Researchers inspect a nearby pulsar wind nebula

Utilizing the Australia Telescope Compact Array (ATCA), astronomers from Hong Kong and Australia have carried out radio observations of a close-by pulsar wind nebula (PWN) powered by the pulsar PSR B1706−44. Outcomes of the research, printed January 31 on the arXiv pre-print server, ship essential insights concerning the properties of this PWN and its related pulsar.

Pulsars are extremely magnetized, rotating neutron stars born supernova (SN) explosions, emitting a beam of electromagnetic radiation. They’re normally detected within the type of brief bursts of radio emission; nonetheless, a few of them are additionally noticed by way of optical, X-ray and gamma-ray telescopes.

PWNe are nebulae powered by the wind of a pulsar. Pulsar wind consists of charged particles and when it collides with the pulsar’s environment, specifically with the slowly increasing supernova ejecta, it develops a PWN. Observations of PWNe have proven that the particles in these objects lose their power to radiation and turn out to be much less energetic with distance from the central pulsar.

At a distance of some 8,500 light years from the Earth, the B1706 PWN is a pulsar wind nebula with a compact torus and jet construction, powered by the Vela-like pulsar PSR B1706−44. The PWN showcases a subtle emission across the torus and has a protracted curved outer-jet. The pulsar, transferring eastward with a projected velocity of 130 km/s, has a attribute age of 17,100 years and a spin-down energy of about 4.0 erg/s.

PSR B1706−44 is situated on the east-west ridge of the southern a part of a supernova remnant (SNR) referred to as G343.1−2.3. Earlier research advised that PSR B1706−44 is related to this SNR, discovering an prolonged TeV emission west of the pulsar, which has some reference to the remnant.

A crew of astronomers led by Yihan Liu of the College of Hong Kong has carried out high-resolution radio observations of B1706 PWN so as be taught extra about its properties, which may additionally shed extra gentle on the potential connection of the pulsar with G343.1−2.3.

“On this paper, we analyze new and archival radio observations of the PWN powered by PSR B1706−44 (hereafter B1706 PWN) and SNR G343.1−2.3 taken with the Australia Telescope Compact Array (ATCA) at 3, 6, 13, and 21 cm pictures. We employed new observations with excessive decision aiming to higher research the morphology and polarization info of this PWN,” the researchers defined.

The radio observations discovered that B1706 PWN displays an total arc-like morphology at 3 and 6 cm, and that this “arc” exhibits two distinct peaks at 6 cm. The arc-like construction has dimensions of 4 by 2 arcminutes and wraps round PSR B1706−44 within the north.

In response to the research, no radio emission was detected on the PWN’s X-ray torus and jet location, however was recognized solely past 10 arcseconds from the pulsar. The astronomers assume that the radio PWN morphology could be match by a thick torus mannequin with Doppler boosting impact. They famous that this may imply a bulk movement velocity at a degree of about 20% the velocity of sunshine, subsequently decrease than that within the X-ray torus.

The research discovered that B1706 PWN has a toroidal magnetic field with a subject energy of about 10 µG—assuming equipartition between particle and magnetic subject energies. This implies a slight decay in contrast with that of the X-ray brilliant area.

The observations additionally discovered that the ridge of G343.1−2.3 displays elongation and magnetic subject effectively aligned with the correct movement route of PSR B1706−44, in addition to a radio spectrum flatter than the remainder of the shell. The researchers concluded that these outcomes could point out that the ridge is a pulsar tail as an alternative of being a filamentary construction of the SNR.

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