Tidal disruption event

A tidal disruption event (TDE) is a transient astronomical source produced when a star passes so close to a supermassive black hole (SMBH) that it is pulled apart by the black hole's tidal force.^[2][3] The star undergoes spaghettification, producing a tidal stream of material that loops around the black hole. Some portion of the stellar material is captured into orbit, forming an accretion disk around the black hole, which emits electromagnetic radiation. In a small fraction of TDEs, a relativistic jet is also produced. As the material in the disk is gradually consumed by the black hole, the TDE fades over several months or years.

TDEs were predicted in the 1970s and first observed in the 1990s. Over a hundred have since been observed, with detections at optical, infrared, radio and X-ray wavelengths. Sometimes a star can survive the encounter with an SMBH, leaving a remnant; those events are termed partial TDEs.^[4][5]

TDEs were first theorized by Jack G. Hills in 1975.^[6] A consequence of a star getting sufficiently close to a SMBH that the tidal forces between the star will overcome the star's self-gravity. In 1988 Martin Rees described how approximately half of the disrupted stellar material will remain bound, eventually accreting onto the black hole and forming a luminous accretion disk.^[7]

According to early studies, tidal disruption events are an inevitable consequence of massive black holes' activity hidden in galaxy nuclei. Later theorists concluded that the resulting explosion or flare of radiation from the accretion of the stellar debris could reveal the presence of a dormant black hole in the center of a normal galaxy.^[8]

TDEs were first observed in the early 1990s using the X-ray ROSAT All-Sky Survey.^[9]

As of May 2024, roughly 100 TDEs are known,^[10][11][12] and have been discovered through several astronomical methods, such as optical transient surveys including Zwicky Transient Facility (ZTF)^[12] and the All Sky Automated Survey for SuperNovae (ASAS-SN).^[13] Other TDEs have been discovered in X-rays, using the ROSAT, XMM-Newton, and eROSITA.^[14] TDEs have also been discovered in the ultraviolet.^[15] The James Webb Space Telescope is capable of detecting the dust heated by TDEs because of its ability to detect infrared light.^[16]

The light curves of TDEs have an initially sharp rise in brightness, as the disrupted stellar material falls towards the black hole, followed by a more gradual decline lasting months or years. During the declining phase, the luminosity is proportional to ${\displaystyle t^{-5/3}}$, where t is time,^[17] although some TDEs have been observed to deviate from the typical ${\displaystyle t^{-5/3}}$rate.^[18] These properties allow TDEs to be distinguished from other transient astronomical sources, such as supernovae. The peak luminosity of TDEs is proportional to the central black hole mass; it can approach or exceed that of their host galaxies, making them some of the brightest sources observed in the Universe.^[19]

There are two broad classes of TDEs. The majority of TDEs consist of "non-relativistic" events, where the outflows from the TDE are akin to the energetics seen in Type Ib and Ic supernovae.^[20]

Approximately 1% of TDEs, however, are relativistic TDEs, where an astrophysical jet is launched from the black hole shortly after the star is destroyed. This jet persists for several years before shutting off.^[21] As of 2023 only four TDEs with jets have been observed.^[22]

Ein Stern wird durch Gezeitenkräfte zerrissen, wenn die Gezeitenkraft eines Schwarzen Lochs die Eigengravitation an der Sternoberfläche übersteigt . Der Abstand unterhalb dieser Grenze wird als Gezeitenradius bezeichnet und ist näherungsweise gegeben durch: ^{[ 23 ] [ 24 ]}${\displaystyle f_{tidal}\approx {\frac {2GM_{BH}R^{*}}{R^{3}}}}$${\displaystyle f_{sg}\approx {\frac {GM^{*}}{R^{*2}}}}$${\displaystyle f_{tidal}>f_{sg}}$

${\displaystyle R_{T}\approx R^{*}\left({\frac {2M_{BH}}{M^{*}}}\right)^{\frac {1}{3}}}$

Dies ist identisch mit der Roche-Grenze für die Zerstörung fester Planetenkörper.

Um ein Gezeitenzerstörungsereignis zu beobachten, muss der Gezeitenzerstörungsradius eines Schwarzen Lochs größer sein als sein Schwarzschildradius . Bei gegebenem Sternradius und gegebener Sternmasse existiert daher eine Masse für das Schwarze Loch, bei der beide Radien gleich groß werden und der Stern verschwinden würde, bevor er zerrissen wird. ^{[ 25 ] [ 7 ]} Für einen Stern mit Sonnenmasse beträgt diese Masse ungefähr ^{[ 26 ]} .${\displaystyle R_{S}={\frac {2GM}{c^{2}}}}$${\displaystyle M_{\rm {BH}}\approx 10^{8}M_{\odot }}$

• Swift J1644+57 ^{[ 27 ]} Ein relativistischer Jet, der bei der Zerstörung eines 3,8 Milliarden Lichtjahre entfernten Sterns entstand. Der Jet war 1,5 Jahre aktiv und erlosch dann. ^{[ 28 ]}
• ASASSN-14li ^{[ 29 ] [ 30 ]} Die erste Radiodetektion eines nicht-relativistischen Ausflusses aus einem TDE im Jahr 2014.
• AT 2018hyz ^{[ 31 ]} Ein TDE, das bis etwa 750 Tage nach dem initialen TDE-Ereignis radiostill war und seitdem einen raschen Anstieg der Radiofrequenzen verzeichnet. Dies wurde als verzögerter Radioausfluss oder als ein außermittiger Jet interpretiert. ^{[ 32 ]}
• ASASSN-19bt wurde im Rahmen des Projekts „All Sky Automated Survey for SuperNovae “ (ASAS-SN) entdeckt , wobei der TESS- Satellit frühzeitig detaillierte Beobachtungen durchführte . ^{[ 13 ] [ 33 ]}
• AT 2019qiz ^{[ 34 ]}
• AT 2022cmc ^{[ 35 ]} ist ein Jet-TDE, der 2022 von ZTF entdeckt wurde.
• AT 2022dbl is hypothesized to be a repetitive TDE, where a star has passed at least twice near a supermassive black hole and survived the first encounter, implying that perhaps at least some “standard” optical TDEs are in fact partial disruptions.^[36]
• ASASSN-20hx, located near the nucleus of galaxy NGC 6297, was discovered in July 2020 and noted that the observation represented one of the "very few tidal disruption events with hard powerlaw X-ray spectra".^[37][38]
• AT 2024tvd - the first TDE that doesn't seem to be located at the center of a galaxy, but rather 2600 light years from a larger supermassive black hole at the center of the host galaxy.^[39]

• Gamma-ray burst#Tidal disruption events
• Super soft X-ray source#Large amplitude outbursts
• RX J1242-11

• The Open TDE catalog, a catalog of claimed tidal disruption events.