Periodic Reporting for period 4 - BUILDUP (Galaxy Buildup in the Young Universe: from the First Billion Years through the Peak Activity Epoch)
Période du rapport: 2021-03-01 au 2022-02-28
Deep galaxy surveys are the most valuable asset to understand the history of our Universe. Still to date, important
discrepancies still exist between galaxy formation models and the results of galaxy observations, most notably for galaxies in the young Universe. The BUILDUP
Project aims to investigate the history of galaxy buildup from the first billion years of cosmic time
through the peak activity epoch of the Universe, which occurred 10 billion years ago, providing
fundamental constraints for galaxy formation models.
The BUILDUP Project has shed new light on our knowledge about galaxy formation and evolution in the first few billion years of cosmic time by:
- investigating, for the first time, the relation between galaxies and their large-scale environment at such early cosmic times;
- showing that galaxies can grow their stellar content in two different modes. The starburst mode, which is basically absent in galaxy formation theories, makes for most of the cosmic star formation rate budget of the Universe in the first few billion years.
Interestingly, rather than resolving some tensions between observations and galaxy models, the BUILDUP Project has demonstrated that there are even more aspects than thought in which the observational results and theoretical predictions for galaxy evolution are at odds. The results of my Project have then produced new challenges for galaxy formation theories.
discrepancies still exist between galaxy formation models and the results of galaxy observations, most notably for galaxies in the young Universe. The BUILDUP
Project aims to investigate the history of galaxy buildup from the first billion years of cosmic time
through the peak activity epoch of the Universe, which occurred 10 billion years ago, providing
fundamental constraints for galaxy formation models.
The BUILDUP Project has shed new light on our knowledge about galaxy formation and evolution in the first few billion years of cosmic time by:
- investigating, for the first time, the relation between galaxies and their large-scale environment at such early cosmic times;
- showing that galaxies can grow their stellar content in two different modes. The starburst mode, which is basically absent in galaxy formation theories, makes for most of the cosmic star formation rate budget of the Universe in the first few billion years.
Interestingly, rather than resolving some tensions between observations and galaxy models, the BUILDUP Project has demonstrated that there are even more aspects than thought in which the observational results and theoretical predictions for galaxy evolution are at odds. The results of my Project have then produced new challenges for galaxy formation theories.
In order to address the general goal of this Project, we are working with the most comprehensive infrared galaxy survey ever conducted with the Spitzer Space Telescope for the study of the early Universe (Spitzer Exploration Science Programme SMUVS - PI K. Caputi). The unprecedented characteristics of this survey, which has obtained deep infrared images over a relatively large area of the sky, are allowing us to study 66,000 galaxies present in the Universe in the first few billions years of cosmic time. Our main results in the BUILDUP Project so far can be summarised as follows.
1) We have discovered a new population of intense star-forming galaxies when the Universe was only 1.5 billion years old, i.e. about 10% of its present age. Although in number these galaxies were only a small percentage of all galaxies in the Universe, their individual star formation rates were so high that they were making altogether more than a half of all the stars being formed in the Universe at those cosmic times.
2) We have found that there are fundamental differences in the evolution of large and small galaxies in the young Universe. This refers to the way in which they form their stars, as well as how star formation eventually declines to make galaxies become quiescent.
3) We have quantitatively proved, for the first time, the large-scale structure traced by galaxies when the Universe was only a few billion years old. The early onset of galaxy large-scale structure is one of the key predictions of the most accepted cosmological model, which is the Lambda cold dark matter model.
In addition, we are conducting simulations to prepare for the scientific exploitation of the galaxy surveys that we will conduct with the forthcoming James Webb Space Telescope (JWST). This will be one of the most important telescopes operating next decade and is expected to revolutionise our view of the early Universe. With our ongoing work, we the BUILDUP Team are positioning ourselves as leaders for the analysis of JWST data.
Update at the end of the Project: The JWST has been successfully launched in December 2021. Indeed my research group is in a leading position to scientifically exploit its observations, which will start in the second half of 2022. Although my ERC CoG is over, the PI Caputi has secured a new big grant (1.5 MEUR) from the Dutch Research Council NWO to work on high-z galaxy studies with JWST data. This new Project will leverage all our work done during the ERC CoG period.
1) We have discovered a new population of intense star-forming galaxies when the Universe was only 1.5 billion years old, i.e. about 10% of its present age. Although in number these galaxies were only a small percentage of all galaxies in the Universe, their individual star formation rates were so high that they were making altogether more than a half of all the stars being formed in the Universe at those cosmic times.
2) We have found that there are fundamental differences in the evolution of large and small galaxies in the young Universe. This refers to the way in which they form their stars, as well as how star formation eventually declines to make galaxies become quiescent.
3) We have quantitatively proved, for the first time, the large-scale structure traced by galaxies when the Universe was only a few billion years old. The early onset of galaxy large-scale structure is one of the key predictions of the most accepted cosmological model, which is the Lambda cold dark matter model.
In addition, we are conducting simulations to prepare for the scientific exploitation of the galaxy surveys that we will conduct with the forthcoming James Webb Space Telescope (JWST). This will be one of the most important telescopes operating next decade and is expected to revolutionise our view of the early Universe. With our ongoing work, we the BUILDUP Team are positioning ourselves as leaders for the analysis of JWST data.
Update at the end of the Project: The JWST has been successfully launched in December 2021. Indeed my research group is in a leading position to scientifically exploit its observations, which will start in the second half of 2022. Although my ERC CoG is over, the PI Caputi has secured a new big grant (1.5 MEUR) from the Dutch Research Council NWO to work on high-z galaxy studies with JWST data. This new Project will leverage all our work done during the ERC CoG period.
The strategic importance of the BUILDUP Project resides in bridging current infrared galaxy surveys with the next generation of either much more sensitive or wider-area galaxy surveys for the early Universe. This connection has been possible by exploiting the most sophisticated infrared deep galaxy surveys available to date and making quantitative predictions for future studies of galaxies in the early Universe with the two major infrared telescopes of this new decade: JWST and Euclid. With JWST now starting to be operational and the Euclid mission soon to be launched, the full legacy of the BUILDUP Project will be evident in the coming years.