arXiv subjects

Tana Joseph

Publications and source records attributed to Tana Joseph.

2 recordsLinked to original sources

arXiv2020

Discovering Exotic AGN behind the Magellanic Clouds

The nearby Magellanic Clouds system covers more than 200 square degrees on the sky. Much of it has been mapped across the electromagnetic spectrum at high angular resolution and sensitivity X-ray (XMM-Newton), UV (UVIT), optical (SMASH), IR (VISTA, WISE, Spitzer, Herschel), radio (ATCA, ASKAP, MeerKAT). This provides us with an excellent dataset to explore the galaxy populations behind the stellar-rich Magellanic Clouds. We seek to identify and characterise AGN via machine learning algorithms on this exquisite data set. Our project focuses not on establishing sequences and distributions of common types of galaxies and active galactic nuclei (AGN), but seeks to identify extreme examples, building on the recent accidental discoveries of unique AGN behind the Magellanic Clouds.

astro-ph.GA↗

arXiv2011

The unusual radio transient in M82: an SS 433 analogue?

In this paper we discuss the recently discovered radio transient in the nuclear region of M\,82. It has been suggested that this source is an X-ray binary, which, given the radio flux density, would require an X-ray luminosity, $L_{\rm X}\,\sim6\times10^{42}$\,erg\,s$^{-1}$ if it were a stellar mass black hole that followed established empirical relations for X-ray binaries. The source is not detected in the analysis of the X-ray archival data. Using a 99% confidence level upper limit we find that $L_{\rm X} \leq 1.8 \times 10^{37}$\,erg\,s$^{-1}$ and $1.5 \times 10^{37}$\,erg\,s$^{-1}$, using powerlaw and disk blackbody models respectively. The source is thus unlikely to be a traditional microquasar, but could be a system similar to SS\,433, a Galactic microquasar with a high ratio of radio to X-ray luminosity.

astro-ph.HE↗