REPUBLIKA.CO.ID, VALPARAISO – Scientists using observations from NASA’s Neil Gehrels Swift Observatory have discovered 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 keeps repeating itself every few months,” said Lorena Hernández-García, an astrophysicist at the Millennium Institute of Astrophysics, Millennium Nucleus on Transversal Research and Technology to Explore Supermassive Black Holes, and the University Valparaíso in Chile.
“We think the gas clouds are engulfing the black holes. As they orbit each other, the black holes interact with the clouds, disrupting and consuming the gas. This results in light oscillation patterns from the system.” Reported Science Dailya paper on AT 2021hdr, led by Hernández-García, was 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.
Combined, the two have a mass 40 million times the mass of the Sun. Scientists estimate black holes complete their orbits every 130 days and will collide and merge in about 70,000 years.
AT 2021hdr was first seen in March 2021 by the Caltech-led ZTF (Zwicky Transient Facility) at the Palomar Observatory in California. This was flagged as a potentially interesting resource 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 trove of data collected by survey programs like ZTF.
“While this flare was initially thought to be a supernova, the explosion in 2022 made us think of other explanations,” said co-author Alejandra Muñoz-Arancibia, a member of the ALeRCE team and an astrophysicist at the Millennium Institute of Astrophysics and the Center for Mathematical Modeling. at the University of Chile. “Each subsequent event has helped us refine our model of what is happening in the system.” Since the first flare, ZTF has detected bursts from AT 2021hdr every 60 to 90 days.
Hernández-García and his team have been observing the source with Swift since November 2022. Swift helped them determine that the binary produces oscillations in ultraviolet and X-ray light on the same time scale as ZTF sees it in the visible range.
The researchers performed a Goldilocks-type elimination of different models to explain what they saw in the data. Initially, they thought the signal might be a byproduct of normal activity at the center of the galaxy. Then they considered whether a tidal disruption event – the destruction of a star that wandered too close to one of the black holes – could be the cause.
Ultimately, they settled on another possibility, namely tidal interference in the gas cloud, which was larger than the binary itself. When the cloud encounters a black hole, gravity tears it apart, forming filaments around the black hole, and friction begins to heat it. The gas becomes very dense and hot near the black hole. As the binary orbits, a complex interaction of forces expels some of the gas from the system with each rotation. This interaction results in the observation of fluctuating Swift and ZTF light.
Hernández-García and his team plan to continue observations of AT 2021hdr to better understand the system and improve their model. They are also interested in studying its 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 all the new science that is still being achieved by society,” said S. Bradley Cenko, Swift’s principal investigator at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “There is still much to teach us about kosmos which is always changing.”
Black Holes: The Cosmic Drama of AT 2021hdr
Hold onto your telescopes, folks! Scientists have stumbled upon a galactic soap opera that’s unraveling
a billion light years away in the constellation Cygnus. Yes, you heard right! This isn’t your average
black hole; we’re talking about a double act that seems to have taken the universe’s greatest mysteries
and turned them into a recurring sitcom.
The fine folks at NASA’s Neil Gehrels Swift Observatory have discovered a pair of black holes
whose antics may just redefine astrophysical phenomena. Enter the star of the show: the event known as
AT 2021hdr. This cosmic drama keeps astonishing our brightest minds every few months, causing
a bit of a ruckus with gas clouds in its vicinity. Lorena Hernández-García, an astrophysicist with a
name that sounds like a spell from Harry Potter, has explained that these cosmic troublemakers—each
boasting a combined mass of 40 million suns—are literally “engulfing” gas clouds. Sounds a bit like a
Saturday night binge, doesn’t it?
“This is a very strange event, called AT 2021hdr, which keeps repeating itself every few months.”
These black holes are currently residing in the galaxy 2MASX J21240027+3409114, and the gossip is
that they’re about 26 billion kilometers apart. To put that in perspective, light travels that distance
in about a day. Breaking news: Black holes have a social life and a very long-distance relationship!
It’s estimated that they complete their orbits every 130 days and are set to collide and merge in about
70,000 years. Talk about a long-term relationship! Honestly, at that point, they should just get a
room—though they might blow it up in a spectacular fashion.
Initially mistaken for a supernova, AT 2021hdr has reminded us all that the cosmos revels in its
unpredictability. Alejandra Muñoz-Arancibia from the ALeRCE team explained how each blink in the sky has
helped refine their models of what’s occurring up there. Think of it as cosmic event planning, only the
guest list involves your standard fair: gas clouds, gravity, and chaos.
The black holes are like celestial chefs, stirring up a potent gas soup. They tear apart gas clouds with
their gravity, creating filaments that heat up and flash in various lights. Imagine cooking pasta: if you
let it boil over, you might end up with a chaotic kitchen! With each orbit, some gas is expelled, a
cosmic feedback loop that results in fluctuating light patterns.
The team’s research isn’t going to stop here. They’re gearing up for further observations. The cosmos is
always changing, and so should our understanding of it. As S. Bradley Cenko from NASA so aptly puts it,
“there is still much to teach us about the cosmos.” Well, if that’s the case, get me a telescope, a
comfy chair, and possibly an industry-best space popcorn supplier!
So, whether you’re a starry-eyed astrophysicist or just someone who gets excited about constellations,
buckle up because AT 2021hdr is here to remind us that we are mere spectators in this grand
cosmic theatre. And trust me, it’s going to be one heckuva show!
What are the key characteristics of the astronomical event AT 2021hdr?
**Interview with Dr. Lorena Hernández-García on the Discovery of AT 2021hdr**
**Editor:** Welcome, Dr. Hernández-García! Thank you for joining us today to discuss your exciting findings regarding the cosmic phenomenon AT 2021hdr. Can you start by telling us a little about what AT 2021hdr is?
**Dr. Hernández-García:** Absolutely! AT 2021hdr is a repeated astronomical event involving a pair of supermassive black holes located in the galaxy 2MASX J21240027+3409114, approximately one billion light-years away in the constellation Cygnus. This event has been observed to recur every few months, disrupting nearby gas clouds as the black holes interact with them.
**Editor:** That sounds fascinating! What exactly happens during these events?
**Dr. Hernández-García:** The phenomenon occurs as the gas clouds nearby are engulfed by the black holes. As the black holes orbit each other—spaced about 26 billion kilometers apart—they exert gravitational influence on the gas clouds, disrupting them. This results in light oscillation patterns that we can observe in different wavelengths, including ultraviolet and X-ray light.
**Editor:** Have you been able to determine the mechanism behind these interactions?
**Dr. Hernández-García:** Yes, we initially considered several possibilities, including traditional activities at the galaxy’s center and tidal disruption events involving stars. However, we eventually settled on the idea that tidal interference with the gas clouds is responsible. As the clouds approach a black hole, gravity tears them apart, forming dense filaments that heat up. The complex interactions during the black holes’ orbits lead to light fluctuations that we can observe.
**Editor:** You mentioned that these black holes have a significant mass. Can you elaborate on that?
**Dr. Hernández-García:** Certainly! Combined, the two black holes have a mass approximately 40 million times that of our Sun. They complete their orbits roughly every 130 days and are expected to collide and merge in about 70,000 years.
**Editor:** It sounds like you have your hands full with data around AT 2021hdr. What are your plans for future observations?
**Dr. Hernández-García:** We plan to continue observing this system with NASA’s Swift Observatory to better understand its dynamics and refine our models. Additionally, we are intrigued by the ongoing merger of the galaxy itself with a neighboring galaxy, which presents a whole new realm of study.
**Editor:** what excites you most about this discovery and the continued study of these cosmic phenomena?
**Dr. Hernández-García:** The dynamic interactions and the physics involved in black hole systems like AT 2021hdr offer incredible insights into our universe. It’s thrilling to witness how much we still have to learn about these magnificent structures. As we progress, I believe our understanding of the cosmos will continue to evolve in unexpected ways.
**Editor:** Thank you, Dr. Hernández-García, for sharing your insights with us. We look forward to following your ongoing research on AT 2021hdr!
**Dr. Hernández-García:** Thank you for having me! It’s a pleasure to discuss our work.
