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Astronomers Identify Potential Supernova Remnants Near Galactic Center and in Galaxy M83

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Supernova Secrets Unveiled: From the Milky Way's Core to a Cosmic Neighbor

Astronomers using data from multiple space-based observatories have reported findings related to supernova remnants in two distinct galactic locations: one candidate near the center of the Milky Way and a population of variable X-ray sources in the galaxy Messier 83 (M83).

Candidate Supernova Remnant Near the Milky Way’s Center

Location and Distance

A candidate supernova remnant has been identified in the Sagittarius C region, approximately 26,000 light-years from Earth, near the supermassive black hole at the center of the Milky Way galaxy. If confirmed, it would represent one of the closest supernova remnants to the galactic center.

Detection and Evidence

  • Data from NASA's Chandra X-ray Observatory and the European Space Agency's XMM-Newton satellite revealed a "blob" of X-ray emission in this region.
  • The candidate is located within an H II region, a bubble of ionized gas surrounding a massive young star. This area is a bright radio source also known as Sagittarius C.
  • The expanding material is estimated to be moving at approximately 3.2 million kilometers per hour (2 million miles per hour).
  • Researchers estimate the explosion occurred around 1,700 years ago.

Observational Data

A composite image of the region was created using:

  • X-ray data (blue) from Chandra and XMM-Newton.
  • Radio data (red) from the MeerKAT telescope in South Africa.
  • Optical data from the Pan-STARRS telescopes in Hawaii.
  • Infrared data (light blue) from the James Webb Space Telescope, showing gas in the H II region.

Alternative Hypotheses

  • Researchers did not detect elevated levels of elements typically expected from a supernova. One explanation is that the stellar debris has already mixed with the surrounding gas.
  • An alternative hypothesis is that the X-ray emission could be caused by gas heated by hot, massive stars in the region. The research team considers this unlikely because the X-ray brightness of the blob is over ten times greater than that typically emitted by known clusters of massive stars.

Attribution and Publication

The study was led by Zhenlin Zhu and Mark Morris (UCLA), Gabriele Ponti (INAF, Italy), and Ping Zhou (Nanjing University, China). The paper was published in The Astrophysical Journal.

Variable X-ray Sources in Supernova Remnants of M83

Overview

Astronomers using NASA's Chandra X-ray Observatory have detected significant brightness variability in approximately half of 22 X-ray sources associated with supernova remnants in the galaxy Messier 83 (M83). This observation was considered unexpected because older supernova remnants were previously thought to fade gradually.

Observational Details

  • Galaxy: M83, located about 15 million light-years from Earth.
  • Data: Chandra observations from 2000 to 2014, including single observations in 2000 and 2001, ten observations from 2010 to 2011, and one observation in 2014.
  • Finding: About half of the 22 X-ray sources previously identified as supernova remnants showed dramatic X-ray brightness variability over the 14-year period.

Proposed Explanations

  1. High-Mass X-ray Binaries (HMXBs): The variability may arise from systems where a massive star survived its companion's supernova and now orbits a black hole or neutron star. Material pulled from the surviving star onto the compact object can produce variable X-rays. HMXBs are known to be highly variable.
  2. Fallback Recycling: Black holes or neutron stars might recapture material ejected by the original supernova, producing variable X-rays.
  3. Specific Remnant: For one particular remnant, SN 1957D (observed approximately 70 years ago), the variability is attributed to the blast wave colliding with surrounding material.

Related Findings

A follow-up study of the galaxy M51, using Chandra and ground-based optical data, found a similar population of variable X-ray sources associated with supernova remnants. This suggests such systems may be common in galaxies with active star formation.

Publication

The results were presented at the American Astronomical Society meeting in Pasadena, California, and published in The Astrophysical Journal.