DUST-CORRECTED COLORS REVEAL BIMODALITY IN THE HOST-GALAXY COLORS OF ACTIVE GALACTIC NUCLEI AT z {approx} 1

Journal Article · Mon Sep 20 00:00:00 EDT 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/721/1/L38· OSTI ID:21452803

Cardamone, Carolin N; Megan Urry, C; Brammer, Gabriel ^[1]; Schawinski, Kevin ^[2]; Treister, Ezequiel ^[3]; Gawiser, Eric ^[4]

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1. Department of Astronomy, Yale University, New Haven, CT 06511 (United States)
2. Yale Center for Astronomy and Astrophysics, Yale University, P.O. Box 208120, New Haven, CT 06520 (United States)
3. Institute for Astronomy, 2680 Woodlawn Drive, University of Hawaii, Honolulu, HI 96822 (United States)
4. Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854-8019 (United States)

Using new, highly accurate photometric redshifts from the MUSYC medium-band survey in the Extended Chandra Deep Field-South (ECDF-S), we fit synthetic stellar population models to compare active galactic nucleus (AGN) host galaxies to inactive galaxies at 0.8 {<=} z {<=} 1.2. We find that AGN host galaxies are predominantly massive galaxies on the red sequence and in the green valley of the color-mass diagram. Because both passive and dusty galaxies can appear red in optical colors, we use rest-frame near-infrared colors to separate passively evolving stellar populations from galaxies that are reddened by dust. As with the overall galaxy population, {approx}25% of the 'red' AGN host galaxies and {approx}75% of the 'green' AGN host galaxies have colors consistent with young stellar populations reddened by dust. The dust-corrected rest-frame optical colors are the blue colors of star-forming galaxies, which imply that these AGN hosts are not passively aging to the red sequence. At z {approx} 1, AGN activity is roughly evenly split between two modes of black hole growth: the first in passively evolving host galaxies, which may be heating up the galaxy's gas and preventing future episodes of star formation, and the second in dust-reddened young galaxies, which may be ionizing the galaxy's interstellar medium and shutting down star formation.

• OSTI ID: 21452803
• Journal Information: Astrophysical Journal Letters, Vol. 721, Issue 1; Other Information: DOI: 10.1088/2041-8205/721/1/L38; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
BLACK HOLES
COLOR
DUSTS
GALAXY NUCLEI
RED SHIFT
STARS
X-RAY GALAXIES
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
GALAXIES
OPTICAL PROPERTIES
ORGANOLEPTIC PROPERTIES
PHYSICAL PROPERTIES