Probing Unification With Chandra HETGS and XMM-Newton EPIC And RGS Spectroscopy of the Narrow Emission Line Galaxy NGC 2110

TL;DR

This study uses Chandra and XMM-Newton spectroscopy to analyze NGC 2110, revealing a complex, multi-layered absorber, narrow emission lines, and evidence of ionized emission, supporting its classification as a Seyfert 2 galaxy with a patchy absorber.

Contribution

First detailed X-ray spectral analysis of NGC 2110 combining Chandra and XMM-Newton data, revealing absorber structure and emission line properties.

Findings

Detection of Fe Kα and Si Kα lines, marginally resolved.

Absorber layers consistent with broad-line region clouds.

Evidence for ionized emission possibly linked to extended X-ray regions.

Abstract

We present results from Chandra HETGS (250 ks over two epochs) and XMM-Newton EPIC and RGS (60 ks) observations of NGC 2110, which has been historically classified as a Narrow Emission Line Galaxy galaxy. Our results support the interpretation that the source is a Seyfert 2 viewed through a patchy absorber. The nuclear X-ray spectrum of the source is best described by a power law of photon index $\Gamma$ ~1.7, modified by absorption from multiple layers of neutral material at a large distance from the central supermassive black hole. We report the strong detections of Fe K$\alpha$ and Si K$\alpha$ lines, which are marginally resolved with the Chandra HETGS, and we constrain the emission radius of the fluorescing material to >1 pc. There is some evidence for modest additional broadening at the base of the narrow Fe K$\alpha$ core with a velocity ~4500 km s$^{-1}$. We find tentative evidence for ionized emission (O VIII Ly $\alpha$, an O VIII RRC feature, and possibly a Ne IX forbidden line) in the Chandra MEG and XMM-Newton RGS spectra, which could be associated with the known extended X-ray emission that lies ~160 pc from the nucleus. We suggest that the $10^{23}$ cm$^{-2}$ partially covering absorber originates in broad-line region clouds in the vicinity of the AGN, and that the $3\times10^{22}$ cm$^{-2}$ coverer is likely to have a more distant origin and have a flattened geometry in order to allow the small-scale radio jet to escape.