Strange Glow Detected From Colossal Burst

Astronomers have detected the brightest infrared light from a short gamma-ray burst ever with a comical glow that happened long ago. The light reached earth in May 2020 and it was observed by NASA’s Neil Gehrels Swift Observatory. It is 10 times brighter than it was estimated.

Various telescopes were put into observation including NASA’s Hubble Space Telescope, Very Large Array radio observatory, the W. M. Keck Observatory, and the Las Cumbres Observatory Global Telescope network to analyze the aftermath of the burst.

The image shows the light glowing from the kilonova which occured by the merge of two neutron star / Image Source – nasa

The brightness observed is estimated to form a magnetar with the merging of two neutron stars. The gamma-ray explosion occurred billions of light-years away which unleashed greater energy within half of a second that the sun would produce in its entire 10-billion-year-lifetime.

Wen-fai Fong the study head said “These observations do not fit traditional explanations for short gamma-ray bursts. Given what we know about the radio and X-rays from this blast, it just doesn’t match up. The near-infrared emission that we’re finding with Hubble is way too bright. In terms of trying to fit the puzzle pieces of this gamma-ray burst together, one puzzle piece is not fitting correctly.”

Adding to it she said “It’s amazing to me that after 10 years of studying the same type of phenomenon, we can discover unprecedented behavior like this. It just reveals the diversity of explosions that the universe is capable of producing, which is very exciting.”

The study has been accepted by The Astrophysical Journal and it will be published online this year. A preprint of the research is now available in arxiv.

The intensifying flashes of the gamma rays from the burst are said to be coming from a rapid stream of liquid or gas forced out of it which is moving extremely close to the speed of light. They do not contain an enormous amount of mass.

Image describing the arrangement of magnetar-powered kilonova / Image Source – nasa

Co-investigator of the study Tanmoy Laskar said “As the data were coming in, we were forming a picture of the mechanism that was producing the light we were seeing.As we got the Hubble observations, we had to completely change our thought process, because the information that Hubble added made us realize that we had to discard our conventional thinking, and that there was a new phenomenon going on. Then we had to figure out what that meant for the physics behind these extremely energetic explosions.”

Gamma-ray bursts is the most dynamic event known and they live faster and die harder. On the basis of the duration they are classified into two classes –

  • Long gamma-ray burst – If the gamma-ray emission is greater than two seconds it it said to be long gamma-ray burst and is formed from the core of a massive star. With this kind of burst it is expected to have a supernova.
  • Short gamma-ray burst – If the gamma-ray emission is less than two seconds it forms a short burst. It occurs with the merge of two neutron stars and is considered to form a black hole.

These are rare but they are very important as they are considered as the main source of heavy elements present in the universe. With short-gamma ray burst scientists expect it to be a kilonova. The brightness of the light observed in this case was tremendous and so it is estimated that the two neutron stars that merged combioned to form a magnetar here.

Laskar explained “You basically have these magnetic field lines that are anchored to the star that are whipping around at about a thousand times a second, and this produces a magnetized wind. These spinning field lines extract the rotational energy of the neutron star formed in the merger, and deposit that energy into the ejecta from the blast, causing the material to glow even brighter.”

Fong said “With its amazing sensitivity at near-infrared wavelengths, Hubble really sealed the deal with this burst. Amazingly, Hubble was able to take an image only three days after the burst. Through a series of later images, Hubble showed that a source faded in the aftermath of the explosion. This is as opposed to being a static source that remains unchanged. With these observations, we knew we had not only nabbed the source, but we had also discovered something extremely bright and very unusual. Hubble’s angular resolution was also key in pinpointing the position of the burst and precisely measuring the light coming from the merger.”

It is expected that NASA’s James Webb Space Telescope will be able to provide much more detailed information about such emission occurring in the universe covering further more distance.

Source – nasa

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