ICATE   21876
INSTITUTO DE CIENCIAS ASTRONOMICAS, DE LA TIERRA Y DEL ESPACIO
Unidad Ejecutora - UE
artículos
Título:
Characterizing the Mid-infrared Extragalactic Sky with WISE and SDSS
Autor/es:
YAN, LIN; DONOSO, E.; TSAI, CHAO-WEI; STERN, D.; ASSEF, R. J.; EISENHARDT, P.; BLAIN, A. W.; CUTRI, R.; JARRETT, T.H.; STANDORD, S.A.; WRIGHT, E.; BRIDGE, C.; RIECHERS, D.A.
Revista:
ASTRONOMICAL JOURNAL
Editorial:
IOP PUBLISHING LTD
Referencias:
Lugar: Londres; Año: 2013 vol. 145 p. 55 - 71
ISSN:
0004-6256
Resumen:
The Wide-field Infrared Survey Explorer (WISE) has completed its all-sky survey in four channels at 3.4–22um, detecting hundreds of millions of objects. We merge the WISE mid-infrared data with optical data from the Sloan Digital Sky Survey (SDSS) and provide a phenomenological characterization of WISE extragalactic sources. WISE is most sensitive at 3.4um (W1) and least sensitive at 22um (W4). The W1 band probes massive early-type galaxies out to z~1. This is more distant than SDSS identified early-type galaxies, consistent with the fact that 28% of 3.4um sources have faint or no r-band counterparts (r > 22.2). In contrast, 92%–95% of 12um and 22um sources have SDSS optical counterparts with r7σ, but only 18.9% at 22um with S/N W4 > 5 sigma. We show that WISE colors alone are effective in isolating stars (or local early-type galaxies), star-forming galaxies, and strong active galactic nuclei (AGNs)/QSOs at z~3. We highlight three major applications of WISE colors: (1) Selection of strong AGNs/QSOs at z~3 using W1−W2>0.8 and W20.8, W2 < 15.2 combined with r−W2>6 (Vega) colors can be used to identify type-2 AGN candidates. The fraction of these type-2 AGN candidates is one-third of all WISE color-selected AGNs. (3) Selection of ultraluminous infrared galaxies (ULIRGs) at z∼2 with extremely red colors, r − W4 > 14 or well-detected 22um sources lacking detections in the 3.4 and 4.6um bands. The surface density of z∼2 ULIRG candidates selected with r −W4 > 14 is 0.9$pm$0.07 deg−2 at S/N W4~5 (the corresponding, lowest flux density of 2.5 mJy), which is consistent with that inferred from smaller area Spitzer surveys. Optical spectroscopy of a small number of these high-redshift ULIRG candidates confirms our selection, and reveals a possible trend that optically fainter or r−W4 redder candidates are at higher redshifts.