REPUBLIKA.CO.ID, VALPARAISO – Scientists using observations from NASA’s Neil Gehrels Swift Observatory have received signals from a pair of black hole a monster that disturbs the gas clouds at the center of the galaxy. This is the first discovery of this phenomenon.

“This is a very strange event, called AT 2021hdr, which repeats itself every few months,” said Lorena Hernández-García, an astronomer at the Millennium Astrophysics Institute, Nucleus de la Nucleus A Year of Transversal Research and Technology to Study Supermassive Black Holes, and the University of Valparaiso in Chile.

“We think that the gas clouds surround the black holes. As they orbit each other, the black holes interact with the clouds, disrupting it and consuming it ‘ gas. This introduces light oscillation patterns from the system.” Reported Science every daypaper on AT 2021hdr, led by Hernández-García, published on November 13 in the journal Astronomy and Astrophysics.

The double black hole is in the center galaxy named 2MASX J21240027 + 3409114, located 1 billion light years in the northern constellation Cygnus. The distance between the two is about 26 billion kilometers, close enough that light only takes a day to travel between them.

Together, both are 40 million times the mass of the Sun. Scientists believe that black holes complete their orbits every 130 days and that they merge and merge in about 70,000 years.

AT 2021hdr was first observed in March 2021 by the Caltech-led ZTF (Zwicky Transient Facility) at the Palomar Observatory in California. This has been identified as a resource of potential interest by ALeRCE (Automatic Learning for Rapid Event Classification). This multidisciplinary team combines artificial intelligence tools with human expertise to report events in the night sky to the astronomical community using a pool of data collected by observational programs such as ZTF.

“Although this flare was originally thought to be a supernova, the explosion in 2022 made us think about other explanations,” said co-author Alejandra Muñoz-Arancibia, a member of the ALeRCE team and an astronomer at the Institute Millennium Astrophysics and the Center for Mathematical Modeling. at the University of Chile. “Each subsequent event has helped us refine our model of what’s happening in the system.” Since the first flare, ZTF has detected outbursts from AT 2021hdr every 60 to 90 days.

Hernández-García and his team have been monitoring the source with Swift since November 2022. Swift helped them confirm that the binary produces oscillations in ultraviolet light and X-ray on the same time scale as ZTF is seen in the visible range.

The researchers eliminated various Goldilocks-type models to explain what they saw in the data. At first, they thought the signal could be a byproduct of normal activity in the center of the galaxy. They then considered whether a tidal disruption event – the destruction of a star passing too close to one of the black holes – was to blame.

In the end, they settled on another possibility, namely a tidal barrier in the gas cloud, which was larger than the binary itself. When the cloud meets a black hole, gravity tears it apart, forming filaments around the black hole, and friction begins to heat it up. The gas becomes very dense and hot near the black hole. As the orbits are binary, a complex interaction of forces expels some of the gas from the system with each rotation. This interaction leads to the observation of variable light Swift and ZTF.

Hernández-García and his team plan to continue observing AT 2021hdr to better understand the system and improve their model. They are also interested in studying their home galaxy, which is currently merging with another nearby galaxy – an event first reported in their paper.

“As Swift approaches its 20th birthday, it’s amazing to see the new science that continues to be achieved by society,” said S. Bradley Cenko, Swift’s principal investigator at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We still have a lot to learn kosmos which is always changing. “