The Astrophysical Journal (Jan 2024)

CSS 161010: A Luminous Fast Blue Optical Transient with Broad Blueshifted Hydrogen Lines

  • Claudia P. Gutiérrez,
  • Seppo Mattila,
  • Peter Lundqvist,
  • Luc Dessart,
  • Santiago González-Gaitán,
  • Peter G. Jonker,
  • Subo Dong,
  • Deanne Coppejans,
  • Ping Chen,
  • Panos Charalampopoulos,
  • Nancy Elias-Rosa,
  • Thomas M. Reynolds,
  • Christopher Kochanek,
  • Morgan Fraser,
  • Andrea Pastorello,
  • Mariusz Gromadzki,
  • Jack Neustadt,
  • Stefano Benetti,
  • Erkki Kankare,
  • Tuomas Kangas,
  • Rubina Kotak,
  • Maximilian D. Stritzinger,
  • Thomas Wevers,
  • Bing Zhang,
  • David Bersier,
  • Subhash Bose,
  • David A. H. Buckley,
  • Raya Dastidar,
  • Anjasha Gangopadhyay,
  • Aleksandra Hamanowicz,
  • Juna A. Kollmeier,
  • Jirong Mao,
  • Kuntal Misra,
  • Stephen. B. Potter,
  • Jose L. Prieto,
  • Encarni Romero-Colmenero,
  • Mridweeka Singh,
  • Auni Somero,
  • Giacomo Terreran,
  • Petri Vaisanen,
  • Łukasz Wyrzykowski

DOI
https://doi.org/10.3847/1538-4357/ad89a5
Journal volume & issue
Vol. 977, no. 2
p. 162

Abstract

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We present ultraviolet, optical, and near-infrared photometric and optical spectroscopic observations of the luminous fast blue optical transient (LFBOT) CSS 161010:045834–081803 (CSS 161010). The transient was found in a low-redshift ( z = 0.033) dwarf galaxy. The light curves of CSS 161010 are characterized by an extremely fast evolution and blue colors. The V -band light curve shows that CSS 161010 reaches an absolute peak of ${{M}}_{V}^{\max }=-20.66\pm 0.06$ mag in 3.8 days from the start of the outburst. After maximum, CSS 161010 follows a power-law decline ∝ t ^−2.8±0.1 in all optical bands. These photometric properties are comparable to those of well-observed LFBOTs such as AT 2018cow, AT 2020mrf, and AT 2020xnd. However, unlike these objects, the spectra of CSS 161010 show a remarkable transformation from a blue and featureless continuum to spectra dominated by very broad, entirely blueshifted hydrogen emission lines with velocities of up to 10% of the speed of light. The persistent blueshifted emission and the lack of any emission at the rest wavelength of CSS 161010 are unique features not seen in any transient before CSS 161010. The combined observational properties of CSS 161010 and its M _* ∼ 10 ^8 M _⊙ dwarf galaxy host favor the tidal disruption of a star by an intermediate-mass black hole as its origin.

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