Exploring the origin of a large cavity in Abell 1795 using deep Chandra observations

TL;DR

This study investigates a large X-ray cavity in galaxy cluster Abell 1795, exploring its possible origins, including AGN activity, gas sloshing, or a dwarf galaxy outburst, using deep Chandra observations.

Contribution

It provides a detailed analysis of the cavity's properties and evaluates various formation scenarios, including the unlikely role of a dwarf galaxy outburst.

Findings

No radio emission or metal enhancement associated with the cavity.

Projection effects may hide a potential counterpart bubble.

A dwarf galaxy outburst is an unlikely cause for the cavity.

Abstract

We examine deep stacked Chandra observations of the galaxy cluster Abell 1795 (over 700ks) to study in depth a large (34 kpc radius) cavity in the X-ray emission. Curiously, despite the large energy required to form this cavity (4PV=4x10^60 erg), there is no obvious counterpart to the cavity on the opposite side of the cluster, which would be expected if it has formed due to jets from the central AGN inflating bubbles. There is also no radio emission associated with the cavity, and no metal enhancement or filaments between it and the BCG, which are normally found for bubbles inflated by AGN which have risen from the core. One possibility is that this is an old ghost cavity, and that gas sloshing has dominated the distribution of metals around the core. Projection effects, particularly the long X-ray bright filament to the south east, may prevent us from seeing the companion bubble on the opposite side of the cluster core. We calculate that such a companion bubble would easily have been able to uplift the gas in the southern filament from the core. Interestingly, it has recently been found that inside the cavity is a highly variable X-ray point source coincident with a small dwarf galaxy. Given the remarkable spatial correlation of this point source and the X-ray cavity, we explore the possibility that an outburst from this dwarf galaxy in the past could have led to the formation of the cavity, but find this to be an unlikely scenario.