Project Overview

The Cosmic dawn represents the first billion years in our Universe's history, where the seeds of galaxies such as our Milky Way first formed. These early galaxies, mostly dwarfs similar to the Large and Small Magellanic Clouds, were producing stars 100 times faster than today’s galaxies. According to current understanding, galaxies initially grow by accumulating gas from their surroundings, and later growth is predominantly driven by mergers with other galaxies. However, the exact moment when this transition occurs remains a key missing ingredient in our understanding of the early universe.   

Traditional observations struggle to analyse how galaxies formed within the first billion years due to their faintness and compactness. However, there is a special class of galaxies called Extreme Emission Line Galaxies (EELGs), where gas emits as intensely as stars at certain wavelengths. Less than 1% of the galaxies are EELGs in today’s universe, but EELGs made up almost 80-90% of the galaxies in the first billion year of the universe. Leveraging the nearer, hence brighter and easier to study galaxies, this research project aims to use EELGs as proxies (mimics) for the first galaxies. We will indirectly determine the physical process feeding the star formation and growth of central supermassive blackhole in EELGs.

Aims

Our project will use data from a new Australia-led survey on JWST “OutThere”. The OutThere survey will utilize the NIRISS instrument on JWST to target a small patch of sky, acquiring prism spectra in the F115W, F150W, and F200W filters for everything within the field of view. The survey will target either the Halpha or [OIII] emission lines for galaxies with redshifts between 1<z<5, detecting approximately 60,000 galaxies and roughly 600 EELGs within this redshift range.  We plan to combine the optical plus near-infrared data from the OutThere survey with the deep radio imaging from the MIGHTHEE survey on MeerKAT to reconstruct the star formation history and identify the contribution of active black holes to extreme emission lines.

Objectives

Year 1: Estimate emission line equivalent widths and identify extreme emission line galaxies  
Year 2: Reconstruct star formation history using gas emission (~ 10 Myr), radio luminosity (0.1-1 Gyr), and stellar continuum (>1Gyr) as probes at various timescales  
Year 3: Optical to radio spectral energy distribution fitting to determine the energy budget of AGNs

Significance 

JWST has is finding extremely massive galaxies as early as z~10 (300 Million years after the big bang), which requires extremely rapid stellar mass build-up. However, star formation history model remains one of the biggest uncertainty with different models producing wildly different stellar masses. Moreover, the observation of a hidden population of active black holes, some as massive as entire galaxies, has raised numerous questions about the seeds of early black holes and the mechanisms fueling their rapid growth.  This project will use radio observations to provide independent measurements of star formation history and the accreting black holes.

This research will be conducted at the Curtin Institute of Radio Astronomy (CIRA), which is the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR), a joint venture with the University of Western Australia supported by the Western Australian State government. The successful candidate will be in a vibrant research environment interacting with staff and students across the two ICRAR nodes who specialise in astronomical science, engineering, and high-performance computing.  

Data processing requirements are not expected to be significant, and can be met on any number of existing machines or facilities to which the candidate will be granted access, including dedicated machines and national facilities. They will also be part of the OutThere and MIGHTEE collaboration which are huge international projects. Along with the standard University support for computing and travel, additional ICRAR resources may be available to send PhD students to present their work at the Astronomical Society of Australia’s annual meeting, and participate in training and networking opportunities.

• Future Students

• Faculty of Science & Engineering
  • Science courses
  • Engineering courses

• Higher Degree by Research

• Australian Citizen
• Australian Permanent Resident
• New Zealand Citizen
• Permanent Humanitarian Visa
• International Student

• Merit Based

The annual scholarship package, covering both stipend and tuition fees, amounts to approximately $70,000 per year.

In 2024, the RTP stipend scholarship offers $35,000 per annum for a duration of up to three years. Exceptional progress and adherence to timelines may qualify students for a six-month completion scholarship.

Selection for these scholarships involves a competitive process, with shortlisted applicants notified of outcomes by November 2024.

1

All applicable HDR courses.

We are looking for a self-motivated PhD candidate with excellent organisation, problem solving and project management skills. Candidates with strong quantitative skills, including familiarity with python and astronomy are desired for this project. Must be eligible to enrol in PhD programs at Curtin.

 

Please send your CV, academic transcripts and brief rationale why you want to join this research project via the HDR expression of interest form to the project lead researcher, listed below. 

You must be enrolled in a Higher Degree by Research Course at Curtin University by March 2025.

Project Lead: Dr Anshu Gupta