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

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 ? YOUNG OLD Do LMXBs in Ellipticals form in Globular Clusters exclusively ? Does the galactic field contribute at all ? Why are red GCs better LMXB hosts than blue GCs?

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

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 E TC x P orb ~ L Edd Analytical estimate of TC rate for 1,000M o IMBH for ANY orbital period Mass Transfer and L X calculation for isolated IMBH binaries with 5-15M o MS donors No dynamical interactions and evolution included ULX phase duration per IMBH binary: >10Myr Fraction of Clusters with IMBH-MS ULX: 30-50%

Do accreting IMBH in clusters form observable ULXs ? Blecha, Ivanova, Kalogera, et al. 2005: NOT LIKELY Cluster core simulations with full binary evolution and dynamical interactions: TC, exchanges, disruptions, collisions (N. Ivanova’s talk from Monday’s morning session) M o IMBH, 100Myr old clusters, T rc < 30Myr Average ULX phase duration per cluster: <0.1Myr 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%

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

Kaaret et al L x ≥ (0.5-3)x10 36 erg/s Distribution of point X-ray sources < 1 XRB per cluster! Do Super Star Clusters form High-Mass XRBs ?

Kaaret et al L x ≥ 5x10 35 erg/s XRBs closely associated with star clusters Median distance ~ pc < 1 XRB per cluster! M82 N5253 N % Is this all due to Supernova Kicks ? Do Super Star Clusters form High-Mass XRBs ?

cluster mass: ~5x10 4 M o L X > 5x10 35 erg/s average of 1,000 cluster simulations Significant age dependence < 1 XRB per cluster Models: Population Syntheses of XRBs and Kinematic Orbit Evolution in Cluster Potential Sepinsky, Kalogera, & Belczynski 2005 Do Super Star Clusters form High-Mass XRBs ?   Distance from Cluster Center [pc]

YES! XRB models without cluster dynamics appear in agreement with observations Mean XRB number per SSC < 1 and spatial distribution: M < 10 5 M o and 10-50Myr or more massive and ~50Myr Supernova kicks: eject D > 10pc especially for M < 10 5 M o Do Super Star Clusters form High-Mass XRBs ?

LMXB origin in Ellipticals: Clusters and/or Field ? Bildsten & Deloye 2004:NS Ultra-Compact Binaries from Clusters Matches observed XLF slope below BREAK at ~5x10 38 erg/s Formation rate: 1/2Myr per 10 7 M o 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 ?

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 S N Issues with incompatible coverage for definition of f LMXB,GC and S N ?

LMXB origin in Ellipticals: Clusters and/or Field ? Irwin 2005:Ellipticals’ Field Must Contribute Reason: non-zero y-intercept of L X /L B vs. S N (AS N +B,  Bildsten & Deloye 2004:NS Ultra-Compact Binaries from Clusters Juett 2005:Ellipticals’ Field Must Contribute Reason: Fraction of GC-LMXBs depends on S N Not due to: large-scale GC disruption or variations in red/blue GC ratio

LMXB origin in Ellipticals: Clusters and/or Field ? Irwin 2005:Ellipticals’ Field Must Contribute Bildsten & Deloye 2004:NS Ultra-Compact Binaries from Clusters Juett 2005:Ellipticals’ Field Must Contribute Ivanova & Kalogera 2005: Brightest are BH LMXBs from Field Sources with 5x10 38 < L X < fewx10 39 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 L outburst ~ L edd : XLF slope above BREAK is a footprint of BH mass spectrum Current L max ~ 2x10 39 erg/s implies max BH mass of 15-20M o consistent with stellar evolution

LMXB origin in Ellipticals: Clusters and/or Field ? Irwin 2005:Ellipticals’ Field Must Contribute Bildsten & Deloye 2004:NS Ultra-Compact Binaries from Clusters Juett 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 …

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 ! 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

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/ M o 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.

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 ?