A double quasar spiraling towards a big merger has been discovered, lighting up the ‘cosmic dawn’, just 900 million years after the Big Bang.
They are the first quasar pair spotted this far in cosmic time.
Quasars are growing rapidly supermassive black holes in the nuclei of hyperactive people galaxies. Torrents of gas are thrown down the throats of black holes and become stuck in the bottleneck of an accretion disk, which is a dense ring of ultrahot gas that is lining up to fall into the black hole. All this does not fall through; The magnetic fields enveloped in the rotating accretion disk are capable of lifting many charged particles and sending them back into deep space as two jets fleeing at almost the same distance. speed of light. The jets and accretion disk combined make the quasar appear very bright, even over billions of distances. Light years.
Since every large galaxy has a monstrous black hole Just like its dark heat, when galaxies collide and merge, their supermassive black holes eventually do the same. At the Cosmic Dawn – which describes the first billion years of cosmic history, when stars and galaxies first appeared on the scene – the expanding universe was smaller than it is today, and therefore galaxies were closer together and merged more often. Yet while more than 330 single quasars have been spotted so far in the universe’s first billion years, the expected abundant population of double quasars has been conspicuous by their absence – until now.
The newly discovered double quasar, J121503.42-014858.7 and J121503.55-014859.3 — called C1 and C2 by their discoverers — was spotted using the Subaru Telescope on Mauna Kea in Hawaii by a team led by Yoshiki Matsuoka of Ehime University in Japan.
Astronomers conducted spectroscopic tracking using the Faint Object Camera and Spectrograph (FOCAS) on Subaru and the Gemini Near-Infrared Spectrograph (GNIRS) on the Gemini North Telescope, which is also on the summit of Mauna Kea.
“What we learned from the GNIRS observations is that quasars are too faint to be detected in the near-infrared, even with one of the largest ground-based telescopes,” Matsuoka said in a statement. statement.
After traveling for 12.9 billion years, the light from quasars was redshifted and stretched to longer wavelengths by cosmic expansion, so that light that started as X-rays or ultraviolet ends near the red and infrared end of the wave. electromagnetic spectrum. Light from quasars should be detectable in the near infrared, but the fact that they are faint at this wavelength means that much of their light is actually at other wavelengths produced by the increased star formation in galaxies that host quasars.
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Increased star formation, which for C1 and C2 is estimated between 100 and 550 solar masses per year (compared to one to 10 solar masses per year in our Milky Way), is a common symptom of galaxy mergers, as raw molecular hydrogen is stirred up by the interaction and triggered by the formation of new stars.
The two black holes also came closer than 40,000 light years (12,000 parsecs). Although the distance is still great, observations with the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile found a gas bridge spanning this distance between C1 and C2. The two black holes are already connected, and this connection will only get stronger as they continue to get closer to each other.
The existence of C1 and C2 is further evidence that galaxies and their black holes grows quickly, and of immense size and mass, in the Age of Cosmic Dawn, challenging our models of how they should form. Black holes each have a mass approximately 100 million times that of our planet. sunwhich is enormous; Sagittarius A*, the black hole at the center of our Milky Way galaxy, is tiny in comparison, with a mass of just 4.1 million solar masses. Additionally, the host galaxies of C1 and C2 have overall masses on the order of 90 billion and 50 billion solar masses, respectively, which, while significantly lower than that of the Milky Way, is nonetheless gargantuan for the era.
As such, the discovery of this double quasar and its host galaxies provides vital data to better understand the early universe and in particular the reionization epoch, when most of the gas in the universe was ionized by the radiation of the first stars, galaxies and galaxies. quasars, ending the cosmic dark ages. One of the great enigmas of cosmology is which of these three things contributed the most to reionization.
“The statistical properties of quasars at the time of reionization tell us many things, such as the progression and origin of reionization, the formation of supermassive black holes at the cosmic dawn, and the first evolution of host galaxies of quasars,” Matsuoka said.
We see these two quasars as they were about 12.9 billion years ago. What has become of them since then? Simulations indicate that the two black holes will eventually merge in an explosion of gravitational waves. This will make the combined quasar even brighter and increase the rate of star formation in the merged galaxy above 1,000 solar masses per year, creating one of the most extreme galaxies in the universe. Ultimately, he could become one of the giants elliptical galaxies at the heart of a massive galaxy cluster, like M87 in the Virgo cluster.
The results were published on April 5 in Letters from the astrophysical journalwith a accompanying paper discuss ALMA measures.