Serendipitous Discovery of Warm Absorbers in the Seyfert 2 Galaxy IRAS 18325-5926

TL;DR

This study reports the first detection of warm absorbers in a Seyfert 2 galaxy, revealing high-resolution spectral features that suggest origins from accretion disk winds and providing new insights into AGN outflows.

Contribution

It presents the first high-resolution detection of warm absorbers in Seyfert 2 galaxy IRAS 18325-5926, highlighting their properties and potential origins from accretion disk winds.

Findings

Detected two warm absorbers with specific velocities and widths.

Constrained the absorbers' distance, indicating origin from accretion disk winds.

Identified a weak absorption system possibly due to Galactic or high-velocity intrinsic outflow.

Abstract

Warm absorption is a common phenomenon in Seyfert 1s and quasars, but rare in Seyfert 2s. In this paper, we report the detection of warm absorbers with high energy resolution in the Seyfert 2 galaxy IRAS 18325-5926 for the first time with Chandra HETGS spectra. An intrinsic absorbing line system with an outflow velocity ~400 km/s was found, which is contributed by two warm absorbers with FWHM of 570 km/s and 1360 km/s, respectively. The two absorbers were adjacent, and doing a transverse motion across our line of sight. We constrained the distance of the absorbers to a small value, suggesting that the absorbers may originate from the highly ionized accretion disk wind. The perspective of this type 2 Seyfert provides the best situation to investigate the vertical part of the funnel-like outflows. Another weak absorbing line system with zero redshift was also detected, which could be due to Galactic absorption with very high temperature, or an intrinsic outflow with very high velocity ~6000 km/s.