Download X-ray Binaries in Nearby Galaxies - CIERA

Theoretical Studies of
X-Ray Binaries in Clusters
ExtraGalactic only…
Vicky Kalogera
MODEST-6
In this review:
Do IMBH in clusters form observable ULXs ?
Do Super Star Clusters form High-Mass XRBs ?
YOUNG
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 blue GCs?
OLD
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 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%
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)
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
IMBH Companions
Blecha, Ivanova, Kalogera, et al. 2005
Mass distribution
Orbital separation distribution
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!
Do Super Star Clusters form High-Mass XRBs ?
Kaaret et al. 2004
• XRBs closely associated
with star clusters
• Median distance ~30-100 pc
• Lx ≥ 5x1035
Is this all due to
erg/sSupernova Kicks ?
N1569
50%
N5253
< 1 XRB per cluster!
M82
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]
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
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 ?
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 ?
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
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
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 …
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
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.
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 ?