The Neil Gehrels Swift Observatory

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Oct 8, 2019

Astronomers Find New Evidence for a Kilonova in Old Swift Data

GRB 070809 is a short duration gamma-ray burst discovered by the Neil Gehrels Swift Observatory in August 2007. Very recently, a team of astronomers, led by Zhi-Ping Jin from Purple Mountain Observatory, showed that the optical light from GRB070809 had a peculiar behavior. Its luminosity and red color appear different than the standard afterglow emission seen by the X-ray Telescope aboard Swift. Instead, the optical light can be naturally interpreted as a kilonova (also known as macronova), a kind of transient powered by the radioactive decay of heavy elements synthesized in the ejecta of a neutron star collision. The kilonova signal was identified at a distance larger than 1 Gpc, well beyond the reach of the second-generation gravitational wave detectors.
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Sep 27, 2019

NASA's Swift Reveals Depressure in a Galaxy Cluster

Galaxy clusters are some of the largest cosmic structures, made of hundreds to thousands of galaxies. They are generally thought to have nearly identical structure and radial profiles. Using NASA's Neil Gehrels Swift Observatory observations of the nearby galaxy cluster CL2015 (Abell 117, z=0.05), researchers found a cluster that does not follow this universal profile: it displays a very low pressure for a cluster of its mass. The low pressure profile of CL2015 is likely due to the low concentration of its matter distribution, i.e. a lack of mass in the cluster center. A paper describing these results is being published in the Astronomy and Astrophysics Journal.

Sep 26, 2019

NASA's Swift and TESS Observe a Star-shredding Black Hole

For the first time, NASA's planet-hunting Transiting Exoplanet Survey Satellite (TESS) watched a black hole tear apart a star in a cataclysmic phenomenon called a tidal disruption event. Follow-up observations by NASA's Neil Gehrels Swift Observatory and other facilities have produced the most detailed look yet at the early moments of one of these star-destroying occurrences.
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Aug 27, 2019

Astronomers Find a Golden Glow From a Distant Stellar Collision

On August 21, 2016 NASA's Neil Gehrels Swift Observatory discovered a new gamma-ray burst, named GRB160821B, and began tracking its light minutes after it was detected. The burst, which lasted less than two seconds, was localized in the outskirts of a distant spiral galaxy, 2.5 billion years away from Earth. By using a wide array of ground-based and space-based telescopes, astronomers followed the evolution of its light and found the best evidence for a kilonova - a turbocharged explosion that instantly forged several hundred planets' worth of gold and platinum. Astronomers suspect that all of the gold and platinum on Earth formed as a result of ancient kilonovae created during the collisions of neutron stars.
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May 1, 2019

Swift Hunts for Colliding Black Holes and Neutron Stars

On April 1st, 2019, LIGO and its Italian partner, VIRGO began their search for gravitational waves, called O3 for third observing run. During the first month of operations the LIGO-VIRGO network spotted five stellar collisions. The Neil Gehrels Swift Observatory responded to the alerts and observed thousands of galaxies within the LIGO-VIRGO localizations in order to find the luminous electromagnetic counterparts of the gravitational wave signal.

On April 26th, 2019, the LIGO-VIRGO network issued an alert for the possible collision of a neutron star with a black hole. This event was named S190426c. Swift began pointed UV and X-ray tiling of the localization region of S190426c 142 minutes after the GW alert. The campaign continued for 2 days and observed over 32% of the galaxy-convolved localization in >800 fields covering thousands of massive galaxies.

Nov 8, 2018

Swift data help to reveal the final stages of colliding black holes

The Burst Alert Telescope aboard the Neil Gehrels Swift Observatory continuously scans the sky producing one of the most sensitive all-sky surveys in the hard X-rays. The survey is especially useful at finding nearby active galaxies, even those obscured at other wavelengths by gas and dust. Using high resolution IR observations of active galaxies detetected with BAT, a team of astronomers found a surprising number of galaxies in the final stages of merging together into single, larger galaxies. Peering through thick walls of gas and dust surrounding the merging galaxies' messy cores, the research team captured pairs of supermassive black holes drawing closer together before they coalescence into one giant black hole. It is not easy to find galactic nuclei so close together. Most prior observations of merging galaxies have caught the coalescing black holes at earlier stages, when they were about 10 times farther away. When the black holes finally do collide, they will unleash enormous energy in the form of gravitational waves.
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Oct 16, 2018

All in the Family: Kin of Gravitational-Wave Source Discovered by NASA's Satellites

About a year ago, astronomers excitedly reported the first detection of electromagnetic waves, or light, from a gravitational wave source. Now, a year later, researchers are announcing the existence of a cosmic relative to that historic event. GRB150101B was a gamma-ray burst that lasted less than a second, localized by the NASA's Neil Gehrels Swift Observatory in an old elliptical galaxy 1.7 billion years away. The apparent match between GRB 150101B and GW170817 is striking: both produced an unusually faint and short-lived gamma ray burst, and both were a source of bright, blue optical light lasting a few days, and X-ray emission lasted much longer. The host galaxies are also remarkably similar. Both are bright elliptical galaxies with a population of stars a few billion years old and displaying no evidence for new stars forming. A paper reporting the results was published today in Nature Communications.
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