Supermassive Black Holes Are Outgrowing Their Galaxies

Chandra Deep Field South 
Credit  X-ray: NASA/CXC/Penn. State/G. Yang et al & NASA/CXC/ICE/M. Mezcua et al.; 
Optical: NASA/STScI; Illustration: NASA/CXC/A. Jubett

The growth of the biggest black holes in the Universe is outrunning the rate of formation of stars in the galaxies they inhabit, according to two new studies using data from NASA’s Chandra X-ray Observatory and other telescopes and described in our latest press release.
In this graphic an image from the Chandra Deep Field-South is shown. The Chandra image (blue) is the deepest ever obtained in X-rays. It has been combined with an optical and infrared image from the Hubble Space Telescope (HST), colored red, green, and blue. Each Chandra source is produced by hot gas falling towards a supermassive black hole in the center of the host galaxy, as depicted in the artist’s illustration.
One team of researchers, led by Guang Yang at Penn State, calculated the ratio between a supermassive black hole’s growth rate and the growth rate of stars in its host galaxy and found it is much higher for more massive galaxies. For galaxies containing about 100 billion solar masses worth of stars, the ratio is about ten times higher than it is for galaxies containing about 10 billion solar masses worth of stars.
Using large amounts of data from Chandra, HST and other observatories, Yang and his colleagues studied the growth rate of black holes in galaxies at distances of 4.3 to 12.2 billion light years from Earth. The X-ray data included the Chandra Deep Field-South and North surveys and the COSMOS-Legacy surveys.
Another group of scientists, led by Mar Mezcua of the Institute of Space Sciences in Spain, independently studied 72 galaxies located at the center of galaxy clusters at distances ranging up to about 3.5 billion light years from Earth and compared their properties in X-ray and radio waves. Their work indicates that the black hole masses were about ten times larger than masses estimated by another method using the assumption that the black holes and galaxies grew in tandem.

Hercules A
Credit: X-ray: NASA/CXC/SAO, Optical: NASA/STScI, Radio: NSF/NRAO/VLA
The Mezcua study used X-ray data from Chandra and radio data from the Australia Telescope Compact Array, the Karl G. Jansky Very Large Array (VLA) and Very Long Baseline Array. One object in their sample is the large galaxy in the center of the Hercules galaxy cluster. The image shown above includes Chandra data (purple), VLA data (blue) and HST optical data (appearing white).
Two papers describing these results have been accepted in the Monthly Notices of the Royal Astronomical Society (MNRAS). The work by Mezcua et al. was published in the February 2018 issue MNRAS (available online: The paper by Yang et al. will appear in its April 2018 issue (available online:
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.

Fast Facts for Chandra Deep Field South:

Scale: Image is 9.25 arcsec (About 574,000 light years) across;
Category: Cosmology/Deep Fields/X-ray Background, Black Holes
Constellation: Fornax
Observation Date: 54 pointings between Oct 15, 1999 to Jul 22, 2010

Observation Time: 1111 hours 6 minutes (46 days 7 hours 6 min)
Obs. ID: 441, 581-582, 1431, 1672, 2239, 2312-2313, 2405-2406, 2409, 8591-8597, 9575, 9578, 9593, 9596, 9718, 12043-12055, 12123, 12128-12129, 12135, 12137-12138, 12213, 12218-12220, 12222-12223, 12227, 12230-12234

Instrument: ACIS

References: “Linking black hole growth with host galaxies: the accretion-stellar mass relation and its cosmic evolution”,G. Yang et al., 2018, MNRAS, 475, 1887. arXiv:1710.09399 “The most massive black holes on the Fundamental Plane of Black Hole Accretion”, M. Mazcua et al., 2018, MNRAS, 474, 1342. arXiv:1710.10268

Color Code: X-ray (Blue); IR (Red, Green); Optical (Green, Blue)
Distance Estimate: Range of about 12.7 – 12.9 billion light years

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2018 February 15 Enceladus in Silhouette Image Credit: Cassini…

2018 February 15

Enceladus in Silhouette
Image Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA

Explanation: One of our Solar System’s most tantalizing worlds, Enceladus is backlit by the Sun in this Cassini spacecraft image from November 1, 2009. The dramatic illumination reveals the plumes that continuously spew into space from the south pole of Saturn’s 500 kilometer diameter moon. Discovered by Cassini in 2005, the icy plumes are likely connected to an ocean beneath the ice shell of Enceladus. They supply material directly to Saturn’s outer, tenuous E ring and make the surface of Enceladus as reflective as snow. Across the scene, Saturn’s icy rings scatter sunlight toward Cassini’s cameras. Beyond the rings, the night side of 80 kilometer diameter moon Pandora is faintly lit by Saturnlight.

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The search for dark matter: axions have ever-fewer places to hide

If they exist, axions, among the candidates for dark matter particles, could interact with the matter comprising the universe, but at a much weaker extent than previously theorized. New, rigorous constraints on the properties of axions have been proposed by an international team of scientists.

The search for dark matter: axions have ever-fewer places to hide
The distribution of dark matter (colored in blue) in six galaxy clusters, mapped from the visible-light images from
the Hubble Space Telescope [Credit: NASA, ESA, STScI, and CXC) Credit: NASA, ESA, STScI, and CXC]

The latest analysis of measurements of the electrical properties of ultracold neutrons, published in the scientific journal Physical Review X, has led to surprising conclusions. On the basis of data collected in the Electric Dipole Moment of Neutron (nEDM) experiment, an international group of physicists demonstrated that axions, hypothetical particles that may comprise cold dark matter, would have to comply with much stricter limitations than previously believed with regard to their mass and manners of interacting with ordinary matter. The results are the first laboratory data imposing limits on the potential interactions of axions with nucleons (i.e. protons or neutrons) and gluons (the particles bonding quarks in nucleons).

“Measurements of the electric dipole moment of neutrons have been conducted by our international group for a good dozen or so years. For most of this time, none of us suspected that any traces associated with potential particles of dark matter might be hidden in the collected data. Only recently, theoreticians have suggested such a possibility and we eagerly took the opportunity to verify the hypotheses about the properties of axions,” says Dr. Adam Kozela (IFJ PAN), one of the participants in the experiment.

Dark matter was first proposed to explain the movements of stars within galaxies and galaxies within galactic clusters. The pioneer of statistical research on star movements was the Polish astronomer Marian Kowalski. In 1859, he noticed that the movements of nearby stars could not be explained solely by the movement of the sun. This was the first observational evidence suggesting the rotation of the Milky Way. Kowalski is thus the man who “shook the foundations” of the galaxy. In 1933, the Swiss astronomer Fritz Zwicky went one step further. He analyzed the movements of structures in the Coma galaxy cluster using several methods. He then noticed that they moved as if there were a much larger amount of matter in their surroundings than that observed by astronomers.

Astronomers believe there should be almost 5.5 times as much dark matter in the universe as ordinary matter, as background microwave radiation measurements suggest. But the nature of dark matter is still unknown. Theoreticians have constructed many models predicting the existence of particles that are more or less exotic, which may account for dark matter. Among the candidates are axions. These extremely light particles would interact with ordinary matter almost exclusively via gravity. Current models predict that in certain situations, a photon could change into an axion, and after some time, transform back into a photon. This hypothetical phenomenon is the basis of the famous “lighting through a wall” experiments. These involve directing an intense beam of laser light onto a thick obstacle, and observing those photons that change into axions that penetrate the wall. After passing through, some of the axions could become photons again, with features exactly like those originally directed at the barrier.

Experiments related to measuring the electric dipole moment of neutrons have nothing to do with photons. In experiments conducted for over 10 years, scientists measured changes in the frequency of nuclear magnetic resonance (NMR) of neutrons and mercury atoms in a vacuum chamber in the presence of electric, magnetic and gravitational fields. These measurements enabled the researchers to draw conclusions about the precession of neutrons and mercury atoms, and consequently on their dipole moments.

Theoretical works have appeared in recent years that envisage the possibility of axions interacting with gluons and nucleons. Depending on the mass of the axions, these interactions could result in smaller or larger disturbances with the character of oscillations of dipole electrical moments of nucleons, or even whole atoms. The predictions meant that experiments conducted as part of the nEDM cooperation could contain valuable information about the existence and properties of potential particles of dark matter.

“In the data from the experiments at PSI, our colleagues conducting the analysis looked for frequency changes with periods in the order of minutes, and in the results from ILL—in the order of days. The latter would appear if there was an axion wind, that is, if the axions in the near Earth space were moving in a specific direction. Since the Earth is spinning, at different times of the day our measuring equipment would change its orientation relative to the axion wind, and this should result in cyclical, daily changes in the oscillations recorded by us,” explains Dr. Kozela.

The results of the search turned out to be negative. No trace of the existence of axions with masses between 10-24 and 10-17 electron volts were found (for comparison: the mass of an electron is more than half a million electron volts). In addition, the scientists managed to tighten the constraints imposed by theory on the interaction of axions with nucleons by 40 times. In the case of potential interactions with gluons, the restrictions have increased more than 1000-fold. So if axions do exist, in the current theoretical models, they have fewer places to hide.

Source: The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences [February 15, 2018]