J/A+A/690/A279 Cir X-1 dip width and peak flux correlation (Yu+, 2024)
The correlation between dip width and peak flux in Cir X-1.
Yu Z.-L., Zhang S., Zhang S.-N., Li X.-D., Chen Y.-P., Peng J.-Q.,
Shui Q.-C., Yan Z., Kong L.-D., Wang P.-J.
<Astron. Astrophys. 690, A279 (2024)>
=2024A&A...690A.279Y 2024A&A...690A.279Y (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, X-ray ; Stars, variable
Keywords: accretion, accretion disks - binaries: general -
stars: individual: Cir X-1
Abstract:
In this work we analyzed the long-term X-ray variation of Cir X-1 and
its NICER spectra. The dip width and the peak flux after periastron
are obtained. Our findings show a negative correlation between the dip
width and the peak flux. A new scenario is introduced to explain the
correlation. The disk height is higher at a larger radius in the
standard model. When the neutron star (NS) moves away from periastron,
the contraction of the equipotential surface causes the height of the
outer disk to increase significantly. It blocks the X-ray emission
near the NS. Subsequently, the height of the outer disk gradually
decreases due to the viscosity. The viscous timescale is inversely
proportional to the height of the disk, and the height of the outer
disk is proportional to the mass transferred from the companion near
periastron, thus the peak flux. Consequently, the duration of the
obscuring, corresponding to the dip width, is inversely proportional
to the peak flux. Moreover, we introduce a new ephemeris
MJD(N)=43075.0+16.5843N-4.778x10-5N2 based on the dip-in phases
(ingress phase of the dip).
Description:
In this work we analyzed the variation of X-ray flux in Cir X-1 from
1996-2023 with the Bayesian blocks technique. The dip width in every
orbit and the peak flux after periastron were obtained. We find that
the dip width is negatively correlated with the peak flux in Cir X-1.
The X-ray spectroscopy was also performed using the NICER spectra
during the entry into the dip state. We find that it remains unclear
whether the obscuring is responsible for the dips observed after
MJD 59000.
Objects:
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RA (2000) DE Designation(s)
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15 20 40.85 -57 10 00.2 Cir X-1 = V* BR Cir
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table.dat 53 373 Derived phases from Bayesian blocks technique
and peak fluxes in Cir X-1
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Byte-by-byte Description of file: table.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Orbit [432/1042] Orbit number (1)
6- 11 F6.3 --- Dip-in ? Dip-in (ingress of the dip) orbital phase
13- 18 F6.3 --- e_Dip-in []? Dip-in (ingress of the dip) orbital phase
error
20- 25 F6.3 --- Dip-out ? Dip-out (egress of the dip) orbital phase
27- 31 F5.3 --- e_Dip-out ? Dip-out (egress of the dip) orbital phase
error
33- 37 F5.3 --- Dip-width ? Dip width
39- 43 F5.3 --- e_Dip-width ? Dip width error
45- 48 F4.2 Crab Fpeak ? Peak flux
50- 53 F4.2 Crab e_Fpeak ? Peak flux error
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Note (1): the orbits of Cir X-1 in Nicolson (2007ATel..985....1N 2007ATel..985....1N)'s ephemeris.
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History:
From electronic version of the journal, https://zenodo.org/records/13271411
(End) Patricia Vannier [CDS] 21-Mar-2025