KFU. Card publication. First tidal disruption events discovered by SRG/eROSITA: X-ray/optical properties and X-ray luminosity function at z

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FIRST TIDAL DISRUPTION EVENTS DISCOVERED BY SRG/EROSITA: X-RAY/OPTICAL PROPERTIES AND X-RAY LUMINOSITY FUNCTION AT Z < 0.6

Form of presentation

Articles in international journals and collections

Year of publication

2021

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Authors, employees of KFU

Bikmaev Ilfan Fyaritovich, author

Gumerov Rustam Iskhakovich, author

Bibliographic description in the original language

Sazonov S., Gilfanov M., Medvedev P., First tidal disruption events discovered by SRG/eROSITA: X-ray/optical properties and X-ray luminosity function at z < 0.6//MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. - 2021. - Vol.508, Is.3. - P.3820-3847.

Annotation

We present the first sample of tidal disruption events (TDEs) discovered during the SRG all-sky survey. These 13 events were selected among X-ray transients detected in the 0? < l < 180? hemisphere by eROSITA during its second sky survey (2020 June 10 to December 14) and confirmed by optical follow-up observations. The most distant event occurred at z = 0.581. One TDE continued to brighten at least 6 months. The X-ray spectra are consistent with nearly critical accretion on to black holes of a few ×103 to 108M⊙ , although supercritical accretion is possibly taking place. In two TDEs, a spectral hardening is observed 6 months after the discovery. Four TDEs showed an optical brightening apart from the X-ray outburst. The other nine TDEs demonstrate no optical activity. All 13 TDEs are optically faint, with Lg/LX < 0.3 (Lg and LX being the g band and 0.2-6 keV luminosity, respectively). We have constructed a TDE X-ray luminosity function, which can be fit by a power law with a slope of -0.6 ? 0.2, similar to the trend observed for optically selected TDEs. The total rate is estimated at (1.1 ? 0.5) × 10-5 TDEs per galaxy per year, an order of magnitude lower than inferred from optical studies. This suggests that X-ray bright events constitute a minority of TDEs, consistent with models predicting that X-rays can only be observed from directions close to the axis of a thick accretion disc formed from the stellar debris. Our TDE detection threshold can be lowered by a factor of ~2, which should allow a detection of ~700 TDEs by the end of the SRG survey.

Keywords

accretion; accretion discs; black hole physics; quasars: supermassive black holes; X-rays: galaxies; transients: tidal disruption events;

The name of the journal

Monthly Notices of the Royal Astronomical Society

URL

https://academic.oup.com/mnras/article-abstract/508/3/3820/6381721?redirectedFrom=fulltext

Please use this ID to quote from or refer to the card

https://repository.kpfu.ru/eng/?p_id=260992&p_lang=2

Full metadata record

Field DC	Value	Language
dc.contributor.author	Bikmaev Ilfan Fyaritovich	ru_RU
dc.contributor.author	Gumerov Rustam Iskhakovich	ru_RU
dc.date.accessioned	2021-01-01T00:00:00Z	ru_RU
dc.date.available	2021-01-01T00:00:00Z	ru_RU
dc.date.issued	2021	ru_RU
dc.identifier.citation	Sazonov S., Gilfanov M., Medvedev P., First tidal disruption events discovered by SRG/eROSITA: X-ray/optical properties and X-ray luminosity function at z < 0.6//MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. - 2021. - Vol.508, Is.3. - P.3820-3847.	ru_RU
dc.identifier.uri	https://repository.kpfu.ru/eng/?p_id=260992&p_lang=2	ru_RU
dc.description.abstract	Monthly Notices of the Royal Astronomical Society	ru_RU
dc.description.abstract	We present the first sample of tidal disruption events (TDEs) discovered during the SRG all-sky survey. These 13 events were selected among X-ray transients detected in the 0? < l < 180? hemisphere by eROSITA during its second sky survey (2020 June 10 to December 14) and confirmed by optical follow-up observations. The most distant event occurred at z = 0.581. One TDE continued to brighten at least 6 months. The X-ray spectra are consistent with nearly critical accretion on to black holes of a few ×103 to 108M⊙ , although supercritical accretion is possibly taking place. In two TDEs, a spectral hardening is observed 6 months after the discovery. Four TDEs showed an optical brightening apart from the X-ray outburst. The other nine TDEs demonstrate no optical activity. All 13 TDEs are optically faint, with Lg/LX < 0.3 (Lg and LX being the g band and 0.2-6 keV luminosity, respectively). We have constructed a TDE X-ray luminosity function, which can be fit by a power law with a slope of -0.6 ? 0.2, similar to the trend observed for optically selected TDEs. The total rate is estimated at (1.1 ? 0.5) × 10-5 TDEs per galaxy per year, an order of magnitude lower than inferred from optical studies. This suggests that X-ray bright events constitute a minority of TDEs, consistent with models predicting that X-rays can only be observed from directions close to the axis of a thick accretion disc formed from the stellar debris. Our TDE detection threshold can be lowered by a factor of ~2, which should allow a detection of ~700 TDEs by the end of the SRG survey.	ru_RU
dc.language.iso	ru	ru_RU
dc.subject		ru_RU
dc.title	First tidal disruption events discovered by SRG/eROSITA: X-ray/optical properties and X-ray luminosity function at z < 0.6	ru_RU
dc.type	Articles in international journals and collections	ru_RU