J/A+A/568/A55 Supergiant fast X-ray transients monitoring (Romano+, 2014)
Soft X-ray characterisation of the long-term properties of supergiant fast
X-ray transients.
Romano P., Ducci L., Mangano V., Esposito P., Bozzo E., Vercellone S.
<Astron. Astrophys. 568, A55 (2014)>
=2014A&A...568A..55R 2014A&A...568A..55R
ADC_Keywords: Binaries, X-ray
Keywords: X-rays: binaries - X-rays: individual: IGR J08408-4503 -
X-rays: individual: IGR J16328-4726 -
X-rays: individual: IGR J16465-4507
Abstract:
We perform the first high-sensitivity soft X-ray long-term monitoring
with Swift/XRT of three relatively unexplored supergiant fast X-ray
transients (SFXTs), IGR J08408-4503, IGR J16328-4726, and IGR
J16465-4507, whose hard X-ray duty cycles are the lowest measured
among the SFXT sample, and compare their properties with those of the
prototypical SFXTs. The behaviour of J08408 and J16328 resembles that
of other SFXTs, and it is characterized by a relatively high
inactivity duty cycle (IDC) and pronounced dynamic range (DR) in the
X-ray luminosity. Like the SFXT prototypes, J08408 shows two distinct
populations of flares, the first one associated with the brightest
outbursts (LX≥1035-36erg/s), the second one comprising less bright
events with LX≤1035erg/s.
This double-peaked distribution seems to be a ubiquitous feature of
the extreme SFXTs. The lower DR of J16328 suggests it is an
intermediate SFXT. We find J16465 is characterized by IDC∼5% and
DR∼40, reminiscent of classical supergiant HMXBs.
The duty cycles measured with XRT are found to be comparable with
those reported previously by BAT and INTEGRAL, when the higher
limiting sensitivities of these instruments are taken into account and
sufficiently long observational campaigns are available. We prove that
no clear correlation exists between the duty cycles of the SFXTs and
their orbital periods, which makes it difficult to interpret the SFXT
peculiar variability by only using arguments related to the properties
of supergiant star winds. Our findings favour the idea that a correct
interpretation of the SFXT phenomenology requires a mechanism to
strongly reduce the mass accretion rate onto the compact object during
most of its orbit around the companion, as proposed in a number of
theoretical works.
Description:
The Swift/XRT monitoring campaign commenced on 2011 October 20 with a
focus on IGR J08408-4503 and IGR J16328-4726 for one solar year, and
continued in 2013 with one year on IGR J16465-4507. Given our
preliminary results at the end of 2012, we also collected more data on
IGR J16328-4726 during 2013 to improve the statistics.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 48 10 List of studied sources
table1.dat 67 81 Observation log for IGR J08408-4503 (J08408)
table2.dat 67 97 Observation log for IGR J16328-4726 (J16328)
table3.dat 67 61 Observation log for IGR J16465-4507 (J16465)
table4.dat 91 19 Observation log for outburst data
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See also:
IX/43 : 1SXPS Swift X-ray telescope point source catalogue (Evans+ 2014)
J/A+A/562/A2 : 100-month Swift catalogue of SFXTs (Romano+, 2014)
http://www.ifc.inaf.it/sfxt : Swift Home Page
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name Source name
17- 18 I2 h RAh Right ascension (J2000)
20- 21 I2 min RAm Right ascension (J2000)
23- 28 F6.3 s RAs Right ascension (J2000)
30 A1 --- DE- Declination sign (J2000)
31- 32 I2 deg DEd Declination (J2000)
34- 35 I2 arcmin DEm Declination (J2000)
37- 41 F5.2 arcsec DEs Declination (J2000)
43- 48 A6 --- SName Short name used in the paper
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Byte-by-byte Description of file: table1.dat table2.dat table3.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Seq Observation identifier
14- 20 A7 --- Inst Instrument setup
22- 31 A10 "YYYY-MM-DD" Start.date Starting UT date
33- 40 A8 "h:m:s" Start.time Starting UT date
43- 52 A10 "YYYY-MM-DD" Stop.date Stop UT date
54- 61 A8 "h:m:s" Stop.time Stop UT date
64- 67 I4 s Exp [65/1319] Net Exposure time
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Name Source Name
18- 23 A6 --- SName Source Nickname
25- 35 A11 --- Seq Observation identifier
38- 43 A6 --- Inst Instrument setup
46- 55 A10 "YYYY-MM-DD" Start.date Starting UT date
57- 64 A8 "h:m:s" Start.time Starting UT date
67- 76 A10 "YYYY-MM-DD" Stop.date Stop UT date
78- 85 A8 "h:m:s" Stop.time Stop UT date
88- 91 I4 s Exp [257/8181] Net Exposure time
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Acknowledgements:
Patrizia Romano, patrizia.romano(at)inaf.it,
INAF-IASF Palermo, Italy
References:
Romano et al., 2014A&A...562A...2R 2014A&A...562A...2R, Cat. J/A+A/562/A2
The 100-month Swift catalogue of supergiant fast X-ray transients.
I. BAT on-board and transient monitor flares
Romano et al., 2011MNRAS.410.1825R 2011MNRAS.410.1825R,
Two years of monitoring supergiant fast X-ray transients with Swift
Romano et al., 2009MNRAS.399.2021R 2009MNRAS.399.2021R,
Monitoring supergiant fast X-ray transients with Swift:
results from the first year
(End) Patrizia Romano [INAF-IASF Palermo], Patricia Vannier [CDS] 25-Jul-2014