The Phoenix galaxy as seen by NuSTAR

TL;DR

This study analyzes 20 years of X-ray observations of the Seyfert 2 galaxy Mrk 1210, highlighting its long-term variability, spectral characteristics, and the nature of its obscuring material using NuSTAR data.

Contribution

It provides the first high-quality hard X-ray spectrum of Mrk 1210 with NuSTAR and constrains the geometry and variability of its obscuring material over 16.9 years.

Findings

Mrk 1210 shows consistent Compton-thin obscuration over 20 years.

The 1995 ASCA observation captured a low flux, possibly Compton-thick state.

The distance to the reflector is at least ~2 parsecs, or the eclipsing cloud is a water maser-emitting clump.

Abstract

Aims. We study the long-term variability of the well-known Seyfert 2 galaxy Mrk 1210 (a.k.a. UGC 4203, or the Phoenix galaxy). Methods. The source was observed by many X-ray facilities in the last 20 years. Here we present a NuSTAR observation and put the results in context of previously published observations. Results. NuSTAR observed Mrk 1210 in 2012 for 15.4 ks. The source showed Compton-thin obscuration similar to that observed by Chandra, Suzaku, BeppoSAX and XMM-Newton over the past two decades, but different from the first observation by ASCA in 1995, in which the active nucleus was caught in a low flux state - or obscured by Compton-thick matter, with a reflection-dominated spectrum. Thanks to the high-quality hard X-ray spectrum obtained with NuSTAR and exploiting the long-term spectral coverage spanning 16.9 years, we can precisely disentangle the transmission and reflection components and put constraints on both the intrinsic long-term variability and hidden nucleus scenarios. In the former case, the distance between the reflector and the source must be at least ~ 2 pc, while in the latter one the eclipsing cloud may be identified with a water maser-emitting clump.