A catalogue of X-ray emitting WR stars
Ada Nebot, C. Motch, and the
ARCHES collaboration
ARCHES workshop
Paris, 30 Novembre - 2 Dicembre 2015
The Galactic science case
l.: X-ray luminosity function
lumiminosof the
127
Fig. 13. Upper panel: XLF of Galactic low-mass close binaries. The
Galaxy stellar mass is assumed to be 7 × 1010 M⊙ and the LMXB part
of the XLF is averaged over nearby galaxies (Gilfanov 2004). Lower
•
What is the XLF of the hard X-ray
low to intermediate luminosity
sources?
- CVs, AB (Sazonov+2006)
- OB, WR too!! (Mauerhan+2010,
Anderson+2011)
•
What is the origin of the hard X-ray
emission in O,B and WRs?
- Intrinsic X-ray emission
- Wind accretion onto a compact
object
- Colliding winds in a binary
How can XMM-Newton help?
•
•
Large FOV ~30 min + high sensitivity
30-100 serendipitous sources/pointing
~133.000 sources with multi-wavelength
information
•
Statistical identification based on
different surveys:
- Bright flux sample Della Ceca+2004
- Medium flux sample Barcons+2002
- Faint flux sample
- Galactic Plane Survey Hands+2004, Motch
+2010, Nebot Gómez-Morán+2013
EPIC-pn 0.2-12 keV image of field 3C436
The cross-correlation
EPIC-pn
DSS
GLIMPSE
AllWISE
2MASS
2MASS
Cross-correlation with
optical/infrared catalogues
Wolf-Rayet stars
•
WC
The input catalogue: 639 WRs from the catalogue from P. Crowther 43%
WO
1%
WN
57%
Wolf-Rayet stars
•
WC
The input catalogue: 639 WRs from the catalogue from P. Crowther 43%
• The coverage: ~one third within the ARCHES catalogue coverage
WC
39%
WO
1%
WN
57%
WO
1%
WN
60%
Wolf-Rayet stars
•
WC
The input catalogue: 639 WRs from the catalogue from P. Crowther 43%
• The coverage: ~one third within the ARCHES catalogue coverage
• The detections: 29 WRs with an entry in the ARCHES catalogue
WC
39%
WO
1%
WN
57%
WO
1%
WN
60%
WO
WC 7%
21%
WN
72%
Wolf-Rayet stars: fraction of X-ray active WRs
• What is the fraction of active WRs ? Does it depend on the spectral type?
- ~17% of the WN (mostly binaries but some single too)
- ~8% of the WC (binaries + the single ? WR102-1)
- 100% WO (WR 30a binary, WR142 is likely single fast rotator)
• But need to correct for detection biases:
f = # WRs detected / # WRs covered x detection biases
•
Detection biases depend on: Lx, Nh, distance, exposure time, sensitivity,
… (work in progress)
Using WR as learning sample…
Using WR as learning sample…
X-ray and infrared colours
• (H-K) estimate on the
extinction AK Indebetouw et
al. (2005)
1.0
HR3
0.5
0
-0.5
1: WR
0
0.5
1.0
1.5
H-Ks
2.0
2.5
• Modelled the evolution of HR
with extinction for different
populations:
- Young stars (dashed line)
(kT1,kT2) = (0.2,0.8)keV
- Hard WR (solid line)
kT = 5 keV (e. g. WR 142,
Oskinova et al. 2009)
Using WR as learning sample…
X-ray and infrared colours
• (H-K) estimate on the
extinction AK Indebetouw et
al. (2005)
1.0
HR3
0.5
0
Hard
-0.5
0
Soft
0.5
1.0
1.5
H-Ks
2.0
1: WR
2.5
• Modelled the evolution of HR
with extinction for different
populations:
- Young stars (dashed line)
(kT1,kT2) = (0.2,0.8)keV
- Hard WR (solid line)
kT = 5 keV (e. g. WR 142,
Oskinova et al. 2009)
Using WR as learning sample…
X-ray and infrared colours
1.0
What is the nature of the hard
X-ray sources with infrared
(2MASS & GLIMPSE)
associations?
HR3
0.5
0
Hard
-0.5
0
Soft
0.5
1.0
1.5
H-Ks
2.0
Hard X-ray
1: WR
2.5
Using WR as learning sample…
X-ray and infrared colours
1.0
What is the nature of the hard
X-ray sources with infrared
(2MASS & GLIMPSE)
associations?
HR3
0.5
0
Hard
-0.5
0
Soft
0.5
1.0
1.5
H-Ks
2.0
Hard X-ray
1: WR
7: HMXB
7: Be
2.5
Using WR as learning sample…
X-ray and infrared colours
1.0
What is the nature of the hard
X-ray sources with infrared
(2MASS & GLIMPSE)
associations?
HR3
0.5
0
Hard
-0.5
0
Soft
0.5
1.0
1.5
H-Ks
2.0
Hard X-ray
1: WR
7: HMXB
7: Be
2.5
Pilot Survey:
Awarded 1/2 night at the WHT
0.2-12 keV, XMM
8 µm, GLIMPSE
24 µm, MIPSGAL
0.2-12 keV, XMM
5.6 µm, GLIMPSE
1.4 GHz,VLA
0.2-12 keV, XMM
24 µm, MIPSGAL
1.4 GHz,VLA
WN8h
Ofpe/WN9
0.2-12 keV, XMM
8 µm, GLIMPSE
24 µm, MIPSGAL
0.2-12 keV, XMM
8 µm, GLIMPSE
24 µm, MIPSGAL
Be
Nebot Gómez-Morán et al 2015 (astro-ph XXX)
Investigating multi-wavelength properties…
Investigating multi-wavelength properties…
X-ray-to-infrared flux ratio
14
12
What is the nature of the hard
X-ray sources with infrared
(2MASS & GLIMPSE)
associations?
Ks
10
8
6
Unidentified
log (fx/fk) < -2 — WR
log (fx/fk) ~ -2.5 — γ-Cas analogs
log (fx/fk) > -3 — HMXBs
Be γ-Cas
HMXB
4
WR
2
-5
-4
-3
-2
-1
0
log10(fx/fk)
Nebot Gómez-Morán et al 2015
Lx versus Period
Preliminary results…
Distance known for 24 of these 31 WRs, and period for 12 binaries
Computed mean Lx in three bands: Total (0.2-12 keV), soft (0.2-2 keV), hard (2-12keV)
Lx in 0.2-12 keV
Lx (0.2-12keV) [ergs/s]
34.0
a
WN
33.5
133
33.0
32.5
139
46
141
47
138
32.0
-1
0
1
2
log (Period [days])
3
4
Lx versus Period
Preliminary results…
Distance known for 24 of these 31 WRs, and period for 12 binaries
Computed mean Lx in three bands: Total (0.2-12 keV), soft (0.2-2 keV), hard (2-12keV)
Lx in 0.2-12 keV
Lx (0.2-12keV) [ergs/s]
34.0
a
WO
a
WC
a
WN
140
33.5
133
33.0
48
30a
32.5
139
46
141
47
138
11
32.0
79
-1
0
1
2
log (Period [days])
3
4
Lx versus Period
Preliminary results…
Distance known for 24 of these 31 WRs, and period for 12 binaries
Computed mean Lx in three bands: Total (0.2-12 keV), soft (0.2-2 keV), hard (2-12keV)
0.2-2 keV
a
Lx (0.2-2keV) [ergs/s]
32.5
a
34.0
133
a
WO
WC
a
WC
WN
a
WN
48
WO
140
33.5
Lx (2-12keV) [ergs/s]
a
2-12 keV
46
138
32.0
30a
139
47
31.5
11
33.0
30a
133
32.5
48
141
139
32.0
31.0
140
47
46
11
79
141
79
-1
0
1
138
2
log (Period [days])
3
4
-1
0
1
2
log (Period [days])
3
4
Summary
•
The WR catalogue will provide SED for at least 31 WRs (WN, WC and
WO) detected in X-rays.
•
Hard X-ray sources with log(fx/fk) < -3 are dominated by WR stars
•
We have WR candidates and we plan to take more spectra to confirm
their nature.
•
and…