Study of Temporal and Spectral variability for Blazar PKS 1830-211 with Multiwavelength Data

Abhir, Jayant; Prince, Raj; Joseph, J.; Bose, D.; Gupta, Nayantara

doi:10.3847/1538-4357/abfd33

Cited by 4 publications

(2 citation statements)

References 41 publications

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“…In this section, we investigate the intrinsic variability of the quasar and the evolution of the line profile within the time span of our observations. We note that PKS 1830−211 endured a period of strong radio and gamma flaring activity about three months before our observations but had returned to an apparent quiescent stage by the time of our campaign (see, e.g., Martí-Vidal et al 2020;Abhir et al 2021).…”

Section: Time Variability Of the Quasar And Of The Absorption Linesmentioning

confidence: 77%

A study of submillimeter methanol absorption toward PKS 1830−211:

Müller

Ubachs

Menten

et al. 2021

A&A

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Context. Methanol is an important tracer to probe physical and chemical conditions in the interstellar medium of galaxies. Methanol is also the most sensitive target molecule for probing potential space-time variations of the proton-electron mass ratio, μ, a dimensionless constant of nature. Aims. We present an extensive study of the strongest submillimeter absorption lines of methanol (with rest frequencies between 300 and 520 GHz) in the z = 0.89 molecular absorber toward PKS 1830−211, the only high-redshift object in which methanol has been detected. Our goals are to constrain the excitation of the methanol lines and to investigate the cosmological invariance of μ based on their relative kinematics. Methods. We observed 14 transitions of methanol, five of the A-form and nine of the E-form, and three transitions of A-13CH3OH, with ALMA. We analyzed the line profiles with a Gaussian fitting and constructed a global line profile that is able to match all observations after allowing for variations of the source covering factor, line opacity scaling, and relative bulk velocity offsets. We explore methanol excitation by running the non local thermal equilibrium radiative transfer code RADEX on a grid of kinetic temperatures and H2 volume densities. Results. Methanol absorption is detected in only one of the two lines of sight (the southwest) to PKS 1830−211. There, the excitation analysis points to a cool (∼10 − 20 K) and dense (∼104 − 5 cm−3) methanol gas. Under these conditions, several methanol transitions become anti-inverted, with excitation temperatures below the temperature of the cosmic microwave background. In addition, we measure an abundance ratio A/E = 1.0 ± 0.1, an abundance ratio CH3OH/H2 ∼ 2 × 10−8, and a 12CH3OH/13CH3OH ratio 62 ± 3. Our analysis shows that the bulk velocities of the different transitions are primarily correlated with the observing epoch due to morphological changes in the background quasar’s emission. There is a weaker correlation between bulk velocities and the lower level energies of the transitions, which could be a signature of temperature-velocity gradients in the absorbing gas. As a result, we do not find evidence for variations of μ, and we estimate Δμ/μ=(−1.8 ± 1.2) × 10−7 at 1-σ from our multivariate linear regression. Conclusions. We set a robust upper limit |Δμ/μ| < 3.6 × 10−7 (3σ) for the invariance of μ at a look-back time of half the present age of the Universe. Our analysis highlights that systematics need to be carefully taken into account in future radio molecular absorption studies aimed at testing Δμ/μ below the 10−7 horizon.

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Section: Time Variability Of the Quasar And Of The Absorption Linesmentioning

confidence: 77%

A study of submillimeter methanol absorption toward PKS 1830−211:

Müller

Ubachs

Menten

et al. 2021

A&A

View full text Add to dashboard Cite

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“…GAMERA has been mostly employed for AGN modelling [55][56][57]. In Figure 2 we show the model obtained with GAMERA fitting the MWL emission of the BL Lac OJ 287 observed during 2017-2020 [56].…”

Section: Gameramentioning

confidence: 99%

Open-Source Radiative Modeling Tools for Extragalactic VHE Gamma-ray Sources

Nigro

Tramacere

2022

Galaxies

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In this review, we discuss various open-source software for modeling the broadband emission of extragalactic sources from radio up to the highest gamma-ray energies. As we provide an overview of the different tools available, we discuss the physical processes that such tools implement and detail the computations they can perform. We also examine their conformity with modern good software practices. After considering the currently available software as a first generation of open-source modeling tools, we outline some desirable characteristics for the next generation.

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Multiwavelength study of TeV blazar 1ES 1218+304 using gamma-ray, X-ray and optical observations

Diwan

Prince

Agarwal

et al. 2023

Monthly Notices of the Royal Astronomical Society

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We report the multi-wavelength study for a high-synchrotron-peaked BL Lac 1ES 1218+304 using near-simultaneous data obtained during the period from January 1, 2018, to May 31, 2021 (MJD 58119-59365) from various instruments including Fermi-LAT, Swift-XRT, AstroSat, and optical from Swift-UVOT & TUBITAK observatory in Turkey. The source was reported to be flaring in TeV γ-ray band during 2019, but no significant variation is observed with Fermi-LAT. A sub-hour variability is seen in the SXT light curve, suggesting a compact emission region for their variability. However, hour scale variability is observed in the γ-ray light curve. A ‘softer-when-brighter’ trend is observed in γ-rays, and an opposite trend is seen in X-rays suggesting both emissions are produced via two different processes as expected from an HBL source. We have chosen the two epochs in January 2019 to study and compare their physical parameters. A joint fit of SXT and LAXPC provides a constraint on the synchrotron peak, roughly estimated to be ∼1.6 keV. A clear shift in the synchrotron peak is observed from ∼1 keV to above 10 keV revealing its extreme nature or behaving like an EHBL-type source. The optical observation provides color-index variation as ‘blue-when-brighter’. The broadband SED is fitted with a single-zone SSC model, and their parameters are discussed in the context of a TeV blazar and the possible mechanism behind the broadband emission.

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Study of Temporal and Spectral variability for Blazar PKS 1830-211 with Multiwavelength Data

Cited by 4 publications

References 41 publications

A study of submillimeter methanol absorption toward PKS 1830−211:

A study of submillimeter methanol absorption toward PKS 1830−211:

Open-Source Radiative Modeling Tools for Extragalactic VHE Gamma-ray Sources

Multiwavelength study of TeV blazar 1ES 1218+304 using gamma-ray, X-ray and optical observations

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