Spatial distribution of luminous X-ray binaries in galaxies

Spatial distribution of luminous X-ray binaries in galaxies

introduction

• Chandra observations have revolutionized XRB studies with the discovery of large numbers of point X-ray sources in galaxies even beyond the Local Group (Fabbiano et al. 2003)

• Cumulative X-ray luminosity functions analysis (Grimm et al. 2003;Zezas & Fabbiano 2002)

• Spatial distribution of luminous XRBs (Jonker et al. 2004; Grimm et al. 2002; Temple et al. 2005).

Methods

Luminosity function

(1)Luminosity Calculation:2cMLbol

(Belczynski 2003)

(3) If a MS donor star is three times massive than the accretor, let the binary coalescence.(?)

(2)

(4) Critical luminosity:• For kw2=0-9 :

• For kw2=10-12(WD) ：

BH

NS

hrP

hrP

L

L

sun

critX

)/lg(07.122.2

)/lg(07.162.1)log( ,

(5) Magnetic Braking:

(6)the mass of NS and BH

(7)

(8) During the SN explosions, a kick velocity vk is imparted on the newborn compact stars with the Maxwellian distribution:

Spatial distribution of X-ray binaries

• born uniformly in the young Galactic disk(z = 70pc), Rmin = 0 out to Rmax = 15Kpc

• born uniformly during the past 12Gyr• the direction of the initial velocity vector was cho

sen randomly• integrated motion equations with a fourth-order

Runge-Kutta method

Result

Observation

high luminosity cut-off of the LMXB XLF and power-law distribution of the HMXB XLF

Combined luminosity function of compact X-ray sources in the starburst galaxies M82, NGC 4038/9, NGC 4579, NGC

4736 and Circinus with a total SFR of 16 M /yr⊙

the radial distribution of LMXBs is modified by the effect of the galactic potential.

The radial distribution of XRBs is constructed by the combination of H-XRBs and He-XRBs, where H-XRBs can be modified greatly by the galactic potential while He-XRBs can not.

The radial distribution of ULXs in starburst galaxies directly reflects the birth radial distribution.

Vertical distributions of HMXBs&LMXBs in the luminosity interval Log(LX) = [37, 38] in the Milky Way

LMXBs

Log Lx=[37,38]

Log Lx=[38,39]

HMXBs

Log Lx=[37,38]

Log Lx=[38,39]

conclusion

• the more luminous the XRBs are, the more concentrated they are towards the Galactic plane.

• persistent sources are more concentrated towards the Galactic plane than transient ones.

• LMXBs in the luminosity range of 10^37 -10^38 erg/s show clear concentrations towards the Galactic buldge and include a number of sources at high Galactic z while others do not.

• BH-XRBs are more concentrated towards the Galactic plane than NS-XRBs

• He-XRBs are more concentrated towards the Galactic plane than H-XRBs

• the radial distribution of LMXBs and HMXBs is modified by the effects of the galactic potential.