Open AccessCompton‐thick X‐ray absorption in the Seyfert galaxies Tololo 0109–383 and ESO 138–G1
Author(s) -
Collinge M. J.,
Brandt W. N.
Publication year - 2000
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2000.03871.x
Subject(s) - physics , balmer series , astrophysics , galaxy , spectral line , emission spectrum , astronomy , active galactic nucleus , x ray , flux (metallurgy) , equivalent width , optics , materials science , metallurgy
We present analyses of the ASCA X‐ray spectra of two Seyfert galaxies, Tololo 0109–383 and ESO 138–G1. In both cases, spectral fitting reveals two statistically acceptable continuum models: Compton reflection and partial covering. Both spectra have strong iron K α lines, with equivalent widths greater than 1.5 keV. These large equivalent widths are suggestive of heavier obscuration than that directly indicated by the partial‐covering models (≈ 2×10 23 cm ‐2 ), with the actual column densities being ‘Compton‐thick’ (i.e. N H ≳1.5×10 24 cm ‐2 ). We use the hard X‐ray/[O iii ] flux correlation for Seyferts and data from the literature to provide additional support for this hypothesis. Since Tololo 0109–383 is known to have optical type 1 characteristics such as broad Balmer line components and Fe ii emission, this result marks it as a notable object.