New Chandra images of Sagittarius A* (Sgr A*), which is located about 26,000 light-years from Earth, indicate that less than 1 percent of the gas initially within Sgr A*'s gravitational grasp ever reaches the point of no return, also called the event horizon. Instead, much of the gas is ejected before it gets near the event horizon and has a chance to brighten, leading to feeble X-ray emission.
X-ray: NASA/UMass/D. Wang et al., IR: NASA/STScI
One of the biggest observing campaigns ever performed by Chandra has provided new understanding into why gas near the giant black hole at the center of the Milky Way is extraordinarily faint in X-rays. The large image contains X-rays from Chandra (blue) and infrared emission from the Hubble (red and yellow). The inset shows a close-up of Sgr A* in X-rays only, covering a region half a light year wide. The diffuse X-ray emission is from hot gas captured by the black hole and being pulled inwards. The new results indicate that less than 1% of the material that is initially within the black hole’s gravitational grasp reaches the event horizon, or, point of no return.
These new findings are the result of one of the longest observation campaigns ever performed with Chandra. The spacecraft collected five weeks' worth of data on Sgr A* in 2012. The researchers used this observation period to capture unusually detailed and sensitive X-ray images and energy signatures of super-heated gas swirling around Sgr A*, whose mass is about 4 million times that of the sun.
"We think most large galaxies have a supermassive black hole at their center, but they are too far away for us to study how matter flows near it," said Q. Daniel Wang of the University of Massachusetts at Amherst, who led a study published Thursday in the journal Science. "Sgr A* is one of very few black holes close enough for us to actually witness this process."
The researchers found that the Chandra data from Sgr A* did not support theoretical models in which the X-rays are emitted from a concentration of low-mass stars around the black hole. Instead, the X-ray data show the gas near the black hole likely originates from winds produced by a disk-shaped distribution of young massive stars.
"This new Chandra image is one of the coolest I’ve ever seen," said co-author Sera Markoff of the University of Amsterdam in the Netherlands. "We're watching Sgr A* capture hot gas ejected by nearby stars, and funnel it in towards its event horizon."
To plunge over the event horizon, material captured by a black hole must lose heat and momentum. The ejection of matter allows this to occur.
"Most of the gas must be thrown out so that a small amount can reach the black hole", said co-author Feng Yuan of Shanghai Astronomical Observatory in China. "Contrary to what some people think, black holes do not actually devour everything that’s pulled towards them. Sgr A* is apparently finding much of its food hard to swallow."
The gas available to Sgr A* is very diffuse and super-hot, so it is hard for the black hole to capture and swallow it. The gluttonous black holes that power quasars and produce huge amounts of radiation have gas reservoirs much cooler and denser than that of Sgr A*.
The event horizon of Sgr A* casts a shadow against the glowing matter surrounding the black hole. This research could aid efforts using radio telescopes to observe and understand the shadow. It also will be useful for understanding the effect orbiting stars and gas clouds may have on matter flowing toward and away from the black hole.
NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.
Megan Watzke | Newswise
Structured light and nanomaterials open new ways to tailor light at the nanoscale
23.04.2018 | Academy of Finland
On the shape of the 'petal' for the dissipation curve
23.04.2018 | Lobachevsky University
Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.
Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.
Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
23.04.2018 | Physics and Astronomy
23.04.2018 | Physics and Astronomy
23.04.2018 | Trade Fair News