All articles tagged with #gamma ray bursts
A comprehensive review of 65 observations from pulsars, active galaxies, and gamma-ray bursts tightens the limits on any energy-dependent variation in photon speed, finding no violation of Lorentz invariance and reinforcing Einstein’s relativity; it also refines how such limits are calculated and points to future instruments for even tighter tests.
The Vela satellites, built to detect secret nuclear tests, recorded a mysterious 1967 gamma-ray flash that didn’t fit terrestrial or solar sources, initiating gamma-ray burst research. Over time, improved timing allowed precise localization, establishing bursts as cosmic in origin. BeppoSAX’s 1997 afterglow localizations linked bursts to distant galaxies and revealed two main classes—short bursts from compact mergers and long bursts from collapsing massive stars—while extraordinary events like GRB 221009A in 2022 showed bursts can outshine almost all prior records, marking gamma-ray bursts as a central field in high-energy astrophysics.
New simulations suggest ultrahigh-energy cosmic rays hitting Earth could be atomic nuclei heavier than iron, which lose energy more slowly over cosmic distances; events like neutron-star mergers or massive star collapses into black holes may accelerate these ultraheavy nuclei, reshaping how scientists search for their sources and understand cosmic-ray acceleration.
Astronomers connecting the November 2024 gravitational-wave event S241125n with a brief gamma-ray and X-ray flash propose the merger happened inside the accretion disk of a supermassive black hole at the center of a galaxy. If true, the environment would feed rapid accretion and jets, producing light from an event usually expected to be dark, offering a new scenario for how black hole mergers in galactic nuclei might be observed. Further observations and modeling are needed to confirm this explanation.
Astronomers using NASA's Chandra X-ray Observatory and Hubble traced a short gamma-ray burst (GRB 230906A) to a neutron-star merger inside a tiny dwarf galaxy, revealed by its placement in a long tidal tail; the finding shows such powerful explosions can occur in faint hosts and helps explain how heavy elements are dispersed into galactic outskirts.
Astronomers detected a neutron-star collision in a tiny, faint galaxy inside a 600,000-light-year gas stream, about 4.7 billion light-years away, challenging where such events occur and linking them to gamma-ray bursts and the production of heavy elements like gold and platinum, with observations from Fermi, Chandra, Swift, and Hubble.
Astronomers using the Australian SKA Pathfinder (ASKAP) detected the long‑lived radio afterglow of a powerful gamma‑ray burst that emitted little or no high‑energy light, revealing an orphan afterglow (ASKAP J005512-255834). The radio source brightened to about 10^32 watts of energy and faded over about 1,000 days, and lies in a distant, star‑forming galaxy ~1.7 billion light‑years away. This finding provides a clearer example of hidden GRB events and could help map the full gamma‑ray burst population, though an alternative explanation — a star torn apart by an intermediate‑mass black hole — remains possible.
NASA has paused most Swift Observatory science operations to reduce atmospheric drag and slow its orbital decay, as the 21-year-old gamma-ray telescope faces a rising risk of uncontrolled reentry by mid-2026. To extend its life, NASA awarded a $30 million contract to Katalyst Space Technologies for a rescue mission to rendezvous with Swift and boost its orbit, with a launch aimed for June to keep the spacecraft above about 185 miles in altitude. The Burst Alert Telescope will still detect gamma-ray bursts, while other telescopes remain on hold to minimize drag.
Astronomers using the Fermi Gamma-ray Space Telescope detected GRB 250702B, a gamma-ray burst lasting about seven hours—the longest on record—challenging standard GRB models. A helium-merger scenario, where a black hole accretes a helium star and transfers angular momentum to power an unusually long jet, offers a natural explanation. Future work with the COSI gamma-ray telescope, set to launch in 2027, aims to find more long-duration GRBs to unravel the underlying physics.
A NASA Goddard-led study used the NASA Pleiades supercomputer to simulate the final orbits of a binary neutron-star system, showing magnetospheres continually reconnecting as the stars spiral in. The simulations indicate high-energy gamma-ray emission is largely trapped by electron-positron pair production, while lower-energy gamma-rays and X-rays may escape depending on the observer's viewpoint. The work helps predict pre-merger signals for future gamma-ray telescopes and gravitational-wave detectors like LISA.
In 2023, astronomers observed a black hole merger that defied existing physics, involving black holes within a forbidden mass range and spinning at near light speed. New simulations incorporating magnetic fields reveal that these fields can eject mass during a star's collapse, producing lighter, fast-spinning black holes and potentially observable gamma-ray bursts, offering insights into these 'impossible' black holes.
Australia's SpIRIT nanosatellite has successfully completed its commissioning phase, taking its first space selfie and preparing to detect cosmic gamma-ray bursts, marking a significant milestone for Australian space technology and international scientific collaboration.
Astronomers have observed a rare series of repeating gamma-ray bursts, lasting much longer than typical bursts and originating outside our galaxy, which could reveal new insights into the death of stars and extreme cosmic events. The cause remains uncertain, with theories including unusual supernovae or star-black hole interactions, and ongoing observations aim to uncover more about these extraordinary phenomena.
Astronomers have discovered a record-breaking, unusually long gamma-ray burst, GRB 250702B, which lasted about a day and originated from a galaxy billions of light-years away. Its peculiar duration and repeated signals challenge existing theories about such cosmic explosions, suggesting a possible involvement of an intermediate black hole and a white dwarf, but the exact cause remains unknown.
Astronomers have studied the most powerful gamma-ray burst ever detected, called BOAT, which originated from a supernova in a star 2.4 million light-years away, providing new insights into the structure of jets in such explosions and demonstrating the capabilities of advanced telescopes like LST-1.