Free Astronomy Magazine September-October 2022

54 SEPTEMBER-OCTOBER 2022 ASTRO PUBLISHING ered, astronomers thought that this burst might be coming from a nearby gal- axy,” said Laskar, adding that a significant amount of dust in the area also obscured the object from detection in optical obser- vations with the Hubble Space Telescope. Each wavelength added a new dimension to scien- tists’ understanding of the GRB, and millimeter, in particular, was critical to uncovering the truth about the burst. “The Hubble observations revealed an unchanging field of galaxies. ALMA’s unparalleled sensitivity al- lowed us to pinpoint the location of the GRB in that field with more preci- sion, and it turned out to be in another faint galaxy, which is further away. That, in turn, means that this short-duration gamma- ray burst is even more powerful than we first thought, making it one of the most luminous and energetic on record, ” said Laskar. Wen-fai Fong, an Assis- tant Professor of Physics and Astronomy at North- western University added, “This short gamma-ray burst was the first time we tried to observe such an event with ALMA. Afterglows for short bursts are very difficult to come by, so it was spec- tacular to catch this event shining so bright. After many years of observ- ing these bursts, this surprising dis- covery opens up a new area of study, as it motivates us to observe many more of these with ALMA, and other telescope arrays, in the future.” Joe Pesce, National Science Founda- And there’s plenty of work still to be done across multiple wave- lengths, both with new GRBs and with GRB 211106A, which could uncover additional sur- prises about these bursts. “The study of short-dura- tion GRBs requires the rapid coordination of tel- escopes around the world and in space, oper- ating at all wave- lengths,” said Edo Berger, Professor of Astronomy at Harvard University. “In the case of GRB 211106A, we used some of the most powerful telescopes available — ALMA, the National Science Founda- tion’s Karl G. Jansky Very Large Array (VLA), NASA’s Chandra X-ray Observa- tory, and the Hubble Space Telescope. With the now-operational James Webb Space Telescope (JWST), and future 20-40 meter optical and radio telescopes such as the next generation VLA (ngVLA) we will be able to produce a complete picture of these cata- clysmic events and study them at unprecedented distances.” Laskar added, “With JWST, we can now take a spectrum of the host galaxy and easily know the distance, and in the future, we could also use JWST to capture infrared afterglows and study their chemical composition. With ngVLA, we will be able to study the geometric structure of the afterglows and the star-forming fuel found in their host environ- ments in unprecedented detail. I am excited about these upcoming dis- coveries in our field.” I n the first-ever time-lapse sequence of a short-dura- tion gamma-ray burst in mil- limeter-wavelength light, we see GRB 21106A as cap- tured with the Atacama Large Millimeter/submillime- ter Array. The millimeter light seen here pinpoints the location of the event to a distant host galaxy in im- ages captured using the Hubble Space Telescope. The evolution of the millimeter light’s brightness provides infor- mation on the energy and geometry of the jets produced in the explosion. [ALMA (ESO/NAOJ/ NRAO), T. Laskar (Utah), S. Dagnello (NRAO/AUI/NSF)] tion Program Officer for NRAO/ ALMA said, “These observations are fantastic on many levels. They pro- vide more information to help us understand the enigmatic gamma- ray bursts (and neutron-star astro- physics in general), and they demon- strate how important and comple- mentary multi-wavelength observa- tions with space- and ground-based telescopes are in understanding as- trophysical phenomena.” !