X-ray Bright Nuclear Transient with Bowen Fluorescence Lines

ATel #13127; S. Gezari (UMd), S. van Velzen (UMd), D. Perley (LJMU), S. Frederick (UMd), C. Ward (UMd), and T. Hung (UCSC)
on 24 Sep 2019; 21:24 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Suvi Gezari (suvi@astro.umd.edu)

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We report follow-up observations of bright, nuclear transient AT2019pev/ZTF19abvgxrq/Gaia19eby. Our spectroscopic follow-up campaign, initiated on 2019 September 08 with the Palomar 60in SEDM, and most recently with the Discovery Channel Telescope DeVeny Spectrograph on 2019 September 23, shows the presence of strong narrow-line emission consistent with a star-forming galaxy at z=0.097, a blue continuum, and a resolved He II 4786+[NIII] line complex and relatively narrow broad Balmer lines (FWHM ~ 1300 km/s) characteristic of the new class of flaring accreting SMBHs like AT2018bgt (Trakhtenbrot et al. 2019). ZTF measures the smooth rise of the transient from g=20.0 mag on 2019 Aug 29 to a peak of g=17.42 mag on 2019 Sep 22. Our Swift follow-up observations on 2019 Sep 24 confirm that the source is UV-bright (uvw2=17.24 mag) and X-ray bright (~2e-12 ergs/s/cm^2). The current UV flux is 1.6 mag brighter than the archival GALEX magnitude for the host galaxy, and the current X-ray flux is a factor of ~10 brighter than an archival ROSAT detection. The NVSS archival radio image shows a peak flux of 2.6 mJy/beam with an offset of 7 arcsec from the transient location, although potentially associated with a companion galaxy separated ~11 arcsec away, although this galaxy also doesn't show any obvious AGN features. Follow-up observations are strongly encouraged, especially in the X-rays and radio.