The Brightest point X-ray sources in elliptical galaxies and the mass spectrum of accreting black holes N. Ivanova, V. Kalogera astro-ph/

Introduction X-ray map of the Chandra era now extends to the Virgo cluster (18Mpc) and beyond. Elliptical galaxies out to the Virgo cluster have surprised us with the large number of point X-ray sources down to Lx~10^37 erg s^-1 a break of 4-5×10^38 in the XLF a break of 4-5×10^38 in the XLF a high fraction of sources coincident with identified globular clusters (GCs) a high fraction of sources coincident with identified globular clusters (GCs)

Kim & Fabbiano 2004

Interpretations For lower end, NS accretors, H rich donor: long obital period  transient, poor knowledge of DC H rich donor: long obital period  transient, poor knowledge of DC He/C/O white dwarf donor, persistent He/C/O white dwarf donor, persistent Bildsten & Deloye 2004

Interpretation For upper end, BH accretors, transient  outburst at L_Edd  constrain on the mass spectrum of BHs 8-12 Gyr old population in ellipticals  M_donor<1.0~1.5 M_sun MS, RG, WD

Assuming the outburst luminosity is equal to L_Edd, Duty cycle (DC) prescription, 1) η=0.01 1) η=0.01 2) 2) 3) 3)

1) MS donor

MS donor RVJIT M_PT=10 M_sun

MS donor Conclusion: Regardless of the specific MB law, it is unlikely that persistent sources contribute any significant fraction to the upper end XLF of ellipticals. Only BH-MS transients driven by the IT MB law can populate this X-ray luminosity range.

2) RG donor Webbink, Rappaport, Savonije 1983 Conclusion: transient

3) WD donor WD has a mass-radius exponent of -1/3 He WD

WD donor For CO WD, the evolution is rather similar

WD donor Conclusion: BH-WD binaries that contribute to the upper end of XLF are expected to be transient, and M_donor<0.03 M_sun. Note: This would not be true if BH-WD continuously formed, but this is not possible in the galactic field of ellipticals and is not even expected in GCs.

Mass spectrum L_X=L_Edd~M_BH

1) MS donor

MS donor

Robust?

RG donor

WD donor

Relative contribution For the case of a constant DC, WD would dominate the transient population. Therefore we conclude that the assumption of a constant DC is not realistic.

discussion Constraints on the accreting BH mass spectrum could contribute to our understanding of core collapse, and the connection of BH masses to their progenitor masses.

discussion

Origin of the Galactic ridge X-ray emission Revnivtsev et al. Revnivtsev et al.

Introduction CXB and GRXE GRXE: Extending tens of degrees in longitude and a few degrees in latitude Energy spectrum contains a number of emission lines of highly ionized heavy elements, indicating a thermal component of up to 5-10 keV. The total GRXE luminosity ~ 1- 2×10^38 erg s^-1 The total GRXE luminosity ~ 1- 2×10^38 erg s^-1

GRXE The GRXE has been detected at least up to keV energies, and its spectrum in keV range consists of … Gama~2.1 and powerful lines at 6-7 keV. It consists of qLMXBs, HMXBs, CVs, and coronally active binaries (ABs) etc. or truly diffuse? Ebisawa Difficulty met by the hypothesis of diffuse origin of the GRXE Other difficulties

RXTE observations and analysis The best instrument so far for large-scale mapping of the X-ray sky is the PCA (Proportional Counter Array) spectrometer abroad the RXTE (Rossi X-ray Timing Explorer). ~6400 cm^2 at 6 keV 1 degree field of view Data are from the first layers of all PCA

Map of GRXE

Map of the GRXE Henceforth we reserve the term “GRXE” to describe Galactic X-ray emission which cannot be resolved into discrete sources with flux higher than 10^-12 erg s^-1 cm^-2. Disk/bulge-like component

Galactic bulge Mask out bright point sources. To this end we filtered out 1.5 deg radius regions around point sources with flux higher than ~1 cnts/s/PCU/beam~1.2×10^-11 erg s^-1 cm^-2, corresponding to… 10% systematics

bulge

bulge

bulge An analytic model of the bulge/bar stellar volume emissivity developed by Dwek et al according to the near-IR surface brightness distribution of the Galaxy measured by COBE/DIRBE,

bulge

Galactic disk

Y. Xu et al. 2005

disk

disk

disk Cosmic Background Explorer (COBE) / Diffuse Infrared Background Experiment (EIRBE)

disk

Broad-band spectrum of the GRXE A Galactic center “point source” (innermost 30 pc) measured by Integral/IBIS with hard X-ray luminosity L_20-60keV=4×10^35 erg s^-1 Deriving from the bulge/bar data, L_3- 20keV~3.5×10^27 erg s^-1 M_sun^-1, the “cusp” contains 10^8 M_sun, this predicts a 3-20keV luminosity of 4×10^35 erg s^-1. Assuming a Gama=2.1 power law, L_20-60 keV=2×10^35 erg s^-1

Broad-band spectrum

Thank you!