Nasin rentgenski observatorij Chandra je zaznal dva para supermasivnih črnih lukenj na poteh trčenja v pritlikavih galaksijah, kar je prvi dokaz tako neizbežnega srečanja. Odkritje zagotavlja pomembne informacije o razvoju črnih lukenj v zgodnjem vesolju.

• Milky Way, likely formed larger galaxies through collisions in the early Universe.
• These newly-discovered merging dwarf galaxies can be used as analogs for more distant ones that are too faint to observe.
• The dwarf galaxies are on collision courses and are found in the galaxy clusters Abell 133 and Abell 1758S.

Evidence for two pairs of supermassive black holes in dwarf galaxies on collision courses has been found with Chandra. The two pairs are shown in X-rays from Chandra and optical light from the Canada-France-Hawaii telescope. The merger on the left is in a late stage and was given the single name of Mirabilis. The other merger is in the early stages and the two dwarf galaxies are named Elstir (bottom) and Vinteuil (top). Astronomers think that dwarf galaxies – those about 20 times less massive than the Milky Way – grow through mergers with others. This is an important process for galaxy growth in the early Universe and this discovery provides examples for scientists to study in greater detail. Credit: X-ray: NASA/CXC/Univ. of Alabama/M. Micic et al.; Optical: International Gemini Observatory/NOIRLab/NSF/AURA

A new study using NASA’s Chandra X-ray Observatory has tracked two pairs of supermassive black holes in dwarf galaxies on collision courses. This is the first evidence for such an impending encounter, providing scientists with important information about the growth of black holes in the early Universe.

By definition, dwarf galaxies contain stars with a total mass less than 3 billion Suns — or about 20 times less than the Milky Way. Astronomers have long suspected that dwarf galaxies merge, particularly in the relatively early Universe, in order to grow into the larger galaxies seen today. However, current technology cannot observe the first generation of dwarf galaxy mergers because they are extraordinarily faint at their great distances. Another tactic — looking for dwarf galaxy mergers closer by — had not been successful to date.

Nova študija je premagala te izzive z izvajanjem sistematične raziskave globokih lunarnih rentgenskih opazovanj in njihovo primerjavo z infrardečimi podatki iz Nasinega Wide Infrared Survey Explorer (WISE) in optičnimi podatki iz kanadsko-francosko-havajskega teleskopa (CFHT).

Chandra je bila še posebej dragocena za to študijo zaradi materiala, ki ga obdaja črne luknje se lahko segreje na milijone stopinj, kar povzroči velike količine rentgenskih žarkov. Ekipa je iskala pare svetlih virov rentgenskih žarkov v trkih pritlikavih galaksij kot dokaz za dve črni luknji in našla dva primera.

Najdeni so bili dokazi za dva para supermasivnih črnih lukenj v pritlikavih galaksijah na trkih s Chandro. Oba para sta prikazana na rentgenskih žarkih iz Chandre in v optični svetlobi s teleskopa Kanada-Francija-Havaji. Združitev na levi je v zaključni fazi in je dobila enotno ime mirabilis. Druga združitev je v zgodnji fazi in dve pritlikavi galaksiji se imenujeta Elastir (spodaj) in Vinteuil (zgoraj). Astronomi menijo, da pritlikave galaksije – ki so približno 20-krat manjše od Rimske ceste – rastejo z združitvijo z drugimi. To je pomemben proces za razvoj galaksij v zgodnjem vesolju in odkritje daje znanstvenikom primere za podrobnejše preučevanje. Zasluge: Rentgen: NASA/CXC/Univerza. Alabama / M. Micič et al.; Optično: Mednarodni observatorij Gemini/NOIRLab/NSF/AURA

En par je v jati galaksij Abell 133, ki se nahaja 760 milijonov svetlobnih let od Zemlje, kar lahko vidite na sestavljeni sliki na levi. Rentgenski podatki Chandra so rožnati, optični podatki CFHT pa modri. Zdi se, da je ta par pritlikavih galaksij v poznejših fazah združitve in ima dolg rep zaradi učinkov plimovanja zaradi trka. Avtorji nove študije so ga po ogroženih poimenovali “mirabilis”.[{” attribute=””>species of hummingbird known for their exceptionally long tails. Only one name was chosen because the merger of two galaxies into one is almost complete. The two Chandra sources show X-rays from material around the black holes in each galaxy.

X-ray and optical composite of Mirabilis. Credit: X-ray: NASA/CXC/Univ. of Alabama/M. Micic et al.; Optical: International Gemini Observatory/NOIRLab/NSF/AURA

The other pair was discovered in Abell 1758S, a galaxy cluster about 3.2 billion light-years away. The composite image from Chandra and CFHT is on the right, using the same colors as for Mirabilis. The researchers nicknamed the merging dwarf galaxies “Elstir” and “Vinteuil,” after fictional artists from Marcel Proust’s “In Search of Lost Time”. Vinteuil is the galaxy on the top and Elstir is the galaxy on the bottom. Both have Chandra sources associated with them, again from X-rays from material around the black holes in each galaxy. The researchers think these two have been caught in the early stages of a merger, causing a bridge of stars and gas to connect the two colliding galaxies from their gravitational interaction.

X-ray and optical composite of Elstir & Vinteuil. Credit: X-ray: NASA/CXC/Univ. of Alabama/M. Micic et al.; Optical: International Gemini Observatory/NOIRLab/NSF/AURA

The details of merging black holes and dwarf galaxies may provide insight to our Milky Way’s own past. Scientists think nearly all galaxies began as dwarf or other types of small galaxies and grew over billions of years through mergers. Follow-up observations of these two systems will allow astronomers to study processes that are crucial for understanding galaxies and their black holes in the earliest stages of the Universe.

Članek, ki opisuje te rezultate, je bil objavljen v zadnji številki Astrophysical Journal,

Referenca: Marko Mikić, Olivia J. Holmes, Brenna N. Wells in Jimmy A. “Dva kandidata za dvojni AGN v združitvah pritlikavih in pritlikavih galaksij”, avtor Irwin, 22. februar 2023, na voljo tukaj. Astrophysical Journal,
DOI: 10.3847/1538-4357/aca1bb

Avtorji študije so Marco Mick, Olivia Holmes, Brenna Wells in Jimmy Irwin, vsi z Univerze Alabama v Tuscaloosi.

Nasin Marshall Space Flight Center upravlja lunarni program. Rentgenski center Chandra astrofizikalnega observatorija Smithsonian nadzoruje znanstvene operacije iz Cambridgea v Massachusettsu in letalske operacije iz Burlingtona v Massachusettsu.