MATs (Monday Afternoon Talks), 05/22/2023 – Speakers: Cheng-Lin Liao, Ben Zhang

Monday May 22, 2023 3:00 pm

MATs (Monday Afternoon Talks)

3:00pm  – Cheng-Lin Liao
Extending to the Brightest End: Physical Properties of the 870μm Brightest Dusty Star-forming Galaxies at z~3
Dusty star-forming galaxies (DSFGs), luminous in the infrared, are dust-rich galaxies with intense star formation (SFR~10-1000 Msun/yr) predominantly at cosmic noon (z~1-3). They are crucial for understanding galaxy formation and evolution, as they are closely linked to quasars and thought to be the progenitors of massive elliptical galaxies in the local Universe. Recent ALMA studies of a DSFG sample have revealed positive scaling relations on dust mass and SFR against the 870-micron. By adopting a sample of z~3 ALMA-selected DSFGs with CO/[CI] lines detected, we extend these relations to the brightest end at ~20 mJy, which is essential for understanding galaxy evolution at the brightest end. In combination with the UV-to-radio data, we explore the interstellar medium properties through multi-wavelength spectral energy distribution fitting. In this talk, I will focus on comparing the gas and dust properties of this brightest subset to the typical DSFGs whose 870μm flux are lower than ~10 mJy. Our results reveal that our brightest DSFGs are more gas and dust-rich but share similar dust properties with those DSFGs from local to high redshift.

3:30pm – Ben Zhang
Impact of Property Covariance on Galaxy Cluster Weak-lensing Mass Calibration
Galaxy cluster abundance is one of the pillars of modern cosmology, with weak-lensing the gold standard for cluster mass calibration. Despite this achievement in modern cosmology, uncertainties and systematics in cluster observables hamper this probe in cosmological studies. We provide for the first time a model for the intrinsic correlated scatter between weak lensing signal and cluster richness and find a negative correlation between lensing signal and galaxy number count at small scales. We find that the size of the covariance can be explained by the halo formation history. Furthermore, by modeling the cluster richness and weak lensing as multi-(log)-linear equations of secondary halo properties, we provide a quantitative explanation for the physical origin of the negative covariance at small scales. These findings highlight the importance of accounting for the covariance between observables in cluster mass estimation, which is crucial for obtaining accurate constraints on cosmological parameters.

Host: Josh Burrow


  • Cheng-Lin Liao, Institute of Astronomy and Astrophysics, Academia Sinica, (ASIAA) Taiwan
  • Ben Zhang, University of Chicago

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