AGN in deep radio/X-ray surveys: hunting the earliest massive galaxies

Abstract

Despite the plethora of deep (sub-mJy) radio surveys there remains considerable doubt as to the exact nature of the galaxies contributing to the source counts. Current evidence suggests that starformation in moderately luminous 'normal' galaxies is responsible for the bulk of the emission below 1mJy. However given the sensitivities of these surveys we would expect a fraction of these sources to be distant radio galaxies. Using deep VLA and GMRT data we have found ~20 high-z candidate radio galaxies in two fields using the classical ultra-steep radio spectrum technique (De Breuck et al., 2000) and selecting galaxies with faint (i'>25) optical counterparts. Several of these sources have X-ray detections in our deep XMM/Chandra observations and have fluxes high enough to put them in the quasar regime if they lie above redshift 3. Recently performed Spitzer GTO observations and upcoming near-infrared observations will help reveal the nature of these sources.

arXiv comment4 pages, 5 figures, "Granada Workshop on High Redshift Radiogalaxies"

References in corpus (20)

• The Demography of Massive Dark Objects in Galaxy Centres
• The slope of the black-hole mass versus velocity dispersion correlation
• On the evolution of star forming galaxies
• The radio luminosity function from the low-frequency 3CRR, 6CE & 7CRS complete samples
• The Nature of Radio Emission from Distant Galaxies: The 1.4 GHz Observations
• Spectroscopic Redshifts to z > 2 for Optically Obscured Sources Discovered with the Spitzer Space Telescope
• A submillimetre survey of the star-formation history of radio galaxies
• A Sample of 669 Ultra Steep Spectrum Radio Sources to Find High Redshift Radio Galaxies
• Faint Radio Sources and Star Formation History
• Faint Radio Sources and Star Formation History
• The Phoenix Deep Survey: The 1.4 GHz microJansky catalogue
• The VLA-VIRMOS Deep Field I. Radio observations probing the microJy source population
• The Scatter in the Relationship between Redshift and the Radio-to-Submm Spectral Index
• The radio galaxy K-z relation: the 10^12 Msol mass limit; masses of galaxies from the L_K luminosity, up to z >4
• NICMOS observations of high redshift radio galaxies: witnessing the formation of bright elliptical galaxies?
• A Deep VLA survey at 20cm of the ISO ELAIS survey regions
• The ATESP radio survey III. Source counts
• Radio Observations of the 13hr XMM/ROSAT Deep X-ray Survey Area
• The Phoenix Deep Survey: spectroscopic catalog
• Spectroscopic Confirmation of a Radio-Selected Galaxy Overdensity at z=1.11