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Jeanette Gladstone - University of Alberta Tim Roberts, Chris Done - Durham University Jeanette Gladstone - University of Alberta Tim Roberts, Chris Done.

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Presentation on theme: "Jeanette Gladstone - University of Alberta Tim Roberts, Chris Done - Durham University Jeanette Gladstone - University of Alberta Tim Roberts, Chris Done."— Presentation transcript:

1 Jeanette Gladstone - University of Alberta Tim Roberts, Chris Done - Durham University Jeanette Gladstone - University of Alberta Tim Roberts, Chris Done - Durham University Unlocking the nature of ULXs using their X-ray spectra

2 University of AlbertaJeanette GladstoneMadrid 2010 Ultraluminous X-ray Sources  Early XMM-Newton studies fit with standard disc + power-law (as used in Galactic sources)  Detection of cool disc component suggested IMBH  Early XMM-Newton studies fit with standard disc + power-law (as used in Galactic sources)  Detection of cool disc component suggested IMBH e.g. NGC 1313 X-1 Miller et al. (2003) kT in ~ 0.15,  ~ 1.8 ~1000M  BHs disk power-law

3 University of AlbertaJeanette GladstoneMadrid 2010 Ultraluminous X-ray Sources  Early XMM-Newton studies fit with standard disc + power-law (as used in Galactic sources)  Detection of cool disc component suggested IMBH  Resultant fits are not disc dominated - mass estimates uncertain.  Early XMM-Newton studies fit with standard disc + power-law (as used in Galactic sources)  Detection of cool disc component suggested IMBH  Resultant fits are not disc dominated - mass estimates uncertain. e.g. NGC 1313 X-1 Miller et al. (2003) kT in ~ 0.15,  ~ 1.8 ~1000M  BHs disk power-law

4 University of AlbertaJeanette GladstoneMadrid 2010 Ultraluminous X-ray Sources  Spectral features

5 University of AlbertaJeanette GladstoneMadrid 2010 Ultraluminous X-ray Sources  Spectral features  Soft excess

6 University of AlbertaJeanette GladstoneMadrid 2010 Ultraluminous X-ray Sources  Spectral features  Soft excess  High energy break ( e.g. Roberts 2007 )

7 University of AlbertaJeanette GladstoneMadrid 2010 Explanations for spectral break  Slim accretion discs (e.g. Watarai et al. 2000)  Fully Comptonised VHS with spectrum modified by ionised fast outflow (Goncalves & Soria 2006).  Disc plus Comptonised corona models - find fits with cool disc and cool, optically thick corona (Stobbart et al. 2006)

8 University of AlbertaJeanette GladstoneMadrid 2010 Understanding ULX spectra  Only the highest quality data (>10,000 counts)  Characterise the shape of the spectrum  Gain greater understanding of spectral shape by applying current physically motivated models  Only the highest quality data (>10,000 counts)  Characterise the shape of the spectrum  Gain greater understanding of spectral shape by applying current physically motivated models

9 University of AlbertaJeanette GladstoneMadrid 2010 Understanding ULX spectra Sample of 12 sources lying within 10 Mpc, covering the range of ULX luminosities (~ a few  erg s -1 )

10 University of AlbertaJeanette GladstoneMadrid 2010 Characterising ULX Spectra Holmberg IX X-1 model fit disk power-law

11 University of AlbertaJeanette GladstoneMadrid 2010 Characterising ULX Spectra Holmberg IX X-1 model fit disk power-law  11/12 show improvement (  2 > 30) with addition of disc component (soft excess)

12 University of AlbertaJeanette GladstoneMadrid 2010 power-law Characterising ULX Spectra Holmberg IX X-1  11/12 show improvement (  2 > 30) with addition of disc component (soft excess)  11/12 >98% statistical improvement for Broken power-law vs. power-law above 2 keV

13 University of AlbertaJeanette GladstoneMadrid 2010 Sample spectra

14 University of AlbertaJeanette GladstoneMadrid 2010 Sample spectra

15 University of AlbertaJeanette GladstoneMadrid 2010 Sample spectra

16 University of AlbertaJeanette GladstoneMadrid 2010 Sample spectra Soft excess + break not seen in any other accretion state, this is something new …

17 University of AlbertaJeanette GladstoneMadrid 2010 Sample spectra Soft excess + break not seen in any other accretion state, this is something new … … but what? Soft excess + break not seen in any other accretion state, this is something new … … but what?

18 University of AlbertaJeanette GladstoneMadrid 2010 Physically motivated modelling

19 University of AlbertaJeanette GladstoneMadrid 2010 Physically motivated modelling  Slim discs?

20 University of AlbertaJeanette GladstoneMadrid 2010 Physically motivated modelling  Slim discs?  Comptonisation models?  Slim discs?  Comptonisation models?

21 University of AlbertaJeanette GladstoneMadrid 2010 Physically motivated modelling  Slim discs?  Comptonisation models?  Worked well on XRBs so why not?  Slim discs?  Comptonisation models?  Worked well on XRBs so why not?

22 University of AlbertaJeanette GladstoneMadrid 2010 Physically motivated modelling  Slim discs?  Comptonisation models?  Worked well on XRBs so why not?  Slim discs?  Comptonisation models?  Worked well on XRBs so why not? Holmberg IX X-1

23 University of AlbertaJeanette GladstoneMadrid 2010 Physically motivated modelling  Slim discs?  Comptonisation models?  Worked well on XRBs so why not?  Slim discs?  Comptonisation models?  Worked well on XRBs so why not? Holmberg IX X-1

24 University of AlbertaJeanette GladstoneMadrid 2010 Slim disc fits  0.4 < p < 0.6 could imply support for slim disc Holmberg IX X-1 diskpbb

25 University of AlbertaJeanette GladstoneMadrid 2010 Slim disc fits  0.4 < p < 0.6 could imply support for slim disc  Problem < T in < 13 keV, higher disc temperature values are physically unrealistic  0.4 < p < 0.6 could imply support for slim disc  Problem < T in < 13 keV, higher disc temperature values are physically unrealistic Holmberg IX X-1 diskpbb

26 University of AlbertaJeanette GladstoneMadrid 2010 Slim disc fits  0.4 < p < 0.6 could imply support for slim disc  Problem < T in < 13 keV, higher disc temperature values are physically unrealistic  0.4 < p < 0.6 could imply support for slim disc  Problem < T in < 13 keV, higher disc temperature values are physically unrealistic Holmberg IX X-1 diskpbb

27 University of AlbertaJeanette GladstoneMadrid 2010 Slim disc fits  0.4 < p < 0.6 could imply support for slim disc  Problem < T in < 13 keV, higher disc temperature values are physically unrealistic  0.4 < p < 0.6 could imply support for slim disc  Problem < T in < 13 keV, higher disc temperature values are physically unrealistic Holmberg IX X-1 diskpbb

28 University of AlbertaJeanette GladstoneMadrid 2010 Comptonisation models  Two different Comptonisation models applied  COMPTT  EQPAIR  Two different Comptonisation models applied  COMPTT  EQPAIR DISKPN + COMPTT model fit disk comptt

29 University of AlbertaJeanette GladstoneMadrid 2010 Comptonisation models  Two different Comptonisation models applied  COMPTT  EQPAIR  Fit with cool disc + cool optically thick corona (  > 6)  Two different Comptonisation models applied  COMPTT  EQPAIR  Fit with cool disc + cool optically thick corona (  > 6) DISKPN + COMPTT model fit disk comptt

30 University of AlbertaJeanette GladstoneMadrid 2010 Comptonisation models  Galactic sources? All thin (  < 1-2) except in VHS (  ~3, kT ~20 keV) DISKPN + EQPAIR model fit disk eqpair

31 University of AlbertaJeanette GladstoneMadrid 2010 Comptonisation models  Galactic sources? All thin (  < 1-2) except in VHS (  ~3, kT ~20 keV)  More extreme - super-Eddington?  Galactic sources? All thin (  < 1-2) except in VHS (  ~3, kT ~20 keV)  More extreme - super-Eddington? DISKPN + EQPAIR model fit disk eqpair

32 University of AlbertaJeanette GladstoneMadrid 2010 Implications of Corona? model fit disk comptt model fit disk eqpair

33 University of AlbertaJeanette GladstoneMadrid 2010 Implications of Corona? FMasking of innermost regions of the accretion disc FMaterial and power may be drawn from the disc to feed the corona FMasking of innermost regions of the accretion disc FMaterial and power may be drawn from the disc to feed the corona model fit disk comptt model fit disk eqpair

34 University of AlbertaJeanette GladstoneMadrid 2010  As accretion rate increases, material & energy fed into corona Energetic disc-corona coupling

35 University of AlbertaJeanette GladstoneMadrid 2010  As accretion rate increases, material & energy fed into corona  Observe  Outer disc  Corona  As accretion rate increases, material & energy fed into corona  Observe  Outer disc  Corona Energetic disc-corona coupling model fit disk corona

36 University of AlbertaJeanette GladstoneMadrid 2010 Energetic disc-corona coupling  Energetically coupled inner disc cannot be seen  Neither feature can give direct information on temperature of inner accretion disc model fit disk corona

37 University of AlbertaJeanette GladstoneMadrid 2010 Spectra of ULXs

38 University of AlbertaJeanette GladstoneMadrid 2010 Spectra of ULXs

39 University of AlbertaJeanette GladstoneMadrid 2010 Disc- like spectra?  Looks disc-like  Recovered disc similar to actual data  Looks disc-like  Recovered disc similar to actual data

40 University of AlbertaJeanette GladstoneMadrid 2010 Disc- like spectra?  Looks disc-like  Recovered disc similar to actual data  Disc + power-law reveals warm disc fit  Looks disc-like  Recovered disc similar to actual data  Disc + power-law reveals warm disc fit

41 University of AlbertaJeanette GladstoneMadrid 2010 Disc- like spectra?  Looks disc-like  Recovered disc similar to actual data  Disc + power-law reveals warm disc fit  Physical meaning?  Broadening to create more realistic disc in this energy band (e.g. Done & Davis 2008)  Looks disc-like  Recovered disc similar to actual data  Disc + power-law reveals warm disc fit  Physical meaning?  Broadening to create more realistic disc in this energy band (e.g. Done & Davis 2008)

42 University of AlbertaJeanette GladstoneMadrid 2010 Ultraluminous state spectra  Double hump feature  First modelled by cool disc  Second modelled by break, or by Comptonising corona when applying more physical models  Double hump feature  First modelled by cool disc  Second modelled by break, or by Comptonising corona when applying more physical models

43 University of AlbertaJeanette GladstoneMadrid 2010 Ultraluminous state spectra  Double hump feature  First modelled by cool disc  Second modelled by break, or by Comptonising corona when applying more physical models  Both features, new state?  Double hump feature  First modelled by cool disc  Second modelled by break, or by Comptonising corona when applying more physical models  Both features, new state?

44 University of AlbertaJeanette GladstoneMadrid 2010 Low temperature discs?  IMBH?

45 University of AlbertaJeanette GladstoneMadrid 2010 Low temperature discs?  IMBH?  Something else?  So far we have tracked increasing mass accretion rate  IMBH?  Something else?  So far we have tracked increasing mass accretion rate

46 University of AlbertaJeanette GladstoneMadrid 2010 Low temperature discs?  IMBH?  Something else?  So far we have tracked increasing mass accretion rate  IMBH?  Something else?  So far we have tracked increasing mass accretion rate  Theory predicts that a photosphere + wind are key components of super-Eddington accretion  First observational evidence of photosphere?

47 University of AlbertaJeanette GladstoneMadrid 2010 Low temperature discs?  IMBH?  Something else?  So far we have tracked increasing mass accretion rate  IMBH?  Something else?  So far we have tracked increasing mass accretion rate  Theory predicts that a photosphere + wind are key components of super-Eddington accretion  First observational evidence of photosphere?  If this is the case we are looking at stellar-mass black hole in an extreme accretion state

48 University of AlbertaJeanette GladstoneMadrid 2010 Extreme accretion?

49 University of AlbertaJeanette GladstoneMadrid 2010 Extreme accretion?

50 University of AlbertaJeanette GladstoneMadrid 2010 Extreme accretion?

51 University of AlbertaJeanette GladstoneMadrid 2010 Extreme accretion?

52 University of AlbertaJeanette GladstoneMadrid 2010 Where do we go from here?  This work provides a prediction for the evolution of ULXs, so next stage is to follow evolution of ULXs with high quality data  Not the easiest of challenges, given sparsity of observations of these sources  Recent studies have found a variety of spectral behaviours (e.g. Feng & Kaaret 2009, Kajava & Poutanen 2009)  This work provides a prediction for the evolution of ULXs, so next stage is to follow evolution of ULXs with high quality data  Not the easiest of challenges, given sparsity of observations of these sources  Recent studies have found a variety of spectral behaviours (e.g. Feng & Kaaret 2009, Kajava & Poutanen 2009)

53 University of AlbertaJeanette GladstoneMadrid 2010 Spectral evolution? (Vierdayanti et al. 2010)  Using XMM-Newton observations and grouped Swift data (based on count rate) Swift spectra of Ho IX X-1, stacked on increasing count rate and compared to XMM-Newton data (in light blue). Underlying model is diskbb + comptt

54 University of AlbertaJeanette GladstoneMadrid 2010 Spectral evolution? (Vierdayanti et al. 2010)  Using XMM-Newton observations and grouped Swift data (based on count rate)  As luminosity increases, kT e ,    Using XMM-Newton observations and grouped Swift data (based on count rate)  As luminosity increases, kT e ,   Swift spectra of Ho IX X-1, stacked on increasing count rate and compared to XMM-Newton data (in light blue). Underlying model is diskbb + comptt

55 University of AlbertaJeanette GladstoneMadrid 2010 Spectral evolution? (Vierdayanti et al. 2010)  Using XMM-Newton observations and grouped Swift data (based on count rate)  As luminosity increases, kT e ,    This supports theory of increasing mass accretion rate  Using XMM-Newton observations and grouped Swift data (based on count rate)  As luminosity increases, kT e ,    This supports theory of increasing mass accretion rate Swift spectra of Ho IX X-1, stacked on increasing count rate and compared to XMM-Newton data (in light blue). Underlying model is diskbb + comptt

56 University of AlbertaJeanette GladstoneMadrid 2010 Spectral evolution? (Vierdayanti et al. 2010)  Using XMM-Newton observations and grouped Swift data (based on count rate)  As luminosity increases, kT e ,    This supports theory of increasing mass accretion rate  Results also show further complexity in spectral variability - difference spectral shape at same flux - hysteresis?  Using XMM-Newton observations and grouped Swift data (based on count rate)  As luminosity increases, kT e ,    This supports theory of increasing mass accretion rate  Results also show further complexity in spectral variability - difference spectral shape at same flux - hysteresis? Swift spectra of Ho IX X-1, stacked on increasing count rate and compared to XMM-Newton data (in light blue). Underlying model is diskbb + comptt

57 University of AlbertaJeanette GladstoneMadrid 2010 Conclusions  Ultraluminous state is characterised by cool disc + break above 3keV  Combination different from other observed accretion states  Application of Comptonisation models explains shape, and implies more extreme version of VHS  Energetic coupling reveals the presence of (large?) stellar-mass black holes  Some sources indicate presence of possibly the most extreme accretion environments  Initial spectral variability studies (with increased data quality) appear to support this  Ultraluminous state is characterised by cool disc + break above 3keV  Combination different from other observed accretion states  Application of Comptonisation models explains shape, and implies more extreme version of VHS  Energetic coupling reveals the presence of (large?) stellar-mass black holes  Some sources indicate presence of possibly the most extreme accretion environments  Initial spectral variability studies (with increased data quality) appear to support this


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