A red, metal-rich relic

 NGC 1277

Credit: NASA, ESA, and M. Beasley (Instituto de Astrofísica de Canarias)

This idyllic scene, packed with glowing galaxies, has something truly remarkable at its core: an untouched relic of the ancient Universe. This relic can be seen in the large galaxy at the centre of the frame, a lenticular galaxy named NGC 1277. This galaxy is a member of the famous Perseus Cluster — one of the most massive objects in the known Universe, located some 220 million light-years from Earth.

NGC 1277 has been dubbed a “relic of the early Universe” because all of its stars appear to have formed about 12 billion years ago. To put this in perspective, the Big Bang is thought to have happened 13.8 billion years ago. Teeming with billions of old, metal-rich stars, this galaxy is also home to many ancient globular clusters: spherical bundles of stars that orbit a galaxy like satellites.

Uniquely, the globuar clusters of NGC 1277 are mostly red and metal-rich — very different to the blue, metal-poor clusters usually seen around similarly-sized galaxies. In astronomy, a metal is any element heavier than hydrogen and helium; these heavier elements are fused together in the hot cores of massive stars and scattered throughout the Universe when these stars explode as they die. In this way, a star’s metal content is related to its age: stars that form later contain greater amounts of metal-rich material, since previous generations of stars have enriched the cosmos from which they are born.

Massive galaxies — and their globular clusters — are thought to form in two phases: first comes an early collapse accompanied by a giant burst of star formation, which forms red, metal-rich clusters, followed by a later accumulation of material, which brings in bluer, metal-poor material. The discovery of NGC 1277’s red clusters confirms that the galaxy is a genuine antique that bypassed this second phase, raising important questions for scientists on how galaxies form and evolve: a hotly debated topic in modern astronomy.

Link

• NASA/STScI release

Source: ESA/Hubble/Potw

Hubble Finds Relic Galaxy Close to Home

Galaxy NGC 1277

Credit: NASA, ESA, M. Beasley (Instituto de Astrofísica de Canarias), and P. Kehusmaa

Released images (3) 

Release videos (2) 

Astronomers have put NASA’s Hubble Space Telescope on an Indiana Jones-type quest to uncover an ancient “relic galaxy” in our own cosmic backyard.

The very rare and odd assemblage of stars has remained essentially unchanged for the past 10 billion years. This wayward stellar island provides valuable new insights into the origin and evolution of galaxies billions of years ago.

The galaxy, NGC 1277, started its life with a bang long ago, ferociously churning out stars 1,000 times faster than seen in our own Milky Way today. But it abruptly went quiescent as the baby boomer stars aged and grew ever redder.

The findings are being published online in the March 12 issue of the science journal Nature.

Though Hubble has seen such “red and dead” galaxies in the early universe, one has never been conclusively found nearby. Where the early galaxies are so distant, they are just red dots in Hubble deep-sky images. NGC 1277 offers a unique opportunity to see one up close and personal. “We can explore such original galaxies in full detail and probe the conditions of the early universe,” said Ignacio Trujillo, of the Instituto de Astrofísica de Canarias at the University of La Laguna, Spain.

The researchers learned that the relic galaxy has twice as many stars as our Milky Way, but physically it is as small as one quarter the size of our galaxy. Essentially, NGC 1277 is in a state of “arrested development.” Perhaps like all galaxies it started out as a compact object but failed to accrete more material to grow in size to form a magnificent pinwheel-shaped galaxy.

Approximately one in 1,000 massive galaxies is expected to be a relic (or oddball) galaxy, like NGC 1277, researchers say. They were not surprised to find it, but simply consider that it was in the right place at the right time to evolve — or rather not evolve — the way it did.

The telltale sign of the galaxy’s state lies in the ancient globular clusters of stars that swarm around it. Massive galaxies tend to have both metal-poor (appearing blue) and metal-rich (appearing red) globular clusters. The red clusters are believed to form as the galaxy forms, while the blue clusters are later brought in as smaller satellites are swallowed by the central galaxy. However, NGC 1277 is almost entirely lacking in blue globular clusters. “I’ve been studying globular clusters in galaxies for a long time, and this is the first time I’ve ever seen this,” said Michael Beasley, also of the Instituto de Astrofísica de Canarias.

The red clusters are the strongest evidence that the galaxy went out of the star-making business long ago. However, the lack of blue clusters suggests that NGC 1277 never grew further by gobbling up surrounding galaxies.

By contrast, our Milky Way contains approximately 180 blue and red globular clusters. This is due partly to the fact that our Milky Way continues cannibalizing galaxies that swing too close by in our Local Group of a few dozen small galaxies.

It’s a markedly different environment for NGC 1277. The galaxy lives near the center of the Perseus cluster of over 1,000 galaxies, located 240 million light-years away. But NGC 1277 is moving so fast through the cluster, at 2 million miles per hour, that it cannot merge with other galaxies to collect stars or pull in gas to fuel star formation. In addition, near the galaxy cluster center, intergalactic gas is so hot it cannot cool to condense and form stars.

The team started looking for “arrested development” galaxies in the Sloan Digital Sky Survey and found 50 candidate massive compact galaxies. Using a similar technique, but out of a different sample, NGC 1277 was identified as unique in that it has a central black hole that is much more massive than it should be for a galaxy of that size. This reinforces the scenario that the supermassive black hole and dense hub of the galaxy grew simultaneously, but the galaxy’s stellar population stopped growing and expanding because it was starved of outside material.

“I didn’t believe the ancient galaxy hypothesis initially, but finally I was surprised because it’s not that common to find what you predict in astronomy,” Beasley added. “Typically, the universe always comes up with more surprises that you can think about.”

The team has 10 other candidate galaxies to look at with varying degrees of “arrested development.”

The upcoming NASA James Webb Space Telescope (scheduled for launch in 2019) will allow astronomers to measure the motions of the globular clusters in NGC 1277. This will provide the first opportunity to measure how much dark matter the primordial galaxy contains.

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

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• The science paper by M. Beasley et al.
• NASA's Hubble Portal

Contact

Ray Villard
Space Telescope Science Institute, Baltimore, Maryland
410-338-4514
villard@stsci.edu

Michael Beasley
Instituto de Astrofísica de Canarias, Tenerife, Spain
011-34-922-605-200 x5382
beasley@iac.es

Source: HubbleSite/News

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

Giant black hole could upset galaxy evolution models

A group of astronomers led by Remco van den Bosch from the Max Planck Institute for Astronomy (MPIA) have discovered a black hole that could shake the foundations of current models of galaxy evolution. At 17 billion times the mass of the Sun, its mass is much greater than current models predict – in particular in relation to the mass of its host galaxy. This could be the most massive black hole found to date.

 Figure 1: Image of the disk galaxy (lenticular galaxy) NGC 1277, taken with the Hubble Space Telescope. This small, flattened galaxy contains one of the biggest central super-massive black holes ever found in its center. With the mass of 17 billion Suns, the black hole weighs in at an extraordinary 14% of the total galaxy mass.  Image credit: NASA / ESA / Andrew C. Fabian / Remco C. E. van den Bosch (MPIA).  [Larger version for download]

Figure 2: NGC 1277 is embedded in the nearby Perseus galaxy cluster, at a distance of 250 million light-years from Earth. All the ellipticals and round yellow galaxies in the picture are galaxies located in this cluster. Compared to all the other galaxies around it, NGC 1277 is a relatively compact. Image credit: David W. Hogg, Michael Blanton, and the SDSS Collaboration.  [Larger version for download]

Figure 3: The Hobby-Eberly Telescope gleams in silver and gold against a deep blue night sky. This telescope, located at McDonald Observatory in Texas, was used for the survey of 700 galaxies that formed the first step of the systematic search by van den Bosch and his colleagues for the most massive galactic black holes.  Image credit: Damond Benningfield.   [Larger version for download]

Video: NGC 1277 is a compact disk galaxy with one of the biggest black holes known to date. Its black hole weighs 17 billion times the mass of the Sun, which amounts to a remarkable 14% of this galaxy's total mass. Most of the stars in the galaxy are strongly affected by the gravitational pull of this black hole. The black hole was found by van den Bosch and collaborators and published in Nature on 29 November 2012.

 The animation shows representative orbits of the galaxy's stars in this, taken from the dynamical model that was used to measure the black hole mass. The green orbit shows the orbit of the stars in the disk. The red orbit shows the strong gravitational pull near the black hole. The blue orbit is strongly influenced by the (round) dark matter halo. One second in this animation represents 22 million years of simulated time, and the horizontal size of this image amounts to 41 million lightyears (36 arcsec).

 This animation has been produced by Remco van den Bosch. It is released under creative commons and can be freely embedded.  Credit for the background Hubble Space Telescope image:  NASA / ESA / Fabian / Remco C. E. van den Bosch (MPIA).

Video 2: Remco van den Bosch (Max Planck Institute for Astronomy), lead author of the study, describes the discovery of the unusually massive black hole in the galaxy NGC 1277 in this 5 minute video.

A group of astronomers led by Remco van den Bosch from the Max Planck Institute for Astronomy (MPIA) have discovered a black hole that could shake the foundations of current models of galaxy evolution. At 17 billion times the mass of the Sun, its mass is much greater than current models predict – in particular in relation to the mass of its host galaxy. This could be the most massive black hole found to date.

To the best of our astronomical knowledge, almost every galaxy should contain in its central region what is called a supermassive black hole: a black hole with a mass between that of hundreds of thousands and billions of Suns. The best-studied super-massive black hole sits in the center of our home galaxy, the Milky Way, with a mass of about four million Suns.

For the masses of galaxies and their central black holes, an intriguing trend has emerged: a direct relationship between the mass of a galaxy's black hole and that of the galaxy's stars.

Typically, the black hole mass is a tiny fraction of the galaxy's total mass. But now a search led by Remco van den Bosch (MPIA) has discovered a massive black hole that could upset the accepted relationship between black hole mass and galaxy mass, which plays a key role in all current theories of galaxy evolution. The observations used the Hobby-Eberly Telescope and existing images from the Hubble Space Telescope.

With a mass 17 billion times that of the Sun, the newly discovered black hole in the center of the disk galaxy NGC 1277 might even be the biggest known black hole of all: the mass of the current record holder is estimated to lie between 6 and 37 billion solar masses (McConnell et al. 2011); if the true value lies towards the lower end of that range, NGC 1277 breaks the record. At the least, NGC 1277 harbors the second-biggest known black hole.

The big surprise is that the black hole mass for NGC 1277 amounts to 14% of the total galaxy mass, instead of usual values around 0,1%. This beats the old record by more than a factor 10. Astronomers would have expected a black hole of this size inside blob-like ("elliptical") galaxies ten times larger. Instead, this black hole sits inside a fairly small disk galaxy.

Is this surprisingly massive black hole a freak accident? Preliminary analysis of additional data suggests otherwise – so far, the search has uncovered five additional galaxies that are comparatively small, yet, going by first estimates, seemed to harbor unusually large black holes too. More definite conclusions have to await detailed images of these galaxies.

If the additional candidates are confirmed, and there are indeed more black holes like this, astronomers will need to rethink fundamentally their models of galaxy evolution. In particular, they will need to look at the early universe: The galaxy hosting the new black hole appears to have formed more than 8 billion years ago, and does not appear to have changed much since then. Whatever created this giant black hole must have happened a long time ago.

Contact

Remco van den Bosch (first author)
Max Planck Institute for Astronomy 
Heidelberg, Germany
Phone: (+49|0) 6221 – 528 381
Email: bosch@mpia.de

Arjen van der Wel (co-author)
Max Planck Institute for Astronomy
Heidelberg, Germany
Phone: (+49|0) 6221 – 528 461
Email: vdwel@mpia.de

 Markus Pössel (public relations)
 Max Planck Institute for Astronomy
 Heidelberg, Germany
 Phone: (+49|0) 6221 – 528 261
 Email: pr@mpia.de


Background information

The work described here will be published as van den Bosch et al., "An over-massive black hole in the compact lenticular galaxy NGC 1277", in the November 29 edition of the journal Nature.

• For access to the original article please refer to Nature (press@nature.com)

The co-authors are Remco C. E. van den Bosch (Max Planck Institute for Astronomy; MPIA), Karl Gebhardt (University of Texas at Austin), Kayhan Gültekin (University of Michigan, Ann Arbor), Glenn van de Ven, Arjen van der Wel (both MPIA) and Jonelle L. Walsh (University of Texas at Austin).

Questions and Answers

What was the motivation for the present study? 

The accepted relationship between the mass of a galaxy and the mass of its central black hole is not completely understood - at least three completely different models have been put forth to explain the connection. One of the reasons we lack a complete picture of the black hole mass-galaxy mass relation is the paucity of data points: there are less than a hundred galaxies for which the central black hole mass can be measured.

A good way of testing a relationship is to look at the extremes. For the correlation of black hole and galaxy mass, little was known about the very biggest masses. That is why, in 2010, Remco van den Bosch began a systematic search for the most massive black holes in the cosmos. For black holes of this mass, it should be possible to trace stellar motion (and hence measure black hole masses) out to distances of hundreds of millions of light-years.

The initial step of the systematic search uses the Hobby-Eberly Telescope at McDonald Observatory in Texas. This telescope has a mirror of unrivaled size, with a total area of 11 by 9.8 meters, composed of 91 hexagonal mirrors. The total size makes the telescope particularly well suited for survey work of this kind, as observations for each galaxy can be completed fairly quickly. Using this telescope, van den Bosch tackled the task of taking spectra of nearly 700 nearby galaxies.

The result reported here is one of the first from this systematic search; additional results will be published as follow-up observations and black hole mass-modeling are completed for additional galaxies.

From the spectra taken with the Hobby-Eberly Telescope alone, van den Bosch and his colleagues derived a first estimate, using a well-known relation between the broadness of certain spectral lines (indicating the "velocity dispersion", roughly the amount by which stellar velocities deviate from the average) and central black hole mass. This uncovered a total of six candidates of relatively small galaxies with very large black holes. For only one of these six galaxies high spatial resolution imaging is available and it was thus the focus of the black hole mass measurement. For the five other galaxies more observations are required to measure the distribution of stars in their centers.

How was the black hole mass determined?

In order to measure the mass of the central black hole, astronomers need to track the motion of the galaxy's innermost stars – those whose orbits are strongly influenced by the black hole's gravity. The greater the black hole mass, the greater its influence and the speed of the stars in orbit around it.

Aspects of stellar motion can be measured by looking at the spectrum of light emitted in the galaxy's central region. Movement influences specific features ("Doppler shifts of spectral lines") in the galaxy's light in a systematic way, and these changes can be detected in the spectrum, allowing astronomers to reconstruct stellar motion.

The speeds and direction in which the stars move is influenced by the distribution of mass in the galaxy. The heavier the black hole, the faster the stars move in the center. The centers of galaxies are too dense and too distant to resolve the individual stars, and so we can only measure the distribution of velocities of the spectral lines.

To measure the black hole mass, van den Bosch et al. create a dynamical model of the galaxies that consists of all possible orbits along which stars can travel. Through a systematic search, they then find out which combination of orbits and black hole mass fit the observed distribution of stellar velocities best. In the case of NGC 1277, van den Bosch found the black hole mass to be 17±3 billion times that of the Sun, while the galaxy as a whole weighs in at 120 billion solar masses.