Mode changing and giant pulses found in a millisecond pulsar

Canadian astronomers have identified mode changing and giant pulses in the millisecond pulsar known as PSR B1957+20. It is the first time when mode changing mechanism has been observed in a millisecond pulsar. The finding is detailed in a paper published July 4 on the arXiv pre-print server.

Radio pulsars showcase various variability in emission ranging from extremely short bursts like giant pulses to long-term changes in their emission profiles. Some of them exhibit even mode changing where the emission profile switches between two or more quasi-stable modes of emission. To date, mode changing has been only observed in normal pulsars.

Continued...
Source

Credit: X-ray: NASA/CXC/ASTRON/B.Stappers et al.; Optical: AAO/J.Bland-Hawthorn & H.Jones

Chandra image of PSR B1957+20. The blue and green are optical images of the field in which the pulsar is found, the green indicating the H-alpha bow shock. The red and white are secondary shock structures discovered in x-ray by the Chandra X-ray Observatory.

Source / Image Courtesy

Astronomers Have Observed A Black Widow Pulsar In The Closest Detail Yet

Astronomers have taken one of the highest resolution observations ever, giving us the clearest look yet at a distant pulsar, a pulsating type of neutron star.

The object, known as PSR B1957+20, is one of the heaviest pulsars known, and studying it will help us understand how matter behaves at the highest densities.

Black widow spiders and their Australian cousins, known as redbacks, are notorious for an unsettling tendency to kill and devour their male partners. Astronomers have noted similar behavior among two rare breeds of binary system that contain rapidly spinning neutron stars, also known as pulsars.

The essential features of black widow and redback binaries are that they place a normal but very low-mass star in close proximity to a millisecond pulsar, which has disastrous consequences for the star. Black widow systems contain stars that are both physically smaller and of much lower mass than those found in redbacks.

So far, astronomers have found at least 18 black widows and nine redbacks within the Milky Way, and additional members of each class have been discovered within the dense globular star clusters that orbit our galaxy.

In late June 2013, an exceptional binary system containing a rapidly spinning neutron star underwent a dramatic change in behavior never before observed.

The pulsar's radio beacon vanished, while at the same time the system brightened fivefold in gamma rays, the most powerful form of light, according to measurements by NASA's Fermi Gamma-ray Space Telescope.