Detail View: NASA Astronomy Picture of the Day Collection: Cyg X-1: Can Black Holes Form in the Dark?

Cyg X-1: Can Black Holes Form in the Dark?
The formation of a black hole [ black_holes.html ] from the collapsing core of a massive star is thought to be heralded by a spectacular supernova explosion. Such an extremely energetic collapse is also a leading explanation [ ] for the mysterious cosmic gamma-ray bursts [ ]. But researchers now suggest that the Milky Way's most famous black hole, Cygnus X-1 [ blkbin.html#c2 ], was born when a massive star collapsed -- without any supernova explosion [ ] at all. Their dynamical evidence is summarized in this color image of a gorgeous region in Cygnus [ cygX1-more3.html ], showing Cyg X-1 and a cluster of massive stars (yellow circles) known as Cygnus OB3. Arrows compare the measured direction and speed of Cyg X-1 and the average direction and speed of the massive stars of Cyg OB3. The similar motions indicate that Cyg X-1's progenitor star was itself a cluster member and that its path was not altered at all when it became a black hole [ blackholes_stellar.html ]. In contrast, if Cyg X-1 were born in a violent supernova it would have likely received a fierce kick [ ], changing its course. If not a supernova, could the formation of the Cyg X-1 black hole have produced a dark gamma-ray burst in the Milky Way [ ]?
Credit and Copyright: 
I. F. Mirabel [ ] and I. Rodrigues (IAFE [ ], SAp/CEA [ ])
Goddard Space Flight Center (GSFC)
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