OMC-INTEGRAL: OPTICAL OBSERVATIONS OF
X-RAY BINARIES
M.D. Caballero-García1, A. Domingo1, D. Rísquez1, J.M. Mas-Hesse2, A.
Jiménez3, F. Figueras4,5, C. Jordi4,5
1LAEFF-INTA
Madrid (Spain
(Spain))
2CAB-INTA Madrid (Spain
(Spain))
3ESTEC-ESA Noordwijk (The
(The Netherlands)
Netherlands)
4UB Barcelona (Spain
(Spain))
5IEEC Barcelona (Spain
(Spain))
JENAM 2004, Granada
Summary
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Cyg X-1: temporal analysis (simultaneous
optical, high and low energy light curves).
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ROSAT sources probably detected in the
optical band by OMC.
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LMC X-4: optical light curve.
Cyg X-1
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HMXB discovered in 1962. The optical counterpart
(HD 226868/V1357 Cyg) discovered by Bolton 1972
and Webster & Murdin 1972.
Masses: 17.5 Msun for the optical counterpart
(O9.7Iab) and 10.1 Msun for the black hole (Herrero
et al. 1995). The blue giant is filling the Roche Lobe
and is transferring mass into the black hole.
Optical light curve period: 5.599836±0.000024 days
(Brocksopp et al. 1999). This corresponds to the
orbital period of the system.
Distance: 1700 pc
Cyg X-1
Optical light curve
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Double-peaked ellipsoidal
modulation due to the tidally
and rotationally distorted star.
<Amplitude>=0.06 mag.
τ = 5.6 days
Inclination of the orbit:
i ≈ 40-60º (Bruevich et al. 1978)
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Cyg X-1
Correlation with X-rays
INTEGRALà simultaneous
measurements of the same field
in optical (OMC) and hard Xrays (IBIS). Rev. 16-18.
Ø X-ray flares in the scale of a few
days probably due to
focalization of the supergiant’s
wind by the BH.
Ø The X-ray flares correspond to
optical minima.
à optical-x-ray correlations will be
studied in the future.
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OMC data (top panel) and IBIS-ISGRI
(bottom panel, courtesy of A. Bazzano and
the ISGRI team).
Cyg X-1
SPI: γ-ray
spectrograph
Multiwavelength correlation
IBIS: γ-ray imager
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Simultaneous measurements
of the same field in optical
(OMC), hard X-rays (SPI and
IBIS) and soft X-rays (JEMX). Rev. 79-80.
Once more the highest high
energy flares corresponds to
optical minima.
INTEGRAL Þ flares are real.
OMC Þ relation with the
orbital configuration.
JEM-X: X-rays
radio
OMC: optical
SPI, IBIS, JEM-X radio and OMC data (top to
bottom).
ROSAT sources
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OMC monitors ∼ 100 stars in each field, all extracted from
The OMC Input Catalogue (Domingo et al. 2003). ROSAT
catalogues (Bright and Faint) are included.
OMC extracts the photometric information from the
photon counting of pixels in a 11x11 pixels box centered
on the ROSAT coordinates.
5 ROSAT sources monitored (distance to ROSAT
coordinates < 30 arcsec, inside the ROSAT error circle)
showed a large degree of variability in the optical band,
unknown before. à Possible optical counterparts of
the ROSAT sources.
OMC 3’x3’
photometric box
ROSAT sources
Optical light curves
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Names of the sources:
IOMC 0237000035 ↔ 1RXS J095156.0+004722
IOMC 1306000026 ↔ 1RXS J054101.8+203624
IOMC 2674000067 ↔ 1RXS J200219.0+333912
IOMC 2675000078 ↔ 1RXS J200912.0+323344
IOMC 4896000046 ↔ 1RXS J095706.3-012019
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Optical variations typical of binary
systems (blue fig.). Periods
ranging from 0.4 to 1.9 days.
Spectral types ranging from F to
K.
V magnitudes relatively bright
(from 8.9 to 11.5).
Observations in X-rays will be
made in the future.
IOMC 2675000078
IOMC 0237000035
IOMC 4896000046
IOMC 1306000026
IOMC 2674000067
ROSAT sources
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Binary system of
contact type.
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τ = 0.42233 ± 0.00003
days
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G0 spectral type.
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14’’ away from 1RXS
J200912.0+323344
IOMC 2675000078
ROSAT sources
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Binary system of
contact type.
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τ = 0.46515 ± 0.00018
days
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F8 spectral type.
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8’’ away from 1RXS
J095156.0+004722
IOMC 0237000035
ROSAT sources
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Binary system of
detached type.
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τ = 0.9871 ± 0.0008
days
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F5 spectral type.
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20’’ away from 1RXS
J095706.3-012019
IOMC 4896000046
ROSAT sources
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Probably pulsating stars.
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Light curves not folded
with the period.
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K2 and G8 spectral types.
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8’’ away from 1RXS
J054101.8+203624 and
41.7’’ away from 1RXS
J200219.0+333912
IOMC 1306000026
IOMC 2674000067
LMC X-4
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It is a HMXB with a possible neutron star as the
compact object.
Ellipsoidal modulation in the optical light curve due to
the tidally and rotationally distorted star.
∆V = 0.4 mag.
τ = 1.4 days
Faint (V∼14) and located in an optically crowded field
(LMC).
The OMC extracted photometric box (∼1’) is strongly
affected by the nearby stars.
LMC X-4
OMC 3’x3’
photometric box
Optical light curve
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Some dispersion is intrinsic
to the source.
A sinusoidal fit to the light
curve was made to know the
parameters τ and ∆V.
Values obtained:
∆Vcalculated=0.036 mag.
τcalculated=1.35 days
in agreement with that we
expected.
OMC data fitted with a sinus
function.