OzGrav

  • Home
  • About
    • Vision & Mission
    • Join OzGrav
    • Mental Health and Wellbeing
    • Getting started in OzGrav
    • Funding Opportunities
    • Diversity and Inclusion
    • Code of Conduct
    • OzGrav Mentoring Program
    • Nodes & Partners
    • Facilities & Capabilities
    • Reports >
      • Annual Reports
      • Industry Success Stories
      • Strategic Plan
    • Member resources
  • Our People
    • Chief Investigators
    • Partner Investigators
    • Associate Investigators
    • Postdocs and Students >
      • Faces of OzGrav
    • Professional & Outreach staff
    • Governance Advisory Committee
    • Scientific Advisory Committee
    • Executive Committee
    • Equity & Diversity Committee
    • Early Career Researcher Committee
    • Professional Development Committee
    • Research Translation Committee
    • OzGrav Alumni
  • Research Themes
    • Instrumentation
    • Data/Astro
  • Education and Outreach
  • Events
    • OzFink workshop 2023
    • 2022 OzGrav ECR Workshop and Annual Retreat
    • Upcoming and Past Events
  • News/Media
    • News
    • Newsletter
    • How to write a research brief
  • Contact Us
  • Home
  • About
    • Vision & Mission
    • Join OzGrav
    • Mental Health and Wellbeing
    • Getting started in OzGrav
    • Funding Opportunities
    • Diversity and Inclusion
    • Code of Conduct
    • OzGrav Mentoring Program
    • Nodes & Partners
    • Facilities & Capabilities
    • Reports >
      • Annual Reports
      • Industry Success Stories
      • Strategic Plan
    • Member resources
  • Our People
    • Chief Investigators
    • Partner Investigators
    • Associate Investigators
    • Postdocs and Students >
      • Faces of OzGrav
    • Professional & Outreach staff
    • Governance Advisory Committee
    • Scientific Advisory Committee
    • Executive Committee
    • Equity & Diversity Committee
    • Early Career Researcher Committee
    • Professional Development Committee
    • Research Translation Committee
    • OzGrav Alumni
  • Research Themes
    • Instrumentation
    • Data/Astro
  • Education and Outreach
  • Events
    • OzFink workshop 2023
    • 2022 OzGrav ECR Workshop and Annual Retreat
    • Upcoming and Past Events
  • News/Media
    • News
    • Newsletter
    • How to write a research brief
  • Contact Us

Exploring the mysterious origins of the most extreme light flashes in the Universe

18/10/2021

0 Comments

 
Picture
Artist's illustration of a gamma ray burst - Carl Knox, OzGrav-Swinburne University

​Our Universe shines bright with light across the electromagnetic spectrum. While most of this light comes from stars like our Sun in galaxies like our own, we are often treated with brief and bright flashes that outshine entire galaxies themselves. Some of these brightest flashes are believed to be produced in cataclysmic events, such as the death of massive stars or the collision of two stellar corpses known as neutron stars. Researchers have long studied these bright flashes or ‘transients’ to gain insight into the deaths and afterlives of stars and the evolution of our Universe.
 
Astronomers are sometimes greeted with transients that defy expectations and puzzle theorists who have long predicted how various transients should look. In October 2014, a long-term monitoring programme of the southern sky with the Chandra telescope—NASA’s flagship X-Ray telescope—detected one such enigmatic transient called CDF-S XT1: a bright transient lasting a few thousands of seconds. The amount of energy CDF-S XT1 released in X-rays was comparable to the amount of energy the Sun emits over a billion years. Ever since the original discovery, astrophysicists have come up with many hypotheses to explain this transient; however, none have been conclusive.
 
In a recent study, a team of astrophysicists led by OzGrav postdoctoral fellow Dr Nikhil Sarin (Monash University) found that the observations of CDF-S XT1 match predictions of radiation expected from a a high-speed jet travelling close to the speed of light. Such “outflows” can only be produced in extreme astrophysical conditions, such as the disruption of a star as it gets torn apart by a massive black hole, the collapse of a massive star, or the collision of two neutron stars.
 
Sarin et al’s study found that the outflow from CDF-S XT1 was likely produced by two neutron stars merging together. This insight makes CDF-S XT1 similar to the momentous 2017 discovery called GW170817—the first observation of gravitational-waves, cosmic ripples in the fabric of space and time—although CDF-S XT1 is 450 times further away from Earth. This huge distance means that this merger happened very early in the history of the Universe; it may also be one of the furthest neutron star mergers ever observed.
 
Neutron star collisions are the main places in the Universe where heavy elements such as gold, silver, and plutonium are created. Since CDF-S XT1 occurred early on in the history of the Universe, this discovery advances our understanding of Earth’s chemical abundance and elements.
 
Recent observations of another transient AT2020blt in January 2020—primarily with the Zwicky Transient Facility—have puzzled astronomers. This transient’s light is like the radiation from high-speed outflows launched during the collapse of a massive star. Such outflows typically produce higher energy gamma-rays; however, they were missing from the data – they were not observed. These gamma rays can only be missing due to one of three possible reasons: 1) The gamma-rays were not produced. 2) The gamma rays were directed away from Earth. 3) The gamma-rays were too weak to be seen.
 
In a separate study, led again by OzGrav researcher Dr Sarin, the Monash University astrophysicists teamed up with researchers in Alabama, Louisiana, Portsmouth and Leicester to show that AT2020blt probably did produce gamma-rays pointed towards Earth, they were just really weak and missed by our current instruments.
 
Dr Sarin says: “Together with other similar transient observations, this interpretation means that we are now starting to understand the enigmatic problem of how gamma-rays are produced in cataclysmic explosions throughout the Universe”.
 
The class of bright transients collectively known as gamma-ray bursts, including CDF-S XT1, AT2020blt, and AT2021any, produce enough energy to outshine entire galaxies in just one second.
 
“Despite this, the precise mechanism that produces the high-energy radiation we detect from the other side of the Universe is not known,” explains Dr Sarin. “These two studies have explored some of the most extreme gamma-ray bursts ever detected. With further research, we’ll finally be able to answer the question we’ve pondered for decades: How do gamma ray bursts work?” 
0 Comments



Leave a Reply.

         


    OzGrav News


    Archives

    March 2023
    December 2022
    November 2022
    September 2022
    July 2022
    June 2022
    May 2022
    April 2022
    March 2022
    February 2022
    January 2022
    December 2021
    November 2021
    October 2021
    September 2021
    August 2021
    July 2021
    June 2021
    May 2021
    April 2021
    March 2021
    February 2021
    January 2021
    December 2020
    November 2020
    October 2020
    September 2020
    August 2020
    July 2020
    June 2020
    May 2020
    April 2020
    March 2020
    February 2020
    January 2020
    December 2019
    August 2019
    July 2019
    June 2019
    April 2019
    March 2019
    December 2018
    November 2018
    October 2018
    September 2018
    August 2018
    July 2018
    April 2018
    March 2018
    February 2018
    December 2017
    November 2017
    October 2017
    September 2017
    August 2017
    June 2017
    May 2017
    April 2017
    March 2017
    February 2017
    December 2016
    September 2016
    June 2016
    February 2016

    Categories

    All
    Event
    Media

      Keep up to date with ozgrav news and events

    Subscribe to Newsletter

    RSS Feed

Picture
Picture
Picture
Picture
Picture
Picture
Picture
Picture
We acknowledge and pay respects to the Elders and Traditional Owners of the land on which our six Australian nodes stand

​© 2022   The ARC Centre of Excellence for Gravitational  Wave Discovery (OzGrav)
Banner images: An artist's impression of gravitational waves generated by binary neutron stars.  Credits: R. Hurt/Caltech-JPL
Picture