Dr. Guido Roberts-Borsani 


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My name is Guido Roberts-Borsani,

I'm a postdoctoral researcher at the University of California, Los Angeles (UCLA) working on galaxy formation and evolution over the first billion years of the Universe in Prof. Tommaso Treu's group. Below you can find a brief summary of my education and career to date.

I completed an MPhys degree (First Class) in Astronomy, Space Science & Astrophysics at the University of Kent in 2014, while also spending a year at the University of California, San Diego. Following the completion of my MPhys, I worked at the European Space Agency (ESTEC) in the Netherlands as a research intern and subsequently remained in the country to work at Leiden University where I contributed to numerous high-impact scientific publications on distant (or high redshift) galaxies. I began my Ph.D at University College London (UCL) in the early months of 2015 working with Prof. Am‌élie Saintonge (primary supervisor) and Prof. Richard Ellis (secondary supervisor) on the cycle of gas in and out of galaxies in the local Universe and how these shape galaxy evolution over cosmic time, as well as the development of detection and characterisation techniques of ultra-distant galaxies at the boundary of our most powerful telescopes' capabilities. I successfully defended my thesis in July of 2019 and have since started a postdoc at the University of California, Los Angeles (UCLA), on ultra high redshift galaxies in preparation for the arrival of the James Webb Space Telescope in 2021.

For more information, see a list of my publications on NASA ADS or download my full CV below. Alternatively, click on the Research tab above to read about my past and current research.




Astronomers try to map out the mass build-up of galaxies over cosmic time. To do this, we must understand the key periods and phenomena that shape them, their surroundings, and the Universe as a whole. My research interests fall under two broad categories: a period of the early Universe called the "Epoch of Reionization", when the first stars and galaxies formed and largely shaped the Universe into what we see today, and the cycling of gas in and out of galaxies that regulates their gas contents, star formation, and metallicities.

To observe these galaxies and phenomena, astronomers require powerful telescopes to build up large samples with which to understand their properties. My research primarily makes use of optical, near-infrared, sub-millimetre and radio data coming from several space- and ground-based telescopes (e.g., Hubble Space Telescope/WFC3Spitzer Space Telescope/IRACKeck/MOSFIREVLT/X-ShooterIRAM 30mArecibo), however much of my work also makes use of large dedicated surveys such as the SDSS DR7SDSS-IV/MaNGAxCOLD GASS, and ALFALFA.

Currently, the main focus of my research revolves around developing detection and characterisation techniques of galaxies right at the frontier of the high-redshift Universe (roughly redshifts z>8). This research is roughly divided into (i) the analysis of spectral observations from Keck and (ii) the detection of z~8-10 galaxies with HST and Spitzer from e.g., the "Brightest of Reionizing Galaxies" (BoRG) survey. The predominant fraction of my work, however, revolves around leading preparatory efforts (i.e., simulating observations of the z>8 Universe, developing data reduction pipelines, and outreach communication) for the much-anticipated James Webb Space Telescope, as part of the approved ERS program "Through the Looking GLASS" (ERS 1324, PI: Treu) - which will observe the Abell 2744 Frontier Field cluster with the NIRISS and NIRSpec instruments, in tandem with NIRCam parallel observations - and my own approved Cycle 1 program "Linking Bright Galaxy Properties to IGM Opacity and Environment in the Early Epoch of Reionization with NIRSpec" (GO 1747, PI: Roberts-Borsani) which will observe 10 of the most distant galaxies currently known with NIRSpec.

For a more in-depth look at my research interests and recent contributions, click on any of the thumbnails below.


Local Universe


Distant Universe


Recent Contributions

Recent highlights

11.06.2021  We present the largest space-based search to date of the first galaxies with the Hubble Space Telescope, and use complementary observations with the Keck and Spitzer Space telescopes to characterize their properties! Have a read here!

16.04.2021  Our work on characterising Balmer breaks in ultra-distant (z>9) galaxies with ground based spectroscopy (Keck, VLT, ALMA and Gemini) has been accepted for publication in MNRAS! Have a read here!

30.03.2021  We have been awarded valuable 25.1 hrs of JWST Cycle 1 time (GO 1747, PI Roberts-Borsani) to observe 10 distant galaxies with NIRSpec! Read more on the Space Telescope website here!



I am a regular and keen partaker in outreach events and science communication to the general public, and also regularly give interviews with the press on findings and upcoming events. Should you like to get in touch, please feel free to contact me using any of the details highlighted below.
Department of Physics & Astronomy,
University of California, Los Angeles,
475 Portola Plaza, CA 90095, USA

guidorb -at-