Gemini North ayuda a confirmar la naturaleza de un sistema cósmico a punto de convertirse en una galaxia elíptica gigante.

Utilizando una combinación de telescopios terrestres y espaciales, incluido Gemini North en Hawái, los astrónomos han descubierto un par de cuásares activos muy unidos, el sello distintivo de un par de galaxias fusionadas, visto cuando el universo tenía solo tres mil millones de años. . El descubrimiento arroja luz sobre la evolución de las galaxias en un «mediodía cósmico», un período en la historia del universo cuando las galaxias experimentaron estallidos de furiosa formación estelar. Esta fusión también marca un sistema a punto de convertirse en una galaxia elíptica gigante.

Las galaxias crecen y evolucionan fusionándose con otras galaxias, mezclando sus miles de millones de estrellas, provocando ráfagas de poderosa formación estelar y, a menudo, alimentando agujeros negros supermasivos centrales para producir cuásares luminosos que eclipsan a toda la galaxia. Eventualmente, algunas de estas fusiones se convirtieron en enormes galaxias elípticas que contienen agujeros negros de miles de millones de veces la masa de nuestro sol. Aunque los astrónomos han observado un verdadero grupo de fusiones de galaxias con más de un cuásar en nuestro vecindario cósmico, los ejemplos distantes, vistos cuando el universo tenía solo una cuarta parte de su edad actual, son muy raros y difíciles de encontrar.

Al aprovechar una combinación de observatorios terrestres y espaciales, incluido Gemini North, la mitad del Observatorio Internacional Gemini, que es operado por NSF[{» attribute=»»>NOIRLab — a team of astronomers has discovered a closely bound pair of actively feeding supermassive black holes — quasars. This discovery is the first confirmed detection of a pair of supermassive black holes in the same galactic real estate at ‘cosmic noon’ — a period of frenetic star formation at a time when the Universe was only three billion years old.

Previous observations have identified similar systems in the early stages of merging, when the two galaxies could still be considered clearly separate entities. But these new results show a pair of quasars blazing away in such close proximity, a mere 10,000 light-years apart, that their original host galaxies are likely well on their way to becoming a single giant elliptical galaxy.

Searching for pairs of supermassive black holes so close to each other during this early epoch is like trying to find the proverbial needle in a haystack. The challenge is that most black-hole pairs are too close to distinguish individually. To definitively detect such a system, the two supermassive black holes need to be actively accreting and shining as quasars simultaneously, conditions that are extremely rare. Statistically, for every 100 supermassive black holes only one should be actively accreting at a given time.

Astronomers know, however, that the distant Universe should be brimming with pairs of supermassive black holes embedded within merging galaxies. The first hints of such a system were found in data from the NASA/ESA Hubble Space Telescope, which revealed two closely aligned pinpoints of light in the distant Universe.

To verify the true nature of this system, the team searched through ESA’s Gaia observatory’s vast database and found that this system had an apparent “jiggle,” which could be the result of sporadic changes in a black hole’s feeding activity.

The team then used the Gemini Multi-Object Spectrograph (GMOS) and GNIRS on Gemini North, which provided the team with independent measurements of the distance to the quasars and confirmed that the two objects were both quasars rather than a chance alignment of a single quasar with a foreground star. Further studies with the W.M. Keck Observatory, NSF’s Karl G. Jansky Very Large Array, and NASA’s Chandra X-ray Observatory also helped to confirm these observations.

“The confirmation process wasn’t easy and we needed an array of telescopes covering the spectrum from X-rays to the radio to finally confirm that this system is indeed a pair of quasars, instead of, say, two images of a gravitationally lensed quasar,” said co-author Yue Shen, an astronomer at the University of Illinois.

“We don’t see a lot of double quasars at this early time. And that’s why this discovery is so exciting. Knowing about the progenitor population of black holes will eventually tell us about the emergence of supermassive black holes in the early Universe, and how frequent those mergers could be,” said graduate student Yu-Ching Chen of the University of Illinois at Urbana-Champaign, lead author of this study, which is published in the journal Nature.

For more on this discovery:

Reference: “A close quasar pair in a disk–disk galaxy merger at z = 2.17” by Yu-Ching Chen, Xin Liu, Adi Foord, Yue Shen, Masamune Oguri, Nianyi Chen, Tiziana Di Matteo, Miguel Holgado, Hsiang-Chih Hwang and Nadia Zakamska, 5 April 2023, Nature.
DOI: 10.1038/s41586-023-05766-6