X-ray Observations of Galaxies & X-ray Binary Populations of Elliptical Galaxies

1. NGC 3379 X-ray Observations of Galaxies & X-ray Binary Populations of Elliptical Galaxies NGC 4365 G. Fabbiano CfA

2. Outline • I. Preamble • X-ray observations of galaxies • II. XRB populations of elliptical galaxies • Issues & history • Landscape • New results from very deep Chandra observations

3. Chandra X-ray Observations of Galaxies • X-ray source populations • The hot ISM (e.g. the Antennae) • Plasma properties • Metal enrichment • Hot outflows • Quiescent SMBHs and their environment • BH-galaxy feedback

4. The Milky WayWang et al 2002 M 83Soria & Wu 2002 NGC 4038/9Fabbiano et al 2003

5. Hot ISM: the Antennae

6. Hot ISM: the Antennae • A deep view • Baldi et al 2004astro-ph 0410192 Deep Chandra – diffuse emission Baldi et al 2006a, b

7. Hot ISM: the Antennae See papers by A. Baldi et al • Copious and complex hot ISM • Cooling times 107-8 yrs • Masses 105-6 Msol • Temperatures in the range 0.3 – 0.7keV • 3-7 times those of the Galactic hot ISM • Very high pressures • 10-100 that of solar neighborhood

8. Sub-solar abundanceskT1~0.2keV, kT2~0.6keV Very high abundanceskT~0.3keV Spatially variable enrichment Ne Fe Si Mg Mg 20 5 Ne 20 0.4-2 --solar abundanceskT~0.6keV, strong power-law • Red- Fe • Green – Mg • Blue - Si

9. Element ratios in the Antennae (Baldi et al 2006) Ratios consistent with SNII yields, except for depleted Si SNII SNIa

10. Superwinds, large scale expansion, formation of hot halos in E galaxies The Antennae?? M82 The Antennae

11. Quiescent SMBHs

12. Why are most SMBH quiescent? • Similar BH masses to AGN • Much fainter: How faint? • Obscured AGNs? • Lack of fuel? • Low inefficient accretion state? • Interaction with the ISM • Fuel • Outflows / feedback • Remnants of past activity? Tremaine et al 2002

13. . Lbol = (1-PKE)fLX= rM c2 Why are QGN Quiescent (if not absorbed)? Low Radiative Efficiency Low Accretion Rate? Jet power Bolometric correction Limited by gas available: Hot and cool ISM, Bondi limit Observable with Chandra Observable with Chandra Lx~10-8–10-7LEdd ADAF: r << 0.1 standard disk: r ~ 0.1 Model-dependent: R. Soria

14. NGC 821: high resolution & long exposures • Isolated E galaxy with old stellar population • D~24 Mpc • Nuclear SMBH - inactive • MSMBH = 8.7  107 M • LEdd ~ 1 1046 erg/s • First observed with Chandra in 2002 (39~ks, Fabbiano et al 2004) • 11 sources (LX > 1.21038 erg/s) • Fuzzy, S-shaped central emission • Nuclear emission? • Hot ISM to fuel the SMBH?

15. 230 ks - Pellegrini et al 2007a, bAstrometry, Chandra & Hubble, using GC sources • S1, S2, S4 are not point-like • S2 is at the nucleus • LX~61038erg/s • Point-like AGN • LX<2.81038erg/s (0.3-8 keV) • LX/LEdd<2.510-8 • Hard emission~1.5, NH~NHGal.

16. 230 ks - Pellegrini et al 2007a, b • 41 sources within D25 • LX > 31037erg/s X-ray colors consistent with LMXB spectra LMXB XLF Bkg AGN

17. Is there hot ISM to feed the SMBH? • LMXBs, stellar light, diffuse X-ray emission follow each other closely • Cleaned diffuse emission spectrum consistent with LMXBs • Diffuse X-ray emission dominated by (or totally due to) LMXBs Stellar light • Nucleus fed by cold ISM • Stellar outgassing • Hot ISM swept away by past nuclear activity?

18. Is therefuelto feed the SMBH? • Numerical simulations of the hot ISM evolution in NGC821 show that the bulk of gas is expelled by SN (Pellegrini et al 2007) • Include dark and stellar mass • Stellar mass loss rates appropriate for the NGC821 population • LSN from observed SNIa rates (Cappellaro et al 1999) • A small accumulation M’~ a few 10-5 M/ yr at the nucleus (not enough to build the SMBH) • Lacc~M’ c2~(1-4)1041erg/s > Lbol(SED)~a few 1039erg/s • The SMBH is still underluminous! NICMOS

19. X-Ray Source Populations See Fabbiano 2006, ARAA

20. X-ray Binaries - the main component • LMXB -Old • Late type star donor • Roche lobe overflow • Long lifetimes~109-10 yrs • HMXB -Young • Early type star donor • Wind or Roche lobe overflow • Short lifetimes~107 yrs Tracer of mass Tracer of star formation Neutron star Or Black Hole

21. Advantages • External galaxies provide `cleaner’ samples • Distances uncertain for Galactic XRB • Extinction a major problem • Associate XRB with stellar populations • Find and study `extreme’ sources • ULXs

22. Approaches • X-ray colors / spectra • Variability / spectral variability • Association with optical / radio counterparts • X-ray Luminosity Functions

23. An X-ray color-color diagram HMXB LMXB SNR Prestwich et al 2003

24. Studying the evolution of XRBs with XLFs • XLF different in different stellar populations • Younger populations, flatter XLFs M81 – Swartz et al 2003 M81 - arms Old disk Willner et al 2004 – Spitzer/UV M81 – Chandra -Tennant et al 2001

25. Studying the evolution of XRBs with XLFs • XLF different in different stellar populations • Younger populations, flatter XLFs 10 Myrs Belczynski et al, 2004 Comparing observed with synthetic XLF NGC 1569 200 Myr

26. The HMXB and LMXB XLF in the Galaxy(Grimm, Gilfanov & Sunyaev 2002)

27. XLF and Star Formation • Lx ~FIRcorrelations in Sc-Irr(e.g., Fabbiano et al 1988; Fabbiano & Shapley 2002) • XLF ~ SFRin actively star forming galaxies(Grimm, Gilfanov & Suniaev 2003) • Universal XLF cumulative Slope -0.6

28. The XLF of the AntennaeZezas et al 2007 Coadded observation • 120 sources • Cumulative XLF slope ~-0.5 ULX

29. How do LMXBs form? - Debated since 1975… High-resolution imaging, sensitive, time-monitoring • Formation in GCs (efficient two-body encounters; Clark 1975, Katz 1975; Fabian et al 1975)? • Ultra-compact NS-WD binaries(Bildsten & Deloye 2004) • White dwarf orbiting NS • 5-10 min orbit • Short lifetime 107 • Transient at the LX 1037 erg s-1 • LX < ~2 1038 erg s-1 • High luminosity BH binaries(Kalogera, King & Rasio 2004) • Should be rare • Possibly persistent (if from capture) • Evolution of native field binaries (seeVerbunt & van den Heuvel 1995)?(Piro & Bildsten 2002, King 2002, Ivanova & Kalogera 2006) • E.g. semi-detached binaries with large unstable disks and giant donors • Recurrent transients(recurrence time >100yr, outburst 1-100 yr) • Transients [1 + 4 candidates] detected in NGC5128 ( Kraft et al 2001) Question: Do all form in GC then disperse in the Field (J. Grindlay)? Light-curves, XLFs

30. XLFs -norm. (LX,gal.) driven by stellar massGilfanov 2004 • Similar XLF shapes (LMXBs of M.W., spirals, ellipticals) • Normalization is function of global stellar massLX(>1037erg/s) = (8.0 +/- 0.5) x 1039 erg/s per 1011 M

31. LX(LMXBs)~M*…but… • It also depends on the GC content of a galaxy(Kim & Fabbiano 2004)

32. LMXBs in GCs • We are understanding more about • LMXB GC formation, but…. • Are GC and field LMXBs different populations? • Are there any ‘telling’ differences • suggesting different evolution? • Detected widely with Chandra/Hubble • What makes a GC generate an LMXB? • Lots’ of discussion (see Fabbiano 2006 ARAA) • Metallicity (age?) (Red GCs more likely to have LMXBs -see papers by Kundu, Maccarone, Zepf….) • Structural Characteristics • denser(), more compact(rc)and higher encounter rate()GC tend to be X-ray sources (Jordan et al 2004:M87; Sivakoff et al 2007: survey; Jordan et al 2007: CenA) • ..but there is some controversy…

33. NGC 3379 - Deep Chandra ACIS Monitoring Texp=337 ks D= 10.6 Mpc LB = 1.3 1010 L N. Brassington, D.-W. Kim, A. Zezas - CfA L. Angelini - GSFC R. Davies - Oxford J. Gallagher - Wisconsin V. Kalogera, T. Fragos - Northwestern King - Leicester S. Pellegrini - Bologna G. Trinchieri - Milano, Brera S. Zepf, A. Kundu - Michigan S. Blake - Southampton • Little hot gaseous emission, to optimize faint LMXB detection

34. LMXBs in NGC3379Brassington et al 2007 • 132 sources • 98 within D25

35. NGC 3379 - Field LMXB variability • Comparing the 5 observations, ~65% of (132 detected) sources are variable • Different types of long-term variability observed, both in flux and spectrum Variable

36. NGC 3379 - Transients 2001 2005 2006 2002 2003 2004 S128 • Luminous field LMXB are expected to be transients • 15/98 sources (~D25) are field candidate transients (+ 3 in GCs) • 4 on 6 months flares (detected in 1 or two consecutive times) • 2 on for > 5 years • 7 on for > 2 days • 2 on for > 4 months • Persistent sources could be transients with on-time >5yr > 15% of LMXBs are transient

37. NGC 3379 - Transient S128 • Maximum LX~2  1039 erg s-1 • Spectrum at maximum is unusually hard • Ionized absorber? Eddington-driven Outflow? • Ultraluminous (ULX) state of accretion disks? • Soria et al 2007, NGC1365 X-1 • Feng & Kaaret 2007, NGC 1313 X-2 • If that’s the case, S128 could be a neutron star binary

38. R. Soria 2007 Increasing Accretion rate Ultraluminous Very high (SPL) High/soft (TD) Low/hard

39. Field and GC LMXB XLFs • The high luminosity XLFs of GC and Field LMXBs are the same (Kim E. et al 2006) • Consistent with (but not proving) similar origin • Does this similarity extends to lower luminosities? ---GC-LMXBs ---field-LMXBs ? 1038

40. Low luminosity Field and GC LMXB XLFs LMXB-Field LMXB-Field M31 NGC 3379 KS test P = 0.2% • XLFs of GC-LMXB and field-LMXB appear to differ below 1037 erg s-1 • There is a relative lack of GC-LMXBs • Similar to M31 (Voss & Gilfanov 2007) LMXB in WFPC2 field LMXB-GC KMZ 2007 expected GC-LMXB detected 30 ks, LX ~21037 337 ks, LX ~21036 LMXB-GC

41. NGC 4278 16 Mpc, LB~1.61010L Chandra ACIS 470 ks

42. Field and GC LMXB XLFs in NGC4278preliminary results Field - 43 LMXBs GC - 37 LMXBs The GC XLF appears relatively depleted at low LX

43. Why do Field and GC XLFs differ at low LX? • Do we detect multiple LMXBs in a given GC at the high LX end? • This may artificially deplete the low luminosity XLF • NO - variability demonstrates these are single luminous sources • Are GC BH LMXBs persistent capture binaries?(Kalogera, King & Rasio 2004) • At these luminosities field LMXBs would be transients, so field XLF depleted • Sources with LX>1038 erg s-1 vary, but are persistent Different evolution for GC and Field LMXBs and possibly for high and low luminosity GC LMXBs • Are low luminosity (<1037 erg s-1) LMXB-GC transient ultracompact binaries ?(Bildsten and Deloye 2004) • Two transients just above 1037 erg s-1

44. Summary • XRB give a direct detection of the end-point of binary evolution in different stellar populations • With Chandra we now detect populations of XRBs in galaxies • With Hubble XRBs can be associated with stellar and GC counterparts • XRB populations differ depending on the age, metallicity and structural characteristics of the associated stellar populations / systems • LMXB are formed both in the stellar field and in GCs • Hot ISM and its metal content are uniquely detected in X-rays • Getting the full picture of the multiphase ISM • Vector for the dispersion of elements outside the parent galaxy • Active and now Silent nuclear SMBHs can be studied • Accretion processes, fuel • Galaxy feedback