The 2MASS Red AGN Survey R. Cutri, B. Nelson, D. Kirkpatrick (IPAC/Caltech) M. Skrutskie (U. Virginia) P. Francis (ANU/MSSSO) P. Smith. G. Schmidt, D. Hines (U. Arizona) J. Huchra, B. Wilkes (Harvard/Smithsonian)

Is There a Population of Obscured AGN? Far-IR and Radio surveys suggest 50-80% of AGN in local universe are missed by optical/UV surveys because of dust obscuration – IRAS QSOs (Low et al. 1997) – Red QSOs from radio surveys (Webster et al. 1995; Francis et al. 1999) – Very red, luminous, high-z FIRST/2MASS AGN (Gregg et al. 2002) – May account for at least part of XRB (e.g. Comastri et al. 1995) But UV-excess/optical color-selected surveys appear to be 80-90% complete –2dF complete spectroscopic survey <b j <19.7 (Meyer et al. 2001) – SDSS QSO survey (Ivezic et al. 2002) Conduct a large-scale, uniform IR survey for reddened AGN

Red AGN Search Criteria Uniform all-sky photometry of 2MASS provides basis to search for and characterize a population of obscured or intrinsically red AGN 95% of known optical/UV/radio-selected QSOs have J-K s < 2.0 2MASS Red AGN candidate selection – 3 band detection, J-K s > 2 –|b|>30 o, exclude SMC/LMC to avoid AGB stars – 20,400 deg 2 – 16,997 candidates – Brightest candidates are high-latitude AGB stars – <5% are known AGN Histograms of J-K s color (from 2MASS) for (top-to-bottom) PG, northern and southern Hamburg, LBQS and FIRST Bright QSO samples

Preliminary 2MASS Search Results Spectroscopic follow-up of 704 (4.1%) candidates 69% of observed candidates are Type 1 or Type 2 AGN – Remainder are starburst or normal galaxies, AGB stars and L- dwarfs – ~5% unclassifiable because of low SNR Most of the AGN are Type 1 (e.g. broad-line - QSO/Sy1.x) – N(type 1)/N(type 2) ~ 4

Selection Biases Color selection biases search – Reddest objects missed because flux- limited sample driven by J-band – K s <12 m missed because resolved – Dilution by starlight makes blue Redshift distribution: 0.03 < z < 2.52 – Most are low z - Median z = 0.22 – k-correction biases to low-z – Peak near J-K s ~2.2 because H-alpha in K s

Extrapolated surface density is ~0.5 red AGN deg K s <14.5 – Incomplete for K s >13.5 – Corresponds to QSO surface density at b j <18.2 mag (Meyer et al. 2001) Detection in other surveys – 50% detected in FIRST radio survey – 10% detected in Rosat Faint Src. Sur. – 20% detected by IRAS Properties of the New 2MASS AGN Cumulative red AGN number counts as a function of K s magnitude

L K - Redshift Distribution – Type 2 AGN lower luminosity – As expected, IR survey finds highest IR- luminosity objects – But some optical surveys (e.g. Hamburg/ESO) sample similar K s - luminosity range Properties of the New 2MASS AGN K s luminosity function (  1/V max ) – Local space density of 2MASS type 1 AGN comparable to optical/UV selected QSOs at intermediate luminosities – Drop-off at highest luminosity due to redshift bias (fewer high-z objects in 2MASS sample)

Nature of the 2MASS Red AGN Relative near-IR colors of 2MASS red AGN consistent with reddening of optical/UV population Optical/near-IR colors are not consistent with simple screen extinction model 2MASS Red AGN span very large range of blue-IR color (B j ~ 15 to >21)

Polarization of 2MASS AGN Smith, Schmidt, Hines, Cutri, & Nelson (2002 ApJ, 569, 23) 2MASS AGN most strongly polarized sample of radio quiet AGN – 11/89 2MASS red AGN have optical broadband P>3%, with max P=11% (no PG QSOs have P>3%) – Host galaxy dilutes light in some, so %P lower limit –Intermediate types ( ) highest polarized fraction (23%) – Highest degree of polarization seen in reddest objects Spectropolarimetry of two 2MASS AGN shows highly polarized broad lines – Viewing obscured BLR in scattered light

Chandra Observations of 2MASS AGN Wilkes, Cutri, Hines, Nelson, Schmidt, & Smith (2001 ApJ, 564, L65) Subset of Type 1 & 2 AGN with K s 4.3 – 15/26 with ACIS-I observations – Exposures set to detect 1/800 x prediction based on  KX = 2.1 2MASS red AGN are absorbed in X-rays All are X-ray faint Hardness ratios - N H ~ Even after correction for internal extinction, some are still underluminous in X-rays

Summary 2MASS is revealing large numbers of previously unknown, predominantly low redshift, red AGN – >12,000 expected over the entire sky, ~70% of which will be Sy1/QSO Luminosity function implies that space density of intermediate luminosity Type 1 2MASS AGN may be comparable to optical/UV-selected QSOs – Under-represented in optical/UV searches because too faint in blue/UV (e.g. Francis, Whiting and Webster 2000) NIR colors, source counts, polarization properties and X-ray flux and slopes suggest that many 2MASS AGN are red because of obscuration – But geometry and distribution of dust, origin of continuum at different wavelengths complicates interpretation Red AGN may be underluminous in X-rays – Implications for modeling AGN contribution of X-ray background

2MASS Overview Highly uniform digital imaging survey of the entire sky in three near IR bands – Identical, dedicated 1.3m telescopes at Mt. Hopkins and CTIO –Three NICMOS 3 arrays for simultaneous imaging in J(1.25  m) H(1.65  m) and K s (2.17  m) Data Products – Calibrated Image Atlas (~4e6 512x1024 1”/pix FITS images in the 3 survey bands) – Point Source Catalog (astrometry and photometry for ~3.5e8 point sources) SNR=10:1 at ~1mJy (J<15.8, H<15.1 Ks<14.3), positional accuracy <0.3" RMS wrt ICRS – Extended Source Catalog (positions and photometry for ~2e6 resolved sources, mostly galaxies) SNR=10:1 at ~4mJy (J<15.0, H<14.6, K s <13.5) Survey Status – 100% of the sky observed (Feb 2001) – Data products covering 48% of the sky now in public domain – Final data processing of full data set completed Feb 2002, – Catalog generation and validation in progress – Full-sky data release in Sept 2002 All-sky JHK s composite point source surface density map