Researchers discovered an unusual source of light in a distant galaxy that could be a giant star that erupted and exploded as a supernova or a black hole that merged with another.
The mysterious object (dubbed SDSS1133) is located in the bowl of the Big Dipper in a galaxy 90 million light-years away, NASA/Goddard Space Flight Center reported.
"With the data we have in hand, we can't yet distinguish between these two scenarios," said lead researcher Michael Koss, an astronomer at ETH Zurich, the Swiss Federal Institute of Technology. "One exciting discovery made with NASA's Swift is that the brightness of SDSS1133 has changed little in optical or ultraviolet light for a decade, which is not something typically seen in a young supernova remnant."
The researchers observed the source has significantly brightened over the past six months, which makes the black hole theory seem more plausible. The object is part of the dwarf galaxy Markarian 177 and is located about 2,600 light-years from its host galaxy's core (most black holes sit in the center of their host galaxy).
"We suspect we're seeing the aftermath of a merger of two small galaxies and their central black holes," said co-author Laura Blecha, an Einstein Fellow in the University of Maryland's Department of Astronomy. "Astronomers searching for recoiling black holes have been unable to confirm a detection, so finding even one of these sources would be a major discovery."
The collision of two galaxies disrupts their shapes, creating a new star formation. If both galaxies have a central black hole they will form a binary pair, releasing an extraordinary amount of energy in the process. If these black holes have different masses and spins it will create an uneven gravitational pull causing them to be launched in opposite directions; this kick could even be strong enough to hurl one of the objects completely out of the galaxy. The ejected black hole will retain the hot gas trapped inside and continue to shine as it moves along its new path.
If SDSS1133 is not a black hole than it is most likely a rare type of star known of as a Luminous Blue Variable (LBV), which undergo episodic eruptions; if the object is one of these stars, it represents the longest period of LBV eruptions ever observed.
The findings were published in the Nov. 21 edition of the Monthly Notices of the Royal Astronomical Society.
