2026 Project Description

What powers the radio emission from the most luminous starbursts?

Supervisors

Hiddo Algera
Find out more about supervisors on ASIAA website

Task Description and Goals

While the average galaxy in the present-day Universe is only slowly forming stars, galaxy growth happened much more rapidly at earlier cosmic times. In the period known as Cosmic Noon (redshifts z~1-4; roughly 8 to 12 billion years ago), galaxy assembly was at its peak, with the population of Dusty Star-forming Galaxies (DSFGs) being the most extreme star-forming factories. The brightest DSFGs can have star formation rates exceeding 1000 solar masses per year — more than 500x that of the Milky Way — making them a crucial population for our understanding of galaxy evolution.

Radio (cm-wave) observations are particularly important to study DSFGs, as they are uniquely able to reveal both star formation activity without being affected by obscuration from dust, as well as activity from a central accreting black hole (i.e., an active galactic nucleus; AGN). In the absence of a bright radio AGN, the measured radio emission from galaxies is expected to correlate with their star formation rates. However, it is unclear if the brightest DSFGs follow this correlation. Given that in the next few years the Square Kilometer Array (SKA) will begin observing a large fraction of the southern sky, and will thereby undoubtedly reveal tens of thousands of extreme DSFGs, it is crucial to begin understanding the nature of their radio emission now.

In this project, the student will analyze new radio observations from the Very Large Array (VLA), which target 16 of the brightest-known DSFGs at Cosmic Noon initially identified by the Herschel space telescope. All targets have extremely detailed images of their (sub-)millimeter emission from ALMA, which reveals that some are gravitationally lensed by a massive foreground galaxy. Combining the VLA and ALMA data, the student will investigate what powers the radio emission from these luminous starbursts, whether the lensed and un-lensed galaxies differ in their radio properties, and how these extreme starbursts connect to the more normal star-forming galaxies studied in the past.

The main goals of this project are for the students to:

• Familiarize themselves with the field of high-redshift galaxy evolution.
• Infer galaxy properties (luminosities, sizes, …) from radio interferometric data.
• Model the multi-wavelength ALMA and VLA emission of luminous DSFGs.
• Interpret their findings in the context of the existing literature and the upcoming SKA.

Required Background

• Basic knowledge of physics (required) and astronomy (preferred)
• Strong programming skills (python preferred)
• Strong English communication skills (written and spoken)