Astronomers analyzing data from the VLA Sky Survey (VLASS) have discovered one of the little-known neutron stars – a thick fossil of a giant star that exploded like a supernova. Photographs from Karl G. Jansky Very Large Array of the National Science Foundation (VLA) show that light-emitted radio-powered pulsar pulses have just emerged from the dense shell of a supernova explosion shell.
The object, named VT 1137-0337, is located in the 395 million light-year galaxy from Earth. It first appeared in a VLASS image created in January 2018 and did not appear in the same regional image created by VLA’s FIRST Survey in 1998. It continued to appear in the latest VLASS visions for 2018, 2019, 2020, and 2022.
“What we see most is the pulsar wind nebula,” said Dillon Dong, a Caltech graduate who will start the Jansky Postdoctoral Fellowship at the National Radio Astronomy Observatory (NRAO) later this year. A pulsar wind nebula is created when a strong magnetic field of a fast-moving neutron star accelerates the charged particles around the speed of light.
“Based on its features, this is a very small pulsar – which may be as young as 14 years old, but not more than 60 to 80 years old,” said Gregg Hallinan, Dong’s Ph.D. Advisor at Caltech.
Scientists reported their findings at a meeting of the American Astronomical Society in Pasadena, California.
Dong and Hallinan found something in data from VLASS, an NRAO project that began in 2017 to explore the entire visible VLA universe – about 80 percent of the sky. In seven years, VLASS performed a complete sky scan three times, with one goal of obtaining transit objects. Astronomers have received VT 1137-0337 in the first VLASS scan from 2018.
Comparing that VLASS scan with data from a previous VLA study in space called FIRST reveals 20 very bright objects that may be associated with known galaxies.
“This is because of the fact that its galaxy is beginning to form stars, and because of the signs of its emergence on the radio,” said Dong. The galaxy, called the SDSS J113706.18-033737.1, is a small galaxy containing about 100 million times the size of the Sun.
In studying the features of VT 1137-0337, astronomers have considered several possible explanations, including a supernova, a gamma-ray explosion, or the occurrence of a wave disturbance when a giant black hole strikes a star. They conclude that the best explanation is the pulsar wind nebula.
In this case, a star much larger than the Sun exploded like a supernova, leaving a neutron star. The first mass of stars was blown out like a garbage can. A neutron star rotates rapidly, and as its magnetic field sweeps through the atmosphere, it accelerates chargeable particles, emitting powerful radio.
Initially, radio emissions were prevented from detecting the explosive debris shell. As the cover grew, it gradually shrunk until it could absorb radio waves from the pulsar wind nebula.