Why do some pulsars have strange behavior?

Scientists are investigating a special type of neutron stars, which are called rotating radio transients. Unlike conventional pulsars, they emit waves with irregular frequency. Astronomers tried to find out their nature by examining the object RRAT J1854+0306.

Some pulsars behave very strangely. Source: www.thesciencebreaker.org

Rotating radio transients

Using a spherical radio telescope with a 500-meter aperture FAST, Chinese astronomers studied the radio emission of a rotating radio transient known as RRAT J1854+0306.

Rotating radio transients (RRAT) are a subclass of pulsars characterized by sporadic, i.e. non-constant radiation. The first objects of this type were identified in 2006 as separate sporadically appearing pulses, the frequency of which varies from several minutes to several hours. Such events are called transient in astronomy, and in each case, researchers wonder what caused them. In this case, it is assumed that these are ordinary pulsars with which something is happening.

Discovered in 2009, RRAT J1854+0306 has a rotation period of 4.56 seconds and a dispersion measure of 192.4 pc/cm3. It periodically emits strong pulses and is one of the strongest RRAT, which makes it possible to study the details of its radiation.

Research by Chinese astronomers

A team of astronomers led by Qi Guo from Hebei University in China conducted highly sensitive observations of RRAT J1854+0306 in order to study its polarized radiation. For this, they used the central beam of a 19-beam FAST receiver with a frequency range from 1000 to 1500 MHz, which was divided into 2048 channels. 

Observations have shown that periods of complete rest prevail in the radiation of RRAT J1854+0306. Their share of the total time is about 53.2 percent. They are interspersed with narrow (less than 1 degree) and weak (less than 0.5 MJ) pulses with periodic wide and intense bursts. Individual pulses exhibit a diverse profile morphology, showing single, double and multiple peaks.

Are these really pulsars?

According to the study, RRAT J1854+0306 pulses exhibit a variety of polarization behavior, that is, how the oscillations of their electromagnetic waves are aligned. The degree of linear polarization can reach 100 percent for some pulses, and their circular polarization shows different values and variations.

These features are related to the density distribution of relativistic particles and their emission processes and/or are caused by propagation effects. For some pulses, the position angles deviate greatly from the average, which may be caused by emission generated by various plasma conditions of the magnetosphere of a neutron star.

In general, based on the collected data, the researchers concluded that the behavior of the polarized radiation of RRAT J1854+0306 indicates that its radiation originates from a magnetosphere similar to that of ordinary pulsars. This may have implications for the general understanding of rotating radio-transient processes, as the discovery indicates that RRAT may have the same physical origin as the rest of the neutron stars.

According to phys.org

Follow us on Twitter to get the most interesting space news in time