<i>AstroSat</i> observation of the HBL 1ES 1959+650 during its October 2017 flaring

Shah, Zahir; Ezhikode, Savithri H.; Misra, Ranjeev; Rajalakshmi, T. R.

doi:10.1093/mnras/stab1244

Cited by 9 publications

(8 citation statements)

References 52 publications

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“…"Orphan" flares hint at a more complex geometry and/or underlying particle distribution, such as those invoked in multiple-component SSC models and/or external Compton models (e.g., the synchrotron mirror model, Böttcher & Dermer (1999)) within the leptonic schemes. Recently, Shah et al (2021), have reported an anti-correlation between the photon index and X-ray flux using a broken power-law for analysing only a segment of X-ray data presented here.…”

Section: Introductionmentioning

confidence: 77%

X-ray Observations of 1ES 1959+650 in its high activity state in 2016-2017 with AstroSat and Swift

Chandra,

Boettcher,

Goswami

et al. 2021

Preprint

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We present a comprehensive multi-frequency study of the HBL 1ES 1959+650 using data from various facilities during the period 2016-2017, including X-ray data from AstroSat and Swift during the historically high X-ray flux state of the source observed until February 2021. The unprecedented quality of X-ray data from high cadence monitoring with the AstroSat during 2016-2017 enables us to establish a detailed description of X-ray flares in 1ES 1959+650. The synchrotron peak shifts significantly between different flux states, in a manner consistent with a geometric (changing Doppler factor) interpretation. A time-dependent leptonic diffusive-shock-acceleration and radiation transfer model is used to reproduce the spectral energy distributions (SEDs) and X-ray light curves, to provide insight into the particle acceleration during the major activity periods observed in 2016 and 2017. The extensive data of Swift-XRT from December 2015 to February 2021 (Exp. = 411.3 ks) reveals a positive correlation between flux and peak position.

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Section: Introductionmentioning

confidence: 77%

X-ray Observations of 1ES 1959+650 in its high activity state in 2016-2017 with AstroSat and Swift

Chandra,

Boettcher,

Goswami

et al. 2021

Preprint

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“…On the other hand, variations in the acceleration or diffusion time-scales would lead to changes in the distribution shape, which in turn would lead to rather dramatic changes in the density of particles at energies >> γ0. In the simple picture, where the distribution is a power-law, changes in the index would lead to large variations in the value of the distribution at large γ since the power-law would be approximately "pegged" at the pivot point γ0 (Shah et al 2021). This is generically true and one would expect large variations in the inferred normalization at some large γ with spectral shape variations, which is not observed.…”

Section: Summary and Discussionmentioning

confidence: 97%

“…Note that this is not exactly the same as having a one-time injection of particles into the system and studying their evolution but to solve the corresponding time-dependent equation with some physical parameter varying continuously with time. In a recent work Shah et al (2021) have shown that such a model may indeed solve the generic problem of large spectral shape variation with modest changes in the normalization.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…However, the spectral fit parameters show that when p changes from 2.2 to 2.6, the normalization varies only by a few percentage (top right panel of Figure 5). As pointed out by Shah et al (2021), the powerlaw solution to Equation 4 (for γ < γmax), approximately pivots around γ0 when p is varied, leading to large variation in the number density at γ(>> γ0), which is typically not observed.…”

Section: Particle Distribution With a Maximum Energymentioning

confidence: 97%

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Understanding the X-ray spectral curvature of Mkn 421 using broadband AstroSat observations

Hota,

Shah,

Khatoon

et al. 2021

Preprint

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We present a time-resolved X-ray spectral study of the high energy peaked blazar Mkn 421 using simultaneous broadband observations from the LAXPC and SXT instruments on-board AstroSat. The ∼ 400 ksec long observation taken during 3-8 January, 2017 was divided into segments of 10 ksecs. Each segment was fitted using synchrotron emission from particles whose energy distribution was represented by a log-parabola model. We also considered particle energy distribution models where (i) the radiative cooling leads to a maximum energy (ξ max model), (ii) the system has energy dependent diffusion (EDD) and (iii) has energy dependent acceleration (EDA). We found that all these models describe the spectra, although the EDD and EDA models were marginally better. Time resolved spectral analysis allowed for studying the correlation between the spectral parameters for different models. In the simplest and direct approach, the observed correlations are not compatible with the predictions of the ξ max model. While the EDD and EDA models do predict the correlations, the values of the inferred physical parameters are not compatible with the model assumptions. Thus, we show that spectrally degenerate models, can be distinguished based on spectral parameter correlations (especially those between the model normalization and spectral shape ones) making time-resolved spectroscopy a powerful tool to probe the nature of these systems.

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“…Similarly, during a MW campaign of 1ES 1959+650 between April 29 and November 21 of 2016, the MAGIC telescopes observed multi-TeV flaring events for the nights of 13th, 14th of June and 1st of July 2016 when the position of the synchrotron peak was in the EHBL range, and again, exhibiting extreme HBL-like behavior (MAGIC Collaboration et al 2020b). Several other authors have also studied the MW SED of 1ES 1959+650 (Shah et al 2021;Chandra et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Photohadronic interpretation of the different incarnation of 1ES 2344+514

Sahu¹,

Valadez²,

Rajpoot³

2022

Preprint

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Since its discovery in 1995, the high-energy peaked blazar 1ES 2344+514 has undergone several episodes of GeV-TeV flaring and has been observed in the multiwavelength by several other telescopes. The observed X-ray spectrum of 1996 and the flaring event of 2016 establish that 1ES 2344+514 has a temporary EHBL-like behavior. Such behavior has also been observed in several nearby high-energy peaked blazars. We use the photohadronic model to account for the GeV-TeV flaring observed events of 1995 and 2007. Also, a recently proposed two-zone photohadronic model, which is successful in explaining the multi-TeV flaring events of many transient EHBL-like source, is employed to explain the GeV-TeV flaring spectra of MJD 57611 and MJD 57612. We find that the zone-2 parameters of the two-zone photohadronic model play a central role in explaining these spectra. Probably this is an indication of a new type of transient EHBL-like source. We find that our fits to the observed spectra are comparable or better than the other leptonic and hadronic models employed in the literature to address the same issue.

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AstroSat observation of the HBL 1ES 1959+650 during its October 2017 flaring

Cited by 9 publications

References 52 publications

X-ray Observations of 1ES 1959+650 in its high activity state in 2016-2017 with AstroSat and Swift

X-ray Observations of 1ES 1959+650 in its high activity state in 2016-2017 with AstroSat and Swift

Understanding the X-ray spectral curvature of Mkn 421 using broadband AstroSat observations

Photohadronic interpretation of the different incarnation of 1ES 2344+514

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