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Submillimeter Galaxies in the Chandra Deep Field-North (SMG 123616.1+621513):
Era of Galaxy and Black Hole Growth Spurt Discovered

Submillimeter Galaxies in the Chandra Deep Field-North (SMG 123616.1+621513)
Credit: X-ray: NASA/CXC/IoA/D.Alexander et al.; Illustration: NASA/CXC/M.Weiss

The illustration shows two young galaxies in the process of merging. The merger has triggered a prodigious burst of star formation and is providing fuel for the growth of the galaxies' central supermassive black holes.

The inset shows an image from the Chandra Deep Field-North of two central black holes in merging galaxies (known as SMG 123616.1+621513). Although the black holes appear to be very close in this image, they are actually about 70,000 light years apart. The different colors in the image are due to differences in X-ray absorption by gas and dust around the black holes with blue indicating more absorption than red.

By combining data from the Chandra Deep Field-North (CDFN) with observations at submillimeter and optical wavelengths, an international team of scientists has found evidence that many extremely luminous adolescent galaxies and their central black holes underwent a phenomenal spurt of growth 10 billion to 12 billion years ago. This growth spurt may have set the stage for the appearance of quasars, distant galaxies that contain the largest and most active black holes in the Universe.

The galaxies in the image are known as submillimeter galaxies, because they were originally identified by the James Clerk Maxwell submillimeter telescope (JCMT) on Mauna Kea in Hawaii. Hubble Space Telescope observations indicate that most of the submillimeter galaxies are actually two galaxies that are colliding and merging.

Recent sophisticated computer simulations have shown that such mergers drive gas toward the central regions of galaxies, triggering a burst of star formation and providing fuel for the growth of a central supermassive black hole. This explains the observational evidence that in submillimeter galaxies stars are forming at a prodigious rate at the same time that the central black holes are growing rapidly.

A combination of observation and theory suggests that in a few hundred million years the submillimeter galaxies will become quasars, and ultimately, large spherical galaxies that harbor central supermassive black holes with masses of about a billion Suns.

Fast Facts for Submillimeter Galaxies in the Chandra Deep Field-North (SMG 123616.1+621513):
Credit  X-ray: NASA/CXC/IoA/D.Alexander et al.; Illustration: NASA/CXC/M.Weiss
Scale  Inset is 1 arcmin per side.
Category  Cosmology/Deep Fields/X-ray Background, Black Holes
Coordinates (J2000)  RA 12h 36m 45.57s | Dec +62 10' 26.68
Constellation  Ursa Major
Observation Dates  1999: Nov 13, 14, 21 2000: Feb 23; Nov 20, 21, 24 2001: Feb 19, 22, 23; Mar 02, 04; Nov 13, 16, 17, 21 2002: Feb 12, 14, 16, 22
Observation Time  556 hours (23 days)
Obs. IDs  580, 967, 966, 957, 2386, 1671, 2344, 2232, 2233, 2423, 2234, 2421, 3293, 3388, 3408, 3389, 3409, 3294, 3390, 3391
Color Code  Energy: Red 0.5-2keV, Green 2-4keV, Blue 4-8keV
Instrument  ACIS
References D. Alexander et al. Nature 2005 April 7 issue (See also, astro-ph/0503453) T. Di Matteo, et al. 2005, Nature 433, 604 (See also astro-ph/0502199)
Distance Estimate  About About 11 billion light years (redshift z = 2.58) light years
Release Date  April 06, 2005