The Brightest point X-ray The Brightest point X-ray sources in elliptical galaxies sources in elliptical galaxies and the mass spectrum of and the mass spectrum of

accreting black holes accreting black holes N. Ivanova, V. Kalogera N. Ivanova, V. Kalogera

astro-ph/0506471astro-ph/0506471

IntroductionIntroduction

X-ray map of the X-ray map of the ChandraChandra era now extends to era now extends to the Virgo cluster (18Mpc) and beyond. the Virgo cluster (18Mpc) and beyond.

Elliptical galaxies out to the Virgo cluster Elliptical galaxies out to the Virgo cluster have surprised us with the large number have surprised us with the large number of point X-ray sources down to Lx~10^37 of point X-ray sources down to Lx~10^37 erg s^-1 erg s^-1

a break of 4-5a break of 4-5×10^38 in the XLF×10^38 in the XLF a high fraction of sources coincident with a high fraction of sources coincident with

identified globular clusters (GCs)identified globular clusters (GCs)

Kim & Fabbiano 2004

InterpretationsInterpretations

For lower end, NS For lower end, NS accretors,accretors,

H rich donor: long H rich donor: long obital period obital period transient, poor transient, poor knowledge of DCknowledge of DC

He/C/O white He/C/O white dwarf donor, dwarf donor, persistentpersistent

Bildsten & Deloye 2004

InterpretationInterpretation

For upper end, BH accretors, For upper end, BH accretors, transienttransientoutburst at L_Eddoutburst at L_Edd constrain on the mass spectrum of constrain on the mass spectrum of BHsBHs

8-12 Gyr old population in ellipticals 8-12 Gyr old population in ellipticals M_donor<1.0~1.5 M_sunM_donor<1.0~1.5 M_sun

MS, RG, WDMS, RG, WD

Assuming the outburst luminosity is equal to Assuming the outburst luminosity is equal to L_Edd,L_Edd,

Duty cycle (DC) prescription,Duty cycle (DC) prescription,

1) 1) ηη=0.01=0.01

2)2)

3)3)

1) MS donor1) MS donor

dd MdRdn ln/ln

MS donorMS donor

RVJ ITM_PT=10 M_sun

MS donorMS donor

Conclusion:Conclusion:

Regardless of the specific MB law, it is Regardless of the specific MB law, it is unlikely that persistent sources unlikely that persistent sources contribute any significant fraction to contribute any significant fraction to the upper end XLF of ellipticals.the upper end XLF of ellipticals.

Only BH-MS transients driven by the IT Only BH-MS transients driven by the IT MB law can populate this X-ray MB law can populate this X-ray luminosity range.luminosity range.

2) RG donor2) RG donor

Webbink, Rappaport, Savonije 1983Webbink, Rappaport, Savonije 1983

Conclusion: transientConclusion: transient

3) WD donor3) WD donor

WD has a mass-radius exponent of -1/3WD has a mass-radius exponent of -1/3

He WD

WD donorWD donor

For CO WD, the evolution is rather similarFor CO WD, the evolution is rather similar

WD donorWD donorConclusion:Conclusion:

BH-WD binaries that contribute to the BH-WD binaries that contribute to the upper end of XLF are expected to be upper end of XLF are expected to be transient, and M_donor<0.03 M_sun.transient, and M_donor<0.03 M_sun.

Note: This would not be true if BH-WD Note: This would not be true if BH-WD continuously formed, but this is not continuously formed, but this is not possible in the galactic field of possible in the galactic field of ellipticals and is not even expected ellipticals and is not even expected in GCs. in GCs.

Mass spectrumMass spectrumL_X=L_Edd~M_BHL_X=L_Edd~M_BH

1) MS donor1) MS donor

MS donorMS donor

MS donorMS donor

MS donorMS donor

MS donorMS donor

MS donorMS donorRobust?

RG donorRG donor

WD donorWD donor

Relative contributionRelative 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.

discussiondiscussion

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

discussiondiscussion

Origin of the Galactic ridge Origin of the Galactic ridge X-ray emissionX-ray emission

Revnivtsev et al.Revnivtsev et al.

IntroductionIntroduction

CXB and GRXECXB and GRXEGRXE: GRXE: Extending tens of degrees in longitude Extending tens of degrees in longitude

and a few degrees in latitudeand a few degrees in latitudeEnergy spectrum contains a number of Energy spectrum contains a number of

emission lines of highly ionized heavy emission lines of highly ionized heavy elements, indicating a thermal elements, indicating a thermal component of up to 5-10 keV.component of up to 5-10 keV.

The total GRXE luminosity ~ 1-The total GRXE luminosity ~ 1-2×10^38 erg s^-12×10^38 erg s^-1

GRXEGRXEThe GRXE has been detected at least up to The GRXE has been detected at least up to

20-25 keV energies, and its spectrum in 3-20-25 keV energies, and its spectrum in 3-20 keV range consists of … Gama~2.1 and 20 keV range consists of … Gama~2.1 and powerful lines at 6-7 keV. powerful lines at 6-7 keV.

It consists of qLMXBs, HMXBs, CVs, and It consists of qLMXBs, HMXBs, CVs, and coronally active binaries (ABs) etc. or truly coronally active binaries (ABs) etc. or truly diffuse?diffuse?

EbisawaEbisawa

Difficulty met by the hypothesis of diffuse Difficulty met by the hypothesis of diffuse origin of the GRXEorigin of the GRXE

Other difficultiesOther difficulties

RXTE observations and RXTE observations and analysisanalysis

The best instrument so far for large-scale The best instrument so far for large-scale mapping of the X-ray sky is the PCA mapping of the X-ray sky is the PCA (Proportional Counter Array) spectrometer (Proportional Counter Array) spectrometer abroad the RXTE (Rossi X-ray Timing abroad the RXTE (Rossi X-ray Timing Explorer).Explorer).

~6400 cm^2 at 6 keV ~6400 cm^2 at 6 keV

1 degree field of view1 degree field of view

Data are from the first layers of all PCAData are from the first layers of all PCA

Map of GRXEMap of GRXE

Map of the GRXEMap of the GRXE

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

Disk/bulge-like componentDisk/bulge-like component

Galactic bulgeGalactic bulge

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

10% systematics10% systematics

bulgebulge

bulgebulge

bulgebulgeAn analytic model of the bulge/bar stellar An analytic model of the bulge/bar stellar

volume emissivity developed by Dwek et volume emissivity developed by Dwek et al. 1995 according to the near-IR surface al. 1995 according to the near-IR surface brightness distribution of the Galaxy brightness distribution of the Galaxy measured by COBE/DIRBE,measured by COBE/DIRBE,

bulgebulge

Galactic diskGalactic disk

Galactic diskGalactic disk

Y. Xu et al. 2005

diskdisk

diskdisk

diskdisk

Cosmic Background Explorer (COBE)

/Diffuse Infrared

Background Experiment (EIRBE)

diskdisk

Broad-band spectrum of the GRXEBroad-band spectrum of the GRXE

A Galactic center “point source” (innermost A Galactic center “point source” (innermost 30 pc) measured by Integral/IBIS with hard 30 pc) measured by Integral/IBIS with hard X-ray luminosity L_20-60keV=4×10^35 erg X-ray luminosity L_20-60keV=4×10^35 erg s^-1s^-1

Deriving from the bulge/bar data, L_3-Deriving from the bulge/bar data, L_3-20keV~3.5×10^27 erg s^-1 M_sun^-1, the 20keV~3.5×10^27 erg s^-1 M_sun^-1, the “cusp” contains 10^8 M_sun, this predicts a “cusp” contains 10^8 M_sun, this predicts a 3-20keV luminosity of 4×10^35 erg s^-1. 3-20keV luminosity of 4×10^35 erg s^-1. Assuming a Gama=2.1 power law, L_20-60 Assuming a Gama=2.1 power law, L_20-60 keV=2×10^35 erg s^-1 keV=2×10^35 erg s^-1

Broad-band spectrumBroad-band spectrum

Thank you!Thank you!