Possible orphan black hole lies just 90 million light-years from Earth

An unusual object about 90 million light-years from Earth might be a supermassive black hole kicked out of its home galaxy during a collision with another galaxy, a new study suggests. If so, it’s the first evictee to be confirmed as such by astronomers. The object, dubbed SDSS1133, lies about 2600 light-years from the center of a dwarf galaxy known as Markarian 177 (both of which lie within the bowl of the Big Dipper, a familiar star pattern in the constellation Ursa Major). SDSS1133 has brightened substantially over the past 2 years but has been spotted in images taken by various instruments during the past 63 years, hinting that the object—whose brightest features measure less than 40 light-years across—probably isn’t a recently exploded supernova. Recent observations of Markarian 177 reveal specific areas of intense star formation, possible signs of a recent galactic collision that expelled SDSS1133 from the parent galaxy where it once resided, the researchers reported online before print in the Monthly Notices of the Royal Astronomical Society. (The video depicts the purported 2.7-billion-year-long intergalactic collision and its aftermath.) According to an alternate scenario, SDSS1133 is an extraordinarily rare type of massive star called a luminous blue variable. But if that’s the case, the researchers note, SDSS1133’s near-continual eruption since 1950 would be the most persistent yet reported for that type of star. A series of observations in ultraviolet wavelengths planned for next year may help scientists distinguish between these widely disparate explanations.

(Video credit: L. Blecha [UMD])

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