Radio Galaxy Zoo Talk

Binary source

  • Chappers34 by Chappers34

    could this be 2 black holes rotating around each other ?


  • JeanTate by JeanTate in response to Chappers34's comment.

    Welcome to RGZ, Chappers34!

    Not in the sense in which I think you meant the question, but yes, from a very different perspective ... maybe.

    How? Let's start with what the field looks like, through 'SDSS eyes' (centered on the upper-left radio/IR source):

    enter image description here

    Lots and lots and lots of fuzzy yellow balls! 😮

    Almost every fuzzy yellow thing in this field is a galaxy, in a rich cluster of galaxies called Abell 1360. As none of these are dwarf galaxies, every one has a super-massive black hole (SMBH) at its center. All these galaxies are in a complicated dance around the center-of-mass of the cluster, which may well be close to the biggest fuzzy ball; the conductor of the dance is gravity, playing a tune best described by Einstein's General theory of Relativity (GR for short). What you can't see in this picture - nor in the IR or radio one - is that most of the mass is not in the many SMBH, nor even in the many galaxies; rather it's in the form of a mysterious substance that goes by the name of Cold Dark Matter (CDM for short) and a not-so-mysterious one that is a multi-million degree thin plasma (think of it as an extremely hot gas, whose density is far, far below that of the best vacuum we can create in labs here on Earth).

    In this dance, the SMBH are such minor players that they can be largely ignored 😮 Even though they may 'weigh' hundreds of millions times the mass of the Sun, the center of this cluster likely has a mass ~a hundred thousand times greater.

    It may be that when you look carefully at two particular SMBHs - in two particular galaxies - and watch how they dance (you need to be patient, think of a million years as one second), you may be able to describe how they move as 'rotating around each other', approximately. More likely, however, is that they'll seem to be moving like a pair of graceful drunks ...

    Happy hunting!