Black holes are everywhere. They can be left behind as the remnant of a massive star that exploded long ago, being just a few times the mass of our own Sun. Supermassive black holes, containing the mass of million or billions of Suns, sit at the centers of many galaxies. There has been controversy in the astronomical literature about the existence of intermediate mass back holes, and new evidence for one such "middle child" has been presented for an x-ray source in a distant galaxy.
"The candidate's name is HLX-1, and is a bright source of x-rays near a galaxy 300 million light years away. At that distance, it is too bright to be a stellar-mass black hole."
he emission from the accretion disk around a black hole is limited by the balance between the pressure of the stuff falling in and the pressure of the light itself pushing outwards. For it to be a "normal" black hole, such "ultraluminous" sources would have to have some extra effects thrown in to the model. But this "hyper-ultraluminous" one is really difficult to explain unless it is a few hundred times the mass of the sun, putting it in the elusive intermediate size family.
There is the possibility, however, that we're looking at a supermassive black hole in an even more distant galaxy that just happens to line up with the galaxy it appears to be in. A very accurate measurement of the x-ray source's position with the Chandra X-Ray Observatory found that it coincided with a source in visible light, and the ratio of the visible light to x-ray light was not consistent with this hypothesis. However, more evidence is necessary.
That's where the group led by Klaas Wiersema comes in. They used the Very Large Telescope in Chile to take a spectrum of the visible light of the object. (You can think of that as separating the light into its rainbow of colors.)
This is a tricky situation, as they had to subtract out the spectrum of the galaxy itself. After this, they detected an emission line of hydrogen coming from the mysterious source, and confirmed that it did indeed originate from the galaxy it was near by its redshift. This means that the color of the emission line is slightly redder than you would expect as a result of the galaxy moving away from us in the ever-expanding universe.
Astronomers still aren't sure what makes up with visible light source that coincides with HLX-1. It could be a globular star cluster or the remnants of a dwarf galaxy that was torn apart by host spiral galaxy. Either one is a place where intermediate mass black holes are thought to exist. Though the search for such beasts continues, this is looking like a strong case for their existence in the case of these incredibly bright x-ray sources.
This work has been published in Astrophysical Journal Letters and the preprint is available on arxiv.org. Thanks again to Ned Wright's Cosmology Calculator.(source: discovery channel)
"The candidate's name is HLX-1, and is a bright source of x-rays near a galaxy 300 million light years away. At that distance, it is too bright to be a stellar-mass black hole."
he emission from the accretion disk around a black hole is limited by the balance between the pressure of the stuff falling in and the pressure of the light itself pushing outwards. For it to be a "normal" black hole, such "ultraluminous" sources would have to have some extra effects thrown in to the model. But this "hyper-ultraluminous" one is really difficult to explain unless it is a few hundred times the mass of the sun, putting it in the elusive intermediate size family.
There is the possibility, however, that we're looking at a supermassive black hole in an even more distant galaxy that just happens to line up with the galaxy it appears to be in. A very accurate measurement of the x-ray source's position with the Chandra X-Ray Observatory found that it coincided with a source in visible light, and the ratio of the visible light to x-ray light was not consistent with this hypothesis. However, more evidence is necessary.
That's where the group led by Klaas Wiersema comes in. They used the Very Large Telescope in Chile to take a spectrum of the visible light of the object. (You can think of that as separating the light into its rainbow of colors.)
This is a tricky situation, as they had to subtract out the spectrum of the galaxy itself. After this, they detected an emission line of hydrogen coming from the mysterious source, and confirmed that it did indeed originate from the galaxy it was near by its redshift. This means that the color of the emission line is slightly redder than you would expect as a result of the galaxy moving away from us in the ever-expanding universe.
Astronomers still aren't sure what makes up with visible light source that coincides with HLX-1. It could be a globular star cluster or the remnants of a dwarf galaxy that was torn apart by host spiral galaxy. Either one is a place where intermediate mass black holes are thought to exist. Though the search for such beasts continues, this is looking like a strong case for their existence in the case of these incredibly bright x-ray sources.
This work has been published in Astrophysical Journal Letters and the preprint is available on arxiv.org. Thanks again to Ned Wright's Cosmology Calculator.(source: discovery channel)
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