The observations monitor the radio emission of two magnetars

Using the Australia Telescope Compact Array (ATCA) and the Atacama Large Millimeter / submillimeter Array (ALMA), astronomers conducted a study of two magnetars known as PSR J1622−4950 and 1E 1547.0−5408. The results of this survey, published on February 4 on arXiv.org, provide important information about radio broadcasts from these two sources.

Magnetars are neutron stars with extremely strong magnetic fields (greater than 100 trillion G), more than 1 quadrillion times stronger than the magnetic field of our planet. The decay of magnetic fields in magnetars fuels the emission of high energy electromagnetic radiation, for example in the form of x-rays or radio waves.

To date, only 24 magnetars have been discovered and only five of them present a pulsed radio emission, including PSR J1622−4950 and 1E 1547.0−5408. PSR J1622−4950 is the first magnetar discovered in the radio band, while 1E 1547.0−5408 was first detected in a supernova remnant (SNR) G327.24−0.13 and was later confirmed as a magnetar by X-ray and radio observations.

A team of astronomers led by Che-Yen Chu from Tsing Hua National University in Hisnchu, Taiwan, decided to analyze the radio spectra of these two magnetars in order to shed more light on the properties of their radio emission. The analyzed data was obtained by ATCA and ALMA in 2017.

“We studied the radio spectra of two magnetars, PSR J1622−4950 and 1E 1547.0−5408, using observations from the Australia Telescope Compact Array and the Atacama Large Millimeter / submillimeter Array taken in 2017,” the researchers wrote in the article.

The radio emission from PSR J1622−4950 was clearly detected from 5.5 to 45 GHz by ATCA. It exhibits a steep spectrum with a spectral index of about -1.3 in the 5.5-45 GHz range during its reactivation x-ray explosion that occurred in 2017. For this magnetar, a significant improvement radio flux density was detected, when the new results were compared to previous studies.

ATCA observations of 1E 1547.0-5408 found flux densities of 6.2 mJy at 43 GHz, 6.3 mJy at 45 GHz, 8.1 mJy at 93 GHz and 9.0 mJy at 95 GHz. The spectrum is matched to a power law and the researchers found a positive spectral index of about 0.4. The magnetar shows an inverted spectrum of 43 to 95 GHz, which indicates a possible high frequency spectral peak (a few hundred GHz). In addition, the long-term x-ray light curve of this magnetar shows that the absorbed x-ray flux has gradually decreased since the 2009 explosion, but the flux level in 2017 has remained well above the flux level. lowest of 2006.

In general, research has revealed that PSR J1622−4950 and 1E 1547.0−5408 may have different emission mechanisms in the cm and sub-mm bands, resulting in double peak spectra with peaks within a few GHz and a few hundred GHz. The study also provided important information that could improve our understanding of the emission of magnetars and magnetar-like radio pulsars.

“We further obtained radiographic and radio data of radio-magnetars and a magnetar-type pulsar radio from the literature and found, for the first time, that the rise time of the radio emission is very high. longer than that of the X-ray emission in some cases of magnetar explosion, ”concluded the authors of the article.

© Science X Network 2021