X-ray obscuration from a variable ionized absorber in PG 1114+445
Abstract
Photoionized absorbers of outflowing gas are commonly found in the X-ray spectra of active galactic nuclei (AGN). While most of these absorbers are seldom significantly variable, some ionized obscurers have been increasingly found to substantially change their column density on a wide range of time scales. These variations are often considered as the signature of the clumpy nature of the absorbers. Here we present the analysis of a new Neil Gehrels Swift Observatory campaign of the type-1 quasar PG 1114+445, which was observed to investigate the time evolution of the multiphase outflowing absorbers previously detected in its spectra. The analyzed dataset consists of 22 observations, with a total exposure of ks, spanning about months. During the whole campaign, we report an unusually low flux state with respect to all previous X-ray observations of this quasar. From the analysis of the stacked spectra we find a fully covering absorber with a column density . This is an order of magnitude higher than the column density measured in the previous observations. This is either due to a variation of the known absorbers, or by a new one, eclipsing the X-ray emitting source. We also find a ionization parameter of . Assuming that the obscuration lasts for the whole duration of the campaign, i.e. more than months, we estimate the minimum distance of the ionized clump, which is located at pc.
Keywords
Cite
@article{arxiv.2107.06584,
title = {X-ray obscuration from a variable ionized absorber in PG 1114+445},
author = {R. Serafinelli and V. Braito and P. Severgnini and F. Tombesi and G. Giani and E. Piconcelli and R. Della Ceca and F. Vagnetti and M. Gaspari and F. G. Saturni and R. Middei and A. Tortosa},
journal= {arXiv preprint arXiv:2107.06584},
year = {2021}
}
Comments
7 pages, 7 figures, 3 tables. Accepted for publication in Astronomy & Astrophysics