Radio continuum and \HI 21-cm line observations of a nearby luminous infrared galaxy IRAS 17526+3253

TL;DR

This study uses EVN, GMRT, and archival VLA data to analyze the radio continuum and ext{HI} 21-cm line emission in the luminous infrared galaxy IRAS 17526+3253, revealing nuclear activity, gas dynamics, and merger features.

Contribution

First detailed multi-scale radio observations of IRAS 17526+3253, combining continuum and spectral line data to understand its nuclear activity and merger state.

Findings

Detection of radio cores indicating AGN activity in the nuclei.

Diffuse ext{HI} emission with a velocity gradient across the galaxy.

Evidence of low-frequency absorption affecting the radio spectral energy distribution.

Abstract

We present results from our EVN and GMRT observations of the radio continuum and spectral line emission in IRAS 17526+3253, along with an analysis of its arcsecond-scale radio properties using archival VLA data. The EVN observations detected radio continuum emission from both the northwest (NW) and southeast (SE) nuclei. The NW nucleus shows two components with high brightness temperatures and radio luminosities, likely indicating the presence of an AGN core and jet. Meanwhile, our EVN observation failed to detect the OH line emission, possibly due to radio frequency interference and/or the emission being partly resolved out and below our detection limit. The multi-band radio spectral energy distribution (SED) deviates from a single power-law at low frequencies, suggesting low-frequency absorption. The GMRT spectral line data reveal both \HI absorption and emission. The \HI emission is diffuse and shows a velocity gradient from about 7500 \kms in the NW to 7800 \kms in the SE nucleus. On larger scales, the \HI emission extends about 4' along the NW-SE direction, with the southeastern extension matching the optical tidal tail. In addition, the weak \HI absorption features show broad line profiles, possibly due to overlapping \HI gas from the two nuclei. The aforementioned results are consistent with properties of intermediate-stage mergers reported in the literature.