed nearly edge on, the galaxy’s softly luminous bulge and sharply outlined disc resemble the rounded crown and broad brim of the Mexican hat from which the galaxy gets its name.

Though the Sombrero Galaxy is packed with stars, it’s surprisingly not a hotbed of star formation. Less than one solar mass of gas is converted into stars within the knotted, dusty disc of the galaxy each year. Even the galaxy’s central supermassive black hole, which at 9 billion solar masses is more than 2000 times more massive than the Milky Way’s central black hole, is fairly calm.

The galaxy is too faint to be spotted with unaided vision, but it is readily viewable with a modest amateur telescope. Seen from Earth, the galaxy spans a distance equivalent to roughly one third of the diameter of the full Moon. The galaxy’s size on the sky is too large to fit within Hubble’s narrow field of view, so this image is actually a mosaic of several images stitched together.

One of the things that makes this galaxy especially notable is its viewing angle, which is inclined just six degrees off of the galaxy’s equator. From this vantage point, intricate clumps and strands of dust stand out against the brilliant white galactic nucleus and bulge, creating an effect not unlike Saturn and its rings — but on an epic galactic scale.

At the same time, this extreme angle makes it difficult to discern the structure of the Sombrero Galaxy. It’s not clear whether it’s a spiral galaxy, like our own Milky Way, or an elliptical galaxy. Curiously, the galaxy’s disc seems like a fairly typical disc for a spiral galaxy, and its spheroidal bulge and halo seem fairly typical for an elliptical galaxy — but the combination of the two components resembles neither a spiral nor an elliptical galaxy.

Researchers have used Hubble to investigate the Sombrero Galaxy, measuring the amount of metals (what astronomers call elements heavier than helium) in stars in the galaxy’s expansive halo. This type of measurement can illuminate a galaxy’s history, potentially revealing whether it has merged with other galaxies in the past. In the case of the Sombrero Galaxy, extremely metal-rich stars in the halo point to a possible merger with a massive galaxy several billion years ago. An ancient galactic clash, hinted at by Hubble’s sensitive measurements, could explain the Sombrero Galaxy’s distinctive appearance.

This image was developed using data from the Hubble observing programme #9714 (PI: K. Noll)

Source: ESA/Hubble/News

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More information

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

Image Credit: ESA/Hubble & NASA, K. Noll

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Links

• ESA/Hubble 35th anniversary celebrations
• Release on ESA website
• Release on NASA website

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Contacts

Bethany Downer
ESA/Hubble Chief Science Communications Officer
Email: Bethany.Downer@esahubble.org

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Dark Energy Camera Captures the Glittering Galaxies of the Antlia Cluster

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DECam Deep View of the Antlia Cluster

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Cosmic Gems Within the Antlia Cluster

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Ultra-compact Dwarf Galaxy in the Antlia Cluster

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Spiral Galaxy in the Antlia Cluster

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Elliptical Galaxy in the Antlia Cluster

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Galaxy Cluster in the Antlia Cluster

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Videos

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Cosmoview Episode 91: Dark Energy Camera Captures the Glittering Galaxies of the Antlia Cluster

 

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Cosmoview Episodio 91: Miles de galaxias capturadas en una sola foto desde Cerro Tololo

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Pan on the Antlia Cluster

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Zooming into the Antlia Cluster

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Thousands of sparkling galaxies revealed in new ultra-deep DECam image featuring the Antlia Cluster

NSF NOIRLab rings in the New Year with a glittering galaxyscape captured with the Department of Energy-fabricated Dark Energy Camera, mounted on the U.S. National Science Foundation Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory in Chile, a Program of NSF NOIRLab. This ultra-deep view of the Antlia Cluster reveals a spectacular array of galaxy types amongst the hundreds that make up its population.

Galaxy clusters are some of the largest known structures in the known Universe. Current models suggest that these massive structures form as clumps of dark matter and the galaxies that form within them are pulled together by gravity to form groups of dozens of galaxies, which in turn merge to form clusters of hundreds, even thousands. One such group is the Antlia Cluster (Abell S636), located around 130 million light-years from Earth in the direction of the constellation Antlia (the Air Pump).

This image was taken with the 570-megapixel Department of Energy-fabricated Dark Energy Camera (DECam), mounted on the U.S. National Science Foundation (NSF) Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory in Chile, a Program of NSF NOIRLab. It captures only a portion of the 230 galaxies that so far have been found to make up the Antlia Cluster, as well as thousands of background galaxies. DECam’s ultra-deep view showcases the variety of galaxy types within and beyond the cluster in incredible detail.

Several Programs of NOIRLab (NOAO before 2019) have contributed observations of the Antlia Cluster over the past 20 years. Scientists from Chile have used both the Blanco telescope (with its predecessor camera MOSAIC II) and the Gemini South telescope, one half of the International Gemini Observatory, funded in part by NSF and operated by NSF NOIRLab, to examine the cluster through the Antlia Cluster Project. In more recent years, researchers have investigated the cluster from space- and ground-based observatories. These combined efforts have revealed a dynamic menagerie of rarer galaxy types within the cluster.

The Antlia Cluster is dominated by two massive elliptical galaxies — NGC 3268 (center) and NGC 3258 (lower right). These central galaxies are surrounded by a number of faint dwarf galaxies (see this finder chart showing the Altia Cluster in a different orientation). Researchers believe these two galaxies are in the process of merging, based on X-ray observations that revealed a ‘rope’ of globular clusters along the peak area of light between them. This may be evidence that the Antlia cluster is really two smaller clusters that are combining.

The cluster is rich in lenticular galaxies — a type of disk galaxy that has little interstellar matter and thus little ongoing star formation — and also hosts some irregular galaxies. A plethora of rarer, low-luminosity dwarf galaxies have been found in the cluster, including ultra-compact dwarfs, compact ellipticals, and blue compact dwarfs. The cluster may also contain dwarf spheroidal galaxies and the ultra-diffuse galaxy sub-type, though further investigations are needed to confirm them.

Many of these galaxy types have only been identified within the past few decades because of advances in observational equipment and data analysis techniques that can better capture the low luminosity and relatively smaller size of these galaxies. Evaluating galaxy types allows astronomers to plot the fine details of galaxy evolution, and some galaxies rich with dark matter provide further opportunities for astronomers to understand this mysterious substance that makes up 25% of the Universe.

The development of larger and more highly sensitized cameras like DECam allows astronomers to see the fainter details of these superstructures, such as the diffuse light between the cluster galaxies, which is a combination of intracluster light — the feeble glow of stars flung out into the gravitational field of the cluster by the churn of interacting galaxies — and faded light from the nearby Antlia Supernova Remnant discovered in 2002.

NSF–DOE Vera C. Rubin Observatory’s upcoming Legacy Survey of Space and Time will be the first astronomical survey to provide scientists with the data they need to detect intracluster light in thousands of galaxy clusters, unlocking clues to the distribution of dark matter around galaxy clusters and the evolutionary history of the Universe on large scales.

Source: NSF’s National Optical-Infrared Astronomy Research Laboratory (NOIRLab)/News

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More information

NSF NOIRLab, the U.S. National Science Foundation center for ground-based optical-infrared astronomy, operates the International Gemini Observatory (a facility of NSF, NRC–Canada, ANID–Chile, MCTIC–Brazil, MINCyT–Argentina, and KASI–Republic of Korea), NSF Kitt Peak National Observatory (KPNO), NSF Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), and NSF–DOE Vera C. Rubin Observatory (in cooperation with DOE’s SLAC National Accelerator Laboratory). It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona.

The scientific community is honored to have the opportunity to conduct astronomical research on I’oligam Du’ag (Kitt Peak) in Arizona, on Maunakea in Hawai‘i, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence of I’oligam Du’ag (Kitt Peak) to the Tohono O’odham Nation, and Maunakea to the Kanaka Maoli (Native Hawaiians) community.

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Links

• Explore the Antlia Cluster in more detail
• Photos of the Víctor M. Blanco 4-meter Telescope
• Videos of the Víctor M. Blanco 4-meter Telescope
• Photos of DECam
• Images taken by DECam
• Check out other NOIRLab Photo Releases

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Contacts

Josie Fenske
Jr. Public Information Officer
NSF NOIRLab
Email: josie.fenske@noirlab.edu

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Abell 1775: Chandra Catches Slingshot During Collision

Abell 1775
X-ray: NASA/CXC/Leiden Univ./A. Botteon et al.; Radio: LOFAR/ASTRON; Optical/IR:PanSTARRS

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When the titans of space — galaxy clusters — collide, extraordinary things can happen. A new study using NASA's Chandra X-ray Observatory examines the repercussions after two galaxy clusters clashed.

Galaxy clusters are the largest structures in the Universe held together by gravity, containing hundreds or even thousands of individual galaxies immersed in giant oceans of superheated gas. In galaxy clusters, the normal matter — like the atoms that make up the stars, planets, and everything on Earth — is primarily in the form of hot gas and stars. The mass of the hot gas between the galaxies is far greater than the mass of the stars in all of the galaxies. This normal matter is bound in the cluster by the gravity of an even greater mass of dark matter.

Because of the huge masses
and speeds involved, collisions and mergers between galaxy clusters are among the most energetic events in the Universe.

In a new study of the galaxy cluster Abell 1775, located about 960 million light years from Earth, a team of astronomers led by Andrea Botteon from Leiden University in the Netherlands announced that they found a spiral-shaped pattern in Chandra's X-ray data. These results imply a turbulent past for the cluster.

When two galaxy clusters of different sizes have a grazing collision, the smaller cluster will begin to plow through the larger one. (Because of its superior mass, the bigger cluster has the upper hand when it comes to gravitational pull.) As the smaller cluster moves through, its hot gas is stripped off due to friction. This leaves behind a wake, or tail, that trails behind the cluster. After the center of the smaller cluster passes by the center of the larger one, the gas in the tail starts to encounter less resistance and overshoots the center of its cluster. This can cause the tail to "slingshot" as it flies to the side, curving as it extends away from the cluster's center.

The newest Chandra data contains evidence — including the brightness of the X-rays and the temperatures they represent — for one of these curving "slingshot" tails. Previous studies of Abell 1775 with Chandra and other telescopes hinted, but did not confirm, that there was an ongoing collision in this system.

A new image of Abell 1775 contains X-rays from Chandra (blue), optical data from the Pan-STARRS telescope in Hawaii (blue, yellow, and white), and radio data from the LOw Frequency ARray (LOFAR) in the Netherlands (red). The tail is labeled in this image along with a region of gas with a curved edge, called a "cold front," that is denser and cooler than the gas it is plowing into. The tail and the cold front all curve in the same direction, creating a spiral appearance. A separate labeled image shows the field of view of the Chandra data. 

Labeled Multiwavelength Image of Abell 1775

Astronomers previously found that Abell 1775 contains an enormous jet and radio source, which is also seen in this new composite image. This jet is powered by a supermassive black hole in a large elliptical galaxy in the cluster's center. New data from LOFAR and the Giant Metrewave Radio Telescope (GMRT) in India reveals that the radio jet is actually 2.6 million light years long. This is about twice as long as astronomers thought it was before and makes it one of the longest ever observed in a galaxy cluster. The structure of the jet changes abruptly as it crosses into the lower density gas in the upper part of the image, across the edge of the cold front, implying that the collision has affected it.

According to the new study, the gas motions inside the cluster could be responsible for other structures detected by observing Abell 1775 in radio waves, such as two filaments located near the origin of the jet (one of these is labeled). The LOFAR and Chandra data have also enabled the researchers to study in great detail the phenomena that contribute to accelerating electrons both in this galaxy's jet and in the radio emission near the center of the larger cluster.

There is an alternate explanation for the appearance of the cluster. As a small cluster approaches a larger one, the dense hot gas of the larger cluster will be attracted to it by gravity. After the smaller cluster passes the center of the other cluster, the direction of motion of the cluster gas reverses, and it travels back towards the cluster center. The cluster gas moves through the center again and "sloshes" back and forth, similar to wine sloshing in a glass that was jerked sideways. The sloshing gas ends up in a spiral pattern because the collision between the two clusters was off-center.

The Botteon team favors the slingshot tail scenario, but a separate group of astronomers led by Dan Hu of Shanghai Jiao Tong University in China favors the sloshing explanation based on data from Chandra and ESA's XMM-Newton. Both the slingshot and sloshing scenarios involve a collision between two galaxy clusters. Eventually the two clusters will fully merge with each other to form a single, larger galaxy cluster.

Further observations and modeling of Abell 1775 are required to help decide between these two scenarios.

A paper describing the results by Botteon's team has been published in the journal Astronomy and Astrophysics and is available online. The separate work on the "sloshing" theory led by Dan Hu has been accepted for publication in The Astrophysical Journal and is also available online.

NASA's Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory's Chandra X-ray Center controls science from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.

Quick Look: Chandra Catches Slingshot During Collision

Source: NASA's Chandra X-Ray Observatory

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Fast Facts for Abell 1775:

Scale: Image is about 19.4 arcmin (5.3 million light years) across.
Category: Groups & Clusters of Galaxies
Coordinates (J2000): RA 13h 41m 55.6s | Dec +26° 21´ 53"
Constellation: Boötes
Observation  Time:  27 hours 26 minutes (1 day 3 hours 26 minutes)
Obs. ID: 12891, 13510
Instrument: ACIS
References: Botteon, A., et. al, 2021, A&A, 649, A37; arXiv:2103.01989
Color Code: X-ray: blue; Radio: red; Optical/IR: red, green, blue
Distance Estimate: About 960 million light years (z=0.072)

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Peering into a Galaxy's Dusty Core to Study an Active Supermassive Black Hole

Centaurus A sports a warped central disk of gas and dust, which is evidence of a past collision and merger with another galaxy. It also has an active galactic nucleus that periodically emits jets. It is the fifth brightest galaxy in the sky and only about 13 million light-years away from Earth, making it an ideal target to study an active galactic nucleus – a supermassive black hole emitting jets and winds – with NASA's upcoming James Webb Space Telescope. Credits: X-ray: NASA / CXC/SAO; Optical: Rolf Olsen; Infrared: NASA  / CXC/SAO; Optical: Rolf Olsen; Infrared: NASA

Release images / Release Videos

Centaurus A is a giant of a galaxy, but its appearances in telescope observations can be deceiving. Dark dust lanes and young blue star clusters, which crisscross its central region, are apparent in ultraviolet, visible, and near-infrared light, painting a fairly subdued landscape. But by switching to X-ray and radio light views, a far more raucous scene begins to unfold: From the core of the misshapen elliptical galaxy, spectacular jets of material have erupted from its active supermassive black hole – known as an active galactic nucleus – sending material into space well beyond the galaxy's limits.

What, precisely, is happening at its core to cause all this activity? Upcoming observations led by Nora Lützgendorf and Macarena García Marín of the European Space Agency using NASA's James Webb Space Telescope will allow researchers to peer through its dusty core in high resolution for the first time to begin to answer these questions.

"There's so much going on in Centaurus A," explains Lützgendorf. "The galaxy's gas, disk, and stars all move under the influence of its central supermassive black hole. Since the galaxy is so close to us, we'll be able to use Webb to create two-dimensional maps to see how the gas and stars move in its central region, how they are influenced by the jets from its active galactic nucleus, and ultimately better characterize the mass of its black hole."

A Quick Look Back

Let's hit "rewind" to review a bit of what is already known about Centaurus A. It's well studied because it's relatively nearby – about 13 million light-years away – which means we can clearly resolve the full galaxy. The first record of it was logged in the mid-1800s, but astronomers lost interest until the 1950s because the galaxy appeared to be a quiet, if misshapen, elliptical galaxy. Once researchers were able to begin observing with radio telescopes in the 1940s and '50s, Centaurus A became radically more interesting – and its jets came into view. In 1954, researchers found that Centaurus A is the result of two galaxies that merged, which was later estimated to have occurred 100 million years ago.

With more observations in the early 2000s, researchers estimated that about 10 million years ago, its active galactic nucleus shot out twin jets in opposite directions. When examined across the electromagnetic spectrum, from X-ray to radio light, it's clear there is far more to this story that we still have to learn.

"Multi-wavelength studies of any galaxy are like the layers of an onion. Each wavelength shows you something different," said Marín. "With Webb's near- and mid-infrared instruments, we'll see far colder gas and dust than in previous observations, and learn much more about the environment at the center of the galaxy."

Visualizing Webb's Data

The team led by Lützgendorf and Marín will observe Centaurus A not only by taking images with Webb, but by gathering data known as spectra, which spread out light into its component wavelengths like a rainbow. Webb's spectra will reveal high-resolution information about the temperatures, speeds, and compositions of the material at the center of the galaxy.

In particular, Webb's Near Infrared Spectrograph (NIRSpec) and Mid-Infrared Instrument (MIRI) will provide the research team with a combination of data: an image plus a spectrum from within each pixel of that image. This will allow the researchers to build intricate 2D maps from the spectra that will help them identify what's happening behind the veil of dust at the center – and analyze it from many angles in depth.

Compare this style of modeling to the analysis of a garden. In the same way botanists classify plants based on specific sets of features, these researchers will classify spectra from Webb's MIRI to construct "gardens" or models. "If you take a snapshot of a garden from a great distance away," Marín explained, "You will see something green, but with Webb, we will be able to see individual leaves and flowers, their stems, and maybe the soil underneath."

As the research team digs into the spectra, they'll build maps from individual parts of the garden, comparing one spectrum to another nearby spectrum. This is analogous to determining which parts contain which plant species based on comparisons of "stems," "leaves," and "flowers" as they go.

"When it comes to spectral analysis, we conduct many comparisons," Marín continued. "If I compare two spectra in this region, maybe I will find that what was observed contains a prominent population of young stars. Or confirm which areas are both dusty and heated. Or maybe we will identify emission coming from the active galactic nucleus."

In other words, the "ecosystem" of spectra has many levels, which will allow the team to better define precisely what is present and where it is – which is made possible by Webb's specialized infrared instruments. And, since these studies will build on many that came before, the researchers will be able to confirm, refine, or break new ground by identifying new features.

Weighing the Black Hole in Centaurus A

The combination of images and spectra provided by NIRSpec and MIRI will allow the team to create very high-resolution maps of the speeds of the gas and stars at the center of Centaurus A. "We plan to use these maps to model how the entire disk at the center of the galaxy moves to more precisely determine the black hole's mass," Lützgendorf explains.

Since researchers understand how the gravity of a black hole governs the rotation of nearby gas, they can use the Webb data to weigh the black hole in Centaurus A. With a more complete set of infrared data, they will also determine if different parts of the gas are all behaving as anticipated. "I'm looking forward to fully filling out our data," Lützgendorf said. "I hope to see how the ionized gas behaves and twirls, and where we see the jets."

The researchers are also hoping to break new ground. "It's possible we'll find things we haven't considered yet," Lützgendorf explains. "In some aspects, we'll be covering completely new territory with Webb." Marín wholeheartedly agrees, and adds that building on a wealth of existing data is invaluable. "The most exciting aspects about these observations is the potential for new discoveries," she said. "I think we might find something that makes us look back to other data and reinterpret what was seen earlier."

These studies of Centaurus A will be conducted as part of Gillian Wright and Pierre Ferruit's joint MIRI and NIRSpec Guaranteed Time Observations programs. All of Webb's data will ultimately be stored in the publicly accessible Barbara A. Mikulski Archive for Space Telescopes (MAST) at the Space Telescope Science Institute in Baltimore.

The James Webb Space Telescope will be the world's premier space science observatory when it launches in 2021. Webb will solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency. 

 

Contact:  

Claire Blome / Christine Pulliam
Space Telescope Science Institute, Baltimore, Maryland
667-218-6426 / 410-338-4366
cblome@stsci.edu / cpulliam@stsci.edu

Related Links

NASA's Webb Portal

Source:  NASA's James Webb Space Telescope/News

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Astronomers Detect Orbital Motion in Pair of Supermassive Black Holes

Artist's conception of the pair of supermassive black holes at the center of the galaxy 0402+379, 750 million light-years from Earth.Credit: Josh Valenzuela/University of New Mexico. Released image

VLBA image of the central region of the galaxy 0402+379, showing the two cores, labeled C1 and C2, identified as a pair of supermassive black holes in orbit around each other.Credit: Bansal et al., NRAO/AUI/NSF. Released image

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VLBA reveals first-ever black-hole "visual binary" 

Using the supersharp radio “vision” of the National Science Foundation’s Very Long Baseline Array (VLBA), astronomers have made the first detection of orbital motion in a pair of supermassive black holes in a galaxy some 750 million light-years from Earth.

The two black holes, with a combined mass 15 billion times that of the Sun, are likely separated by only about 24 light-years, extremely close for such a system.

“This is the first pair of black holes to be seen as separate objects that are moving with respect to each other, and thus makes this the first black-hole ‘visual binary,'” said Greg Taylor, of the University of New Mexico (UNM).

Supermassive black holes, with millions or billions of times the mass of the Sun, reside at the cores of most galaxies. The presence of two such monsters at the center of a single galaxy means that the galaxy merged with another some time in the past. In such cases, the two black holes themselves may eventually merge in an event that would produce gravitational waves that ripple across the universe.

“We believe that the two supermassive black holes in this galaxy will merge,” said Karishma Bansal, a graduate student at UNM, adding that the merger will come at least millions of years in the future.

The galaxy, an elliptical galaxy called 0402+379, after its location in the sky, was first observed in 1995. It was studied in 2003 and 2005 with the VLBA. Based on finding two cores in the galaxy, instead of one, Taylor and his collaborators concluded in 2006 that it contained a pair of supermassive black holes.

The latest research, which Taylor and his colleagues are reporting in the Astrophysical Journal, incorporates new VLBA observations from 2009 and 2015, along with re-analysis of the earlier VLBA data. This work revealed motion of the two cores, confirming that the two black holes are orbiting each other. The scientists’ initial calculations indicate that they complete a single orbit in about 30,000 years.

“We need to continue observing this galaxy to improve our understanding of the orbit, and of the masses of the black holes,” Taylor said. “This pair of black holes offers us our first chance to study how such systems interact,” he added.

The astronomers also hope to discover other such systems. The galaxy mergers that bring two supermassive black holes close together are considered to be a common process in the universe, so astronomers expect that such binary pairs should be common.

“Now that we’ve been able to measure orbital motion in one such pair, we’re encouraged to seek other, similar pairs. We may find others that are easier to study,” Bansal said.

The VLBA, part of the Long Baseline Observatory, is a continent-wide radio telescope system using ten, 240-ton dish antennas distributed from Hawaii to St. Croix in the Caribbean. All ten antennas work together as a single telescope with the greatest resolving power available to astronomy. That extraordinary resolving power allows scientists to make extremely fine measurements of objects and motions in the sky, such as those done for the research on 0402+379.

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

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Media Contact:

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

Source: National Radio Astronomy Observatory (NRAO)

CXO J101527.2+625911: Astronomers Pursue Renegade Supermassive Black Hole

 CXO J101527.2+625911
 Credit  X-ray: NASA/CXC/NRAO/D.-C.Kim; Optical: NASA/STScI; 
Illustration: NASA/CXC/M.Weiss

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Supermassive holes are generally stationary objects, sitting at the centers of most galaxies. However, using data from NASA's Chandra X-ray Observatory and other telescopes, astronomers recently hunted down what could be a supermassive black hole that may be on the move.

This possible renegade black hole, which contains about 160 million times the mass of our Sun, is located in an elliptical galaxy about 3.9 billion light years from Earth. Astronomers are interested in these moving supermassive black holes because they may reveal more about the properties of these enigmatic objects.

This black hole may have "recoiled," in the terminology used by scientists, when two smaller supermassive black holes collided and merged to form an even larger one. At the same time, this collision would have generated gravitational waves that emitted more strongly in one direction than others. This newly formed black hole could have received a kick in the opposite direction of those stronger gravitational waves. This kick would have pushed the black hole out of the galaxy's center, as depicted in the artist's illustration.

The strength of the kick depends on the rate and direction of spin of the two smaller black holes before they merge. Therefore, information about these important but elusive properties can be obtained by studying the speed of recoiling black holes.

Astronomers found this recoiling black hole candidate by sifting through X-ray and optical data for thousands of galaxies. First, they used Chandra observations to select galaxies that contain a bright X-ray source and were observed as part of the Sloan Digital Sky Survey (SDSS). Bright X-ray emission is a common feature of supermassive black holes that are rapidly growing.

Next, the researchers looked to see if Hubble Space Telescope observations of these X-ray bright galaxies revealed two peaks near their center in the optical image. These two peaks might show that a pair of supermassive black holes is present or that a recoiling black hole has moved away from the cluster of stars in the center of the galaxy.

If those criteria were met, then the astronomers examined the SDSS spectra, which show how the amount of optical light varies with wavelength. If the researchers found telltale signatures in the spectra indicative of the presence of a supermassive black hole, they followed up with an even closer examination of those galaxies.

After all of this searching, a good candidate for a recoiling black hole was discovered. The left image in the inset is from the Hubble data, which shows two bright points near the middle of the galaxy. One of them is located at the center of the galaxy and the other is located about 3,000 light years away from the center. The latter source shows the properties of a growing supermassive black hole and its position matches that of a bright X-ray source detected with Chandra (right image in inset). Using data from the SDSS and the Keck telescope in Hawaii, the team determined that the growing black hole located near, but visibly offset from, the center of the galaxy has a velocity that is different from the galaxy. These properties suggest that this source may be a recoiling supermassive black hole.

The host galaxy of the possible recoiling black hole also shows some evidence of disturbance in its outer regions, which is an indication that a merger between two galaxies occurred in the relatively recent past. Since supermassive black hole mergers are thought to occur when their host galaxies merge, this information supports the idea of a recoiling black hole in the system.

Moreover, stars are forming at a high rate in the galaxy, at several hundred times the mass of the Sun per year. This agrees with computer simulations, which predict that star formation rates may be enhanced for merging galaxies particularly those containing recoiling black holes.

Another possible explanation for the data is that two supermassive black holes are located in the center of the galaxy but one of them is not producing detectable radiation because it is growing too slowly. The researchers favor the recoiling black hole explanation, but more data are needed to strengthen their case.

A paper describing these results was recently accepted for publication in The Astrophysical Journal and is available online. The first author is Dongchan Kim from the National Radio Astronomy Observatory in Charlottesville, Virginia. NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.

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Fast Facts for CXO J101527.2+625911:

Scale: Inset images are 10 arcsec across (about 163,000 light years)
Category: Quasars & Active Galaxies, Black Holes
Coordinates (J2000): RA 10h 15m 27.2s | Dec +62° 59' 11.5"
Constellation: Ursa Major
Observation Date: 1 pointing in Apr 2008
Observation Time: 0 hours 51 minutes 40 seconds
Obs. ID: 9203
Instrument: ACIS
References: Kim, D.-C. et al., 2017, ApJ [in print]; arXiv: 1704.05549v1
Distance Estimate: About 3.9 billion light years (z=0.3504)

Source: NASA’s Chandra X-ray Observatory

A transformation in Virgo

NGC 4388

Credit: ESA/Hubble & NASA

The constellation of Virgo (The Virgin) is especially rich in galaxies, due in part to the presence of a massive and gravitationally-bound collection of over 1300 galaxies called the Virgo Cluster. One particular member of this cosmic community, NGC 4388, is captured in this image, as seen by the NASA/ESA Hubble Space Telescope’s Wide Field Camera 3 (WFC3). 

Located some 60 million light-years away, NGC 4388 is experiencing some of the less desirable effects that come with belonging to such a massive galaxy cluster. It is undergoing a transformation, and has taken on a somewhat confused identity. 

While the galaxy’s outskirts appear smooth and featureless, a classic feature of an elliptical galaxy, its centre displays remarkable dust lanes constrained within two symmetric spiral arms, which emerge from the galaxy’s glowing core — one of the obvious features of a spiral galaxy. Within the arms, speckles of bright blue mark the locations of young stars, indicating that NGC 4388 has hosted recent bursts of star formation. 

Despite the mixed messages, NGC 4388 is classified as a spiral galaxy. Its unusual combination of features are thought to have been caused by interactions between NGC 4388 and the Virgo Cluster.

Gravitational interactions — from glancing blows to head-on collisions, tidal influencing, mergers, and galactic cannibalism — can be devastating to galaxies. While some may be lucky enough to simply suffer a distorted spiral arm or newly-triggered wave of star formation, others see their structure and contents completely and irrevocably altered.

Source: ESA/Hubble/images

Tangled threads weave through cosmic oddity

PR Image heic1621a

Dusty filaments in NGC 4696 

PR Image heic1621b

Wide-field image of NGC 4696 (ground-based image)

Videos

PR Video heic1621a

Zoom in on NGC 4696 

PR Video heic1621b

Pan across NGC 4696

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New observations from the NASA/ESA Hubble Space Telescope have revealed the intricate structure of the galaxy NGC 4696 in greater detail than ever before. The elliptical galaxy is a beautiful cosmic oddity with a bright core wrapped in system of dark, swirling, thread-like filaments.

NGC 4696 is a member of the Centaurus galaxy cluster, a swarm of hundreds of galaxies all sitting together, bound together by gravity, about 150 million light-years from Earth and located in the constellation of Centaurus.

Despite the cluster’s size, NGC 4696 still manages to stand out from its companions — it is the cluster’s brightest member, known for obvious reasons as the Brightest Cluster Galaxy . This puts it in the same category as some of the biggest and brightest galaxies known in the Universe.

Even if NGC 4696 keeps impressive company, it has a further distinction: the galaxy’s unique structure. Previous observations have revealed curling filaments that stretch out from its main body and carve out a cosmic question mark in the sky (heic1013), the dark tendrils encircling a brightly glowing centre.

An international team of scientists, led by astronomers from the University of Cambridge, UK, have now used new observations from the NASA/ESA Hubble Space Telescope to explore this thread-like structure in more detail. They found that each of the dusty filaments has a width of about 200 light-years, and a density some 10 times greater than the surrounding gas. These filaments knit together and spiral inwards towards the centre of NGC 4696, connecting the galaxy’s constituent gas to its core.

In fact, it seems that the galaxy’s core is actually responsible for the shape and positioning of the filaments themselves. At the centre of NGC 4696 lurks an active supermassive black hole. This floods the galaxy’s inner regions with energy, heating the gas there and sending streams of heated material outwards.

It appears that these hot streams of gas bubble outwards, dragging the filamentary material with them as they go. The galaxy’s magnetic field is also swept out with this bubbling motion, constraining and sculpting the material within the filaments.

At the very centre of the galaxy, the filaments loop and curl inwards in an intriguing spiral shape, swirling around the supermassive black hole at such a distance that they are dragged into and eventually consumed by the black hole itself.

Understanding more about filamentary galaxies such as NGC 4696 may help us to better understand why so many massive galaxies near to us in the Universe appear to be dead; rather than forming newborn stars from their vast reserves of gas and dust, they instead sit quietly, and are mostly populated with old and aging stars. This is the case with NGC 4696. It may be that the magnetic structure flowing throughout the galaxy stops the gas from creating new stars.

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More Information

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

Image credit: NASA, ESA, Andy Fabian

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Links

• Images of Hubble 

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Contacts

Andy Fabian

University of Cambridge

Cambridge, United Kingdom

Tel: +44 1223 337509

Email: acf@ast.cam.ac.uk

Mathias Jäger

ESA/Hubble, Public Information Officer

Garching bei München, Germany

Tel: +49 176 62397500

Email: mjaeger@partner.eso.org

Source: ESO/Hubble/News

Twin jets pinpoint the heart of an active galaxy

3-mm GMVA image of the galaxy NGC 1052 showing a compact region at the centre and two jets (bottom), and sketch of the system with an accretion disk and two regions of entangled magnetic fields forming two powerful jets (top).  The compact region in the image pinpoints the location of the supermassive black hole at the heart of NGC 1052, and the enormous magnetic fields surrounding the event horizon trigger the two powerful jets observed with our radio telescopes. © Anne-Kathrin Baczko et al., Astronomy & Astrophysics

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Magnetism dominates environment of the central black hole

An international team of astronomers has measured the magnetic field in the vicinity of a supermassive black hole. A bright and compact feature of only 2 light days in size was directly observed by a world-wide ensemble of millimeter-wave radio telescopes in the heart of the active galaxy NGC 1052. The observations yield a magnetic field value at the event horizon of the central black hole between 0.02 and 8.3 Tesla. The team, led by the PhD student Anne-Kathrin Baczko, believes that such a large magnetic field provides enough magnetic energy to power the strong relativistic jets in active galaxies. The results are published in the present issue of Astronomy & Astrophysics.

The technique used to investigate the inner details of NGC 1052 is known as very-long-baseline interferometry, and has the potential to locate compact jet cores at sizes close to the event horizon of the powering black hole. The black hole itself remains invisible. Usually, the black hole position can only be inferred indirectly by tracking the wavelength-dependent jet-core position, which converges to the jet base at zero wavelength. The unknown offset from the jet base and the black hole makes it difficult to measure fundamental physical properties in most galaxies. The striking symmetry observed in the reported observations between both jets in NGC1052 allows the astronomers to locate the true center of activitiy inside the central feature, which makes, with the exception of our Galactic Centre, the most precisely known location of a super massive black hole in the universe. Anne-Kathrin Baczko, who performed this work at the Universities of Erlangen-Nürnberg and Würzburg and at the Max-Planck-Institut für Radioastronomie, says: “NGC 1052 is a true key source, since it pinpoints directly and unambiguously the position of a supermassive black hole in the nearby universe.”

NGC 1052 is an elliptical galaxy in a distance of approximately 60 million light years in the direction of the constellation Cetus (the Whale).

The magnetic field by the supermassive black hole was determined measuring the compactness and the brightness of the central region of the elliptical galaxy NGC 1052. This feature is as compact as 57 microarcseconds in diameter, equivalent to the size of a DVD on the surface of the moon. This amazing resolution was obtained by the Global mm-VLBI Array, a network of radio telescopes in Europe, the USA, and East Asia, that is managed by the Max-Planck-Institut für Radioastronomie. “It yields unprecedented image sharpness, and is soon to be applied to get event-horizon scales in nearby objects”, says Eduardo Ros from the MPI für Radioastronomie and collaborator in the project.

The unique powerful twin jets at a close distance, similar to the well-known active galaxy M 87, puts NGC 1052 in the pole position for future observations of nearby powerful galaxies in the oncoming era opened by the addition of ALMA, the Atacama Large Millimetre array, to the world-wide networks in radio interferometry.

The observation may help solving the long-standing mystery of how the powerful relativistic jets are formed, that can be seen in many active galaxies. The result has important astrophysical implications, since we see that jets can be driven by the extraction of magnetic energy from a rapidly rotating supermassive black hole.

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Three telescopes participating in the Global Millimetre VLBI Array (GMVA): MPIfR’s Effelsberg 100m (above), IRAM’s Pico Veleta 30m (lower left) and Plateau de Bure 15m telescopes (lower right). © IRAM (Pico Veleta & Plateau de Bure); Norbert Junkes (Effelsberg & compilation)

 

The Global Millimetre VLBI Array consists of telescopes operated by the MPIfR, IRAM, Onsala, Metsähovi, Yebes and the VLBA. The data were correlated at the correlator of the MPIfR in Bonn, Germany. The VLBA is an instrument of the National Radio Astronomy Observatory, a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. MPIfR scientists involved in the project are Anne-Kathrin Baczko, the first author, Eduardo Ros, Thomas Krichbaum, Andrei Lobanov and J. Anton Zensus

Source: Max Planck Institute for Radio Astronomy

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Contact:

Anne-Kathrin Baczko
Phone:+49 2228 525 366
Email: baczko@mpifr-bonn.mpg.de
Max-Planck-Institut für Radioastronomie, Bonn

Prof. Dr. Eduardo Ros
Phone:+49 228 525-125
Email: ros@mpifr-bonn.mpg.de
Max-Planck-Institut für Radioastronomie, Bonn

Dr. Norbert Junkes
Press and Public Outreach
Phone:+49 228 525-399 
Email: njunkes@mpifr-bonn.mpg.de
Max-Planck-Institut für Radioastronomie, Bonn

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Original Paper:

A highly magnetized twin-jet base pinpoints a supermassive black hole?
A.-K. Baczko, R. Schulz, M. Kadler, E. Ros, M. Perucho, T. P. Krichbaum, M. Böck, M. Bremer, C. Grossberger, M. Lindqvist, A. P. Lobanov, K. Mannheim, I. Martí-Vidal, C. Müller, J. Wilms, and J. A. Zensus, 2016, Astronomy & Astrophysics, 593, A47.

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Links

Radio Astronomy / VLBI 
Research Department "Radio Astronomy. VLBI" at MPIfR Bonn

Univ. Würzburg
Lehrstuhl für Astronomie, Universität Würzburg

Dr. Karl-Remeis-Sternwarte
Astronomisches Institut der Univ. Erlangen-Nürnberg

GMVA
Global Millimetre VLBI Array (GMVA)

Radio Telescope
Effelsberg Effelsberg Radio Telescope

IRAM
Institute de Radioastronomie Millimetrique (IRAM)

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Movie

NGC1052

Zoom into the compact central region of NGC1052 observed at 3 mm wavelength (86 GHz). The video starts at an observing wavelength of 1.3 cm (corresponding to a frequency of 22 GHz), and going over 7 mm (43 GHz) to a shortest wavelength of  3 mm.

Behemoth Black Hole Found in an Unlikely Place

Black Hole in NGC 1600

This computer-simulated image shows a supermassive black hole at the core of a galaxy. The black region in the center represents the black hole's event horizon, where no light can escape the massive object's gravitational grip. The black hole's powerful gravity distorts space around it like a funhouse mirror. Light from background stars is stretched and smeared as the stars skim by the black hole.   

Simulation Credit: NASA, ESA, and D. Coe, J. Anderson, and R. van der Marel (Space Telescope Science Institute).  Acknowledgment for Omega Centauri Image: NASA, ESA, and the Hubble SM4 ERO Team. Science Credit: NASA, ESA, C.-P. Ma (University of California, Berkeley), and J. Thomas (Max Planck Institute for Extraterrestrial Physics, Garching, Germany). Release images

NGC 1600

Credit: NASA, ESA, and C.-P. Ma (University of California, Berkeley)

Acknowledgment: Digitized Sky Survey (DSS), STScI/AURA, Palomar/Caltech, UKSTU/AAO, and A. Quillen (University of Rochester)

Astronomers have uncovered a near-record-breaking supermassive black hole, weighing 17 billion suns, in an unlikely place: in the center of a galaxy in a sparsely populated area of the universe. The observations, made by NASA's Hubble Space Telescope and the Gemini telescope in Hawaii, could indicate that these monster objects may be more common than once thought.

Until now, the biggest supermassive black holes — those roughly 10 billion times the mass of our sun — have been found at the cores of very large galaxies in regions of the universe packed with other large galaxies. In fact, the current record holder tips the scale at 21 billion suns and resides in the crowded Coma galaxy cluster, which consists of over 1,000 galaxies.

"The newly discovered supersized black hole resides in the center of a massive elliptical galaxy, NGC 1600, located in a cosmic backwater, a small grouping of 20 or so galaxies," said lead discoverer Chung-Pei Ma, a University of California-Berkeley astronomer and head of the MASSIVE Survey, a study of the most massive galaxies and supermassive black holes in the local universe. While finding a gigantic black hole in a massive galaxy in a crowded area of the universe is to be expected — like running across a skyscraper in Manhattan — it seemed less likely they could be found in the universe's small towns.

"There are quite a few galaxies the size of NGC 1600 that reside in average-size galaxy groups," Ma said. "We estimate that these smaller groups are about 50 times more abundant than spectacular galaxy clusters like the Coma cluster. So the question now is, ‘Is this the tip of an iceberg?' Maybe there are more monster black holes out there that don't live in a skyscraper in Manhattan, but in a tall building somewhere in the Midwestern plains."

The researchers also were surprised to discover that the black hole is 10 times more massive than they had predicted for a galaxy of this mass. Based on previous Hubble surveys of black holes, astronomers had developed a correlation between a black hole's mass and the mass of its host galaxy's central bulge of stars — the larger the galaxy bulge, the proportionally more massive the black hole. But for galaxy NGC 1600, the giant black hole's mass far overshadows the mass of its relatively sparse bulge. "It appears that that relation does not work very well with extremely massive black holes; they are a larger fraction of the host galaxy's mass," Ma said.

Ma and her colleagues are reporting the discovery of the black hole, which is located about 200 million light-years from Earth in the direction of the constellation Eridanus, in the April 6 issue of the journal Nature. Jens Thomas of the Max Planck Institute for Extraterrestrial Physics, Garching, Germany, is the paper's lead author.

One idea to explain the black hole's monster size is that it merged with another black hole long ago when galaxy interactions were more frequent. When two galaxies merge, their central black holes settle into the core of the new galaxy and orbit each other. Stars falling near the binary black hole, depending on their speed and trajectory, can actually rob momentum from the whirling pair and pick up enough velocity to escape from the galaxy's core. This gravitational interaction causes the black holes to slowly move closer together, eventually merging to form an even larger black hole. The supermassive black hole then continues to grow by gobbling up gas funneled to the core by galaxy collisions. "To become this massive, the black hole would have had a very voracious phase during which it devoured lots of gas," Ma said.

The frequent meals consumed by NGC 1600 may also be the reason why the galaxy resides in a small town, with few galactic neighbors. NGC 1600 is the most dominant galaxy in its galactic group, at least three times brighter than its neighbors. "Other groups like this rarely have such a large luminosity gap between the brightest and the second brightest galaxies," Ma said.

Most of the galaxy's gas was consumed long ago when the black hole blazed as a brilliant quasar from material streaming into it that was heated into a glowing plasma. "Now, the black hole is a sleeping giant," Ma said. "The only way we found it was by measuring the velocities of stars near it, which are strongly influenced by the gravity of the black hole. The velocity measurements give us an estimate of the black hole's mass."

The velocity measurements were made by the Gemini Multi-Object Spectrograph (GMOS) on the Gemini North 8-meter telescope on Mauna Kea in Hawaii. GMOS spectroscopically dissected the light from the galaxy's center, revealing stars within 3,000 light-years of the core. Some of these stars are circling around the black hole and avoiding close encounters. However, stars moving on a straighter path away from the core suggest that they had ventured closer to the center and had been slung away, most likely by the twin black holes.

Archival Hubble images, taken by the Near Infrared Camera and Multi-Object Spectrometer (NICMOS), support the idea of twin black holes pushing stars away. The NICMOS images revealed that the galaxy's core was unusually faint, indicating a lack of stars close to the galactic center. A star-depleted core distinguishes massive galaxies from standard elliptical galaxies, which are much brighter in their centers. Ma and her colleagues estimated that the amount of stars tossed out of the central region equals 40 billion suns, comparable to ejecting the entire disk of our Milky Way galaxy.

Contacts:

Donna Weaver / Ray Villard
Space Telescope Science Institute, Baltimore, Maryland
410-338-4493 / 410-338-4514
dweaver@stsci.edu / villard@stsci.edu

Chung-Pei Ma
University of California, Berkeley, California
510-301-3780
cpma@berkeley.edu

Jens Thomas
Max Planck Institute for Extraterrestrial Physics, Garching, Germany
011-49-89-3000-3714
jthomas@mpe.mpg.de

Source: HubbleSite