Exploring the epoch of first light and the cosmic history of galaxies

Lead Research Organisation: University of Edinburgh
Department Name: Sch of Physics and Astronomy


Exploring the epoch of first light and the cosmic history of galaxies. The aim of my research proposal is to explore one of the key frontiers of modern science and address some of the most outstanding questions in extra-galactic astrophysics: when did the first galaxies form and how did they evolve to form the complexity and variety of systems we see around us today? Several pieces of evidence now suggest that the epoch of ``first light'', when the first galaxies formed, should have occurred just a few hundred million years after the initial Big Bang. This early epoch, when the first substantial systems of stars began to shine represents a key step in the history of the Universe, which shaped the entire evolutionary history of galaxies thereafter. However, despite dramatic technological advances in our ability to study distant galaxies, very little is currently known about these primeval epochs, and ``a single example of the first generation of galaxies is yet to be observed''. Therefore, many questions still need to be answered. When did the first star-formation begin and how rapid was it? Were these sources similar to the stars and galaxies we observe today? And how did the heating from these first sources affect the subsequent history of galaxy formation? The main reason for the lack of any direct information on this fundamental epoch is that these sources are completely invisible to classic optical telescopes. In fact, due to the expansion of the Universe, the optical/ultraviolet light from these extremely distant galaxies is shifted towards longer wavelengths and is detectable only in the infrared. Until now, deep astronomical observations in the near-infrared have been technologically challenging and limited to very small areas in the sky. This, combined with the rarity and faintness of the most distant galaxies, has made these sources extremely difficult to discover. However, new facilities on ground-based and space-borne telescopes, have recently facilitated a series of surveys which, over the next 3-5 years, promise to revolutionise our understanding of galaxy formation. Exploiting my key position in these new initiatives and building on my recent successful research, I will be able to explore the uncharted Universe at the epoch of the first galaxies. I will use these revolutionary new datasets to isolate several hundred primeval galaxies, obtaining accurate measurements of their distance and, more crucially, their masses, the rate at which they are forming stars and their age. This will provide the first direct census of the first and most distant galaxies in the Universe, giving fundamental insight into the physics of the first stars and providing invaluable constraints to the models of galaxy formation. In addition to the study of the young Universe described above, I will exploit the unique power of these new surveys to obtain a truly representative picture of the evolution of galaxies over all of cosmic time. In fact, tracing the assembly history of galaxies from the formation of the first stars, 13 billions years ago, through the entire history of the Universe remains a primary goal for observational and theoretical cosmology. In the nearby Universe we observe a large variety of galaxies, differing in size, morphology, stellar content, mass, environment etc. How did this heterogeneity come to be? Armed with a unique sample of half a million galaxies spanning 90\% of the history of the Universe I will be able to directly observe the building process of stars in the various type of galaxies (e.g. ellipticals, spirals, irregulars) as a function of cosmic time. It will be possible, for example, to understand why and when most of the massive galaxies ceased to form stars a long time ago, while other galaxies, like our own Milky Way, are still actively forming stars today.


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Ivison R (2010) The far-infrared/radio correlation as probed by Herschel in Astronomy and Astrophysics

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Bruce V (2014) The bulge-disc decomposed evolution of massive galaxies at 1 < z < 3 in CANDELS in Monthly Notices of the Royal Astronomical Society

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Sobral D (2010) The clustering and evolution of Ha emitters at z ~ 1 from HiZELS in Monthly Notices of the Royal Astronomical Society

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Dunlop J (2010) The BLAST 250 µm-selected galaxy population in GOODS-South BLAST 250 µm galaxies in GOODS-South in Monthly Notices of the Royal Astronomical Society

Description Over the past 5 years I have led several projects on the assembly history of galaxies based on deep multi-wavelength surveys, using both ground-based and space-borne facilities. My expertise in deriving accurate physical properties of distant galaxies (their distance, stellar mass, rate at which they are forming stars, etc.) has proved to be of pivotal importance in several large collaborations (e.g. the UK-led project UKIDSS Ultra Deep Survey and the large Treasury program CANDELS with Hubble Space Telescope). In a series of ground-breaking works, which I co-lead, my modeling of the observed properties of galaxies proved essential in our quest for the very first galaxies. We discovered the most distant and earliest known galaxies, just few hundred million years after the Big Bang more than 13 billion light-years away from us. These publications have placed highly cited constraints on the number density, evolution of physical and clustering properties of the primordial galaxies, helping our understanding of the key epoch of cosmic re-ionization of the Universe.

In 2009, I also became the Instrument Scientist for the new powerful KMOS instrument recently installed at the Very Large Telescope in Chile. KMOS is capable to perform 3D spectroscopy for 24 objects simultaneously at near-infrared wavelengths (see https://www.youtube.com/watch?v=OyXd9gp--5c). I have led the scientific verification of the instrument and the commissioning at the telescope. Building on my scientific expertise and in depth knowledge of KMOS, I am now the Principal Investigator of a large KMOS Guaranteed Time science programme, which just started observations, to unveil the physical processes that drive the evolution of galaxies over the first 4 billion years of the history of the Universe. This is a key epoch encompassing the shining of the first galaxies and the remarkable event of the re-ionization of the Universe; the morphological transformation of galaxies and settling into discs and bulges; the peak of star-formation and the subsequent quenching in the most massive systems.

In 2010, I also saw an opportunity to expand the research capability of the UK astronomy community by developing a new instrument. I took the initiative to launch the MOONS project to build a Multi-Object Optical and Near-infrared Spectrograph for the Very Large Telescope (see www.roe.ac.uk/~ciras/MOONS.html). I am the Principal Investigator of the project, and I coordinate the international consortium and chair the Executive Board. The project has been recently awarded a contract by the European Southern Observatory (ESO), and building such an ambitious and powerful new instrument will take around 200 staff-years of effort and the hardware alone will cost €10M.
This instrument will be even more powerful than KMOS, and able to observe 1000 objects simultaneously. MOONS has the observational power needed to unveil galaxy formation and evolution over the entire history of the Universe, by providing detailed physical, chemical, dynamical and environmental properties of millions of stars in our own Milky Way, as well as for millions of distant galaxies across cosmic time.
Exploitation Route Using new instruments like MOONS, KMOS and James Webb Telescope e have to continue our quest to understand the formation of the very first galaxies and how they evolve in time.

My expertise in near-infrared spectroscopy and the technology development done for MOONS and KMOS (e.g. micro-robotics, near-IR detectors, cryogenic mechanisms) can have other applications in new ground-based instrument and future aerospace projects.
Sectors Aerospace, Defence and Marine,Education

URL http://www.roe.ac.uk/~ciras/MOONS.html
Description The funding has been used to support my research for 5 years. I have focused my activities in the field of Astrophysics and in particular in understanding the formation and evolution of galaxies. Over the duration of the grant (started in October 2009) I have authored 57 articles in international peer-reviewed journals, collecting 3300 citations. Currently my Hirsch index is 39. During the fellowship I have also been active in the field of astronomical instrumentation. I have successfully led the commissioning of the KMOS instrument at the Very Large Telescope in Chile. This is a unique instrument able to perform near-IR spectroscopy of 24 targets simultaneously. It represents a substantial leap forward compared to previous instruments which were able to observe only one object at the time. As part of the Guaranteed Time Observations with KMOS I am leading a large survey to study the chemical and dynamical properties of the very first galaxies at redshift z>3. Building on the experience gained with KMOS, I have the proposed and become Principal Investigator of a new project to build the next generation of multi-object spectrograph for the VLT. The project called MOONS has been recently approved by ESO and signed a contract to go ahead with contraction. The aim is to provide the astronomical community with a powerful and versatile instrument to understand galaxy formation across the entire history of the Universe, from stars in our Milky Way to very distant galaxies. The instrument will be able to observe 1000 targets simultaneously across the optical and near-IR wavelength range and will be fully operational by 2019.
First Year Of Impact 2010
Sector Education,Other
Impact Types Cultural

Description CANDELS 
Organisation Space Telescope Science Institute
Country United States 
Sector Academic/University 
PI Contribution CANDELS is the largest program ever approved with Hubble space telescope. I am co-Investogator of the program, I have contributed to the proposal phase and now start exploiting the new datasets.
Collaborator Contribution Provide access to the CANDELS dataset
Impact The first set of data has been taken last winteer and it is currently being analysed. A series of papers on the nature of very distant galaxies is foreseen to be published in the next few months.
Start Year 2010
Description Herschel HerMES 
Organisation University of Sussex
Department Physics and Astronomy Department
Country United Kingdom 
Sector Academic/University 
PI Contribution I am coordinator of the photometric redshift working group for the Herschel HerMES survey
Collaborator Contribution Access to unique data taken from the Herschel Satellite
Impact Several publications on the nature of dust obscured star-forming galaxies.
Start Year 2010
Description KMOS 
Organisation European Southern Observatory (ESO)
Country Germany 
Sector Charity/Non Profit 
PI Contribution KMOS is an international project to build a new multi-object integral field spectrograph for the Very Large Telescope. I am currently collaborating to the project as intrument scientist.
Collaborator Contribution Provide acceess to the Guaranteed Time Observations with KMOS
Impact KMOS is nearly completed and should start observations early 2012. I will be leading a large observational program to understand the formation and evolution of galaxies.
Start Year 2009
Description Video on KMOS for Backstage science 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact The video is avalable on the Backstage Science webpage (www. backstagescience.com) and youtube, providing large visibility and aiming at disseminating of scientific and technological achievement STFC founded projects.

The video has collected already more than 10,000 viewers.
Year(s) Of Engagement Activity 2011
URL http://www.youtube.com/watch?v=OyXd9gp--5c