ALMA detects molecular gas in the halo of the powerful radio galaxy TXS 0828+193

TL;DR

This study uses ALMA to detect and analyze molecular gas in the halo of the high-redshift radio galaxy TXS 0828+193, revealing multiple CO-emitting regions and potential connections to large-scale cosmic structures.

Contribution

First detection of CO emission in the halo of TXS 0828+193, identifying new molecular gas sources and exploring their possible origins and relation to galaxy formation.

Findings

Molecular gas mass of the galaxy is approximately 9×10^{9} solar masses.

Detected three new potential CO-emitting companions with similar gas masses.

One companion aligns with the radio jet and shows stellar emission, indicating possible star formation or jet-induced activity.

Abstract

Both theoretical and observational results suggest that high-redshift radio galaxies (HzRGs) inhabit overdense regions of the universe and might be the progenitors of local, massive galaxies residing in the centre of galaxy clusters. In this paper we present CO(3-2) line observations of the HzRG TXS 0828+193 (z=2.57) and its environment using the Atacama Large Millimeter/submillimeter Array. In contrast to previous observations, we detect CO emission associated with the HzRG and derive a molecular gas mass of $(0.9\pm0.3)\times10^{10}\,\rm M_{\odot}$. Moreover, we confirm the presence of a previously detected off-source CO emitting region (companion #1), and detect three new potential companions. The molecular gas mass of each companion is comparable to that of the HzRG. Companion #1 is aligned with the axis of the radio jet and has stellar emission detected by Spitzer. Thus this source might be a normal star-forming galaxy or alternatively a result of jet-induced star formation. The newly found CO sources do not have counterparts in any other observing band and could be high-density clouds in the halo of TXS 0828+193 and thus potentially linked to the large-scale filamentary structure of the cosmic web.