2015MNRAS.454.4467P -
Mon. Not. R. Astron. Soc., 454, 4467-4475 (2015/December-3)
Is 4U 0114+65 an eclipsing HMXB?
PRADHAN P., PAUL B., PAUL B.C., BOZZO E. and BELLONI T.M.
Abstract (from CDS):
We present the pulsation and spectral characteristics of the High-Mass X-ray Binary (HMXB) 4U 0114+65 during a Suzaku observation covering the part of the orbit that included the previously known low-intensity emission of the source (dip) and the egress from this state. This dip has been interpreted in previous works as an X-ray eclipse. Notably, in this Suzaku observation, the count rate during and outside the dip vary by a factor of only 2-4 at odds with the eclipses of other HMXBs, where the intensity drops up to two orders of magnitude. The orbital intensity profile of 4U 0114+65 is characterized by a narrow dip in the RXTE-ASM (2-12 keV) light curve and a shallower one in the Swift-BAT (15-50 keV), which is different from eclipse ingress/egress behaviour of other HMXBs. The time-resolved spectral analysis reveal moderate absorption column density (NH - 2-20x1022 atoms/ cm2) and a relatively low equivalent width ( ∼ 30 and 12 eV of the iron Kα and Kβ lines, respectively) as opposed to the typical X-ray spectra of HMXBs during eclipse where the equivalent width is ∼ 1 keV. Both X-ray Imaging Spectrometer and HXD-PIN data show clear pulsations during the dip, which we have further confirmed using the entire archival data of the IBIS/ISGRI and JEM-X instruments onboard INTEGRAL. The results we presented question the previous interpretation of the dip in the light curve of 4U 0114+65 as an X-ray eclipse. We thus discuss alternative interpretations of the periodic dip in the light curve of 4U 0114+65.
Abstract Copyright:
© 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2015)
Journal keyword(s):
pulsars: general - X-rays: binaries - X-rays: individual: 4U 0114+65
Simbad objects:
10
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