The link between X-ray binaries
and stellar populations in spiral
galaxies
Andreas Zezas
University of Crete
SAO
Outline
• XLFs important tool for characterizing X-ray binary
populations
• X-ray binary population synthesis coming of age
• Can set useful constraints on binary formation
parameters
04/12/2011
2
3
The SINGS study
• The SINGS sample
Multiwavelength imaging of 75 galaxies (d<30Mpc)
Wide range of SFR ( 0 – 18 M/yr)
stellar mass (107 to 1.5x1012 M)
metallicity
Uniform estimates of stellar parameters (age,
metallicity, mass, star-formation maps)
Team: T. Fragos, L. Jenkins. A.
Hornschemeier, V. Kalogera, P.
Tzanavaris, A. Zezas
Chandra data
• Detect X-ray sources
Chandra observations down to 1037erg/s
1900 sources (0-230 sources / galaxy)
0.2 M/yr
1.3 M/yr
5.1M04/12/2011
/yr
6
Population simulations
✚

Belczynski, Kalogera,
AZ, Fabbiano, 2004
• Result depends on binary evolution parameters (kicks,
common envelope, stellar winds etc)
• Build a simulation library for each galaxy for
different binary evolution parameters
7
Population simulations
Tzanavaris et al. 2013
 Generally similar models were selected across
the galaxy sample
8
Constraining evolution parameters
Common Envelope ejection
efficiency
Normalized log(likelihood)
Normalized log(likelihood)
Stellar wind strength
Tzanavaris et al. 2013
 Constraints on the common envelope
ejection efficiency
 Consistent parameters over a wide range of
binary populations
9
Understanding the populations
Old accreting
binaries (LMXBs)
Young accreting
binaries (HMXBs)
10
But we can do better !
Synergy of Chandra + HST
• Identify optical counterparts
• Characterize stellar populations
• Resolve star-clusters, and
measure structural parameters
LMXB
• Dissect X-ray source populations
• Study different sub-populations
HMXB
Zezas et al in prep.
GCs
But we can do better: SMC
50-80 Myr
< 10 Myr
60-100Myr
10-20 Myr
20-50 Myr
But we can do better: SMC
Peak in the formation
efficiency
of HMXBs at ~40-60 Myr
.
See poster by V. Antoniou
Summary
• By combining X-ray observations with multi-wavelength
simulations we are starting to have a good understanding of
X-ray binary formation
• Measure directly their formation efficiency
• Constrain factors that affect their evolution
 More to come:
Parametric study of XLFs as function of SFR and stellar
mass
Characterization of X-ray source populations and
connection with their parent stellar populations
First results
The luminosity function:
Flat slope :  ~0.2 / 0.8
Indication for break
consistent with accretion in an
inhomogeneous environment and
the onset of the propeller effect
(c.f. Shtykovskiy & Gilfanov 2004).
Connection with host galaxy
Tzanavaris et al. 2013
16
Luminosity distribution fits
Tzanavaris et al. 2013
17
The High-energy populations
23.0
0.23
1038 erg/s
2.3
Wik et al, 2014; Zezas et al, 2014
Model parameters
19
Tzanavaris et al. 2013
Tzanavaris et al. 2013
20
Intensity
State Transitions
Hardness
Fender et al., 2004
The SINGS study
• The SINGS sample
Multiwavelength imaging of 75 galaxies (d<30Mpc)
Wide range of SFR ( 0 – 18 M/yr)
stellar mass (107 to 1.5x1012 M)
metallicity
Uniform estimates of stellar parameters (age,
metallicity, mass, star-formation maps)
Chandra data for 56 galaxies (d<10Mpc)
Team: T. Fragos, L. Jenkins. A. Hornschemeier, V.
Kalogera, P. Tzanavaris, A. Zezas
Dissecting the populations: M81
Chandra (Sell et al. 2011)
13 Chandra ACIS-S pointings (PI D. Pooley)
Detection limit : ~1037erg/s in each pointing
(21037 erg/s @ 90% compl.)
~61035 erg/s in combined exposure
(4 1036 erg/s @ 90% compl.)
HST
29 ACS fields (50 orbits; PI Zezas, Huchra)
B,V,I down to 26 mag
Bulge and inner disk
5.0
5.4
Comparison with Chandra
4.2
LMXB
HMXB
3.5
Log(LV/L)
GCs
4.6 4.0
3.8
3.6
3.5
log(Teff) (K)
3.3
Zezas et al in prep.
Comparison with Chandra
Nantais, Huchra, AZ, et al, 2011
Sivakoff etal 1997
 M3/2rh2
HMXB
evolution
Discrete
X-ray sources
in galaxies :
The basic ingredients
Associated with young stars
(recent star-formation)
114 systems
mostly pulsars
(and a few black-holes)
  w 
2 3/2
1   w  
4
Ý M
Ýw2
LX  M
Tauris & van den Heuvel 2006
Relation with star-formation
Enhanced formation of X-ray
binaries in the 30-70 Myr
range.
SMC
With HMXBs
Without HMXBs
Consistent with peak in Be-star
phenomenon at these ages
Explains large number of XRBs
in the SMC
Evidence for small kicks (c.f.
van den Heuvel etal. 2000; Coe
2005; Linden etal 2009)
Antoniou
LMC etal, 2010
X-ray source populations
… However the devil is in the details…
- HMXBs
Grimm, Gilfanov, Sunyaev, 2002
Grimm etal 2006
The luminosity function
The luminosity function:
Flat slope :  ~0.2 / 0.8
Indication for break
consistent with accretion in an
inhomogeneous environment and
the onset of the propeller effect.
Zezas etal, in prep.
X-ray source populations
… However the devil is in the details…
- LMXBs
Gilfanov 2004
Kim & Fabbiano 2010
X-ray source populations
Kim etal 2009
SFR
sSFR
(0.2 M/yr, 0.15 yr-1)
(1.3 M/yr, 6.7 yr-1)
(5.1 M/yr, 16.91 yr-1)
IR (Spitzer)
X-ray (Chandra)
33
(Tzanavaris et al. 2013)