Download TDE in the XMM-Newton slew survey

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
Rosat discovered several
quiescent galaxies with soft Xray flux variations > 100. Light
curve decay roughly
compatible with t-5/3 . Dropping
by factors of 1000s in some
cases.
RXJ 1624.9+7554
Grupe, Thomas &
Leighly 1999
NGC 5905
Bade, Komossa &
Dahlem 1996;
Gezari+ 2003
Summary of ROSAT results
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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 Soft Hard Radio
(Log)
NGC 3599
0.002
42
Y
N
?
SDSS 1323
0.07
44
Y
N
?
SDSS 1201
0.15
45
Y
N
N
2MAS 0619
0.07
44
Y
Y
N
2MAS 0740
0.02
44
Y
Y
1 mJy
XMM 0630-60 ?Mainetti, Campana
?
Y ColpiN2016 ?
and
New One
0.029
43
Y
?
?
Slew – temporal characteristics
Overall index -5/3
SDSS 1201+30
SDSS J1323+43
XMM 0630-60
2MASS 0740-85
NGC 3599
2MASS 0619-65
Slew – UV temporal characteristics
2MASS 0619-65
2MASS 0740-85
Slew – temporal characteristics
t-5/3
Soft X-ray
t-1.2
t-5/3
0740-85
uvw2 (2246Å) – GALEX NUV
Slew – dips
Strong dips, due to what ?
SDSS 1201+30
Swift 1644
0740-85
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 ?
18 months
5 months
NGC 3599
0619-65
Tidal stripping of red giant: MacLeod, Guillochon & Ramirez-Ruiz 2012
Delayed TDE : Guillochon & Ramirez-Ruiz 2015
Slew – spectral characteristics
Brem=0.3 keV
SDSS 1201+30
Bbod = 66 eV
SDSS J1323+43
Γ=2, Bbod=86 eV
Bbod = 95 eV
0740-85
NGC 3599
Disk_bbod = 59 eV
0630-60
Γ=2, Bbod=114 eV
2MASS 0619-65
Slew – spectral characteristics
0740-85
Power-law + Disk black-body
Modelling X-ray spec with multicoloured disk black-body
underpredicts the UV.
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
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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.