Obscured AGN from the ELAIS Deep X-ray Survey
| Autor: | Willott, CJ, Simpson, C, Almaini, O, Manners, JC, Johnson, O, Lawrence, A, Dunlop, JS, Ivison, RJ, Rawlings, S, Gonzalez-Solares, E, Perez-Fournon, I, Serjeant, S, Oliver, SJ, Roche, ND, Mann, RG, Rowan-Robinson, M |
|---|---|
| Rok vydání: | 2016 |
| Předmět: | |
| DOI: | 10.1046/j.1365-8711.2003.06192.x |
| Popis: | The sources discovered in deep hard X-ray surveys with 2-8 keV fluxes of 10^-14 erg cm^-2 s^-1 make up the bulk of the X-ray background at these energies. We present here detailed multi-wavelength observations of three such sources from the ELAIS Deep X-ray Survey. The observations include sensitive near-infrared spectroscopy with the Subaru Telescope and X-ray spectral information from the Chandra X-ray Observatory. The sources observed all have optical-to-near-IR colours redder than an unobscured quasar and comprise a reddened quasar, a radio galaxy and an optically-obscured AGN. The reddened quasar is at a redshift z=2.61 and shows a very large X-ray absorbing column of N_H approx 3.10^23 cm^-2. This contrasts with the relatively small amount of dust reddening, implying a gas-to-dust ratio along the line-of-sight a hundred times greater than that of the Milky Way. The radio galaxy at z=1.57 shows only narrow emission lines, but has a surprisingly soft X-ray spectrum. The softness of this spectrum either indicates an unusually low gas-to-dust ratio for the absorbing medium or X-ray emission related to the young radio source. The host galaxy is extremely red (R-K=6.4) and its optical/near-IR spectrum is best fit by a strongly reddened (A_V~2) starburst. The third X-ray source discussed is also extremely red (R-K=6.1) and lies in a close grouping of three other R-K>6 galaxies. No emission or absorption lines were detected from this object, but its redshift (and that of one of the nearby galaxies) are constrained by SED-fitting to be just greater than z=1. The extremely red colours of these two galaxies can be accounted for by old stellar populations. These observations illustrate the diverse properties of hard X-ray selected AGN. 14 pages, 11 figures, MNRAS in press |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|