Discovery of ATLAS17jrp as an Optical, X-ray and Infrared Bright TDE in a Star-forming Galaxy

TL;DR

ATLAS17jrp is a rare, multi-wavelength TDE in a star-forming galaxy with unique dust environment features, revealing insights into TDE detection biases and the role of dust in obscuring optical signals.

Contribution

This study reports the discovery and detailed multi-wavelength analysis of ATLAS17jrp, a TDE in a star-forming galaxy with unusually high dust covering factor, highlighting the importance of infrared and X-ray observations.

Findings

Optical/UV light curves peak at 1.06×10^44 erg/s and decay as t^{-5/3}.

A delayed X-ray flare peaked at 1.27×10^43 erg/s, 170 days post optical peak.

High MIR luminosity indicates a dusty environment with a covering factor of ~0.2.

Abstract

We hereby report the discovery of ATLAS17jrp as an extraordinary TDE in star-forming galaxy SDSSJ162034.99+240726.5 in our recent sample of mid-infrared outbursts in nearby galaxies. Its optical/UV light curves rise to a peak luminosity $\sim1.06\times10^{44}\rm\,erg\,s^{-1}$ in about a month and then decay as $\rm t^{-5/3}$ with a roughly constant temperature around 19000~K, and the optical spectra show a blue continuum and very broad Balmer lines with FWHM$\sim$15000 km/s which gradually narrowed to 1400 km/s within 4 years, all agreeing well with other optical TDEs. A delayed and rapidly rising X-ray flare with a peak luminosity $\rm \sim 1.27\times10^{43}\,erg\,s^{-1}$ was detected at $\rm \sim$ 170 days after the optical peak. The high MIR luminosity of ATLAS17jrp ($\sim2\times10^{43} \rm\,erg\,s^{-1}$) has revealed a distinctive dusty environment with covering factor as high as $\sim0.2$, that is comparable with that of torus in active galactic nuclei but at least one order of magnitude higher than normal optical TDEs. Therefore, ATLAS17jrp turns out to be one of the rare unambiguous TDE found in star-forming galaxies and its high dust covering factor implies that the dust extinction could play an important role in the absence of optical TDEs in star-forming galaxies.