My work

My main research interest is galaxy evolution. I mainly use observations to study the evolution of galaxy baryonic (i.e., gas, stellar, dust and metal) components of distant galaxies at redshift z=1-3, that is when the Universe was only three to five billion years old. Because each baryonic component is traced at different wavelengths, I use multi-wavelength data from various state-of-the-art facilities (e.g., ALMA and JWST) to investigate how baryons cycle in and out of galaxies.

Below you can find an overview of the work I have lead, and here you can find a list of publications I lead or contributed to.

Langan et al. in prep

ACE: The gas fundamental metallicity relation at cosmic noon

I am part of the ALMA Chemical Evolution (ACE) survey -- an ALMA large programme probing a new mass and gas-phase metallicity parameter space of typical star-forming galaxies at cosmic noon. With the unique combination of extensive rest-frame optical/NIR spectroscopic and photometric data, and new ALMA band 3 observations, I am investigating the gas fundamental metallicity relation which is a powerful diagnostic of the baryon cycle, linking chemical enrichment, star formation and the fuel for star formation: the molecular gas.

A search for cold molecular outflows at cosmic noon

Galactic outflows may enrich the CGM of galaxies, which can further impact the next stages of gas accretion and subsequent star formation (SF). In particular, cold outflows are thought to be the main phase responsible for regulating SF by carrying the bulk of the mass of the gas reservoir available for SF. In this work, we used stacking techniques on ALMA data to search for signatures of cold molecular outflows in typical galaxies at cosmic noon. You can find more information on this work in Langan et al. (2026).

An HST-dark galaxy merger at cosmic noon revealed by ALMA

Galaxy mergers are commonly identified via visual inspection of rest-frame optical and NIR data, meaning all the components involved in the merger need to be visible. However, if one (or several) component is heavily dust-obscured, the whole system can be misidentified. With this work, we primarily used ALMA data to highlight the importance of the multi-wavelength approach to properly identify dusty galaxy mergers. We also investigate how such a complex environment impacts the properties of the individual components of the merger. You will find more details in Langan et al. (2024).

MEGAFLOW: The impact of gas flows on galaxy properties

According to models, star-forming galaxies evolve along an equilibrium between pristine gas inflows from the CGM and outflows of processed gas. These gas flow events impact fundamental galaxy properties such as their stellar mass, gas-phase metallicity and star formation rate. As part of the MEGAFLOW survey, we used VLT/MUSE and VLT/X-Shooter data to put direct constraints on models, for the first time, by looking at how the impact of measured gas flows is reflected on key scaling relations, with a focus on the (fundamental) mass-metallicity relation. More information can be found in Langan et al. (2023).

FirstLight simulations: mass-metallicity relation (MZR) at cosmic dawn

Star-forming galaxies show a tight correlation between their stellar mass and gas-phase metallicity: the MZR. This statement is correct in the local Universe, but what about in the very distant Universe, when the first galaxies formed? Thanks to the FirstLight simulations, focused on galaxy formation around the Epoch of Reionization (EoR, z > 6), we studied the MZR during the EoR and provided predictions of strong-line diagnostics to derive the gas-phase metallicity with JWST. You can find more information on this work in Langan, Ceverino and Finlator (2020).

Page updated

Google Sites

Report abuse