Tidal Disruption Events

Tidal Disruption

Events

Andrew LevanUniversity 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

WD, NS, BH

Asteroid, planet, star (MS, WD, RG, NS)

rT = R* (MBH / M*)1/3

Rs ~ 2 GM / c2

rT = R* (MBH / M*)1/3

tmin ~ R*3/2 MBH

1/2

Duration of event:WD = hoursMS = months - yearsRG = 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.

Halpern, Gezari & Komossa 2004 ApJ 604 572

Early work(X-ray’s)

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)

ASASSN-14ae (200 Mpc)HST (13 June 2014)

UVOpt

Holoein et al. 2014 arXiv:1405.1417

Why not both?

Lodato & Rossi 2011 MNRAS 410 359

PS1-10jh

Just disc/wind temperature?Different components at different times?

NUV

X-ray

SGRB LGRB

Galactic Sources

SGR

ULGRB TDE?

Levan et al. 2014 ApJ 781 13

Levan et al. 2011 Science 333 199Levan et al. 2011 Science 333 199, Bloom et al. 2011 Science 333 202

Swift J1644+57

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

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

Bloom et al 2011 Science 333 202

Relativistic outflow

Zauderer et al. 2011 Nature 476 425

Swift J1644+57

Switch-off Swift J1644+57

Switch-off Swift J2058+0516

ImplicationsHost 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 rare3 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

PS1-10jhD23H-1D3-13D1-9

PS1-11afASASSN-14ae

PTF09gePTF09axcPTF09djl

NGC5905RXJ1242-1119RXJ1420+5334

NGC3599SDSSJ1323+4827TDXFJ1347-3254SDSSJ1311-0123

2MMMi J1847-6317

SDSSJ1201+3003

Swift J1644+57Swift J2058+0516Swift J1112-8238

Ultra-long GRBs?

UV/optical X-ray Relativistic

Are these all TDEs? Why are they so diverse?

PTF10iya

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