Holger Stiele

1
Supersoft sources in M 31 Comparing the
XMM-Newton Deep Survey, ROSAT and Chandra
catalogues

• Holger Stiele

SuperSoft X-ray Sources New Developments
ESAC Madrid 20.05.2009
2
The Large Program Collaboration
19 scientists from 7 countries

• PI W.Pietsch (MPE)
• MPE V. Burwitz, M. Freyberg, J. Greiner, F.
  Haberl, H. Stiele
• And R. Barnard (The Open University), D.
  Hatzidimitriou (University of Crete), M. Hernanz
  (CSIC-IEEC), G. Israel (INAF), U. Kolb (The Open
  University), A. Kong (National Tsing Hua
  University), P. Plucinsky (Harvard-Smithsonian
  Centre for Astrophysics), P. Reig (IESL), G. Sala
  (UPC/IEEC), M. Sasaki (Harvard-Smithsonian Centre
  for Astrophysics), L. Shaw Greening (The Open
  University), L. Stella (INAF), B. Williams
  (Pennsylvania State University)

3
Outline

• The XMM-Newton Deep Survey catalogue
• Supersoft sources ? optical novae
• Comparing the XMM-Newton Deep Survey, ROSAT and
  Chandra catalogues
• The catalogues
• The method
• The results

4
Image

• of Deep survey (outer ring) and archival
  (major axis) data (see Pietsch et al. 2005)
• Fields with high background repeated
• Optical extent indicated by D25 ellipse

0.2 1 keV1 2 keV2 12 keV
SSSs fgstars SNRs hard (AGNs,XRBs,Crab like
SNR)
Extended sources ? mostly background galaxy
clusters
5
Hardness Ratios
X-ray colour
i 14
B1 0.2-0.5 keVB2 0.5-1.0 keVB3 1.0-2.0
keVB4 2.0-4.5 keVB5 4.5- 12 keV

• fg star AGN?Gal/GlC

? XRB? SSS? SNR
Further classification methods

• Extent
• Time variability
• Cross correlations with optical and radio source
  catalogues

6
X-ray Sources in M 31 Field Identification and
Classification

• identified classified
• SSS 43
• SNR 25 38
• Globular clusters 36 17
• XRB 10 22
• foreground stars 22 243
• AGN 3 49
• Galaxies 4 21
• Galaxy clusters 1 1
• Hard 1289
• Without 127

• SSS 43

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Supersoft Sources

• Definition
• Radiation with effective temperature of 10 to 100
  eV
• Luminosities 1036-39 erg s-1
• HR1 lt 0 and HR2 - EHR2 lt -0.96 or HR2 not
  defined, HR3, HR4 not defined
• 43 SSSs, 27 new

8
Flux Distribution
Blackbody model withTbb 50 eVNH 6.6?1020
cm-2 Unabs. fluxes
Novae

• Period 217s Trudolyubov Priedhorsky 2008

Number of sources
M31N2001-11a
M31N2005-01c
erg cm-2 s-1
M31N2007-06b
Period 865.5s (Nova?) Osborne et al. 2001
7.3 ? 1036 erg/s
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Optical Novae

• Major class of SSSs in centre of M 31 optical
  novae (Pietsch et al. 2005, 2007)
• Outer regions not deep enough optical and no
  X-ray monitoring for novae/SSSs ? only snapshots
  (X-rays)? only random detections ? difficult to
  determine general properties of disk nova
  population

SSSsNovae
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Optical Novae (II)
M31N a. opt.det. Not vis. Distance Tbb (eV) LX (erg/s)
1994-09a 2591 d 3583 d 3.1 1.6?1036
1995-11c 1486 d --- 2.1 1.68?1037
1996-08b 1880 d --- 1.1 5.6 ?1036
1997-08b 1589 d 2514 d 2.3 0.7 ?1036
1997-10c 982 d 1167 d 1.9 ? 41 5.9 ?1037
1998-06a 1119 d 2235 d 1.1 1.7 ?1036
1999-10a 1751 d --- 1.6 2.12?1037
2000-07a 170 d --- 1.3 1.35 ?1037
2001-10f 84 d 1009 d 0.9 3.7?1037
2001-11a 53 d --- 0.5 Smirnova et al. 2006 Smirnova et al. 2006
2005-01b 535 d 1073 d 4.3 ? 45 1.0?1037
2005-01c 703 d --- 0.9 ? 40.23 1.2 ?1038
2005-09b 299 d 690 d 0.57
2007-06b ? See talk of M. Henze Pietsch et al. 2007 ? See talk of M. Henze Pietsch et al. 2007 ? See talk of M. Henze Pietsch et al. 2007 ? See talk of M. Henze Pietsch et al. 2007 ? See talk of M. Henze Pietsch et al. 2007
? 35
5.4 ?1038
11
Comparing the XMM-Newton Deep Survey, ROSAT and
Chandra catalogues
12
ROSAT PSPC Survey

• PSPC survey covering the entire galaxy twice ?
  560 X-ray sources Supper et al. 1997, 2001
• Supersoft sources selected from Greiner 2000 and
  Kahabka 1999
• Similar selection criterion (as used for
  XMM-Newton)
• Two hardness ratios (based on standard ROSAT
  energy bands)
• band separation energies at 0.5 keV, and 1
  keV
• ROSAT observations taken about gt 10 yr earlier
  than XMM-Newton observations (? investigation of
  long term variability)

13
Chandra Observations

• Observation of selected fields, especially
  central region Kong et al. 2002, Kaaret 2002, Di
  Stefano et al. 2004, Williams et al. 2004, 2006,
• Very soft sources Di Stefano et al. 2004
• Three energy bands S 0.1-1.1 keV M 1.1-2 keV
  H 2-7 keV
• Several criteria to select SSSs and QSSs
• Important difference
• Contamination of SSS class with
• Temporal distance to XMM-

Voss Gilfanov 2007
Only one band below 1 keV
foreground stars, SNRs and soft AGNs
Newton observationscentre and Field 2 lt 1
yrFields 13 gt 4yr
Image Di Stefano et al. 2004
14
Method
Two step process
First step Were the XMM-Newton SSSs detected in
previous surveys?
Full ROSAT PSPC
XMM Newton SSS
Full Chandra
Second step How many ROSAT/Chandra SSSs are
detected with XMM-Newton?
ROSAT SSS
Full XMM Deep Survey
Chandra VSS
15
XMM-Newton SSS to ROSAT PSPC Surveys

• 43 XMM-Newton SSS, 12 brighter than ROSAT
  detection threshold (5.3?10-15 erg cm-2 s-1)
• 2 also found as ROSAT SSSs
• 10 not detected with ROSAT 6 recent novae, 1
  transient, 1 variable ? 2 must be
  transient/highly variable
• 31 XMM-Newton SSS with fluxes below ROSAT
  detection threshold
• 1 also found as ROSAT SSSs (factor 22-25
  brighter in ROSAT observations)
• 3 chance coincidences
• 27 remaining sources 7 recent novae, 1 transient
  (Di Stefano et al. 2004)

16
XMM-Newton SSS to Chandra Surveys

• 9 XMM-Newton SSSs have Chandra counterparts
• 6 are also classified as SSSs from Chandra
• 8 of the 9 sources are located in the centre of M
  31
• 34 sources do not have Chandra counterparts
• 7 are in regions not covered with Chandra
• 10 are novae (4 after 2005, 6 no Chandra
  detections (see Pietsch et al. 2005, 2007 and
  M31N1999-10c, M31N2001-11a))
• 1 variable

17
ROSAT SSSs to XMM-Newton Deep Survey

• 34 ROSAT SSS, 4 not in observed XMM-Newton field
• 14 correlations with XMM-Newton sources
• 16 ROSAT SSS without XMM-Newton counterparts 1
  nova? Where are the novae?No systematic
  search/monitoring campaign in the years before
  1990 ? number of known optical novae very low
  (see talk of W. Pietsch)

3 SSS confirmed with XMM-Newton SSS confirmed with XMM-Newton SSS confirmed with XMM-Newton
5 Fg Star cand 1 Fg Star
1 SNR 1 Galaxy
2 lthardgt 1 No class. (2 XMM)
most of these sources not highly variable (fvar lt
5)
18
Chandra VSSs to XMM-Newton Deep Survey

• 20 Chandra SSSs
• 15 correlations with XMM-Newton sources
• 5 not detected with XMM-Newton (4 transients (Di
  Stefano et al. 2004, 2 of them novae), 1 faint)

5 Confirmed SSSs 2 Fg Star cand.
3 Confirmed fg Stars 1 SNR cand.
2 Confirmed SNRs 2 XRB cnad.
19
Chandra VSSs to XMM-Newton Deep Survey

• 23 Chandra QSSs
• 12 correlations with XMM-Newton sources
• 11 not detected with XMM-Newton (1 outside XMM
  field, 5 transients (Di Stefano et al. 2004), 1
  in crowded centre, 2 faint)

3 Confirmed fg Stars Confirmed fg Stars Confirmed fg Stars
3 Fg Star cand. 1 Fg Star
1 Bg Gal cand. 2 lthardgt
2 No class.
20
What do we learn?

• 3 sources detected in all 3 missions ? visible
  for more than a decade

• Two are located in the central field
• XMMM31 J004318.8412017 r3-8 SHL2001 235
  foreground polar? (Williams et al. 2006)
• XMMM31 J004252.5411540 r2-12 SHL2001 203
  PFJ93 58 TF91 69 217s period
  (Trudolyubov et al. 2008)
• XMMM31 J003840.5401956 s2-26 SHL2001 27

r3-8
r2-12
ROSAT
ROSAT 22-25 ? brighterXMM June 2006 Jan.
2008 in 3 Chandra observations (2000-2001) only
once visible ? variable (Di Stefano et al. 2004)
s2-26
XMM-Newton
Chandra
21
What do we learn? (II)

• Of 12 XMM-Newton sources with brightness above
  ROSAT threshold, only 2 observed by ROSAT ?
  underlines variability of the source class on
  long time scales (83 variable, cf. Greiner et
  al. 2004)
• ROSAT as well as Chandra SSSs contain sources of
  other classes

22
What do we learn? (III)

• Two interesting sources
• XMMM31 J004307.1411810 r3-115 Chandra and
  XMM-Newton observations between 2000-end 2001
  SSSXMM-Newton observation Jan. 2002 hard
  spectrum (Pietsch et al. 2005)
• XMMM31 J004247.9411549 r1-25 Chandra
  observations between 2000-end 2001
  SSSXMM-Newton observation July 2004 hard
  spectrumoptical counterpart within 1.2
  (regular or semi-regular red variable Fliri et
  al. 2006)
• Nature unclear X-ray transient (BH primary) or
  symbiotic

r3-115
r1-25
23
Summary

• Deep XMM-Newton survey of M 31 ? 1951 X-ray
  sources, 43 Supersoft sources
• Optical novae are an important class of SSSs in M
  31 (5 in addition to Pietsch et al. 2005, 2007)
  
• Correlation with ROSAT PSPC surveys and Chandra
  catalogues
• 3 persistent SSSs
• SSSs are a highly variable source class
• Many ROSAT and Chandra SSSs get other classes
  from XMM-Newton observations
• Two sources that show supersoft-hard transition
  between Chandra and XMM-Newton observations

24
Thank you for your attention

• The large program collaboration
• PI W.Pietsch (MPE)
• MPE V. Burwitz, M. Freyberg, J. Greiner, F.
  Haberl, H. Stiele
• And R. Barnard (The Open University), D.
  Hatzidimitriou (University of Crete), M. Hernanz
  (CSIC-IEEC), G. Israel (INAF), U. Kolb (The Open
  University), A. Kong (National Tsing Hua
  University), P. Plucinsky (Harvard-Smithsonian
  Centre for Astrophysics), P. Reig (IESL), G. Sala
  (UPC/IEEC), M. Sasaki (Harvard-Smithsonian Centre
  for Astrophysics), L. Shaw Greening (The Open
  University), L. Stella (INAF), B. Williams
  (Pennsylvania State University)