Discovery and follow-up of the unusual nuclear transient OGLE17aaj

M. Gromadzki, A. Hamanowicz, L. Wyrzykowski, K. V. Sokolovsky, M. Fraser, Sz Kozłowski, J. Guillochon, I. Arcavi, B. Trakhtenbrot, P. G. Jonker, S. Mattila, A. Udalski, M. K. Szymański, I. Soszyński, R. Poleski, P. Pietrukowicz, J. Skowron, P. Mróz, K. Ulaczyk, M. PawlakK. A. Rybicki, J. Sollerman, F. Taddia, Z. Kostrzewa-Rutkowska, F. Onori, D. R. Young, K. Maguire, S. J. Smartt, C. Inserra, A. Gal-Yam, A. Rau, T. W. Chen, C. R. Angus, D. A.H. Buckley

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


Aims. We report on the discovery and follow-up of a peculiar transient, OGLE17aaj, which occurred in the nucleus of a weakly active galaxy. We investigate whether it can be interpreted as a new candidate for a tidal disruption event (TDE). Methods. We present the OGLE-IV light curve that covers the slow 60-day-long rise to maximum along with photometric, spectroscopic, and X-ray follow-up during the first year. Results. OGLE17aaj is a nuclear transient exhibiting some properties similar to previously found TDEs, including a long rise time, lack of colour-temperature evolution, and high black-body temperature. On the other hand, its narrow emission lines and slow post-peak evolution are different from previously observed TDEs. Its spectrum and light-curve evolution is similar to F01004-2237 and AT 2017bgt. Signatures of historical low-level nuclear variability suggest that OGLE17aaj may instead be related to a new type of accretion event in active super-massive black holes.

Original languageEnglish
Article numberL2
Number of pages5
JournalAstronomy and Astrophysics
Publication statusPublished - 01 Feb 2019


  • Black hole physics
  • Galaxy: nucleus

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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