Peering through the dust: NuSTAR observations of two first-2MASS red quasars

Stephanie M. LaMassa, Angelo Ricarte, Eilat Glikman, C. Megan Urry, Daniel Stern, Tahir Yaqoob, George B. Lansbury, Francesca Civano, Steve E. Boggs, W. N. Brandt, Chien-Ting J. Chen, Finn Erland Christensen, William W. Craig, Chuck J. Hailey, Fiona Harrison, Ryan C. Hickox, Michael Koss, Claudio Ricci, Ezequiel Treister, Will Zhang

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Abstract

Some reddened quasars appear to be transitional objects in the paradigm of merger-induced black hole growth/galaxy evolution, where a heavily obscured nucleus starts to be unveiled by powerful quasar winds evacuating the surrounding cocoon of dust and gas. Hard X-ray observations are able to peer through this gas and dust, revealing the properties of circumnuclear obscuration. Here, we present NuSTAR and XMM-Newton/Chandra observations of FIRST-2MASS-selected red quasars F2M 0830+3759 and F2M 1227+3214. We find that though F2M 0830+3759 is moderately obscured (NH,Z = (2.1 ± 0.2) × 1022 cm−2) and F2M 1227+3214 is mildly absorbed ( cm−2) along the line of sight, heavier global obscuration may be present in both sources, with cm−2 and <5.5 × 1023 cm−2 for F2M 0830+3759 and F2M 1227+3214, respectively. F2M 0830+3759 also has an excess of soft X-ray emission below 1 keV, which is well accommodated by a model where 7% of the intrinsic X-ray emission from the active galactic nucleus (AGN) is scattered into the line of sight. While F2M 1227+3214 has a dust-to-gas ratio (E(BV)/NH) consistent with the Galactic value, the value of E(BV)/NH for F2M 0830+3759 is lower than the Galactic standard, consistent with the paradigm that the dust resides on galactic scales while the X-ray reprocessing gas originates within the dust sublimation zone of the broad-line region. The X-ray and 6.1 μm luminosities of these red quasars are consistent with the empirical relations derived for high-luminosity, unobscured quasars, extending the parameter space of obscured AGNs previously observed by NuSTAR to higher luminosities.
Original languageEnglish
Article number70
JournalAstrophysical Journal
Volume820
Issue number1
Number of pages14
ISSN0004-637X
DOIs
Publication statusPublished - 2016

Keywords

  • Galaxies: active
  • Infrared: galaxies
  • quasars: individual (F2M 0380+3759, F2M 1227+3214)
  • Xrays: individual (F2M 0830+3759, F2M 1227+3214)

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