Sunday, October 2, 2022

Astronomers identify the most powerful pulsar ever found in a distant galaxy

Neutron stars are the dense remnants of larger stars. They are the collapsed cores of stars formed during supernova explosions.

While we generally know how they form, we are still learning how they develop, especially when they are young.

But that is starting to change thanks to large-sky surveys, which have allowed astronomers to observe a neutron star that may be a little over a decade old.

The neutron star in question is known as VT 1137-0337. It lies in a dwarf galaxy about 400 million light-years away, and was first observed in 2018 as part of the Very Large Array Sky Survey (VLASS). VLASS is a seven-year project to create a radio map of the sky. When finished it will map about 80 percent of the sky over the course of three separate runs.

After first capturing an image of VT 1137-0337 in 2018, it saw the neutron star again in 2019, 2020 and 2022. So we know it’s not just a momentary radio explosion of some sort.

Based on observations, the object is most likely a pulsar wind nebula. As the neutron star spins, its magnetic field and energy beam pass through the surrounding nebulae, causing the gas in the nebula to ionize and emit radio light.

What’s interesting about VT 1137-0337 is that it was not previously observed in the VLA sky survey known as the Faint Images of the Radio Sky at Twenty-Centimeter (FIRST), which was created in 1998. So somewhere between 1998 and 2018, a neutron star appeared.

Astronomers identify the most powerful pulsar ever found in a distant galaxy(Dong & Hallinan, NRAO/AUI/NSF)

above: VLA images of the location of VT 1137-0337 in 1998, left, and 2018, right. The object became visible to the VLA sometime between these two dates.

On the face of it, this would make VT 1137-0337 less than twenty years old, but it may be a bit out of date. It is possible that the neutron star existed in 1998, but the surrounding nebulae were still dense enough to block radio light from reaching us.

But at the rate at which supernova remnants expand, the fog should have cleared within 60 to 80 years, meaning that even the oldest estimates make it decades old, not centuries or millennia. VT 1137-0337 is a very young neutron star, and probably 14 years old.

The radio energy from VT 1137-0337 is 10,000 times more powerful than that of the Crab Nebula, which was created by a supernova in 1054 CE. This means that it has a much stronger magnetic field. So powerful that VT 1137-0337 may be in the process of becoming a magnet. Magnetars are highly magnetic neutron stars that potentially cause rapid radio bursts (FRBs).

So this may be the first observation of the birth of a magnet, but it will not be the last. As astronomers conduct future sky surveys, they will surely discover even more lifetimes of these powerful objects.

Note: Brian Koberlein serves as a science writer for NRAO, which administers VLAs and VLASS, but was not involved in the research presented here.

This article was originally published by Universe Today. Read the original article.

Nation World News Desk
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