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Theoretical Studies of X-Ray Binaries in Clusters

Vicky Kalogera MODEST-6. Theoretical Studies of X-Ray Binaries in Clusters. ExtraGalactic only…. YOUNG. OLD. In this review:. Do IMBH in clusters form observable ULXs ? Do Super Star Clusters form High-Mass XRBs ? What is the role of SSCs in determining the

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Theoretical Studies of X-Ray Binaries in Clusters

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  1. Vicky Kalogera MODEST-6 Theoretical Studies of X-Ray Binaries in Clusters ExtraGalactic only…

  2. YOUNG OLD In this review: Do IMBH in clusters form observable ULXs ? Do Super Star Clusters form High-Mass XRBs ? What is the role of SSCs in determining the X-ray luminosity functions of Starbursts ? Do LMXBs in Ellipticals form in Globular Clusters exclusively ? Does the galactic field contribute at all ? Why are red GCs better LMXB hosts than blueGCs?

  3. Do accreting IMBH in clusters form observable ULXs ? Hopman, Portegies Zwart, Alexander 2004: YES IMBH binary: through tidal capture (TC) of MS companions ULX phase duration: > 10Myr Blecha, Ivanova, Kalogera, et al. 2005: NOT LIKELY IMBH binary: through exchanges with stellar binaries ULX phase duration: < 0.1Myr

  4. Do accreting IMBH in clusters form observable ULXs ? Hopman, Portegies Zwart, Alexander 2004: YES through TC Most optimistic assumptions for TC survival of MS stars: “hot squeezars” and ETC x Porb ~ LEdd Analytical estimate of TC rate for 1,000Mo IMBH for ANY orbital period Mass Transfer and LX calculation for isolated IMBH binaries with 5-15Mo MS donors No dynamical interactions and evolution included ULX phase duration per IMBH binary: >10Myr Fraction of Clusters with IMBH-MS ULX: 30-50%

  5. Do accreting IMBH in clusters form observable ULXs ? Blecha, Ivanova, Kalogera, et al. 2005: NOT LIKELY Cluster coresimulations with full binary evolutionand dynamical interactions: TC, exchanges, disruptions, collisions (N. Ivanova’s talk from Monday’s morning session) 100-500Mo IMBH, 100Myr old clusters, Trc < 30Myr Time fraction with IMBH binary: > 50% Time fraction with Mass-Transfer: ~1-3% MS donors dominate by time; Post-MS donors dominate by number Fraction of Mass-Transfer time as a ULX: ~2% Average ULX phase duration per cluster: <0.1Myr

  6. IMBH Companions Blecha, Ivanova, Kalogera, et al. 2005 Mass distribution Orbital separation distribution

  7. Do Super Star Clusters form High-Mass XRBs ? Distribution of point X-ray sources Kaaret et al. 2004 • Lx≥ (0.5-3)x1036 erg/s < 1 XRB per cluster!

  8. N1569 50% N5253 M82 Do Super Star Clusters form High-Mass XRBs ? • XRBs closely associated with star clusters • Median distance ~30-100 pc Kaaret et al. 2004 Is this all due to Supernova Kicks ? • Lx≥ 5x1035 erg/s < 1 XRB per cluster!

  9. Do Super Star Clusters form High-Mass XRBs ? Sepinsky, Kalogera, & Belczynski 2005 Models: Population Syntheses of XRBs and Kinematic Orbit Evolution in Cluster Potential • cluster mass: ~5x104 Mo • LX > 5x1035 erg/s • average of 1,000 cluster simulations • Significant age dependence • < 1 XRB per cluster 1 10 100 1000 Distance from Cluster Center [pc]

  10. Do Super Star Clusters form High-Mass XRBs ? YES! XRB models without cluster dynamics appear in agreement with observations • Mean XRB number per SSC < 1 and spatial distribution: M < 105 Mo and 10-50Myr or more massive and ~50Myr • Supernova kicks: eject XRBs @ D > 10pc especially for M < 105 Mo

  11. LMXB origin in Ellipticals: Clusters and/or Field ? Bildsten & Deloye 2004: NS Ultra-Compact Binaries from Clusters Matches observed XLF slope below BREAK at ~5x1038 erg/s Formation rate: 1/2Myr per 107Mo of GCs and this matches cumulative #Ucs for continuous UC formation due to dynamical interactions (Ivanova & Rasio 2004) and observed #MSPc in Galactic GCs prediction: search for orbital periods of 5-10min! questions: MW has H-rich donors in GCs what about above the BREAK ?

  12. LMXB origin in Ellipticals: Clusters and/or Field ? Bildsten & Deloye 2004: NS Ultra-Compact Binaries from Clusters Juett 2005: Ellipticals’ Field Must Contribute Reason: Fraction of GC-LMXBs depends on SN Issues with incompatible coverage for definition of fLMXB,GC and SN ?

  13. LMXB origin in Ellipticals: Clusters and/or Field ? Bildsten & Deloye 2004: NS Ultra-Compact Binaries from Clusters Juett 2005: Ellipticals’ Field Must Contribute Reason: Fraction of GC-LMXBs depends on SN Irwin 2005: Ellipticals’ Field Must Contribute Reason: non-zero y-intercept of LX/LB vs. SN (ASN+B, B<>0 @8s) Not due to: large-scale GC disruption or variations in red/blue GC ratio

  14. LMXB origin in Ellipticals: Clusters and/or Field ? Bildsten & Deloye 2004: NS Ultra-Compact Binaries from Clusters Juett 2005: Ellipticals’ Field Must Contribute Irwin 2005: Ellipticals’ Field Must Contribute Ivanova & Kalogera 2005: Brightest are BH LMXBs from Field Sources with 5x1038 < LX < fewx1039 erg/s too bright for NS accretor BH LMXBs not expected in GCs, (Kalogera, King, & Rasio 2004) but are expected in the Field as BH transients If Loutburst ~ Ledd : XLF slope above BREAK is a footprint of BH mass spectrum Current Lmax ~ 2x1039 erg/s implies max BH mass of 15-20Mo consistent with stellar evolution

  15. LMXB origin in Ellipticals: Clusters and/or Field ? Bildsten & Deloye 2004: NS Ultra-Compact Binaries from Clusters Juett 2005: Ellipticals’ Field Must Contribute Irwin 2005: Ellipticals’ Field Must Contribute Ivanova & Kalogera 2005: Brightest are BH LMXBs from Field Consistent answer appears to be: Both Clusters & Field BUT: Irwin considers sources below the BREAK: mixed Juett considers all sources: mixed B&D can explain all sources below the BREAK as coming from Clusters I&K agree (based on pop-syn models) and propose Field contribution only for sources above the BREAK …

  16. Why are Red Clusters more likely (by ~3) to host LMXBs than Blue Clusters? Maccarone, Kundu, & Zepf 2004: Z-dependence of Irradiation-Induced Winds In Blue, Metal-Poor GCs donors have stronger IIWs (less line-cooling) ---> shorter LMXB lifetimes ---> lower LMXB numbers Number ratio comes to 2.5-3.5! Also accounts for: harder LMXB spectra in Blue, Metal-Poor Clusters Prediction: Should see monotonic # dependence on Z And account for LMC vs. MW observations

  17. Why are Red Clusters more likely (by ~3) to host LMXBs than Blue Clusters? Maccarone, Kundu, & Zepf 2004: Z-dependence of Irradiation-Induced Winds Ivanova 2005: Z-dependence of Magnetic Braking A.M. Loss In Blue, Metal-poor GCs MS donors w/ 0.85-1.25Mo have no outer convective zone ---> no MB ---> harder to start MT Even if MT starts, NS-MS LMXBs are transients (hard to detect) NS-MS LMXBs in Red, Metal-rich GCs are easier to form and have some bright phase Estimate of formation rate of Bright NS-MS LMXBs in Metal-Rich GCs agrees with obs.

  18. Why are Red Clusters more likely (by ~3) to host LMXBs than Blue Clusters? Maccarone, Kundu, & Zepf 2004: Z-dependence of Irradiation-Induced Winds Ivanova 2005: Z-dependence of Magnetic Braking A.M. Loss Not clear (to me!) which of the two is more realistic Any thoughts ? Both deal with NS-LMXBs and MS donors - How are these connected to B&D results about NS Ultra-compacts with WD companions ?

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