New study could help detect more supernovae associated with gamma-ray bursts

The likelihood of detecting a supernova linked to a gamma-ray burst currently stands at a mere 0.00346%. To enhance supernova discovery rates, a network of telescopes spread across various geographic locations, employing diverse photometric filters and considering host galaxy characteristics, has been proposed in a study featured in Pattern Recognition and Image Analysis.

Gamma-ray bursts, the universe’s most powerful outbursts emitting immense gamma-ray energy, were serendipitously found in 1967 when the Vela satellite, designed to monitor atmospheric nuclear explosions, detected a gamma-ray signal from space, not Earth.

Although gamma-ray bursts usually occur far from Earth, posing no direct threat, a nearby burst could damage Earth’s ozone layer, exposing all life to harmful cosmic radiation and causing extinction. Therefore, astrophysicists diligently study this phenomenon to assess potential risks.

While the exact mechanism of gamma-ray bursts is not fully understood, one theory suggests they result from a supernova following a star’s collapse. This occurs when a star, around 8-10 times the mass of the sun, depletes its nuclear fuel and succumbs to gravitational compression, leading to a supernova explosion and gamma radiation.

Surprisingly, supernova explosions are less conspicuous than the gamma-ray bursts they generate. By 2023, despite detecting approximately 13,000 gamma-ray bursts, only 45 have been confirmed to originate from supernovae, possibly due to detection errors and selective effects.

The process for studying gamma-ray bursts involves space observatories like Swift, Fermi, and INTEGRAL detecting gamma radiation and relaying coordinates to Earth. Researchers then measure redshift, a parameter indicating the source’s distance. If the redshift is ≤0.5, there’s a high likelihood of a gamma-ray burst originating from a supernova, which should be observed.

Supernovae typically appear 5-20 days after the gamma-ray burst but may remain undetected if too distant from Earth. Additionally, the brightness or dustiness of the host galaxy can obscure the supernova’s visibility.

An analogy is made to walking in fog with a candle versus a flashlight; the candle’s light is absorbed and scattered, making it less noticeable than the flashlight. Similarly, if a supernova isn’t visible in one filter due to light absorption, observing it in other filters with lower absorption can reveal it.

The location within the host galaxy also matters; being observed in the galaxy’s outer arms increases the chances of supernova detection compared to near the core.

A solution involves observing the host galaxy a few days after the gamma-ray burst and supernova have faded, then correlating these images with the active supernova phase. By removing the galaxy background, the supernova becomes visible near the core.

To mitigate Earth’s adverse weather conditions affecting research, a global network of telescopes across different latitudes and longitudes is recommended. Collaborative efforts among researchers from various countries can help establish such a network and investigate even seemingly insignificant cases thoroughly.

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