MacroCosmos mars-avril 2018

33 MARS-AVRIL 2018 CHRONIQUES DE L'ESPACE a companion galaxy that is linked to J1354 by streams of stars and gas produced by a collision between the two galaxies. The team concluded that clumps of material from the companion galaxy swirled toward the center of J1354 and then were eaten by the supermassive black hole. The team used optical data from Hubble, Keck, and APO to show that electrons had been stripped from atoms in a cone of gas exten- ding some 30,000 light-years south from the galaxy’s center. This strip- ping was likely caused by a burst of radiation from the vicinity of the black hole, indicating that a feas- ting event had occurred. To the north they found evidence for a shock wave, similar to a sonic boom, located about 3,000 light- years from the black hole. This sug- gests that a burp occurred after a different clump of gas had been consumed roughly 100,000 years later. “This galaxy really caught us off guard,” said CU Boulder docto- ral student Rebecca Nevin, a study co-author who used data from APO to look at the velocities and inten- sities of light from the gas and stars in J1354. “We were able to show that the gas from the north- ern part of the galaxy was consistent with an advancing edge of a shock wave, and the gas from the south was consistent with an older out- flow from the black hole.” Our Milky Way galaxy’s supermas- sive black hole has had at least one burp. In 2010, another research team discovered a Milky Way belch using observations from the orbi- ting Fermi Gamma-ray Observatory to look at the galaxy edge on. Astronomers saw gas outflows dub- bed “Fermi bubbles” that shine in the gamma-ray, X-ray, and radio wave portion of the electromagne- tic spectrum. “These are the kinds of bubbles we see after a black hole feeding event,” said CU postdoctoral fellow Scott Barrows. “Our galaxy’s super- massive black hole is now napping after a big meal, just like J1354’s black hole has in the past. So we also expect our massive black hole to feast again, just as J1354’s has.” Other co-authors on the new study include postdoctoral fellow Fran- cisco Muller-Sanchez of CU Boulder, Jenny Greene of Princeton Univer- sity, David Pooley from Trinity Uni- versity, Daniel Stern from NASA’s Jet Propulsion Laboratory in Pasa- dena, California, and Fiona Harri- son from the California Institute of Technology. A paper on the subject was publi- shed in a recent issue of The Astro- physical Journal and is available online. Comerford presented the team’s findings in a January 11 th , 2018 press briefing at the 231 st meeting of the American Astrono- mical Society held in Washington D.C. !