Multiband nonthermal radiative properties of pulsar wind nebulae

Abstract

Aims. The nonthermal radiative properties of 18 pulsar wind nebulae (PWNe) are studied in the 1D leptonic model. Methods. The dynamical and radiative evolution of a PWN in a nonradiative supernova remnant are self-consistently investigated in this model. The leptons (electrons/positrons) are injected with a broken power-law form, and nonthermal emission from a PWN is mainly produced by time-dependent relativistic leptons through synchrotron radiation and inverse Compton process. Results. Observed spectral energy distributions (SEDs) of all 18 PWNe are reproduced well, where the indexes of low-energy electron components lie in the range of 1.0-1.8 and those of high-energy electron components in the range of 2.1-3.1. Our results show that F X /F γ > 10 for young PWNe; 1 < F X /F γ ≤ 10 for evolved PWNe, except for G292.0+1.8; and F X /F γ ≤ 1 for mature/old PWNe, except for CTA 1. Moreover, most PWNe are particle-dominated. Statistical analysis for the sample of 14 PWNe further indicate that (1) not all pulsar parameters have correlations with electron injection parameters, but electron maximum energy and PWN magnetic field correlate with the magnetic field at the light cylinder, the potential difference at the polar cap, and the spindown power; (2) the spin-down power positively correlates with radio, X-ray, bolometric, and synchrotron luminosities, but does not correlate with gamma-ray luminosity; (3) the spin-down power positively correlates with radio, X-ray, and γ-band surface brightness; and (4) the PWN radius and the PWN age negatively correlate with X-ray luminosity, the ratio of X-ray to gamma-ray luminosities, and the synchrotron luminosity.

Radio Proper Motions of the Energetic Pulsar PSR~J1813$-$1749

“…To reach this shift the kinematic age of the pulsar is 1351 +896 −385 years. This age discards that this is a very young pulsar and it is in better agreement with the ages estimated for the pulsar of 5600 years (Halpern et al 2012) and for HESS J1813-178 of 2500 years (Zhu et al 2018) and for SNR G12.82-0.02 (Brogan et al 2005).…”

“…As the pulsar is at an angular distance of ∼ 20 from the center of the SNR G12.82-0.02 the large proper motions would indicate a young age of around 300 years, making it one of the youngest pulsars known. This age, while consistent at the lower end of the age range of 285 to 2500 years for SNR G12.82-0.02 (Brogan et al 2005), is however in conflict with the age estimated for HESS J1813-178 of 2500 years (Zhu et al 2018) and the characteristic age of the pulsar of 5600 years (Halpern et al 2012). As discussed by Camilo et al (2021), the total proper motion of ∼ 66 mas yr −1 would imply a tangential velocity of the order of 2,000 km s −1 at 6.2 kpc, the lower limit of the distance.…”

Radio Detection of PSR J1813-1749 in HESS J1813-178: The Most Scattered Pulsar Known

“…On the other hand, countervailing evidence against such a young age is found in the broadband spectral energy distribution of HESS J1813−178, which is more like those of evolved SNRs, and has been modelled most recently with an age of 2500 yr (Zhu et al 2018). In summary, there would be obstacles to attributing the scattering of PSR J1813−1749 to a very young age.…”

“…Previous modelling of the spectral energy distribution of HESS J1813−178 as leptonic emission from an evolving PWN in an expanding SNR (Fang & Zhang 2010;Zhu et al 2018) used a distance of 4.7 kpc. Models should also be recalculated for the now favored larger distances.…”

Constraining the origin of the puzzling source HESS J1640-465 and the PeVatron candidate HESS J1641-463 using Fermi-LAT observations

“…Currently, this is best done by reproducing the dynamical and radiative properties of a PWN inside a SNR with a model for its evolution, as described in a recent summary by Gelfand (2017). This has been successfully done for numerous systems (e.g., Chevalier 2005;Bucciantini et al 2011;Tanaka & Takahara 2011;Torres et al 2014;Zhu et al 2018) -including HESS J1640−465 using previous measurements of its γ-ray spectrum (e.g., Gotthelf et al 2014). As described in detail in Appendix A, we determined if such models can reproduce the updated γ-ray spectrum derived in Section 2.3.…”