Posted on by Tammy Plotner

Hide And Go Seek…. Supermassive Black Hole Peeks From Behind The Skirt Of A Dwarf Galaxy

Composite image of the dwarf galaxy Henize 2-10. Hubble Space Telescope data is colored red, green and blue, Very Large Array data is yellow and the Chandra X-Ray Observatory data is purple. Cross marks presumed location of the supermassive black hole in the galaxy.

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It’s a bird… It’s a plane… It’s a million times more massive than our Sun! Just how big do you have to be to hide something really big? Well, in the case of a supermassive black hole all you have to be is a small galaxy.

According to the American Astronomical Society Press Release the surprising discovery of a supermassive black hole in a small nearby galaxy has given astronomers a tantalizing look at how black holes and galaxies may have grown in the early history of the Universe. Finding a black hole a million times more massive than the Sun in a star-forming dwarf galaxy isn’t exactly child’s play – but it is a strong indication that supermassive black holes formed before the buildup of galaxies.

So what’s its name? The big little galaxy is called Henize 2-10. Located 30 million light-years from Earth, it’s not unknown to astonomers and is noted for rapid star formation. This irregular player is roughly 3% the size of the Milky Way and scientists think it may greatly resemble some of the first galaxies for form in the early Universe. “This galaxy gives us important clues about a very early phase of galaxy evolution that has not been observed before,” said Amy Reines, a Ph.D. candidate at the University of Virginia.

We’ve been aware for some time that supermassive black holes are present in the cores of all “full-sized” galaxies – however, we’re a bit more used to balancing the scale. In the nearby Universe, there is a direct relationship — a constant ratio — between the masses of the black holes and that of the central “bulges” of the galaxies, leading them to conclude that the black holes and bulges affected each others’ growth.

Two years ago, an international team of astronomers found that black holes in young galaxies in the early Universe were more massive than this ratio would indicate…

The dwarf galaxy Henize 2-10, seen in visible light by the Hubble Space Telescope. The central, light-pink region shows an area of radio emission, seen with the Very Large Array. This area indicates the presence of a supermassive black hole drawing in material from its surroundings.

“Now, we have found a dwarf galaxy with no bulge at all, yet it has a supermassive black hole. This greatly strengthens the case for the black holes developing first, before the galaxy’s bulge is formed,” Reines said. She, along with Gregory Sivakoff and Kelsey Johnson of the University of Virginia and the National Radio Astronomy Observatory (NRAO), and Crystal Brogan of the NRAO, observed Henize 2-10 with the National Science Foundation’s Very Large Array radio telescope and with the inquisitive eye of the Hubble Space Telescope. What did they find hiding behind the neighbor’s hedges? How about a region near the center of the galaxy that strongly emits radio waves with characteristics of those emitted by super-fast “jets” of material spewed outward from areas close to a black hole. A concept we’ve come quite familiar with in recent years!

Next up, they then searched images from the Chandra X-Ray Observatory that showed this same, radio-bright region to be strongly emitting energetic X-rays. This combination, they said, indicates an active, black-hole-powered, galactic nucleus. “Not many dwarf galaxies are known to have massive black holes,” Sivakoff said.

Of course, there are central black holes of roughly the same mass as the one in Henize 2-10 have been found in other galaxies, those galaxies all have much more regular shapes – the “normal” kids of the hood. Henize 2-10 differs not only in its irregular shape and small size but also in its furious star formation, concentrated in numerous, very dense super star clusters. “This galaxy probably resembles those in the very young Universe, when galaxies were just starting to form and were colliding frequently. All its properties, including the supermassive black hole, are giving us important new clues about how these black holes and galaxies formed at that time,” Johnson said.

Kids… Gotta’ love ’em!

CREDIT: Reines, et al., David Nidever, NRAO/AUI/NSF, NASA

Posted on by Nicholos Wethington

Galactic Mergers Fail to Feed Black Holes

By comparing 140 galaxies that had Active Galactic Nuclei with over 1200 galaxies in a "control group", the likelihood that mergers are the cause of AGN has been brought into doubt. Credit: NASA, ESA, M. Cisternas (Max-Planck Institute for Astronomy)

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The large black holes that reside at the center of galaxies can be hungry beasts. As dust and gas are forced into the vicinity around the black holes, it crowds up and jostles together, emitting lots of heat and light. But what forces that gas and dust the last few light years into the maw of these supermassive black holes?

It has been theorized that mergers between galaxies disturbs the gas and dust in a galaxy, and forces the matter into the immediate neighborhood of the black hole. That is, until a recent study of 140 galaxies hosting Active Galactic Nuclei (AGN) – another name for active black holes at the center of galaxies – provided strong evidence that many of the galaxies containing these AGN show no signs of past mergers.

The study was performed by an international team of astronomers. Mauricio Cisternas of the Max Planck Institute for Astronomy and his team used data from 140 galaxies that were imaged by the XMM-Newton X-ray observatory. The galaxies they sampled had a redshift between z= 0.3 – 1, which means that they are between about 4 and 8 billion light-years away (and thus, the light we see from them is about 4-8 billion years old).

They didn’t just look at the images of the galaxies in question, though; a bias towards classifying those galaxies that show active nuclei to be more distorted from mergers might creep in. Rather, they created a “control group” of galaxies, using images of inactive galaxies from the same redshift as the AGN host galaxies. They took the images from the Cosmic Evolution Survey (COSMOS), a survey of a large region of the sky in multiple wavelengths of light. Since these galaxies were from the same redshift as the ones they wanted to study, they show the same stage in galactic evolution. In all, they had 1264 galaxies in their comparison sample.

The way they designed the study involved a tenet of science that is not normally used in the field of astronomy: the blind study. Cisternas and his team had 9 comparison galaxies – which didn’t contain AGN – of the same redshift for each of their 140 galaxies that showed signs of having an active nucleus.

What they did next was remove any sign of the bright active nucleus in the image. This means that the galaxies in their sample of 140 galaxies with AGN would essentially appear to even a trained eye as a galaxy without the telltale signs of an AGN. They then submitted the control galaxies and the altered AGN images to ten different astronomers, and asked them to classify them all as “distorted”, “moderately distorted”, or “not distorted”.

Since their sample size was pretty manageable, and the distortion in many of the galaxies would be too subtle for a computer to recognize, the pattern-seeking human brain was their image analysis tool of choice. This may sound familiar – something similar is being done with enormous success with people who are amateur galaxy classifiers at Galaxy Zoo.

When a galaxy merges with another galaxy, the merger distorts its shape in ways that are identifiable – it will warp a normally smooth elliptical galaxy out of shape, and if the galaxy is a spiral the arms seem to be a bit “unwound”. If it were the case that galactic mergers are the most likely cause of AGN, then those galaxies with an active nucleus would be more probable to show distortion from this past merger.

The team went through this process of blinding the study to eliminate any bias that those looking at the images would have towards classifying AGN as more distorted. By both having a reasonably large sample size of galaxies and removing any bias when analyzing the images, they hoped to definitively show whether the correlation between AGN and mergers exists.

The result? Those galaxies with an Active Galactic Nucleus did not show any more distortion on the whole than those galaxies in the comparison sample. As the authors state in the paper, “Mergers and interactions involving AGN hosts are not dominant, and occur no more frequently than for inactive galaxies.”

This means that astronomers can’t point towards galactic mergers as the main reason for AGN. The study showed that at least 75% of AGN creation – at least between the last 4-8 billion years – must be from sources other than galactic mergers. Likely candidates for these sources include: “galactic harrassment”, those galaxies that don’t collide, but come close enough to gravitationally influence each other; the instability of the central bar in a galaxy; or the collision of giant molecular clouds within the galaxy.

Knowing that AGN aren’t caused in large part by galactic mergers will help astronomers to better understand the formation and evolution of galaxies. The active nuclei in galaxies that host them greatly influence galactic formation. This process is called ‘AGN feedback’, and the mechanisms and effects that result from the interplay between the energy streaming out of the AGN and the surrounding material in the center of a galaxy is still a hot topic of study in astronomy.

Mergers in the more distant past than 8 billion years might yet correlate with AGN – this study only rules out a certain population of these galaxies – and this is a question that the team plans to take on next, pending surveys by the Hubble Space Telescope and the James Webb Space Telescope. Their study will be published in the January 10 issue of the Astrophysical Journal, and a pre-print version is available on Arxiv.

Source: HST news release, Max Planck Institute for Astronomy, Arxiv paper

Posted on by Nancy Atkinson

Oldest Black Holes are Growing the Fastest

Top-down illustration of a black hole
Top-down illustration of a black hole

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Astronomers have determined that the era of first fast growth of the most massive black holes occurred when the universe was much younger than previously thought. A team of researchers from Tel Aviv University found that the epoch of the first fast growth of black holes occurred when the Universe was only about 1.2 billion years old, and not two to four billion years old, as was previously believed. The team also found that these black holes are continuing to grow at a very fast rate.


The supermassive blackholes that most galaxies are thought to have vary in mass from about one million to about 10 billion times the size of our sun. To find them, astronomers look for the enormous amount of radiation emitted by gas which falls into such objects during the times that the black holes are “active,” or accreting matter. This gas infall into massive black holes is believed to be the means by which black holes grow.

Artist concept of a black hole. Credit: Tel Aviv University

Prof. Hagai Hetzer and his research student Benny Trakhtenbrot used data from two different telescopes, Gemini North on top of Mauna Kea in Hawaii, and the Very Large Telescope Array on Cerro Paranal in Chile.

The data show that the black holes that were active when the universe was 1.2 billion years old are about ten times smaller than the most massive black holes that are seen at later times. However, they are growing much faster. The measured rate of growth allowed the researchers to estimate what happened to these objects at much earlier as well as much later times. The team found that the very first black holes, those that started the entire growth process when the universe was only several hundred million years old, had masses of only 100-1000 times the mass of the sun. Such black holes may be related to the very first stars in the universe. They also found that the subsequent growth period of the observed sources, after the first 1.2 billion years, lasted only 100-200 million years.

The team found that the very first black holes ? those that started growing when the universe was only several hundred million years old ? had masses of only 100-1000 times the mass of the sun. Such black holes may be related to the very first stars in the universe. They also found that the subsequent growth period of these black holes, after the first 1.2 billion years, lasted only 100-200 million years.

The new study is the culmination of a seven year-long project at Tel Aviv University designed to follow the evolution of the most massive black holes and compare them with the evolution of the galaxies in which such objects reside.

The results will be reported in the Astrophysical Journal.

Source: American Friends of Tel Aviv University

Posted on by Nancy Atkinson

Will the Milky Way’s Black Hole Become ‘Hyperactive’?

Composite images of galaxies Abell 644, left, and galaxy SDSS J1021+131. Illustration credit: Credits: X-ray: NASA/CXC/Northwestern Univ/D.Haggard et al. Optical: SDSS

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From a NASA press release:

A new study from NASA’s Chandra X-ray Observatory tells scientists how often the biggest black holes have been active over the last few billion years. This discovery clarifies how supermassive black holes grow and could have implications for how the giant black hole at the center of the Milky Way will behave in the future.

Most galaxies, including our own, are thought to contain supermassive black holes at their centers, with masses ranging from millions to billions of times the mass of the Sun. For reasons not entirely understood, astronomers have found that these black holes exhibit a wide variety of activity levels: from dormant to just lethargic to practically hyper.

The most lively supermassive black holes produce what are called “active galactic nuclei,” or AGN, by pulling in large quantities of gas. This gas is heated as it falls in and glows brightly in X-ray light.

“We’ve found that only about one percent of galaxies with masses similar to the Milky Way contain supermassive black holes in their most active phase,” said Daryl Haggard of the University of Washington in Seattle, WA, and Northwestern University in Evanston, IL, who led the study. “Trying to figure out how many of these black holes are active at any time is important for understanding how black holes grow within galaxies and how this growth is affected by their environment.”

This study involves a survey called the Chandra Multiwavelength Project, or ChaMP, which covers 30 square degrees on the sky, the largest sky area of any Chandra survey to date. Combining Chandra’s X-ray images with optical images from the Sloan Digital Sky Survey, about 100,000 galaxies were analyzed. Out of those, about 1,600 were X-ray bright, signaling possible AGN activity.

Only galaxies out to 1.6 billion light years from Earth could be meaningfully compared to the Milky Way, although galaxies as far away as 6.3 billion light years were also studied. Primarily isolated or “field” galaxies were included, not galaxies in clusters or groups.

“This is the first direct determination of the fraction of field galaxies in the local Universe that contain active supermassive black holes,” said co-author Paul Green of the Harvard-Smithsonian Center for Astrophysics in Cambridge, MA. “We want to know how often these giant black holes flare up, since that’s when they go through a major growth spurt.”

A key goal of astronomers is to understand how AGN activity has affected the growth of galaxies. A striking correlation between the mass of the giant black holes and the mass of the central regions of their host galaxy suggests that the growth of supermassive black holes and their host galaxies are strongly linked. Determining the AGN fraction in the local Universe is crucial for helping to model this parallel growth.

One result from this study is that the fraction of galaxies containing AGN depends on the mass of the galaxy. The most massive galaxies are the most likely to host AGN, whereas galaxies that are only about a tenth as massive as the Milky Way have about a ten times smaller chance of containing an AGN.

Another result is that a gradual decrease in the AGN fraction is seen with cosmic time since the Big Bang, confirming work done by others. This implies that either the fuel supply or the fueling mechanism for the black holes is changing with time.

The study also has important implications for understanding how the neighborhoods of galaxies affects the growth of their black holes, because the AGN fraction for field galaxies was found to be indistinguishable from that for galaxies in dense clusters.

“It seems that really active black holes are rare but not antisocial,” said Haggard. “This has been a surprise to some, but might provide important clues about how the environment affects black hole growth.”

It is possible that the AGN fraction has been evolving with cosmic time in both clusters and in the field, but at different rates. If the AGN fraction in clusters started out higher than for field galaxies — as some results have hinted — but then decreased more rapidly, at some point the cluster fraction would be about equal to the field fraction. This may explain what is being seen in the local Universe.

The Milky Way contains a supermassive black hole known as Sagittarius A* (Sgr A*, for short). Even though astronomers have witnessed some activity from Sgr A* using Chandra and other telescopes over the years, it has been at a very low level. If the Milky Way follows the trends seen in the ChaMP survey, Sgr A* should be about a billion times brighter in X-rays for roughly 1% of the remaining lifetime of the Sun. Such activity is likely to have been much more common in the distant past.

If Sgr A* did become an AGN it wouldn’t be a threat to life here on Earth, but it would give a spectacular show at X-ray and radio wavelengths. However, any planets that are much closer to the center of the Galaxy, or directly in the line of fire, would receive large and potentially damaging amounts of radiation.

These results were published in the November 10th issue of the Astrophysical Journal. Other co-authors on the paper were Scott Anderson of the University of Washington, Anca Constantin from James Madison University, Tom Aldcroft and Dong-Woo Kim from Harvard-Smithsonian Center for Astrophysics and Wayne Barkhouse from the University of North Dakota.

Posted on by Nicholos Wethington

Taking a Galaxy’s Temperature

The image above shows the variation in temperature over the span of NGC 5813. The outline encircles a region 367,000 light years in diameter, and the temperatures indicated are in millions of degrees. Red indicates warmer temperatures, blue cooler. This image uses information from the Chandra X-Ray Observatory and optical imaging from the Sloan Digital Sky Survey (SDSS). Image Credit: Credit: X-ray: NASA/CXC/SAO/S.Randall et al., Optical: SDSS

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The role that supermassive black holes play in the formation of galaxies is a “hot” topic in astronomy. Using the Chandra X-Ray Observatory, an international team of astronomers have been able to create a temperature map of one galaxy, NGC 5813, which is located in the Virgo III Group of galaxies. The new map shows in unprecedented detail the history of various periods of activity of the Active Galactic Nucleus (AGN), which is associated with a supermassive black hole that resides at its center. They found that regular outbursts of the AGN maintained the temperature of the gas in the region of the galaxy, continually reheating the gas that would otherwise have cooled down.

Paper co-author Dr. Scott Randall of the Chandra Mission Planning Team at the Harvard-Smithsonian Center for Astrophysics said, “Although there are other systems that show AGN outburst shocks, this is still the only system where unambiguous shocks from multiple outbursts are seen. This allows us to directly measure the heating from shocks, and directly observe how often these shocks take place. Thus, at present NGC 5813 is *uniquely* well suited to the study of AGN heating.”

By studying images taken by the Chandra X-Ray Observatory, and combining these observations with those taken by the Giant Metrewave Radio Telescope (GMRT) and the Southern Astrophysical Research Telescope (SOAR), they were able to make out large cavities produced by periods of activity in the supermassive black hole. The researchers were able to determine that there were three pairs of large cavities, which corresponded to active outbursts of the galactic nucleus 3 million, 20 million and 90 million years ago (from our perspective here on Earth).

What makes the galaxy NGC 5813 especially suited to this study is its relative isolation from other galaxies that could influence the formation of these cavities – it is an older galaxy that is relatively undisturbed, allowing for these cavities in the gas to persist over such a long time period.

Current models of galaxy formation must take into account just how much of an influence the output of the supermassive black hole at the center of a galaxy has on the formation of stars within the galaxy, and the evolution of the shape and size of the galaxy as a whole. This process of “AGN feedback” has a dramatic influence on how the galaxy takes shape. The research by Dr. Randall, et. al shows an intimate portrait of this process.

Dr. Randall explained, “This is an important result for stellar formation and galaxy evolution. The AGN heats the gas, preventing it from cooling and forming large amounts of stars. There have been several galaxy evolution models proposed that require this kind of “AGN feedback” near the centers of galaxies to explain the observed differences in galaxies. Here we show explicitly that this kind of feedback can and does take place, at least in this system.”

A labeled image of the various shock waves and cavities formed by the activity of the AGN. Image Credit: Credit: NASA/CXC/SAO/S.Randall et al.

As you can see in the image directly above, various outbursts of the AGN create shock waves in the gas near the center of the galaxy. As these shock waves expanded and the galaxy evolved over millions of years, the heat generated by the shocks spread outwards and into the gas surrounding NGC 5813. The gas between all of the galaxies in a cluster is called the intracluster medium (ICM). The heat – which is produced by the friction of the gases at the edge of each of the shock waves – radiates outward into the surrounding gas, increasing its temperature.

The output of the jets streaming from the supermassive black hole in the center vary over a span of roughly 10 million years, and the amount of energy that each outburst puts out is rather variable – the difference between the last two largest outbursts, for example, is almost an order of magnitude.

This process is cyclical, though the details of the mechanisms involved are still a topic that isn’t completely understood.

Dr. Randall explained this process as follows:

“…the gas cools radiatively, and flows in towards the AGN. The cool gas is rapidly accreted by the black hole, dirving [sic] an energetic outburst. The outburst heats the gas (via shocks), stopping the inflow and starving the AGN. The gas is then able to cool once more, and the cycle repeats, with, in this case, a period of about 10 million years. However, the fine details of how the jet and the ICM interact are not currently well uderstood [sic], and it is not clear how well this simple model describes reality. Our goal with the upcoming deep Chandra observation is to better understand the details of this process, most likely through comparisons with detailed numerical simulations.”

Further observations of NGC 5813 in the fall of 2011 using Chandra are in the works, Dr. Randall said. The results of their analysis will be published in the Astrophysical Journal. A preprint version of the paper, “Shocks and Cavities from Multiple Outbursts in the Galaxy Group NGC 5813: A Window to AGN Feedback,” is available on Arxiv.

Sources: Chandra press release, Arxiv paper, email interview with Dr. Scott Randall

Posted on by Steve Nerlich

Astronomy Without A Telescope – Black Hole Evolution

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While only observable by inference, the existence of supermassive black holes (SMBHs) at the centre of most – if not all – galaxies remains a compelling theory supported by a range of indirect observational methods. Within these data sources, there exists a strong correlation between the mass of the galactic bulge of a galaxy and the mass of its central SMBH – meaning that smaller galaxies have smaller SMBHs and bigger galaxies have bigger SMBHs.

Linked to this finding is the notion that SMBHs may play an intrinsic role in galaxy formation and evolution – and might have even been the first step in the formation of the earliest galaxies in the universe, including the proto-Milky Way.

Now, there are a number of significant assumptions built into this line of thinking, since the mass of a galactic bulge is generally inferred from the velocity dispersion of its stars – while the presence of supermassive black holes in the centre of such bulges is inferred from the very fast radial motion of inner stars – at least in closer galaxies where we can observe individual stars.

For galaxies too far away to observe individual stars – the velocity dispersion and the presence of a central supermassive black hole are both inferred – drawing on the what we have learnt from closer galaxies, as well as from direct observations of broad emission lines – which are interpreted as the product of very rapid orbital movement of gas around an SMBH (where the ‘broadening’ of these lines is a result of the Doppler effect).

But despite the assumptions built on assumptions nature of this work, ongoing observations continue to support and hence strengthen the theoretical model. So, with all that said – it seems likely that, rather than depleting its galactic bulge to grow, both an SMBH and the galactic bulge of its host galaxy grow in tandem.

It is speculated that the earliest galaxies, which formed in a smaller, denser universe, may have started with the rapid aggregation of gas and dust, which evolved into massive stars, which evolved into black holes – which then continued to grow rapidly in size due to the amount of surrounding gas and dust they were able to accrete.

Distant quasars may be examples of such objects which have grown to a galactic scale. However, this growth becomes self-limiting as radiation pressure from an SMBH’s accretion disk and its polar jets becomes intense enough to push large amounts of gas and dust out beyond the growing SMBH’s sphere of influence. That dispersed material contains vestiges of angular momentum to keep it in an orbiting halo around the SMBH and it is in these outer regions that star formation is able to take place. Thus a dynamic balance is reached where the more material an SMBH eats, the more excess material it blows out – contributing to the growth of the galaxy that is forming around it.

The almost linear correlation between the SMBH mass (M) and velocity dispersion (sigma) of the galactic bulge (the 'M-sigma relation') suggests that there is some kind of co-evolution going on between an SMBH and its host galaxy. The only way an SMBH can get bigger is if its host galaxy gets bigger - and vice versa. The left chart shows data points derived from different objects in a galaxy - the right chart shows data points derived from different types of galaxies. Credit: Tremaine et al. (2002).

To further investigate the evolution of the relationship between SMBHs and their host galaxies – Nesvadba et al looked at a collection of very red-shifted (and hence very distant) radio galaxies (or HzRGs). They speculate that their selected group of galaxies have reached a critical point – where the feeding frenzy of the SMBH is blowing out about as much material as it is taking in – a point which probably represents the limit of the active growth of the SMBH and its host galaxy.

From that point, such galaxies might grow further by cannibalistic merging – but again this may lead to a co-evolution of the galaxy and the SMBH – as much of the contents of the galaxy being eaten gets used up in star formation within the feasting galaxy’s disk and bulge, before whatever is left gets through to feed the central SMBH.

Other authors (e.g. Schulze and Gebhardt), while not disputing the general concept, suggest that all the measurements are a bit out as a result of not incorporating dark matter into the theoretical model. But, that is another story…

Further reading: Nesvadba et al. The black holes of radio galaxies during the “Quasar Era”: Masses, accretion rates, and evolutionary stage.

Posted on by Nancy Atkinson

Penrose: WMAP Shows Evidence of ‘Activity’ Before Big Bang

WMAP data of the Cosmic Microwave Background. Credit: NASA
WMAP data of the Cosmic Microwave Background. Credit: NASA

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Have scientists seen evidence of time before the Big Bang, and perhaps a verification of the idea of the cyclical universe? One of the great physicists of our time, Roger Penrose from the University of Oxford, has published a new paper saying that the circular patterns seen in the WMAP mission data on the Cosmic Microwave Background suggest that space and time perhaps did not originate at the Big Bang but that our universe continually cycles through a series of “aeons,” and we have an eternal, cyclical cosmos. His paper also refutes the idea of inflation, a widely accepted theory of a period of very rapid expansion immediately following the Big Bang.

Penrose says that inflation cannot account for the very low entropy state in which the universe was thought to have been created. He and his co-author do not believe that space and time came into existence at the moment of the Big Bang, but instead, that event was just one in a series of many. Each “Big Bang” marked the start of a new aeon, and our universe is just one of many in a cyclical Universe, starting a new universe in place of the one before.

Penrose’s co-author, Vahe Gurzadyan of the Yerevan Physics Institute in Armenia, analyzed seven years’ worth of microwave data from WMAP, as well as data from the BOOMERanG balloon experiment in Antarctica. Penrose and Gurzadyan say they have identified regions in the microwave sky where there are concentric circles showing the radiation’s temperature is markedly smaller than elsewhere.

These circles allow us to “see through” the Big Bang into the aeon that would have existed beforehand. The circles were created when black holes “encountered” or collided with a previous aeon.

“Black-hole encounters, within bound galactic clusters in that previous aeon, would have the observable effect, in our CMB sky,” the duo write in their paper, “of families of concentric circles over which the temperature variance is anomalously low.”

And these circles don’t jive with the idea of inflation, because inflation proposes that the distribution of temperature variations across the sky should be Gaussian, or random, rather than having discernable structures within it.

Penrose’s new theory even projects how the distant future might emerge, where things will again be similar to the beginnings of the Universe at the Big Bang where the Universe was smooth, as opposed to the current jagged form. This continuity of shape, he maintains, will allow a transition from the end of the current aeon, when the universe will have expanded to become infinitely large, to the start of the next, when it once again becomes infinitesimally small and explodes outwards from the next big bang.

Penrose and Gurzadyan say that the entropy at the transition stage will be very low, because black holes, which destroy all information that they suck in, evaporate as the universe expands and in so doing remove entropy from the universe.

“These observational predictions of (Conformal cyclic cosmology) CCC would not be easily explained within standard inflationary cosmology,” they write in their paper.

Read Penrose and Gurzadyan’s paper: “Concentric circles in WMAP data may provide evidence of violent pre-Big-Bang activity”

Additional source: PhysicsWorld

Posted on by Nancy Atkinson

Has a Recent, Nearby Supernova Become a Baby Black Hole?

This composite image shows a supernova within the galaxy M100 that may contain the youngest known black hole in our cosmic neighborhood. Credits: X-ray: NASA/CXC/SAO/D.Patnaude et al, Optical: ESO/VLT, Infrared: NASA/JPL/Caltech

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Back in 1979, amateur astronomer Gus Johnson discovered a supernova about 50 million light years away from Earth, when a star about 20 times more massive than our Sun collapsed. Since then, astronomers have been keeping an eye on SN 1979C, located in M 100 in the Virgo cluster. With observations from the Chandra telescope, the X-ray emissions from the object have led astronomers to believe the supernova remnant has become a black hole. If so, it would be the youngest black hole known to exist in our nearby cosmic neighborhood and would provide astronomers the unprecedented opportunity to watch this type of object develop from infancy.

“If our interpretation is correct, this is the nearest example where the birth of a black hole has been observed,” said astronomer Daniel Patnaude during a NASA press briefing on Monday. Patnaude is from the Harvard-Smithsonian Center for Astrophysics and is the lead author of a new paper.


SN 1970C belongs to a type of supernova explosions called Type II linear, or core collapse supernovae, which make up about 6% of known stellar explosions. While many new black holes in the distant universe previously have been detected in the form of gamma-ray bursts (GRBs), SN 1979C is different because it is much closer and core collapse supernovae are unlikely to be associated with a GRB. Theories say that most black holes should form when the core of a star collapses and a gamma-ray burst is not produced, but this may be the first time that this method of making a black hole has been observed.

There has been a debate on what size star will create a black hole what size will create a neutron star. The 20 solar mass size is right on the boundary between the two, so astronomers are not completely sure this is a black hole or a neutron star. But since the X-ray emissions from this object have been steady over the past 31 years, astronomers believe this is a black hole, since as a neutron star cools, the X-ray emissions fade.

This animation shows how a black hole may have formed in SN 1979C. The collapse of a massive star is shown, after it has exhausted its fuel. A flash of light from a shock breaking through the surface of the star is then shown, followed by a powerful supernova explosion. The view then zooms into the center of the explosion: Credits: NASA/CXC/A.Hobart

However, as a caveat, co-author Avi Loeb said, it really takes about a lot longer than 31 years to see big changes, but he said the fact that the illumination has been steady gives evidence for a black hole.

Although the evidence does point to a newly formed black hole, there are a few other possibilities of what it could be. Some have suggested the object could be a magnetar or a blast wave, but the evidence is showing those two options are not very probable.

Another intriguing possibility is that a young, rapidly spinning neutron star with a powerful wind of high energy particles could be responsible for the X-ray emission. This would make the object in SN 1979C the youngest and brightest example of such a “pulsar wind nebula” and the youngest known neutron star. The Crab pulsar, the best-known example of a bright pulsar wind nebula, is about 950 years old.

“I’m excited about this discovery regardless if it turns out to be black hole or a pulsar wind nebula,” said astrophysicst Alex Fillipenko, who participated in the briefing. “A pulsar wind nebula would be interesting because it would be the youngest known in that category.”

“What is really exciting is that for the first time we know the exact birth date of this object,” said Kim Weaver, an astrophycisict from Goddard Space Flight Center, “We know it is very young and we want to watch how the system evolves and changes, as it grows into a child and becomes a teenager. More importantly, we’ll be able to understand the physics. This is a story of science in action.”

The age of the possible black hole is, of course, based on our vantage point. Since the galaxy is 50 million light years away, the supernova occurred 50 million years ago. But for us, the explosion took place just 31 years ago.

Read the team’s paper: Evidence for a Black Hole Remnant in the Type IIL Supernova 1979C
Authors: D.J. Patnaude, A. Loeb, C. Jones.

Source: NASA TV briefing, NASA

Posted on by Jon Voisey

What Hanny’s Voorwerp Reveals About Quasar Deaths

The green "blob" is Hanny's Voorwerp. Credit: Dan Herbert, Peter Smith, Matt Jarvis, Galaxy Zoo Team, Isaac Newton Telescope

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Hanny’s Voorwerp is a popular topic of conversation due to its novel discovery by Hanny Van Arkel perusing images from the Galaxy Zoo project. The tale has become so well known, it was made into a comic book (view here as .pdf, 35MB). But another aspect of the story is how enigmatic the object is. Objects that are so green are rare and it lacked a direct power source to energize it. It was eventually realized a quasar in the neighboring galaxy, IC 2497 could supply the necessary energy. Yet images of the galaxy couldn’t confirm a sufficiently energetic quasar. A new paper discusses what may have happened to the source.


The evidence that a quasar must be involved comes from the green color of the voorwerp itself. Spectra of the object has shown that this coloration is due to a strong level of ionized oxygen, specifically the λ5007 line of O III. While other scenarios could account for this feature alone, the spectra also contained He II emission as well as Ne V and the lines were especially narrow. Should star formation or shockwaves energize the gas, the motions would cause Doppler broadening. An quasar powered Active Galactic Nucleus (AGN) was the best fit.

But when telescopes searched for this quasar in the galaxy, it proved elusive. Optical images from WIYN Observatory were unable to resolve the expected point source. Radio observations discovered an object emitting in this range, but far below the amount of energy necessary to power the luminous Voorwerp. Two solutions have been proposed:

“1) the quasar in IC 2497 features a novel geometry of obscuring material and is obscured at an unprecedented level only along our line of sight, while being virtually unobscured towards the Voorwerp; or 2) the quasar in IC 2497 has shut down within the last 70,000 years, while the Voorwerp remains lit up due to the light travel time from the nucleus.”

Recent observations from Suzaku have ruled out the first of these possibilities due to the lack of potassium absorption that would be expected if light from the galaxy were being absorbed in a significant amount. Thus, the conclusion is that the AGN has dropped in total output by at least two orders of magnitude, but more likely by four. In many ways, this is not entirely unexpected since quasars are plentiful in the distant universe where raw material on which to feed was more plentiful. In the present universe, quasars rarely have such material available and can’t maintain it indefinitely.

Analogs exist within our own galaxy. X-Ray Binaries (XRBs) are stellar mass black holes which form similar accretion disks and can shut down and excite on short timescales (~1 year). The authors of the new paper attempted to scale up a model XRB system to determine if the timescales would fit with the ~70,000 year upper limit imposed by the travel time. While they found a good agreement with the output from direct accretion itself (10,000–100,000 years) the team found a discrepancy in the disk. In XRBs, the material around the black hole is heated as well, and takes some time to cool down. In this case, the core of the galaxy should still retain a hot disc of material which isn’t present.

This oddity demonstrates that there is still a large amount of knowledge to be gained on the physics surrounding these objects. Fortunately, the relatively close proximity of IC 2497 allows for the potential for detailed followup studies.

Posted on by Steve Nerlich

Astronomy Without A Telescope – Blazar Jets

A 5000 light year long jet observable in optical light from the giant elliptical galaxy M87 - which is not technically a blazar, but only because it's jet isn't more closely aligned with Earth. Credit: ESA/Hubble.

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Polar jets are often found around objects with spinning accretion disks – anything from newly forming stars to ageing neutron stars. And some of the most powerful polar jets arise from accretion disks around black holes, be they of stellar or supermassive size. In the latter case, jets emerging from active galaxies such as quasars, with their jets roughly orientated towards Earth, are called blazars.

The physics underlying the production of polar jets at any scale is not completely understood. It is likely that twisting magnetic lines of force, generated within a spinning accretion disk, channel plasma from the compressed centre of the accretion disk into the narrow jets we observe. But exactly what energy transfer process gives the jet material the escape velocity required to be thrown clear is still subject to debate.

In the extreme cases of black hole accretion disks, jet material acquires escape velocities close to the speed of light – which is needed if the material is to escape from the vicinity of a black hole. Polar jets thrown out at such speeds are usually called relativistic jets.

Relativistic jets from blazars broadcast energetically across the electromagnetic spectrum – where ground based radio telescopes can pick up their low frequency radiation, while space-based telescopes, like Fermi or Chandra, can pick up high frequency radiation. As you can see from the lead image of this story, Hubble can pick up optical light from one of M87‘s jets – although ground-based optical observations of a ‘curious straight ray’ from M87 were recorded as early as 1918.

Polar jets are thought to be shaped (collimated) by twisting magnetic lines of force. The driving force that pushes the jets out may be magnetic and/or intense radiation pressure, but no-one is really sure at this stage. Credit: NASA.

A recent review of high resolution data obtained from Very Long Baseline Interferometry (VLBI) – involving integrating data inputs from geographically distant radio telescope dishes into a giant virtual telescope array – is providing a bit more insight (although only a bit) into the structure and dynamics of jets from active galaxies.

The radiation from such jets is largely non-thermal (i.e. not a direct result of the temperature of the jet material). Radio emission probably results from synchrotron effects – where electrons spun rapidly within a magnetic field emit radiation across the whole electromagnetic spectrum, but generally with a peak in radio wavelengths. The inverse Compton effect, where a photon collision with a rapidly moving particle imparts more energy and hence a higher frequency to that photon, may also contribute to the higher frequency radiation.

Anyhow, VLBI observations suggest that blazar jets form within a distance of between 10 or 100 times the radius of the supermassive black hole – and whatever forces work to accelerate them to relativistic velocities may only operate over the distance of 1000 times that radius. The jets may then beam out over light year distances, as a result of that initial momentum push.

Shock fronts can be found near the base of the jets, which may represent points at which magnetically driven flow (Poynting flux) fades to kinetic mass flow – although magnetohydrodynamic forces continue operating to keep the jet collimated (i.e. contained within a narrow beam) over light year distances.

Left: A Xray/radio/optical composite photo of Centaurus A - also not technically a blazar because its jets don't align with the Earth. Credit: X-ray: NASA/CXC/CfA/R.Kraft et al.; Submillimeter: MPIfR/ESO/APEX/A.Weiss et al.; Optical: ESO/WFI. Right: A composite image showing the radio glow from Centaurus A compared with that of the full Moon. The foreground antennas are CSIRO's Australia Telescope Compact Array, which gathered the data for this image.

That was about as much as I managed to glean from this interesting, though at times jargon-dense, paper.

Further reading: Lobanov, A. Physical properties of blazar jets from VLBI observations.