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David Sobral supervises 3 postgraduate research students. If these students have produced research profiles, these are listed below:

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Dr David Sobral FHEA FRAS

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David Sobral

Physics Building

LA1 4YB

Lancaster

Tel: +44 1524 593529

Office Hours:

Friday, 10-11am + e-mail and open door policy

Research overview

I conduct a wide range of observations at various wavelengths and use the best telescopes in the world (and in space) in order to understand how galaxies like our own Milky-Way formed and evolved from the primitive Universe till today. I also look for and study some of the most distant, early galaxies. Most of my research is done by conducting and exploring some of the largest/widest narrow-band surveys ever done, particularly for sources with emission lines which result from either very hot, young stars, or super-massive black holes. Due to the uniform and self-consistent selection, galaxies found with the narrow-band technique across cosmic time are ideal to understand how they have changed accross cosmic time, but also to conduct detailed follow-up studies that can really unveil the physics and nature of distant sources. ADS list of all my publications.


I'm also keen to provide the opportunity for students to experience state-of-the-art research, particularly by running the XGAL internships: https://xgalweb.wordpress.com.

PhD supervision

Towards the direct discovery of first generation stars in our backyard


This project will allow the student to take part in a recent hunt for the most metal poor stars up to the outskirts of the halo of our own Milky Way. Finding such extreme stars born in the early Universe but still shinning today allow us to unveil their nature. Most interestingly, very metal-poor stars allow us to become “stellar archeologists” and understand the properties of the very first generation of stars that gave rise to the traces of heavy elements that led to their creation. Potentially, we may be able to find first generation stars which may have survived until today. Finding and studying first-generation stars that may still be shinning in the halo of the Milky Way will be a major breakthrough in Astrophysics, not only to provide new tests and constraints to state-of-the-art models, but also because we will be able to study the generation of stars that literally invented chemistry and that is directly linked with our cosmic origins. The project will involve modelling of several observed and model stars to mimic observations and confront predictions with brand new data taken by us. Data have been taken using the INT telescope in La Palma and the CFHT telescope in Hawaii with narrow-band filters that capture a strong Calcium absorption feature in stars which becomes weaker for the most metal poor stars. Our Lancaster-led data-set is the deepest ever done with this filter in the ultra-violet, and allows us to see metal poor stars individually up to the outskirts of the halo of our Milky Way.


The physics of the first galaxies and their evolution in the epoch of re-ionisation


One of the most exciting open problems in Astrophysics is understanding the nature and evolution of the very first galaxies, stars and black holes, but also how they changed the Universe as a whole and ended the dark ages. This PhD project will allow the student to conduct and explore the largest surveys for very distant galaxies (Lyman-α emitters) and push them to the highest look back times when the Universe was only 700 Myrs or less. The student will reduce, analyse and explore near-infrared photometric data in the COSMOS field from the recently concluded (100%) Y-NBS survey (PI: Sobral) on the Very Large Telescope in Chile, which had an allocation of 50 hours in excellent observing conditions. The Y-NBS survey is the widest ever conducted for distant bright Lyman-α sources, even more distant than the CR7 galaxy (Sobral et al. 2015) and the student is expected to find up to 20 new bright distant galaxies, along with 1000s of other lower redshift starburst galaxies and AGN. The student will also explore our state-of-the-art datasets that have just been obtained with the Hubble Space Telescope, ALMA and with other instruments on the VLT in Chile, to place the newly discovered galaxies into a wider context and test state-of-the-art models. The second part of the project will involve obtaining and exploring follow-up observations, including spectroscopy at a variety of wavelengths with the GTC (on-going program) in La Palma, in order to investigate the physics of the first galaxies. This will involve a close link with photo-ionisation and radiative transfer models and will provide some of the first measurements of the metallicity, ionisation parameters and other properties of early galaxies. The results will provide crucial new information to improve our currently limited understanding of the re-ionisation epoch and how distant bright galaxies may have played a crucial role in such process.

Current Teaching

  • PHYS111: Functions and Differentiation (2016--)
  • PHYS263: Astronomy (2016--)
  • PHYS264: Astrophysics I (2017-2018)
  • PHYS369: Observational Astrophysics group project (2018--)

Research Interests

Galaxy formation and evolution; Emission-line galaxies; High-redshift galaxies; Re-ionisation of the Universe; The star formation history of the Universe; Hot/massive stars; Super-massive black holes

Web Links

Research Grants

  • Observational Astrophysics PATT grant (2018-2020)
  • Observational Astrophysics PATT grant (2016-2018)
  • NWO VENI grant (2012-2016): "From the First Galaxies to the Peak of the Star Formation History"
  • FCT Starting grant (2013-2015)

PhD Supervisions Completed

  • Dr. Andra Stroe (2015, Leiden University, co-supervision). Currently: CfA Clay fellowship at the Harvard-Smithsonian (previously: ESO fellow), U.S.A.
  • Dr. Behnam Darvish (2015, University of California Riverside, co-supervision). Currently a postdoctoral fellow at the California Institute of Technology (Caltech), U.S.A.
  • Dr. Jorryt Matthee (2018). Currently: Zwicky Prize Fellow at ETH Zurich, Switzerland.
  • Dr. Ali Khostovan (2018). Currently: NASA NPP Fellow at NASA Goddard, U.S.A.
  • Ana Paulino-Afonso (2019). Currently: Postdoctoral fellow at the Max Planck Institute for Extraterrestrial Physics (MPE), Garching, Germany.

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