Observations investigate radio emission of two magnets

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

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

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

A team of astronomers led by Che-Yen Chu of Tsing Hua National University in Hisnchu, Taiwan, has decided to analyze radio spectra of these two magnets to shed more light on the characteristics of their radio emissions. The analyzed data were obtained in 2017 by ATCA and ALMA.

“We investigated the radio spectrum 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 said in the report. newspaper written.

The radio emission of PSR J1622−4950 was clearly detected by 5.5 to 45 GHz by ATCA. It shows a steep spectrum with a spectral index of about -1.3 in the region of 5.5-45 GHz during the reactivating X-ray burst that occurred in 2017. For this magnetar, a significant improvement in radiofluid density was detected the new results were compared with previous studies.

ATCA observations of 1E 1547.0-5408 found flood 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 fits a force law and the researchers found a positive spectral index of about 0.4. The magnetar displays an inverse spectrum of 43 to 95 GHz, indicating a possible spectral peak at high frequency (several hundred GHz). The long-term X-ray light curve of this magnetar also shows that the absorbed X-ray flow has gradually decreased since the eruption in 2009, but the flood level in 2017 remained much higher than the lowest flood level in 2006.

In general, the research found that both PSR J1622−4950 and 1E 1547.0-5408 may have different emission mechanisms at cm and sub-mm band, resulting in double peak spectra with peaks at single GHz and single hundreds of GHz. The study also provided important information that could improve our understanding of emission of magnets and magnetar-like radio pulsars.

“We further obtained the X-ray and radio data of radio magnetars and a magnetar-like radio pulsar from the literature and found for the first time that the rising time of radio emission is much longer than that of X-ray emission cases of magnetic burst, “concluded the authors of the paper.

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