Summer Research Programme 2021

Oxford Astrophysics hope to run a summer research programme for undergraduate physics students again in Summer 2021. We anticipate taking about 4 students, who will work with a supervisor in the department, usually a postdoctoral researcher or lecturer, on a self-contained research project. The programme will also include lectures on current astrophysics topics. Students will be encouraged to take part in department life (depending on restrictions at that time), joining researchers for coffee, discussions and seminars (currently taking place virtually).

Since the situation with Covid is currently unclear, we may have to make the difficult decision in the coming months to either cancel the programme, or consider running it remotely. If we do proceed with a remote programme, not all projects listed below may be available but we will be in touch with shortlisted candidates if this is the case. If the programme is run remotely, we will make sure that the computing resources needed for the selected projects are available to all selected candidates.

The projects run for typically 8 weeks, nominally 5 July through till the end of August. The duration may be adjusted to be shorter or longer, or to accommodate summer travel. Students will be paid as employees of the University, receiving a payment of £10.21 per hour (subject to tax and National Insurance deductions). 75% of the salary due for the entire project will be advanced during the first week to cover accommodation expenses, and the rest will be paid after completion of the project. The project is normally full-time but hours can be discussed with your supervisor. This may change if the programme takes place remotely.

Eligibility

Students currently in third year of a relevant undergraduate degree are eligible to apply. Students who have completed a 3-year undergraduate degree and are now taking a taught Masters course are also eligible, as long as they are not in their final year. Applications are welcome from institutes outside of Oxford. Unfortunately, due to UK visa regulations, we are only able to accept applications from candidates who do not require a visa to work in the UK. Note that from January 2021, this will also include students that live in the EU. EU students currently studying in the UK who have obtained Pre-Settled status are also welcome to apply. If you have queries about your personal circumstances, please get in touch with ashling.gordon@physics.ox.ac.uk

How to apply

We are now closed for applications and we expect to be in touch with candidates by the 9th April. Please note that due to the uncertainty of the current situation regarding Covid, we have now decided that this year our intern programme will be run remotely. For any administrative queries, contact Ashling Gordon on ashling.gordon@physics.ox.ac.uk

Projects

NLTE modelling of exoplanetary transmission spectra

Supervisor: Dr Mitchell Young (mitchell.young@physics.ox.ac.uk)

High resolution transit spectroscopy is one of the most powerful tool available to astronomers for studying the composition of exoplanetary atmospheres. However, to interpret such observations, astronomers rely on theoretical models, incorporating realistic physics from multiple disciplines (statistical mechanics, thermodynamics, etc). To prevent these theoretical models from becoming unmanageable, various simplifying assumptions are usually made. One of the most common is the assumption of Local Thermodynamic Equilibrium (LTE), replacing the physically realistic Non-Local Thermodynamic Equilibrium (NLTE). When NLTE is properly accounted for in models, signatures will appear in transmission spectra by changing the depth of absorption lines or causing lines to appear or disappear completely. In this project, the student will simulate exoplanetary atmospheric structures and transmission spectra, investigating the sensitivity of different spectral features to planetary and system parameters, with a focus on identifying observable NLTE effects. The modelling will be done using the multi-purpose NLTE astrophysical code Cloudy (Ferland et al, 2017).

Required Skills: Familiarity with Python, and basic terminal commands. Experience running programs from the command line and/or using SSH to remotely log into computers would be an asset, but not necessary.

Quenching in Galaxy Zoo

Supervisor: Prof Chris Lintott (chris.lintott@physics.ox.ac.uk)

Understanding how galaxies switch from mostly star formation to mostly quiescent is a fundamental problem in modern galaxy evolution theory. This project will use data from the Galaxy Zoo citizen science project, which has recently completed detailed morphological classification of galaxies from the DECaLS survey, to test the theory proposed by Chen et al. 2020, looking particularly at galaxies which are not the most massive in their haloes. It would suit a student who wants to learn or develop skills in coding and dealing with astronomical data.

Required skills: It would suit a student who wants to learn or develop skills in coding and dealing with astronomical data.

Finding the most interesting unusual galaxies

Supervisor: Prof Chris Lintott (chris.lintott@physics.ox.ac.uk)

A major challenge in processing the large datasets obtained by modern astronomical surveys is in finding the most unusual and interesting objects from amongst the millions in catalogues. Modern machine learning can find the most unusual objects (see weirdgalaxi.es for an example) - but most of these are artefacts, such as camera malfunctions, rather than discoveries. Novel citizen science projects, building on the experience gained with Galaxy Zoo and other Zooniverse projects, can work alongside machine learning to find unusual objects such as the Galaxy Zoo Peas, Boyajian’s star and more. This project will build and run such a project using a dataset such as those used by Galaxy Zoo, Planet Hunters or other existing projects. The project would suit a student with broad interests in observational astrophysics, and as citizen science is involved there is potential to get involved in public engagement alongside the main project.

Ignoring the unknown: redshift uncertainties in weak lensing data

Supervisor: Prof David Alonso (david.alinso@physics.ox.ac.uk)

Weak gravitational lensing is one of the most promising probes to shed light on the nature of dark energy and identify potential modifications to the theory of Gravity. Unfortunately, weak lensing constraints are usually contaminated by uncertainties in the radial positions of galaxies. This project will make use of statistical modelling and computing methods to study brute-force and "smart" schemes to fully marginalize over this source of uncertainty.

Required skills: This project is well suited to anyone wanting to develop coding and data analysis skills.

Calibrating the spectra of arc lamps for HARMONI wavelength calibration.

Supervisors: Prof Niranjan Thatte (Niranjan.Thatte@physics.ox.ac.uk) & Dr Matthias Tecza (matthias.tecza@physics.ox.ac.uk)

HARMONI is the first light, integral field spectrograph for the European Southern Observatory’s Extremely Large Telescope – a telescope with a 39 metre primary mirror that will dwarf all present-day ground based telescopes in size, sensitivity and angular resolution. Every spectrograph needs to accurately calibrate the wavelengths of the emission and absorption lines it observes, as this is central to identifying the species that are being observed, and measure the speeds at which they are moving away from us (or towards us). Typically, this is done by using arc lamps (similar in concept to the neon lamps used for illuminated neon signs) filled with a specific inert gas. The wavelengths of emission lines from each of these gases (Argon, Neon, Krypton, Xenon) are well known, but their relative intensities vary depending on the type of lamp used. We are looking to calibrate the relative intensities of the lines, using observed spectra from a number of existing instruments, so as to create a database of lines with correct relative intensities, that can be used (via a pattern matching algorithm) to calibrate the HARMONI spectrograph we are building at Oxford.

The summer student will help correct the observed spectra for instrument throughput and telescope transmission, themselves obtained through observations of standard stars. The fully intensity calibrated spectra will then be used via a pattern matching algorithm to derive the instrument’s wavelength calibration. A decent coding ability will be helpful. The student will learn about astronomical spectroscopy, spectra of stars of different types, and how to calibrate instruments (including effects of the earth’s atmosphere). The project can be done entirely remotely, via zoom / MS Teams.

Building and testing a temperature controlled Fabry-Perot Etalon.

Supervisors: Prof Niranjan Thatte (Niranjan.Thatte@physics.ox.ac.uk) & Dr Darshan Kakkad (darshan.kakkad@physics.ox.ac.uk)

HARMONI is the first light integral field spectrograph for the Extremely Large Telescope. Part of the instrument’s calibration involves calibrating the “line spread function” (LSF) – the response of the instrument to a truly monochromatic source. The LSF is expected to vary considerably with position along the (pseudo) slit and with wavelength. Accurate knowledge of the LSF is required for correct subtraction of the (time variable) sky background at near-infrared wavelengths. To adequately measure the LSF shape, we need a tunable frequency comb that covers the entire wavelength range of the instrument, from 450 nm to 2400 nm. The project will involve building a Fabry-Perot based frequency comb, whose frequency can be controlled by changing the temperature of the Fabry-Perot. A design has already been made as part of a Masters’ thesis project, the summer work will involve actual assembly and testing of the temperature controlled Fabry-Perot. The student will gain experience in optics, and high precision laboratory work in optics, mechanics, automation, and thermal control. The project is experimental in nature, and will only go ahead if pandemic restrictions allow laboratory work.

Characterizing the atmospheres of exoplanets using high-resolution transmission spectroscopy

Supervisor: Dr Baptiste Klein (baptiste.klein@physics.ox.ac.uk)

Over the last decade, high-resolution transmission spectroscopy has emerged as one of the most reliable techniques for probing the composition and physical properties of the atmosphere of transiting planets (see Birkby 2018, for a review). Thanks to its wide spectral domain over the YJHK bands and its high-resolving power of 70,000, the spectrometer SPIRou (Donati et al., 2020) at the Canada-France-Hawaii Telescope (atop Mauna Kea at Hawaii) is one of the best instrument worldwide for such study. Over the past few months, transits of various types of planets (e.g., hot Jupiters, Warm Neptunes) have been observed with SPIRou. The project will consist in searching for planet signatures in a few of these data sets using already-written easy-to-use python routines. This will involve the generation of simple models for the absorption signature of the planet’s atmosphere, and the use of data-driven techiques to reduce spectroscopic data and search for planet signatures therein.

Required skills : Moderate knowledge in statistics, moderate coding ability (preferably python and bash)

Shift-symmetric theories in view of DES and eBOSS

Supervisor: Dr Carlos Garcia-Garcia (carlos.garcia-garcia@physics.ox.ac.uk)

Shift-symmetric scalar-tensor theories can be described by just 4 parameters, those describing the equation of state of Dark Energy (and therefore, the expansion of the Universe), and two extra parameters that define the evolution of scalar perturbations. This project will explore the level to which current constraints from the Cosmic Microwave Background and supernovae can be improved by including galaxy clustering and weak lensing data from the Dark Energy Survey and the eBOSS quasar catalog.

Required skills: some experience with python is desirable, but not necessary.