Host galaxy line diagnostics for the candidate tidal disruption events XMMSL1 J111527.3+180638 and PTF09axc
Abstract
We present results of our analysis of spectra of the host galaxies of the candidate tidal disruption events (TDEs) XMMSL1 J111527.3+180638 and PTF09axc to determine the nature of these transients. We subtract the starlight component from the host galaxy spectra to determine the origin of the nuclear emission lines. Using a Baldwin-Phillips-Terlevich (BPT) diagram, we conclude that the host galaxy of XMMSL1 J111527.3+180638 is classified as a Seyfert galaxy, suggesting this transient is likely to be caused by (extreme) variability in the active galactic nucleus. We find that the host of PTF09axc falls in the 'star-forming' region of the BPT diagram, implying that the transient is a strong TDE candidate. For both galaxies, we find a WISE colour difference of W1 - W2 < 0.8, which means there is no indication of a dusty torus and therefore an active galactic nucleus, seemingly contradicting our BPT finding for the host of XMMSL1 J111527.3+180638. We discuss possible reasons for the discrepant results obtained through these two methods.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- November 2021
- DOI:
- 10.1093/mnras/stab2541
- arXiv:
- arXiv:2109.01092
- Bibcode:
- 2021MNRAS.507.6196I
- Keywords:
-
- black hole physics;
- galaxies: active;
- galaxies: individual: NGC 3599;
- galaxies: nuclei;
- transients: tidal disruption events;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 7 pages, 6 figures, 1 table, 1 appendix (2 additional figures, 1 additional table). Accepted for publication in MNRAS