Disk formation versus disk accretion—What powers tidal disruption events?

Journal Article · Sat Jun 20 04:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/806/2/164· OSTI ID:22883044

Piran, Tsvi; Svirski, Gilad ^[1]; Krolik, Julian; Cheng, Roseanne M.; Shiokawa, Hotaka ^[2]

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1. Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904 (Israel)
2. Physics and Astronomy Department, Johns Hopkins University, Baltimore, MD 21218 (United States)

A tidal disruption event (TDE) takes place when a star passes near enough to a massive black hole to be disrupted. About half the star’s matter is given elliptical trajectories with large apocenter distances, and the other half is unbound. To form an accretion flow, the bound matter must lose a significant amount of energy, with the actual amount depending on the characteristic scale of the flow measured in units of the black hole’s gravitational radius (∼10{sup 51}(R/1000R{sub g}){sup −1} erg). Recent numerical simulations have revealed that the accretion flow scale is close to the scale of the most bound initial orbits, ∼10{sup 3}M{sub BH,6.5}{sup −2/3}R{sub g}∼10{sup 15}M{sub BH,6.5}{sup 1/3} cm from the black hole, and the corresponding energy dissipation rate is ∼10{sup 44}M{sub BH,6.5}{sup −1/6} erg s{sup −1}. We suggest that the energy liberated during the formation of the accretion disk, rather than the energy liberated by subsequent accretion onto the black hole, powers the observed optical TDE candidates. The observed rise times, luminosities, temperatures, emission radii, and line widths seen in these TDEs are all more readily explained in terms of heating associated with disk formation rather than in terms of accretion.

• OSTI ID: 22883044
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 806; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United Kingdom
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCRETION DISKS
BLACK HOLES
COMPUTERIZED SIMULATION
DISTANCE
EMISSION
ENERGY LOSSES
GALAXY NUCLEI
LINE WIDTHS
LUMINOSITY
ORBITS
STARS