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Hinkle, JT, Holoien, TWS, Shappee, BJ, Neustadt, JMM, Auchettl, K, Vallely, PJ, Shahbandeh, M, Kluge, M, Kochanek, CS, Stanek, KZ, Huber, ME, Post, RS, Bersier, D, Ashall, C, Tucker, MA, Williams, JP, De Jaeger, T, Do, A, Fausnaugh, M, Gruen, D , Hopp, U, Myles, J, Obermeier, C, Payne, AV and Thompson, TA (2022) The Curious Case of ASASSN-20hx: A Slowly Evolving, UV- and X-Ray-Luminous, Ambiguous Nuclear Transient. Astrophysical Journal, 930 (1). ISSN 0004-637X
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The curious case of ASASSN-20hx a slowly evolving UV and X-ray-luminous ambiguous nuclear transient.pdf - Published Version Available under License Creative Commons Attribution. Download (9MB) | Preview |
Abstract
We present observations of ASASSN-20hx, a nearby ambiguous nuclear transient (ANT) discovered in NGC 6297 by the All-Sky Automated Survey for Supernovae (ASAS-SN). We observed ASASSN-20hx from -30 to 275 days relative to the peak UV/optical emission using high-cadence, multiwavelength spectroscopy and photometry. From Transiting Exoplanet Survey Satellite data, we determine that the ANT began to brighten on 2020 June 22.8 with a linear rise in flux for at least the first week. ASASSN-20hx peaked in the UV/optical 30 days later on 2020 July 22.8 (MJD = 59052.8) at a bolometric luminosity of L = (3.15 ± 0.04) × 1043 erg s-1. The subsequent decline is slower than any TDE observed to date and consistent with many other ANTs. Compared to an archival X-ray detection, the X-ray luminosity of ASASSN-20hx increased by an order of magnitude to L x ∼1.5 × 1042 erg s-1 and then slowly declined over time. The X-ray emission is well fit by a power law with a photon index of "∼2.3-2.6. Both the optical and near-infrared spectra of ASASSN-20hx lack emission lines, unusual for any known class of nuclear transient. While ASASSN-20hx has some characteristics seen in both tidal disruption events and active galactic nuclei, it cannot be definitively classified with current data.
| Item Type: | Article |
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| Uncontrolled Keywords: | 0201 Astronomical and Space Sciences; 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics; 0306 Physical Chemistry (incl. Structural); Astronomy & Astrophysics |
| Subjects: | Q Science > QB Astronomy |
| Divisions: | Astrophysics Research Institute |
| Publisher: | American Astronomical Society |
| SWORD Depositor: | A Symplectic |
| Date Deposited: | 08 Nov 2022 15:39 |
| Last Modified: | 08 Nov 2022 15:45 |
| DOI or ID number: | 10.3847/1538-4357/ac5f54 |
| URI: | https://researchonline.ljmu.ac.uk/id/eprint/18074 |
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