X-ray binaries. Marat Gilfanov MPA, Garching

Transcription

1 X-ray binaries Marat Gilfanov MPA, Garching

2 Outline observational appearance populations in galaxies relation to star-formation history numbers, luminosity distributions, IMF

3 Hans-Jakob Grimm (CfA) Igor Prokopenko (IKI) Pavel Shtykovskiy (IKI/MPA) Rashid Sunyaev (MPA/IKI) Rasmus Voss (MPA, MPE) Akos Bogdan (MPA)

4 X-ray binaries accretion onto BH or NS in a binary system brightest stellar mass X- ray sources L x ~ erg/s in the X-ray band ~200 bright X-ray binaries in the Milky Way

5 X-ray spectra of accreting BH

6 Spectral states hard/low state soft/high state

7 Spectral states optically thick ~black body kt~0.1-1 kev hard/low state Optically thin kt e ~ kev t T ~1 soft/high state

8 Geometry hard state truncated disk + inner hot flow soft state disk extends to last stable orbit from Zdziarski & Gierlinski, 2004

9 Variability soft band hard band years 1999

10 Variability soft band soft state hard band years 1999

11 Variability Δt=32 msec

12 Power density spectra

13 BH NS Sunyaev & Shakura, 1986 Inogamov & Sunyaev, 1999 NO boundary layer L tot =L disk boundary layer L BL ~L disk L tot =L disk +L BL

14 X-ray spectra: BH and NS black hole neutron star Disk: kt NS > kt BH (difference in size + BL emission in NS) Comptonization: y NS < y BH kte NS < kte BH (hard surface in NS)

15 Populations of compact objects

16 X-ray binaries ~200 bright X-ray binaries in the Milky Way dominate X-ray output in the majority of galaxies two kinds: high- and lowmass X-ray binaries

17 X-ray binaries High mass Low mass

18 X-ray binaries High mass Low mass

19 Simple (and incorrect) sketch of binary evolution primordial binary MS+MS wind accretion or Roche lobe overflow HMXB stellar evolution ~2-40 Myrs massive star: stellar evolution BH/NS+MS SN explosion 50 Myrs low-mass star: stellar evolution or orbital decay 1-10 Gyrs Roche lobe overflow LMXB

20 Time dependence of XRB populations L X, N X HMXB LMXB SF event Myr >1 Gyr log(time)

21 Evolutionary time scales HMXB LMXB t~10-50 Myrs ~ duration of star formation event t~1-10 Gyrs ~ live time of the host galaxy Star formation tracer Stellar mass tracer Marat Gilfanov Shanghai, 25-28/09/2006

22 Images: 35 Andromeda galaxy (M31) Chandra X-ray observatory - resolution 0.5 ~confusion free study of XRB population in nearby galaxies Marat Gilfanov Shanghai, 25-28/09/2006

23 L x -mass relation for LMXBs number of sources total X-ray luminosity

24 L x -SFR relation for HMXBs number of sources total X-ray luminosity Nx~SFR Lx~SFR Non-physical effect of statistics of small numbers L tot =ΣL k

25 A method to measure star-formation rate in (distant) galaxies z~ Marat Gilfanov Crafoord Days 2008

26 Total number and luminosity of X-ray binaries L x ~ SFR M * N x (L x >10 37 ) ~ 7 SFR 10 M * [SFR]= M /yr [M * ]=10 10 M Marat Gilfanov Crafoord Days 2008

27 How many black holes and neutron stars become X-ray sources? Marat Gilfanov Crafoord Days 2008

28 Number of HMXBs observed at any given time: N HMXB ~ N * (M > 8M sun ) f HMXB τ HMXB number of HMXB birth rate of compact objects HMXB fraction f HMXB f bin f surv... duration of X-ray active phase

29 Number of HMXBs observed at any given time: N HMXB ~ N * (M > 8M sun ) f HMXB τ HMXB Salpeter IMF: Nx-SFR relation: N * (M > 8M sun ) SFR N HMXB (L >10 34 ) 500 SFR f HMXB τ HMXB ~ 0.07 Myr

30 Fraction of compact objects X-ray active once in their lifetime f HMXB τ HMXB 0.07 Myr O,B binaries: τ HMXB ~ yrs X/Be binaries: τ HMXB ~ (?) yrs f HMXB 0.7 τ HMXB 0.1 Myr 1

31 in LMXBs Per M sun : Salpeter IMF: ~ BH & NS LMXB-M star relation: N LMXB (L X >10 35 )~50 LMXBs f f LMXB ~ tr 0.1 1

32 Luminosity functions

33 HMXBs X-ray luminosity functions: SFR~ M sun /yr

34 HMXBs X-ray luminosity functions scaled to the same SFR SFR~ M sun /yr

35 LMXBs X-ray luminosity functions: Stellar mass range: x10 11 Msun

36 LMXBs X-ray luminosity functions: scaled to the same mass Stellar mass range: x10 11 Msun

37 Luminosity functions HMXBs and LMXBs: different shapes/slopes different accretion regimes: wind accretion Roche-lobe overflow Marat Gilfanov Crafoord Days 2008

38 HMXB XLF & IMF slope accretion of radiation pressure driven stellar wind M wind L * L * M * 3 M wind M 3 * M acc M 3 wind M * more accurate consideration (Bondi accr. etc): M acc M * L x M * (Postnov, 2004) dn = dn dl x dm * dl x dm * α IMF,α XLF IMF and XLF slopes : 1 α IMF = 2.5 α XLF 1.5 dn α = M XLF * ; dn α = M IMF * dl X dm * α XLF =1.6 ± 0.15 α IMF = 2.5 ± 0.4 (Salpeter : α IMF = 2.35) Marat Gilfanov Crafoord Days 2008

39 LMXB XLF gravitational braking in longer Porb systems magnetic braking (Sco X-1 etc.) Evolved companion and/or Gravitational braking in ultracompact binaries NS+WD, Porb~10 min King, Bildsten, Postnov and others short life-time problem Marat Gilfanov Crafoord Days 2008

40 Thank you! image: Li & Wang

41 ULX and HMXB Cyg X-1 Galactic NS, Be binaries ULX lg(lx)<40 ~featureless power law smooth extension of ordinary HMXB population different population unlikely; high M, high Mdot tail? Cyg X-3 V4641 Sgr (peak) lg(lx)>40 the brightest ULXs - different nature? Eddington limit for a neutron star