FLASH Talks: Ryota Ikeda (NAOJ) & Anniek Gloudemans (NOIRLab)

Friday, 16 February 2024 noon — 1 p.m. MST

NOIRLab Headquarters | 950 North Cherry Ave., Tucson, AZ 85719

Ryota Ikeda (NAOJ) & Anniek Gloudemans (NOIRLab)

Ryota Ikeda, NAOJ
Spatially-resolved studies of z=1.47 cluster galaxies using ALMA
Galaxy clusters in the early universe represent a unique testbed on how massive elliptical galaxies in the present universe evolved. In this talk, I will present the results from spatially-resolved (< 0.5" resolution) ALMA observations of z~1.5 cluster galaxies targeting multi-transition CO lines and FIR continuum emission. We found compact obscured star formation in nine star-forming galaxies and further kinematical analysis revealed steeply increasing rotation curves, both implying the on-going formation of dense stellar component. However, caveats such as the CO-to-H2 conversion factor remain in our analysis, and we argue mapping the stellar mass distributions would be the next step to scrutinize structure formation of these massive galaxies. Lastly, as an on-going project, I will also briefly introduce the results from the ALMA-CRISTAL Survey, a kpc-scale census of [CII] line and FIR continuum emissions in star-forming galaxies at 4<z<6.

Anniek Gloudemans, NOIRLab
Probing the radio-loud quasar population in the early Universe
The last decades of painstaking searches have provided the community with a statistical sample of hundreds of high-redshift (z>5) active galactic nuclei (AGN) and quasars. Their study has been instrumental in investigating the formation and growth of the first supermassive black holes, galaxies, and large cosmic structures. Despite these efforts, however, little is still known about the general properties of the elusive population of high-z radio-loud quasars, both due to their sparsity and the lack of sensitive large-scale radio surveys. In this talk, I will present the discovery and follow-up of a new population of high-z radio-loud quasars using the Low Frequency Array (LOFAR), which operates at 30-200 MHz. These new generation radio telescopes, such as LOFAR and the Square Kilometer Array (SKA), open up a new era of efficient (with a decreased number of stellar contaminants) and less biased (with more relaxed constraints in the drop-out) z>6 quasars selections.