INTEGRAL Cross-calibration Status: Crab observations between 3 keV and 1 MeV

Jourdain, E.; Götz, D.; Westergaard, N. J.; Natalucci, Lorenzo; Roques, J. P.

doi:10.48550/arxiv.0810.0646

Cited by 3 publications

(6 citation statements)

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“…332, 333, 335, 664, 673 and 675 (see Table 3). The cross-calibration studies on the JEM-X and IBIS/ISGRI detectors have been done by Jourdain et al (2008) using the Crab observation data. The calibration between JEM-X and IBIS/ISGRI for OSA 7.0 can be good enough within ∼ 6%.…”

Section: Quiescent Statesmentioning

confidence: 99%

Long-term hard X-ray monitoring of 2S 0114+65 with INTEGRAL/IBIS

Wang¹

2011

Monthly Notices of the Royal Astronomical Society

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We present the results of the long‐term hard X‐ray monitoring of the high‐mass X‐ray binary 2S 0114+65 with INTEGRAL/IBIS from 2003 to 2008. 2S 0114+65 is a variable hard X‐ray source with X‐ray luminosities of 1035–4 × 1036 erg s−1 from 20 to 100 keV due to accretion rate changes in different orbital phases. In several observations when 2S 0114+65 was bright, we found a pulse period evolution of ∼2.67 h to 2.63 h from 2003 to 2008, with a spin‐up rate of the neutron star ∼1.09 × 10−6 s s−1. Compared with the previous reported spin‐up rate, the spin‐up rate of the neutron star in 2S 0114+65 is accelerating. The spectral properties of 2S 0114+65 in the 18–100 keV band which changed with the orbital phases generally could be described with a power‐law model with a high‐energy exponential cut‐off. The variation of the power‐law photon index over orbital phase anticorrelates with hard X‐ray flux, and the variation of Ecut has a positive correlation with the hard X‐ray flux, implying a harder spectrum at the maximum of the light curve. The variations of spectral properties over orbital phase suggested 2S 0114+65 as a highly obscured binary system. In some observational revolutions, hard X‐ray tails above 70 keV are detected. We study the characteristics of the hard X‐ray tails combining JEM‐X and IBIS data in the energy range of 3–100 keV. The 3–100 keV spectra of 2S 0114+65 are generally fitted by an absorbed power‐law model with high‐energy cut‐off. We discover that the hard X‐ray tails are only detected when the column density is very low. Thus, a high column density leads to the disappearance of the hard X‐ray tails in this wind‐fed neutron star accretion binary. Our results would help to understand the origin, evolution and properties of this peculiar class of superslow pulsation neutron stars in high‐mass X‐ray binaries.

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Section: Quiescent Statesmentioning

confidence: 99%

Long-term hard X-ray monitoring of 2S 0114+65 with INTEGRAL/IBIS

Wang¹

2011

Monthly Notices of the Royal Astronomical Society

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“…Moreover, the SPI detector was carefully calibrated before the launch of INTEGRAL (Attié et al 2003), which ensured that the calibration check was independent of the details of the particular model assumed for a calibration source such as the Crab. A lot of effort has been invested since the beginning of the mission to calibrate well the ISGRI and SPI instruments, resulting in a good performance in the energy range below 100 keV (Jourdain et al 2008). Due to a limited ISGRI sensitivity above 100 keV, there is however still a spectral slope issue remaining for the high energy part of the spectra.…”

Section: Calibrationmentioning

confidence: 99%

“…However, the latter value is clearly higher than Γ ≈ 2.2 inferred from the Crab spectral analysis with the standard OSA SPI software, provided in its version 7.0 and several earlier releases. The latest INTEGRAL cross-calibration report (Jourdain et al 2008) presented a new result for SPI: with the updated spectral extraction software used Table 4. Cross-calibration between the INTEGRAL high-energy instruments.…”

Section: Calibrationmentioning

confidence: 99%

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Analysis of extremely low signal-to-noise ratio data from INTEGRAL/PICsIT

Lubiński

2009

A&A

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Context. The PICsIT detector onboard the INTEGRAL satellite was designed to provide information about emission in the soft γ-ray band for many bright sources. Due to strong and variable instrumental background, only 4 objects have been detected so far using standard software. Aims. The moderate sensitivity of PICsIT can be compensated for in the case of many objects by adopting a long exposure time, thanks to INTEGRAL's large field of view and an observing strategy focused on the Galactic plane. With angular resolution far higher than that of all other instruments operating in a similar energy band, PICsIT is suitable for fields too crowded or too significantly affected by Galactic diffuse emission. Therefore, it is desirable to improve the spectral extraction software to both obtain more reliable results and enlarge the number of objects that can be studied. Methods. The new PICsIT spectral extraction method is based on three elements: careful modelling of the background, an energydependent pixel-illumination function, and the computation of the probability density of the source count rate. Background maps of the detector plane are prepared for short periods and relatively narrow energy bands to insure that the background dependence on time and energy is modelled well. The most important element of the new spectral extraction method is the proper treatment of the Poisson-distributed data, developed within a Bayesian framework. Results. The new method was tested extensively on both a large true data set and simulated data. Results assumed in simulations were reproduced perfectly, without any bias and with high precision. Count rates measured for Crab were far more stable than those obtained with the standard software. For weaker sources, the new method produced spectra of far higher quality and allows us to detect at least 8 additional objects. Comparison with other INTEGRAL instruments demonstrated that PICsIT is well calibrated and provides valuable information about the continuum emission in the 250 keV -1 MeV band, detectable currently only by INTEGRAL.

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“…For both the ISGRI and the SPI data, we follow the INTEGRAL Cross-calibration status document by Jourdain et al (2008) and assume the Crab Nebula spectrum between 25 keV and 1 MeV to be a broken powerlaw with break energy fixed at 100 keV (which is close to the break energy we actually measure, see Sect. 4.1).…”

Section: Statistical and Systematic Errorsmentioning

confidence: 99%

Soft gamma-ray sources detected by INTEGRAL

Petry

Beckmann

Halloin

et al. 2009

A&A

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Aims. We aim to exploit the available INTEGRAL/SPI data to provide time-averaged spectra of the brightest soft gamma-ray sources. Methods. Employing a maximum-likelihood fit technique for our SPI data analysis, we take as input to our source model the source catalog derived by Bouchet et al. (2008) from a SPI all-sky study. We use the first four years of public SPI data and extract spectra between 25 keV and 1 MeV for the 20 catalog sources detected by Bouchet et al. at 200−600 keV with ≥2.5σ. In order to verify our analysis, we also extract spectra for the same sources from the corresponding INTEGRAL/ISGRI data. We fit adequate spectral models to the energy range 25−1000 keV for SPI and 25−600 keV for ISGRI. We use our spectra from the Crab (which is among the 20 sources studied here) and an empty location in a crowded field to derive an estimation of the systematic errors. Results. The agreement between our SPI and ISGRI measurements is good if we normalise them on the Crab spectrum. Our SPI flux measurements also agree well with those by Bouchet et al. (2008). All 20 sources in our sample are detected independently in the bands 25−100 keV and 100−200 keV. At 200−600 keV we detect eight sources, at 600−1000 keV we detect two sources. Our spectra agree well with the results from previous publications where available. For six of the 14 XRBs in our sample we find evidence for a hard powerlaw-component which becomes dominant above the cutoff energy of the thermal Comptonization component. In two of these cases, our study provides the first indication of such emission. For the others, our results confirm previous studies. Our spectrum of the Crab, integrated over 1.3 Ms, shows a significant flux in all points and is well described by a powerlaw with a break near 100 keV and spectral indices 2.11 and 2.20.

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INTEGRAL Cross-calibration Status: Crab observations between 3 keV and 1 MeV

Cited by 3 publications

References 0 publications

Long-term hard X-ray monitoring of 2S 0114+65 with INTEGRAL/IBIS

Long-term hard X-ray monitoring of 2S 0114+65 with INTEGRAL/IBIS

Analysis of extremely low signal-to-noise ratio data from INTEGRAL/PICsIT

Soft gamma-ray sources detected by INTEGRAL

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