Gigahertz-peaked Spectra Pulsars and Thermal Absorption Model

Kijak, J.; Basu, Rahul; Lewandowski, Wojciech; Rożko, Karolina; Dembska, M.

doi:10.3847/1538-4357/aa6ff2

Cited by 25 publications

(35 citation statements)

References 45 publications

(102 reference statements)

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“…The data from Kijak et al (2011b) near 1.2 and 4.8 GHz do not provide enough evidence for curvature. In fact, a simple power law also seems to be a better fit than the free-free absorption model in Kijak et al (2017). However, the pulsar might still show GPS at lower frequencies, once measurements below 1 GHz are available.…”

Section: Different and Complex Spectramentioning

confidence: 98%

“…The thermal free-free absorption model as implemented by Rajwade et al (2016) or Kijak et al (2017) is a special case of this model, where the smoothness parameter β is fixed to a constant value of 2.1. As such, it has three free parameters, one less than the more generic low-frequency turn-over model.…”

Section: Examining Evidence For Free-free Absorptionmentioning

confidence: 99%

“…PSR J1825-1446 and PSR J1826-1334: Their spectra peak around 1.3 GHz with a strong LPS classification. PSR J1852-0635: We determine a broken-power law as best-fitting model, with a clear classification category, rather than a power law with low-frequency turn-over, of which the free-free absorption model used by Kijak et al (2017) is a special case. Rajwade et al (2016) and Kijak et al (2017) fit the spectra of a subset of these pulsars using the free-free absorption model, which we have considered separately in §4.10.1.…”

Section: Confirmationsmentioning

confidence: 99%

“…Spectral analysis also led to the recent discovery of a new class of pulsars that have gigahertz-peaked spectra (GPS): convex spectra where the flux density maximum occurs at a frequency around 1 GHz (Kijak et al 2007(Kijak et al , 2011b; Dembska et al 2015b;Kijak et al 2017). It has been proposed that the GPS phenomenon occurs because of thermal free-free absorption in dense ionized material surrounding a pulsar, for example in a pulsar wind nebula, molecular cloud, or supernova remnant (Lewandowski et al 2015;Rajwade et al 2016), or when the radio emission from a pulsar passes through the dense wind of a binary companion.…”

Section: Introductionmentioning

confidence: 99%

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Spectral properties of 441 radio pulsars

Jankowski

Straten

Keane

et al. 2017

Monthly Notices of the Royal Astronomical Society

201

193

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We present a study of the spectral properties of 441 pulsars observed with the Parkes radio telescope near the centre frequencies of 728, 1382 and 3100 MHz. The observations at 728 and 3100 MHz were conducted simultaneously using the dual-band 10-50cm receiver. These high-sensitivity, multi-frequency observations provide a systematic and uniform sample of pulsar flux densities. We combine our measurements with spectral data from the literature in order to derive the spectral properties of these pulsars. Using techniques from robust regression and information theory we classify the observed spectra in an objective, robust and unbiased way into five morphological classes: simple or broken power law, power law with either low or high-frequency cutoff and log-parabolic spectrum. While about 79% of the pulsars that could be classified have simple power law spectra, we find significant deviations in 73 pulsars, 35 of which have curved spectra, 25 with a spectral break and 10 with a low-frequency turn-over. We identify 11 gigahertz-peaked spectrum (GPS) pulsars, with 3 newly identified in this work and 8 confirmations of known GPS pulsars; 3 others show tentative evidence of GPS, but require further low-frequency measurements to support this classification. The weighted mean spectral index of all pulsars with simple power law spectra is −1.60 ± 0.03. The observed spectral indices are well described by a shifted log-normal distribution. The strongest correlations of spectral index are with spin-down luminosity, magnetic field at the light-cylinder and spin-down rate. We also investigate the physical origin of the observed spectral features and determine emission altitudes for three pulsars.

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Section: Different and Complex Spectramentioning

confidence: 98%

Section: Examining Evidence For Free-free Absorptionmentioning

confidence: 99%

Section: Confirmationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Spectral properties of 441 radio pulsars

Jankowski

Straten

Keane

et al. 2017

Monthly Notices of the Royal Astronomical Society

201

193

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show abstract

“…These objects have been called gigahertz-peaked spectra (GPS) pulsars. Currently, there are 17 known objects of this type (Kijak et al 2017). It was suggested that their spectral shape is caused by the influence of a pulsar's environment on its radiation (Kijak et al 2011b).…”

mentioning

confidence: 99%

Modelling the thermal absorption and radio spectra of the binary pulsar B1259–63

Koralewska

Kijak

Lewandowski

2018

Astrophys Space Sci

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We present the results of modelling of the radio spectrum evolution and dispersion measure variations of PSR B1259−63, a pulsar in a binary system with Be star LS 2883. We base our model on a hypothesis that the observed variations of the spectrum are caused by thermal freefree absorption occurring in the pulsar surroundings. We reproduce the observed pulsar spectral shapes in order to examine the influence of the stellar wind of LS 2883 and the equatorial disc on the pulsar's radiation.The simulations of the pulsar's radio emission and its consequent free-free absorption give us an insight into the impact of stellar wind and equatorial disc of LS 2883 has on the shapes of PSR B1259−63 radio spectra, providing an evidence for the connection between gigahertz-peaked spectra phenomenon and the close environment of the pulsar. Additionally, we supplement our model with an external absorbing medium, which results in a good agreement between simulated and observational data.

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The observations of the gigahertz‐peaked spectra pulsars

Rożko

2021

Astron Nachr

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In this short overview, we summarize the current knowledge of the pulsar spectra that exhibit turnovers between 0.5 and 1.5 GHz. We focus on the observations of pulsars, for which the analysis of their spectra allowed a formulation of the hypothesis that external mechanisms are responsible for the high-frequency turnovers. Among these, we discuss the cases of the binary pulsar B1259-63, the Sagittarius A* radiomagnetar (SGR J1745-2900), the variable spectrum of pulsar (PSR) B1800-21, and PSR J1740 + 1000.

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Gigahertz-peaked Spectra Pulsars and Thermal Absorption Model

Cited by 25 publications

References 45 publications

Spectral properties of 441 radio pulsars

Spectral properties of 441 radio pulsars

Modelling the thermal absorption and radio spectra of the binary pulsar B1259–63

The observations of the gigahertz‐peaked spectra pulsars

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