Calibration of the Large Area X-Ray Proportional Counter (LAXPC) Instrument on board
                    <i>AstroSat</i>

Antia, H. M.; Yadav, J. S.; Agrawal, P. C.; Chauhan, Jai Verdhan; Manchanda, R. K.; Chitnis, V. R.; Paul, Biswajit; Dedhia, Dhiraj; Shah, Parag; Gujar, V. M.; Katoch, Tilak; Kurhade, V. N.; Madhwani, P.; Manojkumar, T.K.; Nikam, V. A.; Pandya, A. S.; Parmar, Juveriya; Pawar, D. M.; Pahari, Mayukh; Misra, Ranjeev; Navalgund, K. H.; Pandiyan, R.; Sharma, K. S.; Subbarao, Kamesh

doi:10.3847/1538-4365/aa7a0e

Cited by 170 publications

(119 citation statements)

References 21 publications

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“…We have used 131180s of stare time of AstroSat observation of 4U 1700-37 to achieve 48.62 ks effective exposure for our analysis. LAXPC has an excellent resolution of 10 µs, which is unique when combined with a large effective area of 6500 cm 2 (Agrawal et al 2017;Antia et al 2017;Roy et al 2016) in probing coherent or quasi periodicity. Visible gaps in the 15-50 keV LAXPC light curve pertain to source occultation and south atlantic anomaly (SAA) passages ( Figure 1(c)).…”

Section: Timing Analysismentioning

confidence: 99%

Possible detection of a new cyclotron feature in 4U 1700–37

Bala

Roy

Bhattacharya

2020

Monthly Notices of the Royal Astronomical Society

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We present a spectral and timing study of the High Mass X-ray Binary transient source 4U 1700-37 using NuSTAR and ASTROSAT/LAXPC. The source is observed in two different flux states. A combined spectral analysis of NuSTAR's FPMA and FPMB shows the possible hint of a cyclotron line feature at ∼16 keV. The line feature is consistently present in different continuum models with at least 3σ confidence level. We do not detect the presence of a previously reported 39 keV cyclotron line in the combined spectra. A ∼16 keV cyclotron feature would suggest that the compact object is a neutron star with a magnetic field strength ∼ 2.1×10 12 Gauss in the emission region. We also find the presence of a rare Ni Kα emission line around 7.6 keV in the NuSTAR spectrum. We searched the NuSTAR and ASTROSAT data for coherent or quasi-periodic oscillation signals but found no evidence in the frequency range 0.1 mHz to 10 3 Hz.

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Section: Timing Analysismentioning

confidence: 99%

Possible detection of a new cyclotron feature in 4U 1700–37

Bala

Roy

Bhattacharya

2020

Monthly Notices of the Royal Astronomical Society

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“…The LAXPC instrument provides several advantages compared to RXTE/PCA. The effective area of the LAXPC instrument at energies greater than 30 keV is significantly larger than PCA 4,5 . The event mode data allow for an energy-dependent analysis of any choice of energy and time bins.…”

Section: Introductionmentioning

confidence: 99%

“…At the QPO frequencies, the time lag as a function of energy has a non-monotonic behaviour such that the lags decrease with energy till about 15-20 keV and then increase for higher energies. LAXPC detectors have been extensively studied for effective area, detector response and background using GEANT4 simulation and compared to match with the laboratory calibration 4 . AstroSat observed another black hole system, Cygnus X-1 in the low hard state which shows prominent thermal Comptonization component.…”

Section: Introductionmentioning

confidence: 99%

Large Area X-Ray Proportional Counter Instrument on AstroSat

Yadav¹,

Agrawal²,

Antia³

et al. 2017

Current Science

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Large Area X-ray Proportional Counter (LAXPC) is one of the major AstroSat payloads. The instrument will provide high time-resolution X-ray observations in 3-80 keV energy band with moderate energy resolution. A cluster of three co-aligned identical LAXPC detectors is used in AstroSat to provide large collection area of more than 6000 sq. cm. The large detection volume (15 cm depth) filled with xenon gas at ~2 atm pressure, results in detection efficiency greater than 50% above 30 keV. With its broad energy range and fine-time resolution (10 s), LAXPC instrument is well suited for timing and spectral studies of a wide variety of known and transient X-ray sources in the sky. We have done extensive calibration of all LAXPC detectors using radioactive sources as well as GEANT4 simulation of LAXPC detectors. We describe in brief some of the results obtained during the payload verification phase along with LAXPC capabilities.

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“…LAXPC data are analyzed using the LAXPC software 2 . Details of the response and background spectra generation can be found in Antia et al (2017). Note-NH,ISM and N H,loc are the line-of-sight, inter-stellar medium and local absorption column density respectively, fsc is the scattering fraction, kTin and N dbb are the inner disk temperature and diskbb normalization respectively.…”

Section: Observations and Analysismentioning

confidence: 99%

“…Blank sky SXT observations are used to extract background spectrum. LAXPC consists of three identical X-ray proportional counters with the absolute time resolution of 10 µs in the energy range 3.0-80.0 keV (Yadav et al 2016a,b;Misra et al 2016;Antia et al 2017;Agrawal et al 2017). LAXPC data are analyzed using the LAXPC software 2 .…”

Section: Observations and Analysismentioning

confidence: 99%

Extensive Broadband X-Ray Monitoring During the Formation of a Giant Radio Jet Base in Cyg X-3 with AstroSat

Pahari

Yadav

Chauhan

et al. 2018

ApJL

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We present X-ray spectral and timing behavior of Cyg X-3 as observed by AstroSat during the onset of a giant radio flare on 01-02 April 2017. Within a time-scale of few hours, the source shows a transition from the hypersoft state (HPS) to a more luminous state (we termed as the very high state) which coincides with the time of the steep rise in radio flux density by an order of magnitude. Modeling the SXT and LAXPC spectra jointly in 0.5-70.0 keV, we found that the first few hours of the observation is dominated by the HPS with no significant counts above 17 keV. Later, an additional flat powerlaw component suddenly appeared in the spectra which extends to very high energies with the powerlaw photon index of 1.49 +0.04−0.03 . Such a flat powerlaw component has never been reported from Cyg X-3. Interestingly the fitted powerlaw model in 25-70 keV, when extrapolated to the radio frequency, predicts the radio flux density consistent with the trend measured from RATAN-600 telescope at 11.2 GHz. This provides a direct evidence of the synchrotron origin of flat X-ray powerlaw component and the most extensive monitoring of the broadband X-ray behavior at the moment of decoupling the giant radio jet base from the compact object in Cyg X-3. Using SXT and LAXPC observations, we determine the giant flare ejection time as MJD 57845.34 ± 0.08 when 11.2 GHz radio flux density increases from ∼100 to ∼478 mJy.

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Calibration of the Large Area X-Ray Proportional Counter (LAXPC) Instrument on board AstroSat

Cited by 170 publications

References 21 publications

Possible detection of a new cyclotron feature in 4U 1700–37

Possible detection of a new cyclotron feature in 4U 1700–37

Large Area X-Ray Proportional Counter Instrument on AstroSat

Extensive Broadband X-Ray Monitoring During the Formation of a Giant Radio Jet Base in Cyg X-3 with AstroSat

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