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. =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 (L_X_>=10^35-36^erg/s), the second one comprising less bright events with L_X_<=10^35^erg/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: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- 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 -------------------------------------------------------------------------------- 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 -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 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 -------------------------------------------------------------------------------- Byte-by-byte Description of file: table1.dat table2.dat table3.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 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 -------------------------------------------------------------------------------- Byte-by-byte Description of file: table4.dat -------------------------------------------------------------------------------- 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 -------------------------------------------------------------------------------- Acknowledgements: Patrizia Romano, patrizia.romano(at)inaf.it, INAF-IASF Palermo, Italy References: Romano et al., 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, Two years of monitoring supergiant fast X-ray transients with Swift Romano et al., 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