Abell 644 and SDSS J1021+131: Two galaxies, 920 million and 1.1
billion light years away from Earth respectively, used in a new
study of supermassive black holes. Caption: The galaxy on the
left, Abell 644, is in the center of a cluster of galaxies. The
right panel contains SDSS J1021+131, a so-called field galaxy
because it is isolated. Both images are composites with data
from Chandra (blue) and the Sloan Digital Sky Survey (red,
yellow, white). A survey of these and hundreds of other galaxies
tells scientists how often the biggest black holes in field
galaxies like SDSS J1021+131 have been active over the last few
billion years. This has important implications for how
environment affects black hole growth. Scale:Abell 644 Image is
13.2 arcmin across. SDSS J1021+131 Image is 3.2 arcmin across.
Chandra X-ray Observatory ACIS Image