Astronomers have identified the true nature of an unusual source in the Milky Way galaxy. As described in our latest press release, this discovery implies that there could be a much larger number of black holes in the Galaxy that have previously been unaccounted for.
The result was made by combining data from many different telescopes that detect various forms of light, each providing key pieces of information. These telescopes included NASA's Chandra X-ray Observatory, the Hubble Space Telescope, NSF's Karl G. Jansky Very Large Array (VLA), Green Bank Telescope, Arecibo Observatory, and the European Very Long Baseline Interferometry Network.
The collaborative nature of this study is depicted in this multi-panel graphic. The large panel shows a composite Chandra and optical image of the globular cluster M15 located in our galaxy, where the X-ray data are purple and the optical data are red, green and blue. The source being studied here is bright in radio waves, as shown in the close-up VLA image, but the Chandra data reveal it can only be giving off a very small amount of X-rays.
This new study indicates this source, called VLA J213002.08+120904 (VLA J2130+12 for short), contains a black hole a few times the mass of our Sun that is very slowly pulling in material from a companion star. At this paltry feeding rate, VLA J2130+12 was not previously flagged as a black hole since it lacks some of the telltale signs that black holes in binary systems typically display.
Previously, most astronomers thought that VLA J2130+12 was probably a distant galaxy. Precise measurements from the radio telescopes showed that this source was actually well within our Galaxy and about five times closer to us than M15. Hubble data identified the companion star in VLA J2130+12 having only about one-tenth to one-fifth the mass of the Sun.
The observed radio brightness and the limit on the X-ray brightness from Chandra allowed the researchers to rule out other possible interpretations, such as an ultra-cool dwarf star, a neutron star, or a white dwarf pulling material away from a companion star.
Because this study only covered a very small patch of sky, the implication is that there should be many of these quiet black holes around the Milky Way. The estimates are that tens of thousands to millions of these black holes could exist within our Galaxy, about three to thousands of times as many as previous studies have suggested.
A paper describing these results appeared in the Astrophysical Journal. The authors were Bailey Tetarenko (University of Alberta), Arash Bahramian (Alberta), Robin Aranson (Alberta), James Miller-Jones (International Center for Radio Astronomy Research), Serena Repetto (Technion), Craig Heinke (Alberta), Tom Maccarone (Texas Tech University), Laura Chomiuk (Michigan State Univsersity), Gregory Sivakoff (Alberta), Jay Strader (Michigan State), Franz Kirsten (ICRAR), and Wouter Vlemmings (Chalmers University of Technology).
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.
Unless we were incredibly lucky to find one source like this in a small patch of the sky, there must be many more of these black hole binaries in our Galaxy than we used to think.
Posted by Muhammad Junaid Ajwad on Wednesday, 12.14.16 @ 02:57am
Dear Robert Conrad,
The position that we quote is for the center of the image (not the position of the radio source). We did, however, double check the position of the image's center and found that there was a typo in the position, which has since been fixed. Thank you!
Posted by CXC on Wednesday, 07.6.16 @ 09:00am
Posted by ZL-B on Thursday, 06.30.16 @ 06:51am
Congratulations. Well spotted.
Posted by Mark Ballington on Wednesday, 06.29.16 @ 09:38am
Are the RA and DEC coordinates correct that you posted? Based on the image, it looks like the location is right next to M15 or even part of it but when I plot this on detailed star charts, it's about 2.5 degrees to the right. I did a little research and found the article with the correct coordinates. Should be 21h 30m 02.086s, and 12 9702 09 8242 04.220 which would make more sense. Here is the article - the coordinates can be found on page 2
Posted by Robert Conrad on Monday, 06.27.16 @ 20:12pm