According to them, two of the nodes are probably small galaxies with small inner motions cannibalized by the large galaxy. Measurements of the third knot had such large error bars that it could not yet be ruled out inside or outside as the location of the black hole.
The fourth, very compact knot near the bottom edge of the core was too faint even for the Hubble, Dr Burke-Spoloar reported. “Observing this node would have required an exaggerated amount (hundreds of hours) of time with Hubble Space Telescope,” she said in an email, so it also remains a candidate for the black hole hideout.
The galaxy’s core also radiates radio waves, but this did not help the search, said Dr. Burke-Spolaor said.
“We originally hoped that the radio emission would be a literal smoke gun that would point an active jet pointing directly back at the black hole,” but the radio remnant was at least 50 million years old, according to its spectral properties, which according to her meant that the big black hole would have had enough time to pull elsewhere since the beam went off.
Next stop was the NASA orbit Chandra X-ray Observatory. Kayhan Gultekin of the University of Michigan, another veteran Nuker who was not in the original discovery team, aimed the telescope at the bunch core and the suspicious knots. No dice. The suspected black hole would have to feed at a millionth of its potential rate if it were to be there at all, said dr. Gultekin said.
“Either a black hole in the middle is very faint, or it’s not there,” he wrote in an email. The same is true of a binary black hole system, he said; it must eat very little gas to stay hidden.
Meanwhile, Imran Nasim, from the University of Surrey in the UK, who was not part of the team of Drs. Postman did not, a detailed analysis published of how the fusion of two supermassive black holes can reform the galaxy to what the astronomers found.
“Normal gravity recoil ‘kicks’ the supermassive black hole out of the galaxy,” said Dr. Nasim explained in an email. After losing its supermassive anchor, the cloud of stars spreads around the black hole binary and becomes diffuser. The density of stars in that region – the densest part of the entire giant galaxy – is only a tenth of the density of stars in our own Milky Way environment, resulting in a night sky that looks bloodthirsty compared to our own.