2007/08/02 by Anna Sajina, Lin Yan, Mark Lacy +1 · 2 citations
Physics and Astronomy · #Absorption (acoustics) #Accretion (finance) #Active galactic nucleus #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gamma-ray bursts and supernovae #Infrared #Luminous infrared galaxy #Optics #Physics #Population #Quasar #Radio galaxy #Silicate #Star formation #astro-ph
paper · pdf · doi:10.1086/522050
13 pages, 3 figures, accepted for publication in ApJL
arxiv created 2007/08/02 · openalex publication_date 2007/08/31 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Recent Spitzer observations have revealed a substantial population of z ~ 2 ultraluminous infrared galaxies (ULIRGs) with deep silicate absorption (τ 9.7 > 1). This paper reports a 20 cm radio study of such a sample to elucidate their physical nature. We discover that a substantial fraction (40%) of deep silicate absorption ULIRGs at z ~ 2 are moderately radio-loud, with L 1.4GHz = 10 25 -10 26 W Hz -1 . This is in strong contrast with z ≲ 1 radio galaxies and radio-loud quasars where none of the sources with available IRS spectra have τ 9.7 > 1. In addition, we observe radio jets in two of our sources, with one having a double lobe structure ~200 kpc in extent and the other showing a one-sided jet extending ~90 kpc from the nucleus. The likely high inclination of the latter, coupled with its deep silicate absorption, implies the mid-IR obscuration does not share an axis with the radio jets. These sources are highly obscured quasars, observed in the transition stage after the birth of the radio source, but before feedback effects dispel the interstellar medium and halt the black hole accretion and starburst activity.