Tidal Disruption Events Andrew Levan University of Warwick

rT = R* (MCO / M*)1/3 Bound, falls back Unbound, escapes

rT = R* (MCO / M*)1/3 Bound, falls back Unbound, escapes WD, NS, BH

rT = R* (MCO / M*)1/3 Bound, falls back Unbound, escapes Asteroid, planet, star (MS, WD, RG, NS) WD, NS, BH

rT = R* (MBH / M*)1/3 Rs ~ 2 GM / c2

rT = R* (MBH / M*)1/3 tmin ~ R*3/2 MBH1/2 Duration of event: WD = hours MS = months - years RG = decades - centuries

Tidal disruption events – around massive black holes Probe of the existence of massive BHs in faint galaxies, even globular clusters? Timescales much more rapid than in AGN to probe accretion physics Contribution to the AGN LF Reverberation mapping of circumnuclear material Signposts of gravitational wave sources Signatures of merging BHs (disruption rates 1 per decade) Possible accelerators of ultra-high energy cosmic rays

Finding TDEs Nuclear X-ray and/or optical flares Hot blackbody components (UV, soft X-ray spectrum) Characteristic decay t-5/3 Rates 10-4-5 /yr/L* galaxy (0.1-1% of core collapse SNe rate)

Except…… Nuclear AGN and multiple variable X-ray sources. Often relatively poor X-ray cadence (don’t realise until it is late) X-ray’s often give poor positions compared to optical/radio Nuclear supernovae more common than TDEs Some UV bright at early times, extinction always a concern. Nuclei are bright, and often excluded from optical transient searches due to difficulties in subtractions Contributions from disc, wind etc complicate the lightcurve.

Early work(X-ray’s) Halpern, Gezari & Komossa 2004 ApJ 604 572 Komossa & Bade 1999 A&A 343 775

Recent work(X-ray’s) Saxton et al. 2012 A&A 541 106

Recent work (optical) Wavelength (A) Gezari et al. 2012 Nature 485 217

Recent work (optical) Opt UV ASASSN-14ae (200 Mpc) HST (13 June 2014) Holoein et al. 2014 arXiv:1405.1417

Why not both? PS1-10jh NUV X-ray Just disc/wind temperature? Different components at different times? Lodato & Rossi 2011 MNRAS 410 359

Why not both? ASASSN-14ae NUV X-ray Just disc/wind temperature? Different components at different times? Lodato & Rossi 2011 MNRAS 410 359

SGRB LGRB ULGRB TDE? SGR Galactic Sources Levan et al. 2014 ApJ 781 13

Swift J1644+57 Levan et al. 2011 Science 333 199 Levan et al. 2011 Science 333 199, Bloom et al. 2011 Science 333 202

Levan et al. 2011, Cenko et al. 2012, Brown et al. in prep

In context Levan et al. 2011, Cenko et al. 2012

Host Galaxies All 3 events consistent with nuclei of their hosts Levan et al. 2011 Science 333 199 All 3 events consistent with nuclei of their hosts

Bloom et al 2011 Science 333 202

Relativistic outflow Swift J1644+57 Zauderer et al. 2011 Nature 476 425

Switch-off Swift J1644+57

Switch-off Swift J2058+0516

Implications Host galaxies with MB <-18 have massive black holes in their cores A unique probe of galactic nuclei Miller & Gultekin 2011 ApJ 738 13; Berger et al. 2012 arXiv 1112.1697

Jets are rare 3 relativistic TDEs at z=0.35, 0.89, 1.19 All well detected by Swift No other compelling candidates in BAT archive Jetted TDE rate ~10-6 “classical TDEs” Jet angles much larger than this Requirements for jet creation unclear

UV/optical X-ray Relativistic PS1-10jh D23H-1 D3-13 D1-9 PS1-11af ASASSN-14ae PTF09ge PTF09axc PTF09djl UV/optical NGC5905 RXJ1242-1119 RXJ1420+5334 NGC3599 SDSSJ1323+4827 TDXFJ1347-3254 SDSSJ1311-0123 2MMMi J1847-6317 SDSSJ1201+3003 X-ray Swift J1644+57 Swift J2058+0516 Swift J1112-8238 Ultra-long GRBs? Relativistic PTF10iya Are these all TDEs? Why are they so diverse? A naming convention ala SNe is urgently needed (NT-X 2014A?)

Summary and next steps TDEs are exceptionally useful astrophysical probes But: Candidates to date are extremely diverse. X-ray detected events have poor optical follow-up Many optically detected events don’t have detectable X-ray’s Jetted events appear to be extremely rare We still need to understand the physical mechanisms at play to cleanly identify TDEs from other transients, and deploy them as probes. Multiwavelength follow-up in close to real time is essential Rule out SNe Tie events to SMBH as tightly as possible Map emission processes