An international research team, led by the Italian National Institute of Astrophysics (INAF), has used the James Webb Space Telescope (JWST) to capture an extraordinary event in the distant universe: the spectacular interaction between a quasar and two massive satellite galaxies in the PJ308-21 system.
This remarkable discovery provides new insights into the growth of galaxies in the early universe, offering insight into the processes that shaped the cosmos during its formative years.
Observation of quasar-galaxy interaction
In September 2022, the JWST Near Infrared Spectrograph (NIRSpec) observed the PJ308-21 Systemrevealing unprecedented details about this quasar-galaxy merger. The quasar, located in a galaxy that existed when the universe was less than a billion years old, was observed with remarkable precision.
The NIRSpec instrument captured the quasar’s spectrum with an uncertainty of less than 1% per pixel, allowing researchers to study the physical properties of the gas inside the quasar’s host galaxy and its companion galaxies. This high level of detail has provided valuable data that helps to understand the early stages of galaxy formation and the role of quasars in this process.
High metallicity and star formation
The host galaxy of PJ308-21 exhibits high metallicity and photoionization conditions typical of an active galactic nucleus (AGN), while one of the satellite galaxies exhibits low metallicity and photoionization induced by star formation. The second satellite galaxy, partially photoionized by the quasar, also exhibits high metallicity.
These observations confirm that the quasar and the surrounding galaxies High redshift quasars are highly evolved in terms of mass and metal enrichment and are growing steadily. Roberto Decarli, a researcher at INAF and lead author of the study, said: “Our study reveals that the black holes at the centres of high redshift quasars and the galaxies that host them are growing extremely efficiently and tumultuously from the first billion years of cosmic history, aided by the rich galactic environment in which these sources form.”
Innovative techniques for detailed analysis
The observations were carried out as part of one of nine projects led by Italy as part of the first observation cycle of the JWSTThe team used full-field spectroscopy, allowing them to observe the spectrum of the entire optical band for each pixel in the image.
This technique has made it possible to study various gas tracers and the properties of the ionized interstellar mediumincluding metallicity, dust obscuration, electron density and temperature, and star formation rate.
Federica Loiacono, astrophysicist and researcher at INAFhighlighted the importance of these observations: “Thanks to NIRSpec, we can for the first time study in the PJ308-21 system the optical band, rich in valuable diagnostic data on the properties of the gas near the black hole in the galaxy hosting the quasar and in the surrounding galaxies. We can see, for example, the emission of hydrogen atoms and compare it to the chemical elements produced by the stars to establish the metal richness of the gas of the galaxies.”
Insights from advanced data analytics
The data collected through these observations allowed researchers to delve deeper into the conditions and processes that occur in these first galaxiesBy studying the emission lines of different elements, the team was able to determine the properties of the ionized interstellar medium, such as the source and intensity of photoionizing radiation, metallicity levels, and electron density and temperature.
This detailed analysis gives a clearer picture of the physical conditions in the galaxies and how they interact with the quasar at their center. “The experience gained in reducing and calibrating these data, among the first collected with NIRSpec in integral field spectroscopy mode, has ensured a strategic advantage for the Italian community in managing similar data from other programs,” Loiacono said.
Implications for cosmic history
The ability to study the chemical composition and physical properties of galaxies in such detail has profound implications for our understanding of the cosmic history and chemical evolution of galaxies. The data collected by the JWST allows astronomers to map the metal enrichment in galaxies observed when the universe was still in its infancy.
Roberto Decarli pointed out: “Until a few years ago, data on metal enrichment (essential for understanding the chemical evolution of galaxies) were almost out of our reach, especially at these distances. Today, we can map them in detail in a few hours of observation, even in galaxies observed when the universe was still in its infancy.”
This ability to measure and analyze the chemical properties of first galaxies opens new avenues for understanding the processes that governed their formation and evolution.
The Transformative Impact of the James Webb Space Telescope
The results of this study not only shed light on the early growth and development of galaxies and black holes but also demonstrate the transformative impact of the advanced capabilities of the James Webb Space Telescope.
The JWST The sensitivity in the near and mid-infrared spectrum allows for unprecedented precision in observing distant objects, allowing for the collection of detailed data previously inaccessible. “This work has been a real ‘emotional rollercoaster’, with the need to develop innovative solutions to overcome the initial difficulties related to data reduction,” explained Decarli, highlighting the challenges and triumphs of the research process.
As the JWST As we continue to observe the universe, we hope to unveil revolutionary new discoveries that will deepen our understanding of the cosmos and the fundamental processes that have shaped its evolution.