THE MID-INFRARED ENVIRONMENTS OF HIGH-REDSHIFT RADIO GALAXIES

Journal Article · Fri Apr 20 00:00:00 EDT 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/749/2/169· OSTI ID:22020351

Galametz, Audrey; Stern, Daniel ^[1]; De Breuck, Carlos; Vernet, Joeel ^[2]; Hatch, Nina ^[3]; Mayo, Jack ^[4]; Miley, George ^[5]; Rettura, Alessandro ^[6]; Seymour, Nick ^[7]

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1. Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109 (United States)
2. European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching (Germany)
3. University of Nottingham, School of Physics and Astronomy, Nottingham NG7 2RD (United Kingdom)
4. Institute for Astronomy, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ (United Kingdom)
5. Leiden Observatory, University of Leiden, P.B. 9513, Leiden 2300 RA (Netherlands)
6. Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States)
7. Mullard Space Science Laboratory, UCL, Holmbury St Mary, Dorking, Surrey, RH5 6NT (United Kingdom)

Taking advantage of the impressive sensitivity of Spitzer to detect massive galaxies at high redshift, we study the mid-infrared environments of powerful, high-redshift radio galaxies at 1.2 < z < 3. Galaxy cluster member candidates were isolated using a single Spitzer/IRAC mid-infrared color criterion, [3.6]-[4.5] > -0.1 (AB), in the fields of 48 radio galaxies at 1.2 < z < 3. Using a counts-in-cell analysis, we identify a field as overdense when 15 or more red IRAC sources are found within 1' (i.e., 0.5 Mpc at 1.2 < z < 3) of the radio galaxy to the 5{sigma} flux density limits of our IRAC data (f{sub 4.5} = 13.4 {mu}Jy). We find that radio galaxies lie preferentially in medium to dense regions, with 73% of the targeted fields denser than average. Our (shallow) 120 s data permit the rediscovery of previously known clusters and protoclusters associated with radio galaxies as well as the discovery of new promising galaxy cluster candidates at z > 1.2.

• OSTI ID: 22020351
• Journal Information: Astrophysical Journal, Vol. 749, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
COLOR
FLUX DENSITY
GALACTIC EVOLUTION
GALAXY CLUSTERS
INFRARED RADIATION
RADIO GALAXIES
RED SHIFT