On the nature of the z=0 X-ray absorbers: I. Clues from an external group

TL;DR

This paper investigates the origin of z=0 X-ray absorbers by studying a galaxy group similar to the Local Group, suggesting that these absorbers likely have both Galactic and extragalactic components, and future observations will clarify their nature.

Contribution

It provides new insights into the distribution of z=0 X-ray absorbers by analyzing a Local Group-like environment, highlighting the complexity of their origins.

Findings

z=0 absorbers may originate from both Galactic and extragalactic sources

Current data cannot definitively distinguish the location of z=0 absorbers

Future high-resolution observations are needed to resolve multiple components

Abstract

Absorption lines of OVII at redshift zero are observed in high quality Chandra spectra of extragalactic sightlines. The location of the absorber producing these lines, whether from the corona of the Galaxy or from the Local Group or even larger scale structure, has been a matter of debate. Here we study another poor group like our Local Group to understand the distribution of column density from galaxy to group scales. We show that we cannot yet rule out the group origin of z=0 systems. We further argue that the debate over Galactic vs. extragalactic origin of z=0 systems is premature as they likely contain both components and predict that future higher resolution observations will resolve the z=0 systems into multiple components.