IGR J16460+0849 is reported in the 3rd IBIS catalog with the shortest exposure of about 10 ks among all the detected sources, which makes it the most interesting target to be investigated with a deeper exposure. We analyze all available observations carried out by the International Gamma-Ray Astrophysics
Laboratory (INTEGRAL) on the unidentified source IGR J16460+0849. The data were processed by using the latest version OSA 7.0. In addition we analyze also all the available Swift/XRT data on this source. We find that IGR J16460+0849 has a detection significance of ~ 4.4 sigma in the 20-100 keV band during the observational period between March 2003 and September 2004, when it was exposed by ~ 19 ks. Thereafter the source was not detected anymore, despite an additional exposure of ~ 271 ks. This suggests a flux variability on a timescale of years. The spectral analysis shows that the IBIS/ISGRI data are well presented by a power-law shape, with a photon index obtained as 1.45+-0.86. So far, the source has been detected consistently by IBIS/ISGRI in the subsequent observations and in the adjacent energy bands. We have analyzed the Swift/XRT observations on IGR J16460+0849 as well, and found no source inside the IBIS/ISGRI error circle. The non-detection during the Swift/XRT observation is consistent with the source having a variable nature.
We report the results from pulsations and spectral analysis of a large number of observations of the HMXB pulsar IGR J18027--2016 with {\it Swift}--XRT, carried out at different orbital phases. In some orbital phases, as seen in different XRT observations, the X-ray intensity is found to vary by a large factor, of about $\sim$50. In all the observations with sufficient number of source X-ray photons, pulsations have been detected around the previously known pulse period of $\sim$140 sec, When detected, the pulse profiles do not show any significant variation over a flux difference of a factor …
Many sources listed in the 4th IBIS/ISGRI survey are still unidentified, i.e. lacking an X-ray counterpart or simply not studied at lower energies (< 10 keV). The cross-correlation between the list of IBIS sources in the 4th catalogue and the Swift/XRT data archive is of key importance to search for the X-ray counterparts; in fact, the positional accuracy of few arcseconds obtained with XRT allows us to perform more efficient and reliable follow-up observations at other wavelengths (optical, UV, radio). In this work, we present the results of the XRT observations for four new gamma-ray sources…
IGR J19405-3016 is reported in the 3rd IBIS catalog as being one of its lowest significance sources (~4.6 sigma under an exposure of about 371 ks). This leads to a caveat in multi-wavelength study although the source was identified in optical as a Seyfert 1. The currently increased INTEGRAL data stimulate us to investigate the reality of this source. We analyze all available observations carried out by INTEGRAL and Swift on IGR J19405-3016. We find that IGR J19405-3016 has a detection significance of ~ 9.4 sigma in the 20-60 keV band during the observational period between March 2003 and March…
The orbital profile of the High Mass X-ray binary IGR J16393-4643 shows a dip in its X-ray intensity, which was previously interpreted as an eclipse. Unlike most eclipsing HMXBs, where the X-ray eclipses are about two orders of magnitude fainter compared to the out of eclipse emission, this particular eclipse like feature is narrow and partial, casting doubt if it is indeed an eclipse. To further investigate the nature of this low intensity orbital phase, we use a large number of observations with Swift-XRT, covering the entire orbital phase. The soft X-ray observations also show this low inte…
We report on the Swift/X-ray Telescope (XRT) monitoring of the field of view around the candidate supergiant fast X-ray transient (SFXT) IGR J17354-3255, which is positionally associated with the AGILE/GRID gamma-ray transient AGL J1734-3310. Our observations, which cover 11 days for a total on-source exposure of about 24 ks, span 1.2 orbital periods (P_orb=8.4474 d) and are the first sensitive monitoring of this source in the soft X-rays. These new data allow us to exploit the timing variability properties of the sources in the field to unambiguously identify the soft X-ray counterpart of IGR…
IGR J18179-1621 is a hard X-ray binary transient discovered recently by INTEGRAL. Here we report on detailed timing and spectral analysis on IGR J18179-1621 in X-rays based on available INTEGRAL and Swift data. From the INTEGRAL analysis, IGR J18179-1621 is detected with a significance of 21.6 sigma in the 18-40 keV band by ISGRI and 15.3 sigma in the 3-25 keV band by JEM-X, between 2012-02-29 and 2012-03-01. We analyze two quasisimultaneous Swift ToO observations. A clear 11.82 seconds pulsation is detected above the white noise at a confidence level larger than 99.99%. The pulse fraction is …
We report on the Swift monitoring of the candidate supergiant fast X-ray transient (SFXT) IGR J16418-4532, for which both orbital and spin periods are known (~3.7d and ~1250s, respectively). Our observations, for a total of ~43ks, span over three orbital periods and represent the most intense and complete sampling of the light curve of this source with a sensitive X-ray instrument. With this unique set of observations we can address the nature of this transient. By applying the clumpy wind model for blue supergiants to the observed X-ray light curve, and assuming a circular orbit, the X-ray em…
IGR J17091-3624 is a low mass X-ray binary (LMXB) which received wide attention from the community thanks to its similarities with the bright black hole system GRS 1915+105. Both systems exhibit a wide range of highly structured X-ray variability during outburst, with time scales from few seconds to tens of minutes, which make them unique in the study of mass accretion in LMXBs. In this work we present a general overview into the long-term evolution of IGR J17091-3624, using Swift/XRT observations from the onset of the 2011-2013 outburst in February 2011 to the end of the last bright outburst …
We report on new X-ray outbursts observed with Swift from three Supergiant Fast X-ray Transients (SFXTs): XTEJ1739-302, IGRJ17544-2619 and IGRJ08408-4503. The former two outbursts were caught during the monitoring campaign we have been performing with the Swift satellite since October 2007: XTEJ1739-302 underwent a new outburst on 2008, August 13, IGRJ17544-2619 on 2008, September 4, while IGRJ08408-4503 on 2008, September 21. While XTEJ1739-302 and IGRJ08408-4503 bright emission triggered the Swift/Burst Alert Telescope, IGRJ17544-2619 did not, thus we could perform a spectral investigation o…
IGR J16479-4514 is a member of the Supergiant Fast X-ray transient (SFXT) class. We present the light curves of its latest outburst, which occurred on January 29, 2009. During this outburst, IGR J16479-4514 showed prolonged activity lasting several days. The presence of eclipses was successfully tested.
IGR J18483-0311 is an X-ray pulsar with transient X-ray activity, belonging to the new class of High Mass X-ray Binaries called Supergiant Fast X-ray Transients. This system is one of the two members of this class, together with IGR J11215-5952, where both the orbital (18.52d) and spin period (21s) are known. We report on the first complete monitoring of the X-ray activity along an entire orbital period of a Supergiant Fast X-ray Transient. These Swift observations, lasting 28d, cover more than one entire orbital phase consecutively. They are a unique data-set, which allows us to constrain the…
The 4th IBIS/ISGRI survey lists 723 hard X-ray sources many still unidentified. We cross-correlated the list of the sources included in the 4th IBIS catalogue with the Swift/XRT data archive, finding a sample of 20 objects for which XRT data could help in the search for the X-ray and hence optical counterpart and/or in the study of the source spectral and variability properties below 10 keV. Four objects (IGR J00465-4005, LEDA 96373, IGR J1248.2-5828 and IGR J13107-5626) are confirmed or likely absorbed active galaxies, while two (IGR J14080-3023 and 1RXS J213944.3+595016) are unabsorbed AGN. …
The INTEGRAL and Swift hard X-ray surveys have identified a large number of new sources, among which many are proposed as Cataclysmic Variables (CVs). Here we present the first detailed study of three X-ray selected CVs, Swift J1907.3-2050, IGRJ12123-5802, and IGRJ19552+0044 based on XMM-Newton, Suzaku, Swift observations and ground based optical and archival nIR/IR data. Swift J1907.3-2050 is highly variable from hours to months-years at all wavelengths. No coherent X-ray pulses are detected but rather transient features. The X-ray spectrum reveals a multi-temperature optically thin plasma ab…
IGR J16493-4348 is a supergiant high mass X-ray binary discovered by INTEGRAL in 2004. The source is detected at a significance level of $\sim21$ standard deviations in the Swift-BAT survey data collected during the first 54 months of the Swift mission. The timing analysis reveals an orbital period of $\sim$6.78 days and the presence of a full eclipse of the compact ob\ ject. The dynamical range (variability up to a factor $\sim$20) observed during the BAT monitoring suggests that IGR J16493-4348 is a wind-fed system. The derived semi-major axis of the binary system is $\sim55 R_{\sun}$ with a…
IGR J04571+4527 and Swift J0525.6+2416 are two hard X-ray sources detected in the Swift/BAT and INTEGRAL/IBIS surveys. They were proposed to be magnetic cataclysmic variables of the Intermediate Polar (IP) type, based on optical spectroscopy. IGR J04571+4527 also showed a 1218 s optical periodicity, suggestive of the rotational period of a white dwarf, further pointing towards an IP classification. We here present detailed X-ray (0.3-10 keV) timing and spectral analysis performed with XMM-Newton, complemented with hard X-ray coverage (15-70 keV) from Swift/BAT. These are the first high signal …
We report on the Swift observations of the candidate supergiant fast X-ray transient (SFXT) IGR J16418-4532, which has an orbital period of ~3.7 d. Our monitoring, for a total of ~43 ks, spans over three orbits and represents the most intense and complete sampling along the orbital period of the light curve of this source. If one assumes a circular orbit, the X-ray emission from this source can be explained by accretion from a spherically symmetric clumpy wind from a blue supergiant, composed of clumps with different masses, ranging from ~5x10^16 g to 10^21g.
We report on the temporal and spectral properties of the HMXB IGR J16283-4838 in the hard X-ray band. We searched the first 88 months of Swift BAT survey data for long-term periodic modulations. We also investigated the broad band (0.2--150 keV) spectral properties of IGR J16283--4838 complementing the BAT dataset with the soft X-ray data from the available Swift-XRT pointed observations. The BAT light curve of IGR J16283-4838 revealed a periodic modulation at P_o=287.6+7-1.7 days (with a significance higher than 4 standard deviations). The profile of the light curve folded at P_o shows a shar…
A new accreting millisecond X-ray pulsar, IGR J17511-3057, was discovered in outburst on 2009 September 12 during the INTEGRAL Galactic bulge monitoring programme. To study the evolution of the source X-ray flux and spectral properties during the outburst, we requested a Swift monitoring of IGRJ17511-3057. In this paper we report on the results of the first two weeks of monitoring the source. The persistent emission of IGR J17511-3057 during the outburst is modeled well with an absorbed blackbody (kT~0.9 keV) and a power-law component (photon index~1-2), similar to what has been observed from …
We report the results of a high-energy multi-instrumental campaign with INTEGRAL, RXTE, and Swift of the recently discovered INTEGRAL source IGR J19294+1816. The Swift/XRT data allow us to refine the position of the source to RA= 19h 29m 55.9s Dec=+18deg 18' 38.4" (+- 3.5"), which in turn permits us to identify a candidate infrared counterpart. The Swift and RXTE spectra are well fitted with absorbed power laws with hard (Gamma ~ 1) photon indices. During the longest Swift observation, we obtained evidence of absorption in true excess to the Galactic value, which may indicate some intrinsic ab…
With respect to the recent INTEGRAL/IBIS 9-year Galactic Hard X-ray Survey (Krivonos et al. 2012), we use archival Swift/XRT observations in conjunction with multi-wavelength information to discuss the counterparts of a sample of newly discovered objects. The X-ray telescope (XRT, 0.3-10 keV) on board Swift, thanks to its few arcseconds source location accuracy, has been proven to be a powerful tool with which the X-ray counterparts to these IBIS sources can be searched for and studied. In this work, we present the outcome of this analysis by discussing four objects (SWIFT J0958.0-4208, SWIFT …
We analysed 13 years of the Neil Gehrels Swift Observatory survey data collected on the High Mass X-ray Binary IGR J18214-1318. Performing the timing analysis we detected a periodic signal of 5.42 d. From the companion star characteristics we derived an average orbital separation of $\sim 41 \rm R_{\odot}\simeq 2 R_{\star}$. The spectral type of the companion star (O9) and the tight orbital separation suggest that IGR~J18214-1318 is a wind accreting source with eccentricity lower than 0.17. The intensity profile folded at the orbital period shows a deep minimum compatible with an eclipse of th…
IGR J11305-6256 is one of the numerous sources discovered through the INTEGRAL scan of the Galactic Plane. Thanks to the Swift-BAT survey, that allows the frequent sampling of any sky region, we have discovered in the hard X-ray emission of this source a modulation with a period of ~120.83 d. The significance of this periodic modulation is ~4 standard deviations in Gaussian statistics. We interpret it as the orbital period of the binary system. We derive an orbital separation between IGR J11305-6256 and its companion star of ~286 R$_{\odot}$ corresponding to ~19 times the radius of the compani…
We analysed the IGR J16465-4507 Burst Alert Teelescope survey data collected during the first 54 months of the Swift mission. The source is in a crowded field and it is revealed through an ad hoc imaging analysis at a significance level of ~14 standard deviations. The 15-50 keV average flux is ~3E-11 erg/cm^2/s. The timing analysis reveals an orbital period of 30.243 +/- 0.035 days. The folded light curve shows the presence of a wide phase interval of minimum intensity, lasting ~20% of the orbital period. This could be explained with a full eclipse of the compact object in an extremely eccentr…
The Second Swift-XRT Point Source catalogue offers a combination of sky coverage and sensitivity and presents an invaluable opportunity for transient discovery. We search the catalogue at the positions of inactive and active galaxies, and identify transient candidates by comparison with XMM-Newton and ROSAT. We recover 167 previously known transients and find 19 sources consistent with being new sources, estimating a completeness of $\sim65\%$. These 19 new sources are split approximately equally between inactive and active hosts and their peak X-ray luminosities span $\sim 10^{42} - 10^{47}$ …
We present the results of our study of the X-ray pulsar IGR J21343+4738 based on NuSTAR, Swift, and SRG observations in the wide energy range 0.3 - 79 keV. The absence of absorption features in the energy spectra of the source, both averaged and phase-resolved ones, has allowed us to estimate the upper and lower limits on the magnetic field of the neutron star in the binary system, $B<2.5\times10^{11}$G and $B>3.4 \times 10^{12}$G, respectively. The spectral and timing analyses have shown that IGR J21343+4738 has all properties of a quasi-persistent X-ray pulsar with a pulsation period of $322…
We present the discovery of two distinct classes in the Swift short duration gamma-ray bursts (S-GRBs) from the X-Ray Telescope (XRT) X-ray afterglow light curve. We find that about 40% of the Swift S-GRBs have an X-ray afterglow light curves which only lasts less than 10000 seconds after the burst trigger (hereafter short-lived S-GRBs). On the other hand, another 60% of S-GRBs have a long lasting X-ray afterglow light curve which resembles the long duration gamma-ray bursts. We also find that none of the short-lived S-GRBs shows the extended emission in the Burst Alert Telescope (BAT) energy …
In recent years, thanks to the continuous surveys performed by INTEGRAL and Swift satellites, our knowledge of the hard X-ray/soft gamma-ray sky has greatly improved. As a result it is now populated with about 2000 sources, both Galactic and extra-galactic, mainly discovered by IBIS and BAT instruments. Many different follow-up campaigns have been successfully performed by using a multi-wavelength approach, shedding light on the nature of a number of these new hard X-ray sources. However, a fraction are still of a unidentified nature. This is mainly due to the lack of lower energy observations…
IGR~J19149+1036 is a high mass X-ray binary detected by INTEGRAL in 2011 in the hard X-ray domain. We have analyzed the BAT survey data of the first 103 months of the Swift mission detecting this source at a significance level of ~30 standard deviations. The timing analysis on the long term BAT light curve reveals the presence of a strong sinusoidal intensity modulation of 22.25+/- 0.05 d, that we interpret as the orbital period of this binary system. A broad band (0.3-150 keV) spectral analysis was performed combining the BAT spectrum and the XRT spectra from the pointed follow up observation…
After a careful analysis of the instrumental effects on the Poisson noise to demonstrate the feasibility of detailed stochastic variability studies with the Swift X-Ray Telescope (XRT), we analyze the variability of the black hole X-ray binary SWIFT J1753.5-0127 in all XRT observations during 2005-2010. We present the evolution of the power spectral components along the outburst in two energy bands: soft (0.5-2 keV) and hard (2-10 keV), and in the hard band find results consistent with those from the Rossi X-ray Timing Explorer (RXTE). The advantage of the XRT is that we can also explore the s…
The blazar S5 0716+714 has been monitored in its flaring state between 2015 January 19 and February 22 with Swift/XRT. During this period an exceptional flux level was observed in the X-ray range as well as in the other wavelengths, e.g. optical, near infrared and very high energy $γ$ rays. Here, we report X-ray observations of S5 0716+714 carried out during the outburst. The observed X-ray spectra, well described with broken power-law model, disentangle both synchrotron and inverse Compton components. The break energy shifts towards higher energies with increasing flux, revealing the dominanc…
We present here the main characteristics of the BHC IGR J17091-3624 outbursts occurred several times since 1994. Since 2003, the source has been extensively observed by INTEGRAL and Swift. In particular, we report results on the last 2011 outburst that showed a rare variability behaviour observed before only in the galactic BH GRS 1915+105 but at a different level of flux. Several hypotheses have been proposed in order to explain this particular behaviour. They are all discussed here, in the light of their apparent contradiction. Finally, based on all available informations, we attempt to give…
IGRJ19294+1816 was discovered by INTEGRAL in 2009 during a bright X-ray outburst and was classified as a possible Be X-ray binary or supergiant fast X-ray transient. On 2010 October 28, the source displayed a second X-ray outburst and a 2 months-long monitoring with Swift was carried out to follow the evolution of the source X-ray flux during the event. We report on the INTEGRAL and Swift observations of the second X-ray outburst observed from IGRJ19294+1816. We detected pulsations in the X-ray emission from the source at \sim12.5 s up to 50 keV. The source X-ray flux decreased smoothly during…
We report on the 2016 outburst of the transient Galactic Black Hole candidate IGR J17091-3624 based on the observation campaign carried out with SWIFT and NuSTAR. The outburst profile, as observed with SWIFT-XRT, shows a typical `q'-shape in the Hardness Intensity Diagram (HID). Based on the spectral and temporal evolution of the different parameters, we are able to identify all the spectral states in the q-profile of HID and the Hardness-RMS diagram (HRD). Both XRT and NuSTAR observations show an evolution of low frequency Quasi periodic oscillations (QPOs) during the low hard and hard interm…
IGR J18219-1347 is a hard X-ray source discovered by INTEGRAL in 2010. We have analyzed the X-ray emission of this source exploiting the BAT survey data up to March 2012 and the XRT data that include also an observing campaign performed in early 2012. The source is detected at a significance level of ~14 standard deviations in the 88-month BAT survey data, and shows a strong variability along the survey monitoring, going from high intensity to quiescent states. A timing analysis on the BAT data revealed an intensity modulation with a period of 72.46 days. The significance of this modulation is…
We present the results of the first four (quasi-)simultaneous radio (ATCA), X-ray (Swift, RXTE), and Gamma-ray (INTEGRAL) observations of the black hole candidate IGR J17091-3624, performed in February and March 2011. The X-ray analysis shows that the source was in the hard state, and then it transited to a soft intermediate state. We study the correlated radio/X-ray behaviour of this source for the first time. The radio counterpart to IGR J17091-3624 was detected during all four observations with the ATCA. In the hard state, the radio spectrum is typical of optically thick synchrotron emissio…
We report on a \textit{NuSTAR} and \textit{Swift}/XRT observation of the newly discovered X-ray transient MAXI J1820+070. \textit{Swift}/XRT and \textit{NuSTAR} have concurrently observed the newly detected source on 14 March 2018. We have simultaneously fitted the broad-band spectra obtained from \textit{Swift}/XRT and \textit{NuSTAR}. The observed joint spectra in the energy range 0.6--78.0 keV are well modeled with a weak disk black-body emission, dominant thermal Comptonization and relativistic reflection fraction. We have detected a fluorescent Iron-K$α$ line relativistically broadened, a…
A growing group of low-mass X-ray binaries are found to be accreting at very-faint X-ray luminosities of <1E36 erg/s (2-10 keV). Once such system is the new X-ray transient IGR J17494-3030. We present Swift and XMM-Newton observations obtained during its 2012 discovery outburst. The Swift observations trace the peak of the outburst, which reached a luminosity of ~7 E35 (D/8 kpc)^2 erg/s (2-10 keV). The XMM-Newton data were obtained when the outburst had decayed to an intensity of ~ 8 E34 (D/8 kpc)^2 erg/s. The spectrum can be described by a power-law with an index of ~1.7 and requires an addit…
Resonant absorption cyclotron features are a key diagnostic tool to directly measure the strength of the magnetic field of accreting neutron stars. However, typical values for cyclotron features lie in the high-energy part of the spectrum between 20 keV and 50 keV, where detection is often damped by the low statistics from single pointed observations. We show that long-term monitoring campaign performed with Swift-BAT of persistently, but faint, accreting high-mass X-ray binaries is able to reveal in their spectra the presence of cyclotron features. We extracted the average Swift-BAT 15-150 ke…
We report on the identification of a new soft gamma-ray source, namely IGR J20159+3713/SWIFT J2015.9+3715, first detected by INTEGRAL/IBIS and then confirmed by Swift/BAT. The source, which has an observed 20-100 keV flux in the range (0.7-1.4) x 10^(-11) erg cm^(-2) s^(-1), encloses a Fermi variable source (2FGL J2015.6+3709) and is spatially close to a TeV emitter (VER J2016+372). Thanks to X-ray follow-up observations performed with the X-ray telescope on board Swift, we have been able to identify the new IBIS/BAT detection with the combined emission of the blazar B2013+370 and the cataclys…
A growing number of previously hidden Galactic X-ray sources are now detected with recent surveys performed by the Integral and Swift satellites. Most of these new sources eluded past surveys due to their large local X-ray extinction and consequent low soft X-ray flux. The Swift-BAT performs daily monitoring of the sky in an energy band (15-150 keV) which is only marginally affected by X-ray extinction, thus allowing for the search of long periodicities in the light curve and identification of the nature of the X-ray sources. We performed a period search using the folding technique in the Swif…
We searched for X-ray serendipitous sources in over 370 Swift-XRT fields centered on gamma ray bursts detected between 2004 and 2008 and observed with total exposures ranging from 10 ks to over 1 Ms. This defines the Swift Serendipitous Survey in deep XRT GRB fields, which is quite broad compared to existing surveys (~33 square degrees) and medium depth, with a faintest flux limit of 7.2e-16 erg cm^-2 s^-1 in the 0.5 to 2 keV energy range. The survey has a high degree of uniformity thanks to the stable point spread function and small vignetting correction factors of the XRT, moreover is comple…
The supergiant fast X-ray transient source IGR J16479-4514 was observed in outburst two times with Swift. Its quiescent state was investigated in-depth only once in 2008 through a relatively long pointed observation with XMM-Newton. The latter observation was taken about 1.7 days after the outburst in 2008, and showed an X-ray eclipse-like event, likely caused by the supergiant companion. At present, this is the only supergiant fast X-ray transient that displayed an evidence for an X-ray eclipse. Here we carry out a comparison between the most recent outburst of IGRJ16479-4514, caught by Swift…
Supergiant fast X-ray transients (SFXTs) are high mass X-ray binaries (HMXBs) hosting a neutron star and an OB supergiant companion. We examine the available Swift data, as well as other new or archival/serendipitous data, on three sources: IGR J17407-2808, 2XMM J185114.3-000004, and IGR J18175-2419, whose X-ray characteristics qualify them as candidate SFXT, in order to explore their properties and test whether they are consistent with an SFXT nature. As IGR J17407-2808 and 2XMM J185114.3-000004 triggered the Burst Alert Telescope on board Swift, the Swift data allow us to provide their first…
IGRJ17361-4441 is a hard transient recently observed by the INTEGRAL satellite. The source, close to the center of gravity of the globular cluster NGC 6388, quickly became the target of follow-up observations conducted by the Chandra, Swift/XRT and RXTE observatories. Here, we concentrate in particular on a set of observations conducted by the XMM-Newton satellite during two slews, in order to get the spectral information of the source and search for spectral variations. The spectral parameters determined by the recent XMM-Newton slew observations were compared to the previously known results.…
The long term evolution of ULX with their spectral and luminosity variations in time give important clues on the nature of ULX and on the accretion process that powers them. We report here the results of a Swift-XRT 6-year monitoring campaign of the closest example of a persistent ULX, M33 X-8, that extends to 16 years the monitoring of this source in the soft X-rays. The luminosity of this source is a few 10^39 erg/s, marking the faint end of the ULX luminosity function. We analysed the set of 15 observations collected during the Swift monitoring. We searched for differences in the spectral p…
Physical parameters of both the mass donor and compact object can be constrained in X-ray binaries with well-defined eclipses, as our survey of wind-fed supergiant X-ray binaries (SGXBs) IGR J16393-4643, IGR J16418-4532, IGR J16479-4514, IGR J18027-2016 and XTE J1855-026 reveals. Using the orbital period and Kepler's third law, we express the eclipse half-angle in terms of radius, inclination angle and the sum of the masses. Pulse-timing and radial velocity curves can give masses of both the donor and compact object as in the case of the "double-lined" binaries IGR J18027-2016 and XTE J1855-02…
In the last years the hard X-ray astronomy has made a significant step forward, thanks to the monitoring of the IBIS/ISGRI telescope on board the INTEGRAL satellite and of the Burst Alert Telescope (BAT) on board of the Swift observatory. This has provided a huge amount of novel information on many classes of sources. We have been exploiting the BAT survey data to study the variability and the spectral properties of the new high mass X-ray binary sources detected by INTEGRAL. In this letter we investigate the properties of IGR J015712-7259. We perform timing analysis on the 88-month BAT survey…
We present the Living Swift-XRT Point Source catalogue (LSXPS) and real-time transient detector. This system allows us for the first time to carry out low-latency searches for new transient X-ray events fainter than those available to the current generation of wide-field imagers, and report their detection in near real-time. Previously, such events could only be found in delayed searches, e.g. of archival data; our low-latency analysis now enables rapid and ongoing follow up of these events, enabling the probing of timescales previously inaccessible. The LSXPS is, uniquely among X-ray catalogu…
IGR J16195-4945 is a hard X-ray source discovered by INTEGRAL during the Core Program observations performed in 2003. We analyzed the X-ray emission of this source exploiting the Swift-BAT survey data from December 2004 to March 2015, and all the available Swift-XRT pointed observations. The source is detected at a high significance level in the 123-month BAT survey data, with an average 15-150 keV flux of the source of ~1.6 mCrab. The timing analysis on the BAT data reveals with a significance higher than 6 standard deviations the presence of a modulated signal with a period of 3.945 d, that …
IGR J00291+5934 is the fastest-known accretion-powered X-ray pulsar, discovered during a transient outburst in 2004. In this paper, we report on Integral and Swift observations during the 2015 outburst, which lasts for $\sim25$ d. The source has not been observed in outburst since 2008, suggesting that the long-term accretion rate has decreased by a factor of two since discovery. The averaged broad-band (0.1 - 250 keV) persistent spectrum in 2015 is well described by a thermal Comptonization model with a column density of $N_{\rm H} \approx4\times10^{21}$ cm$^{-2}$, a plasma temperature of $kT…
The source IGR J17200-3116 was discovered in the hard X-ray band by INTEGRAL. A periodic X-ray modulation at ~326 s was detected in its Swift light curves by our group (and subsequently confirmed by a Swift campaign). In this paper, we report on the analysis of all the Swift observations, which were collected between 2005 and 2011, and of a ~20 ks XMM-Newton pointing that was carried out in 2013 September. During the years covered by the Swift and XMM-Newton observations, the 1-10 keV fluxes range from ~1.5 to 4E-11 erg/cm^2/s. IGR J17200-3116 displays spectral variability as a function of the…
Extreme high synchrotron peaked blazars (EHBLs) are amongst the most powerful accelerators found in nature. Usually the synchrotron peak frequency of an EHBL is above $10^{17}\,$Hz, i.e., lies in the range of medium to hard X-rays making them ideal sources to study particle acceleration and radiative processes. EHBL objects are commonly observed at energies beyond several TeV, making them also powerful probes of gamma-ray absorption in the intergalactic medium. During the last decade, several attempts have been made to increase the number of EHBL detected at TeV energies and probe their spectr…
IGR J18483-0311 was discovered with INTEGRAL in 2003 and later classified as a supergiant fast X-ray transient. It was observed in outburst many times, but its quiescent state is still poorly known. Here we present the results of XMM-Newton, Swift, and Chandra observations of IGRJ18483-0311. These data improved the X-ray position of the source, and provided new information on the timing and spectral properties of IGR J18483-0311 in quiescence. We report the detection of pulsations in the quiescent X-ray emission of this source, and give for the first time a measurement of the spin-period deriv…
