Search

We report on observations of redshifted CO(1–0) line emission and observed-frame |$\rm \sim 30\,$| GHz radio continuum emission from five ultra-luminous, mid-IR selected hot, Dust-Obscured Galaxies (Hot DOGs) at |$z\rm \gtrsim 3$| using the Karl G. Jansky Very Large Array. We detect CO(1–0) line emission in all five Hot DOGs, with one of them at high signal-to-noise ratio. We analyse FIR-radio spectral energy distributions, including dust, free–free, and synchrotron emission for the galaxies. We find that most of the |$\rm 115\,$|  GHz rest-frame continuum is mostly due to synchrotron or free–free emission, with only a potentially small contribution from thermal emission. We see a deficit in the rest-frame |$\rm 115\,$|  GHz continuum emission compared to dusty star-forming galaxies and sub-millimetre galaxies (SMGs) at high redshift, suggesting that Hot DOGs do not have similar cold gas reserves compared with star-forming galaxies. One target, W2305−0039, is detected in the FIRST |$\rm 1.4\, GHz$| survey, and is likely to possess compact radio jets. We compare to the FIR–radio correlation, and find that at least half of the Hot DOGs in our sample are radio-quiet with respect to normal galaxies. These findings suggest that Hot DOGs have comparably less cold molecular gas than star-forming galaxies at lower, |$z\rm \sim 2$| redshifts, and are dominated by powerful, yet radio-quiet AGN. [ABSTRACT FROM AUTHOR]

We present an analysis of the joint XMM-Newton and NuSTAR observations of the radio-quiet quasar QSO B2202-209. Using an optical observation from the Hale Telescope at the Palomar Observatory, we revise the redshift of the source from the previously reported z = 1.77 to z = 0.532, and we estimate the mass of the central black hole, log (MBH/M⊙) = 9.08 ± 0.18. The X-ray spectrum of this source can be well described by a power law of photon index G = 1.82 ± 0.05 with Ecut = 152+103-54 keV, in the rest frame of the source. Assuming a Comptonization model, we estimate the coronal temperature to be kTe =42±3 keV and kTe =56±3 keV for a spherical and a slab geometry, respectively. The coronal properties are comparable to the ones derived for local active galactic nuclei, despite a difference of around one order of magnitude in black hole mass and X-ray luminosity (L2 - 10 = 1.93 × 1045 erg s-1). The quasar is X-ray loud, with an unusually flat observed optical-to-X-ray spectral slope aOX = 1.00 ± 0.02, and has an exceptionally strong optical [O III] line. Assuming that both the X-ray emission and the [O III] line are isotropic, these two extreme properties can be explained by a nearly edge-on disc, leading to a reduction in the observed ultraviolet continuum light. [ABSTRACT FROM AUTHOR]