NASA Performs Headcount of Local Black Holes
October 6, 2006
This all-sky map contains all active supermassive black holes out to a distance of 400 million light years from Earth. This is an unbiased survey, and scientists are convinced that no active black hole (called AGN, for Active Galactic Nucleus) has gone uncounted. Shown here are all high-energy X-ray sources, which includes many star systems within our galaxy which are not part of the Swift black hole survey. The AGN are the light blue and green dots, largely "high" in the sky above and below the galactic plane. Credit: NASA/Swift/BAT/Markwardt et al.
NASA scientists using the Swift satellite have conducted the first complete census of galaxies with active, central black holes, a project that scanned the entire sky several times over a nine-month period.
The all-sky survey contains more than 200 supermassive black holes called Active Galactic Nuclei, or AGN, and provides a definitive census of black hole activity in the local universe. The team uncovered many new black holes that were previously missed, even in well-studied galaxies, and other surprises as well.
"We are confident that we are seeing every active, supermassive black hole within 400 million light years of Earth," said Jack Tueller of NASA’s Goddard Space Flight Center, Greenbelt, Md., who led the effort. "With each passing month, we are able to probe deeper into the universe, and the census becomes richer."
AGN have a mass of millions to billions of suns, which are confined within a region about the size of our solar system. The term "active" refers to the process of actively pulling in gas and whole stars and generating copious amounts of energy from a tiny galactic core in the process. Examples include quasars and Seyfert galaxies.
Swift was built primarily to study gamma-ray bursts. During waiting times between bursts, Swift's Burst Alert Telescope, which is sensitive to the highest-energy X-rays, scans the sky. AGN generate X-rays as well as many other forms of light. Many AGN, however, are hidden behind dust and gas, which block lower-energy light, such as visible light. Because higher-energy X-rays are so penetrating, Swift can detect AGN missed by other surveys, allowing for an unbiased count.
Nearly every massive galaxy seems to have a supermassive black hole, but only a few percent appear to be active. Our galaxy's central black hole is dormant, and this and similar black holes are not included in the Swift census. All black holes were likely once active, and why some remain active and others are dormant in the modern, local universe is a mystery.
"You can't understand the universe without understanding black holes," said Richard Mushotzky of Goddard, a census team leader. "Perhaps as much as 20 percent of all of the radiated energy in the universe---most X-rays, large fractions of ultraviolet and infrared light, and a good deal of radio waves---arise in one way or another from AGN activity."
One key census finding is the discovery of AGN in starburst galaxies, which are bright from star formation. These dust-enshrouded AGN, uncovered by Swift, will enable a detailed test of the idea that black hole activity and star formation go hand in glove, feeding each other. Swift also sees hints of cocooned black holes, so embedded in dust that they are completely invisible except in the higher-energy X-ray band.
The initial census results, from data collected in 2005, are a "first taste of things to come," Tueller said. Each scan of the sky is stacked atop existing scans, equivalent to a long camera exposure, so black holes from deeper in the universe will eventually be detected.
Swift builds upon two other surveys. The European INTEGRAL satellite completed a high-energy X-ray survey earlier in 2006, although this focused on the galactic plane and not the whole sky. NASA's Chandra X-ray Observatory conducted a lower-energy X-ray survey of a small fraction of the sky, providing a sample of the more-luminous black holes that formed in the early universe.
Swift also carries X-ray and ultraviolet/optical telescopes, enabling quick confirmation of new active galaxy candidates. This broad coverage in three wavelength regimes is critical for black hole studies.
"The Swift black hole catalogue can be used in a thousand ways," said Craig Markwardt of Goddard and the University of Maryland, who combined the nine-month Swift data into all-sky images. "It's hard to believe the whole sky is peppered with black holes. You need powerful X-ray vision like Swift's to see them."
A NASA Goddard team presents this census at a press conference today in San Francisco at the American Astronomical Society's High Energy Astrophysics Division meeting.
Source: by Christopher Wanjek, NASA/Goddard Space Flight Center
-
NASA's RXTE detect 'heartbeat' of smallest black hole candidate (w/ video)
Dec 15, 2011 |
4.8 / 5 (10) |
27
-
Leicester set to fly high in India's first-ever national astronomy mission
Dec 01, 2011 |
5 / 5 (1) |
0
-
Gamma-ray burst reveals surprising ingredients of early galaxies
Nov 02, 2011 |
4.9 / 5 (12) |
117
-
Stories of missions past: Early explorers
Oct 27, 2011 |
not rated yet |
1
-
Astrophysics and extinctions: News about planet-threatening events
Oct 07, 2011 |
4.4 / 5 (8) |
0
-
Engineers build first sub-10-nm carbon nanotube transistor
Feb 01, 2012 |
4.9 / 5 (28) |
26
-
Something old, something new: Evolution and the structural divergence of duplicate genes
Jan 31, 2012 |
4.6 / 5 (7) |
1
-
The hidden nanoworld of ice crystals: Revealing the dynamic behavior of quasi-liquid layers
Jan 30, 2012 |
5 / 5 (3) |
1
-
Stock market network reveals investor clustering
Jan 27, 2012 |
4 / 5 (22) |
8
-
Of microchemistry and molecules: Electronic microfluidic device synthesizes biocompatible probes
Jan 26, 2012 |
5 / 5 (1) |
0
-
Hypothetical way to travel faster than light, but not technically exceed lightspeed
14 hours ago
-
How do scientists monitor the Sun's activity?
Feb 05, 2012
-
Search patterns in observational studies
Feb 05, 2012
-
Derivation of Pogson's law
Feb 03, 2012
-
Landing on comet by Rosetta probe in 2014 (YouTube)
Feb 02, 2012
-
Star whose pressure support is degenerate electrons.
Feb 01, 2012
- More from Physics Forums - General Astronomy
More news stories
Russia 'drills into' Antarctic subglacial lake
A Russian team has succeeded in drilling through four kilometres (2.5 miles) of ice to the surface of a mythical subglacial Antarctic lake which could hold as yet unknown life forms, reports said Monday.
Space & Earth / Earth Sciences
18 hours ago |
5 / 5 (9) |
13
High planetary tilt lowers odds for life?
Highly-tilted worlds would have extreme seasons, subjecting life to alternating periods of scorching and subzero temperatures. This could make the development of all but hardiest, simplest creatures a long ...
Space & Earth / Space Exploration
18 hours ago |
4.8 / 5 (10) |
10
|
Researchers uncover a mechanism to explain dune field patterns
In a study of the harsh but beautiful White Sands National Monument in New Mexico, University of Pennsylvania researchers have uncovered a unifying mechanism to explain dune patterns. The new work represents a contribution ...
Space & Earth / Earth Sciences
11 hours ago |
3.5 / 5 (2) |
1
|
UNH ocean scientists shed new light on Mariana Trench
An ocean mapping expedition has shed new light on deepest place on Earth, the 2,500-kilometer long Mariana Trench in the western Pacific Ocean near Guam. Using a multibeam echo sounder, state-of-the-art equipment ...
Space & Earth / Earth Sciences
12 hours ago |
4.8 / 5 (5) |
0
|
ESO team succeeds in linking telescopes at Paranal Observatory into giant VLT
(PhysOrg.com) -- Researchers working as part of the European Southern Observatory (ESO) at the Cerra Paranal Mountain Observatory in the Atacama Desert in Chile, have succeeded in virtually connecting all ...
Our Amorphophallus is smaller: New plant species from Madagascar smells like roadkill
The famed "corpse flower" plant known for its giant size, rotten-meat odor and phallic shape has a new, smaller relative: A University of Utah botanist discovered a new species of Amorphophallus that i ...
Invasive alien predator causes rapid declines of European ladybirds
A new study provides compelling evidence that the arrival of the invasive non-native harlequin ladybird to mainland Europe and subsequent spread has led to a rapid decline in historically-widespread species ...
New findings highlight the benefit of exercise ECGs just as they are being scrapped
In the UK, the exercise electrocardiogram (ECG) is the most common initial test for the evaluation of stable chest pain and has been used widely for almost half a century. However, recent NICE guidelines recommend that it ...
Counties with thriving small businesses have healthier residents, researchers find
Counties and parishes with a greater concentration of small, locally-owned businesses have healthier populations with lower rates of mortality, obesity and diabetes than do those that rely on large companies ...
Long-term study shows epilepsy surgery improves seizure control and quality of life
While epilepsy surgery is a safe and effective intervention for seizure control, medical therapy remains the more prominent treatment option for those with epilepsy. However, a new 26-year study reveals that following epilepsy ...
New DVT guidelines: No evidence to support 'economy class syndrome'
New evidence-based guidelines from the American College of Chest Physicians (ACCP) address the many risk factors for developing a deep vein thrombosis (DVT), or blood clot, as the result of long-distance travel. These risk ...