TDE in the XMM-Newton slew survey Richard Saxton S. Komossa, A. Read, P. Lira, K. Alexander, P. Esquej, P. Rodriguez, M. Wieringa, I. Steele

Contents Characteristics of soft-X-ray selected TDE focussing on the ones found in the XMM slew Where do X-rays in TDE come from? Galaxy types Latest results

ROSAT – the first TDE detector Theory had it that disrupted material would circularise and be accreted causing an EUV / soft X-ray flare (Rees 88 etc.) in galactic nuclei. Debris would fall back at a rate of t-5/3 and luminosity would follow the mass. Launched in 1990 Sky survey found 100,000 objects

ROSAT high variability galaxies – Tidal Disruptions (TD) RXJ 1242.6-1119 Komossa & Greiner 1999 RXJ 1420.4+5534 Greiner+ 2000 Komossa 2012 RXJ 1624.9+7554 Grupe, Thomas & Leighly 1999 Rosat discovered several quiescent galaxies with soft X-ray flux variations > 100. Light curve decay roughly compatible with t-5/3 . Dropping by factors of 1000s in some cases. NGC 5905 Bade, Komossa & Dahlem 1996; Gezari+ 2003

Summary of ROSAT results Decays with t-5/3 Decays by factors of 1000s X-ray spectrum is soft as expected Shown to be TDE (candidates) rather than AGN, SNR, ULX, Blazars etc. Number counts low because nothing deep to compare against. Four new ones were found by comparing RASS with XMM pointed obs – 2% of sky hence will be hundreds found when compared with eRosita final cat. (Maksym 2014, Khabibullin & Sazonov 2014)

XMM-Newton slew survey Has covered ~85% of sky in the 0.2-2, 2-12 and 0.2-12 keV bands as of Jan 2015 and found >30,000 sources Compare with ROSAT >10x limit of 3x10-13 ergs/s/cm2 - Nearby X-ray TDE.

List of TDE in XMM slew SRC Z Lbol (Log) Soft Hard Radio NGC 3599 0.002 42 Y N ? SDSS 1323 0.07 44 SDSS 1201 0.15 45 2MAS 0619 2MAS 0740 0.02 1 mJy XMM 0630-60 New One 0.029 43 Mainetti, Campana and Colpi 2016

Slew – temporal characteristics Overall index -5/3 SDSS 1201+30 SDSS J1323+43 XMM 0630-60 Not biased because of 20 yr baseline 2MASS 0740-85 NGC 3599 2MASS 0619-65

Slew – UV temporal characteristics 2MASS 0619-65 2MASS 0740-85

Slew – temporal characteristics Soft X-ray Supernova hump making the UV / optical bump ? t-1.2 t-5/3 0740-85 uvw2 (2246Å) – GALEX NUV

Slew – dips Strong dips, due to what ? SDSS 1201+30 0740-85 Swift 1644 Curtis Saxton et al. 2012

Slew – dips : 0740-85 Dips are not caused by neutral absorption. Could be ionised absorption or intrinsic emission drop

Slew – slow rise Slow rise sometimes ? 0619-65 NGC 3599 18 months 5 months 0619-65 NGC 3599 Tidal stripping of red giant: MacLeod, Guillochon & Ramirez-Ruiz 2012 Delayed TDE : Guillochon & Ramirez-Ruiz 2015

Slew – spectral characteristics Brem=0.3 keV Bbod = 66 eV Disk_bbod = 59 eV SDSS 1201+30 SDSS J1323+43 0630-60 Γ=2, Bbod=86 eV Bbod = 95 eV Γ=2, Bbod=114 eV 0740-85 NGC 3599 2MASS 0619-65

Slew – spectral characteristics 0740-85 Modelling X-ray spec with multi-coloured disk black-body underpredicts the UV. Power-law + Disk black-body

Slew – spectral characteristics Fit UV, soft and hard X-rays Optxagn – Done et al. 2011 Thermal for UV Comptonised thermal – soft Power-law for hard With strongly-ionised absorber cf ASSASN 14li (Miller et al. 2016)

Where do X-rays in TDE come from ? Kara et al. 2016 – Swift 1644 reflection from accreting matter - M_BH a few x 10^6 - 400s doubling = <70 Rg 0740-85 soft X-ray light curve 0740 – variability , hence from within 70 Rg

Galaxy Types Arcavi et al. 2014; French et al. 2016 - E+A galaxies disproportionately represented in optical TDE samples 0740-85 starburst ~2 Gyr ago H_delta (ew) ~3 Ang, H_alpha (ew) < 1 Ang 0740-85 – also resides in a post-starburst host galaxy

New source z=0.029 15x brighter than ROSAT upper limit

Summary Soft X-ray TDE rate about 10-4 /gal/year. 7 events found in slew survey, 3 are well monitored Mix of soft and soft+hard – don’t know how many just hard Index=5/3 over long-term curve but highly variable in detail. Unsure if variability intrinsic or ionised absorption or both. At least one found in E+A galaxy Hard emission most likely from Compton rather than a jet Open question why hard component sometimes not present. Radio usually not present but weak emission in 0740-85.