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Nature of High mass X-ray binaries in the Magellanic Clouds. Andry RAJOELIMANANA 1 , 2 Supervisor : Prof Phil CHARLES 1 , 2 Co-supervisor : Prof Brian Warner 1. 1 University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa . - PowerPoint PPT Presentation
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Nature of High mass X-ray binaries in the Magellanic Clouds
Andry RAJOELIMANANA 1 , 2
Supervisor : Prof Phil CHARLES 1 , 2 Co-supervisor : Prof Brian Warner 1
1 University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa 2 South African Astronomical Observatory , P.O. Box 9, Observatory 7935, South Africa
Outline
Introduction and Background Why are we interested in the SMC ? Be/X-ray binary (BeX) A0538-66 (For Comparison)
data used
results and findings Summary and future work
MMW ~ 50 * MSMC
65 known HMXBs in our galaxy
Where are the Black Hole systems in the SMC ?
( Coe et al., 2008 )
~ 1 - 2 in the SMC
Remarkable number of HMXBs in SMC
System : Be star + X-ray pulsar
Orbit : - wide (Porb ~ months)
- eccentric (0.1<e<0.9)
2 disks : - Be equatorial disk - NS accretion disk
3 possible periods : - Pulse period (X-ray) - Orbital period (X-ray and optical) - Super-orbital period (Optical) such as seen in A0538-66
Be/X-ray binaries (BeX )
• Porb : 16.65 days• Outbursts: during optical minima• Psuper-orbital : ~ 421 days ( Be equatorial disk forms and disperses)
A0538-66 : the archetypal BeX
Alcock et al., 2001
MJD (+2448623.5)
McGowan & Charles, 2003
BeStar
Data used
- MACHO [ MAssive Compact Halo Objects]o 1.27 m telescopeo Data available : from 1992 - 2000( Alcock et al., 1996)
- OGLE [ Optical Gravitational Lensing Experiment] ( Udalsky et al,. 1997)
o 1.3 m Warsaw telescope o Phase II : 1997 - 2000o Phase III : 2001 - 2009o Phase IV : First light on September 2009
MACHO + OGLE projects ~ 16 years
Resultsand findings
Long-term variations
i > 90o - α (where α is the opening angle of the disk)
i < 90o - α
• SXP stands for Small Magellanic clouds X-ray Pulsar
Outbursts amplitude vs. brightness
• The strength of the outburst increases with the brightness of the source.
Outbursts profiles
• Transient profile (faster rise, and slower decline)• Double peaks Misalignment Supernova kick (Brandt & Podsiadlowski, 1995)
Rajoelimanana et al. , 2009 in preparation 17 Psuper-orbital
33 Porb
Super-orbital vs. Orbital periods
Rajoelimanana et al. , 2009 in preparation
We have studied 44 SMC BeX sources. found 17 super-orbital and 33 orbital periods.
Brightness increases with Colour (MACHO ‘blue’ – ’red’) for i < 90o - α
The outbursts amplitude vary with the brightness of the source. outbursts profiles : - faster rise, slower decline - double peaks (misalignment) Future work : Optical Spectroscopy of the SMC Be star using SAAO 1.9 m telescope
( week 20th January – 26th January).
Other SMC HMBXs (not identified as X-ray pulsar, possibly a low-mass BH)
Correlations between Optical and X-ray observations (Time of outbursts, relationship between X-ray outbursts and optical brightness ).
Summary and future work
Thank you