Gigahertz-peaked spectra pulsars in Pulsar Wind Nebulae

Abstract

We have carried out a detailed study of the spectral nature of six pulsars surrounded by Pulsar wind nebulae (PWN). The pulsar flux density were estimated using the interferometric imaging technique of the Giant Metrewave Radio Telescope at three frequencies 325 MHz, 610 MHz and 1280 MHz. The spectra showed a turnover around gigahertz frequency in four out of six pulsars. It has been suggested that the gigahertz peaked spectra (GPS) in pulsars arises due to thermal absorption of the pulsar emission in surrounding medium like PWN, HII regions, Supernova remnants, etc. The relatively high incidence of GPS behaviour in pulsars surrounded by PWN impart further credence to this view. The pulsar J1747−2958 associated with the well known Mouse nebula was also observed in our sample and exhibited GPS behaviour. The pulsar was detected as a point source in the high resolution images. However, the pulsed emission was not seen in the phased array mode. It is possible that the pulsed emission was affected by extreme scattering causing considerable smearing of the emission at low radio frequencies. The GPS spectra were modeled using the thermal free-free absorption and the estimated absorber properties were largely consistent with PWN. The spatial resolution of the images made it unlikely that the point source associated with J1747−2958 was the compact head of the PWN, but the synchrotron self-absorption seen in such sources was a better fit to the estimated spectral shape.

Statistical Research on Pulsars with the Gigahertz-Peaked Spectra

“…The conclusion is consistent with the others' research [17]. J1809-1917 is the first detected magnetic star in the radio band, Basu et al obtained its spectral index as -1.0, but Dai et al (2019) gave its new spectral index as 0.3 [15]. We found the observations in Dai et al ( 2019) was during the radio burst stage of J1809-1917, and the observations in Basu et al ( 2018) was during the radio quiet stage of J1809-1917.…”

The FAST Galactic Plane Pulsar Snapshot survey: I. Project design and pulsar discoveries ⋆

“…Simple alignment of pulsed emission peaks in a wide range of frequency would cause an overestimated DM. In fact, any Galactic pulsars (Kijak et al 2011;Basu et al 2018) or extragalactic radio sources with such an inverted spectrum at lower frequencies (Guerra et al 2002;Gopal-Krishna et al 2014;Mhaskey et al 2019a,b) can be so explained by the scattering effect caused by very cloudy ionized gas in front of or in the environment of a strong emission source. The flux densities and polarization properties may vary if the source and the intervening clouds are moving relatively in any transverse direction.…”

Multi-frequency observations and spectral analysis of two gigahertz-peaked spectra pulsars

“…Both pulsars are associated with the pulsar wind nebulae (PWNe). Recently, Basu et al (2018) have shown that several pulsars with PWNe have a GPS. In the case of PSR J1740+1000 the previous flux measurements were highly spread out (see Figure 4), which makes the correct interpretation of spectral behaviour very difficult.…”