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Nov
10
Thu
Cake talk: Carlos Gómez Guijarro
Nov 10 @ 14:00 – 15:00

Understanding the role of compact star formation in galaxy evolution

Massive elliptical galaxies in the local universe appear to have their high-redshift analogs in the form of extremely compact quiescent galaxies. Therefore, it seems that compact star formation appears to play a pivotal role in the evolutionary pathways of massive galaxies across cosmic history. However, it remains to be understood what this role is in the broader picture set by the main sequence and the scaling relations in galaxy evolution. From an ALMA survey at 1.1mm, we reveal that compact star formation appears to be the norm in massive star-forming galaxies, and sizes as extended as typical star-forming stellar disks are rare. A population of galaxies with modest star formation rates, but which exhibit extremely compact star formation with starburst-like depletion timescales unveils. Compact star formation appears as a physical driver of depletion timescales, gas fractions, and dust temperatures. The new findings suggest that the star formation rate is sustained in very massive SFGs, even when their gas fractions are low and they are presumably on the way to quiescence. Gas and star formation compression seems to be a mechanism that allows to hold their star formation rate.

Nov
17
Thu
Cake talk: Stephanie Ho
Nov 17 @ 16:00 – 17:00
Understanding the Galaxy Ecosystem: Gas Flow in The Circumgalactic Medium
 
The reservoir of baryons and metals surrounding galaxies is known as the circumgalactic medium (CGM).  The CGM plays a crucial role in the growth of galaxies; galaxies require a continuous gas supply to sustain star formation, and this gas accretion process is regulated by feedback from newly formed stars.  However, observational analysis of the CGM is challenging.  Not only because the low gas density makes the CGM difficult to image directly, but the CGM also consists of gas structures of different temperatures and densities.  We will discuss our recent efforts of studying the multiphase circumgalactic gas flow.  We will also present analyses from cosmological simulations and explain the observational bias that potentially affects the interpretation of observed data.  We will discuss how future telescope facilities can overcome some of the observational challenges and create exciting opportunities for future work on understanding the galaxy gaseous ecosystem.
Dec
1
Thu
Cake talk: Victoria Fawcett (Research Associate at Newcastle University)
Dec 1 @ 14:00 – 15:00

Why is colour special? Fundamental differences between red and blue quasars

An important fraction of quasars are red at optical wavelengths, indicating (in the vast majority of cases) that the accretion disc is obscured by a column of dust which extinguishes the shorter-wavelength blue emission. In recent work by our group, we have shown fundamental differences in the radio properties of SDSS optically selected red quasars, which cannot be explained with a simple viewing angle hypothesis (Klindt et al. 2019, Fawcett et al. 2020, Rosario et al. 2020, Rosario et al. 2021, Fawcett et al. 2021). In our latest work, we use VLT/X-shooter spectroscopy of a sample of red and typical quasars to gain insight into these differences (Fawcett et al. 2022). We confirm that dust reddening is the main cause of the red colours and explore the emission line properties of our sample. We confront our spectra against accretion disc models and confirm that red quasars are powered by standard thin-disc accretion once corrected for dust extinction. These results suggest that dusty winds could be driving the fundamental differences in red quasars, and so they may represent an important phase in galaxy evolution. Using DESI spectra, we can now push to more extinguished, lower luminosity systems, which will test whether these results extend to more extreme reddened systems.

Dec
8
Thu
Cake talk: Vicente Estrada-Carpenter (Postdoc at Saint Mary’s University)
Dec 8 @ 14:00 – 15:00

Studying the Spatially Resolved Stellar Populations of High Redshift Galaxies using JWST NIRISSGrism Data

The formation histories of galaxies are encoded in their stars, and by constraining these stellar populations we can derive star-formation histories, chemical abundances, and dust properties. Another essential aspect in understanding the formation histories of galaxies is the spatial distribution of these stellar populations, as this can detail when and where galaxies are experiencing star formation. Spatially resolved SED fitting has been done in the past with photometry which has large sample sizes but limited spectral information, and IFU data which has been limited at high redshifts. In this talk, I will discuss methods I am developing to measure the spatially resolved stellar populations of high redshiftgalaxies using grism spectra from JWST/NIRISS plus photometry from JWST and HST. These methods will allow us to create stellar population maps for hundreds to thousands of high redshift galaxies detailing when and where they formed their stars.

Dec
15
Thu
Cake talk: Judie Prat (University of Chicago)
Dec 15 @ 11:00 – 12:00

Title: Testing cosmological models combining probes from the late-time Universe

Abstract: I will describe how to obtain cosmological information from the late-time Universe, in particular from current and upcoming galaxy survey data. I will focus on a particular combination of large-scale structure and weak gravitational lensing measurements. Then, I will also describe how we can stress-test the current standard cosmological model comparing early- vs late-time Universe results.

 

Cake talk: Kate Whitaker (UMass Amherst, Cosmic DAWN Center)
Dec 15 @ 14:00 – 15:00

My personal journey as an academic mama: Lessons in not only surviving, but thriving

In this talk, I have the great pleasure of sharing with you my own personal journey through academia: starting from the very beginning, to graduate school, and my postdoctoral and faculty years beyond. Through personal anecdotes centered around being a woman, a mother, an astronomer, and a mentor, my goal is to share the lessons learned at each stage of my career. Parallel to my own personal journey, I will give a brief history of how our understanding of galaxy formation and evolution has rapidly evolved over the last few decades.

Jan
12
Thu
Cake talk: Ivan Kostyuk (MPIA)
Jan 12 @ 14:00 – 15:00

Ly continuum photon escape fractions during cosmic reionization in the TNG50 simulation

Jan
19
Thu
Cake talk: Meriem Behiri (SISSA)
Jan 19 @ 14:00 – 15:00

Taking over the Dark Side of Early SFRD through Radio Selected NIR-dark Galaxies

Jan
26
Thu
Cake talk: Carlo Cannarozzo (UNAM)
Jan 26 @ 14:00 – 15:00

Charting the Back-in-Time Evolution of the Stellar Mass–Velocity Dispersion Relation for Early-Type Galaxies

Massive early-type galaxies (ETGs) are “red and dead” systems mainly composed of old and metal-rich stellar populations. In a cosmological context, present-day ETGs are believed to be the remnants of a complex stellar mass assembly history marked by several mergers, which are the consequence of the underlying hierarchical assembly of their host dark matter halos. In this talk, I will deal with the merger-driven evolution of ETGs, describing how the scaling relation between stellar mass and stellar velocity dispersion evolves across cosmic time, and how the stellar populations of progenitor galaxies settled into the final remnants. Specifically, by extending the results of Cannnarozzo, Sonnenfeld & Nipoti (2020), I have been modelling the aforementioned relation through a Bayesian hierarchical approach, considering ETGs with log(M∗/M⊙) ≳ 9 over the redshift range 0 ≲ z ≲ 4. Together with a new characterisation of the relation, I have been reconstructing the back-in-time evolutionary pathways of individual ETGs to answer the question “how did high-redshift ETGs assemble through cosmic time to reach the functional form of the relation in the present-day Universe?“.

Feb
2
Thu
Cake talk: Lamiya Mowla (Dunlap Institute for Astronomy and Astrophysics)
Feb 2 @ 16:00 – 17:00