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Published byMaria Thornton Modified over 9 years ago
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A Simple Discussion on X-ray Luminosity Function Analysis
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The Astrophysical Journal, 611:846–857, 2004 August 20 X-RAY LUMINOSITY FUNCTION AND TOTAL LUMINOSITY OF LOW-MASS X-RAY BINARIES IN EARLY-TYPE GALAXIES Dong-Woo Kim and Giuseppina Fabbiano
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The apparent strong XLF breaks near LX,Edd visible in Figure 1a mostly disappear after the corrections are applied. ‘‘backward’’ method a single, unbroken power law(differential):
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a steepening of the XLF at higher luminosities note that the high-luminosity slope is more uncertain, given the small number of very bright sources.
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compare well with our cumulative XLF absence of the luminous sources (LX > 2*10^38 ergs s1) for M.W.&M31 a low-luminosity break in the XLFs of E and S0
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If the break is real (?)higher luminosity for an Eddington break of normal neutron star binaries. the most massive neutron stars (3.2 ± 1 Msun; see Ivanova & Kalogera 2005) low-mass black hole binaries(3.5 Msun) Both neutron star and black hole binaries (e.g. Sivakoff, Sarazin & Irwin 2003) He-enriched neutron star binaries (1.9 ± 0.6 Msun; see Ivanova & Kalogera 2005) Whatever the cause, the shape of the XLF points to a dearth of very luminous sources in E and S0 galaxies.
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Conclusion After correcting for incompleteness, the individual XLFs are statistically consistent with a single power law of a (differential) slope β = 1.8- 2.2 Although the combined XLF is marginally consistent with a single power law, a broken power law gives an improved fit. If the change in slope is real, the high-luminosity portion of the XLF could reflect the mass function of black holes in these galaxies. The proximity of the Milky Way and M31 sources allows a measurement of their XLFs down to significantly lower luminosities, demonstrating that the single power law (withβ=2.2) continues down to Lx=10^37 erg/s.
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The Astrophysical Journal, 573:138–143, 2002 July 1 A MINISURVEY OF X-RAY POINT SOURCES IN STARBURST AND NONSTARBURST GALAXIES R. E. Kilgard, P. Kaaret, M. I. Krauss, A. H. Prestwich, M. T. Raley, and A. Zezas
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LF slope range is 1.5- 2.1, steeper than the spirals and starbursts the trend of steeper slopes correlating with less star formation extends to early-type spirals and ellipticals.
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Model Luminosity Distribution single population constant luminosity through its lifetime power-law form for the birth rate distribution binaries turn on in X-rays instantaneously after they are formed.
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Model Luminosity Distribution The time evolution of n is : lifetime of an X-ray binary:
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Impulsive Event (1) Impulsive Event (i.e. no subsequent X-ray binary formation) Differential luminosity distribution: Cumulative Number:
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(2) Steady-state star formation event Lifetime of longest lived X-ray point-source < star formation interval equilibrium birth rate ==death rate Cumulative Number: steeper This luminosity distribution is steeper than that of the impulsive case with an exponent that differs by one
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(3) sufficiently low luminosities broken power-law form Differential distribution Below the break : same slope as that of the birth distribution Above the break : slope will be steeper by one Cumulative Number:
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older systems have a steep slope in the high-luminosity range younger systems have a flatter slope over the same luminosity range younger systems extend to higher luminosities X-ray sources in starbursts are likely to be HMXBs old systems is likely to be dominated by LMXBs 10Myr 20Myr 1Gyr 2Gyr
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Conclusions the luminosity distribution of the starburst galaxies directly reflects the birth luminosity distribution other galaxies have a similar birth luminosity distribution and an observed luminosity distribution modified by the effects of an aging X- ray binary population. X-ray point-source luminosity distributions should prove to be a powerful tool in understanding the evolutionary history of massive star populations in external galaxies.
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My Recent Work
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Luminosity Calculation: (Belczynski 2003) for persistent sources: Lx=min(Lx,10L_edd)
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Critical luminosity: For kw2=0-9 : For kw2=10-12(WD) : Magnetic Braking:
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Donor Type 0 = MS star M <0.7 deeply or fully convective 1 = MS star M >0.7 2 = Hertzsprung Gap (HG) 3 = First Giant Branch (GB) 4 = Core Helium Burning (CHeB) 5 = Early Asymptotic Giant Branch (EAGB) 6 = Thermally Pulsing AGB (TPAGB) 7 = Naked Helium Star MS (HeMS) 8 = Naked Helium Star Hertzsprung Gap (HeHG) 9 = Naked Helium Star Giant Branch (HeGB) 10 = Helium White Dwarf (HeWD) 11 = Carbon/Oxygen White Dwarf (COWD) 12 = Oxygen/Neon White Dwarf (ONeWD) 13 = Neutron Star (NS) 14 = Black Hole (BH) 15 = massless remnant
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high luminosity cut-off of the LMXB XLF and power-law distribution of the HMXB XLF
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αce = 1.0 αce = 1.0&10L_edd
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αce = 0.5&10L_eddαce = 1.0&10L_edd
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αce = 0.3&10L_eddαce = 0.1&10L_edd
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αce = 0.3&10L_eddαce = 0.1&10L_edd
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αce = 0.3&10L_edd αce = 0.1&10L_edd
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αce = 0.3&10L_edd αce = 0.1&10L_edd
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αce = 0.3&10L_edd αce = 0.1&10L_edd
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Calculated by Liuxw NS transient sources dominate by short period systems
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Lx revised by critical periods removed αce = 0.3&10L_edd αce = 0.1&10L_edd
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Thanks!
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