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physics & astronomy

Bridging the Gap Between Galaxy and Star Formation with Star Clusters

Over the past decades, the discovery of a large number of young massive clusters (YMCs) in the local Universe and giant clumps in high-z galaxies suggests that clustered star formation is the dominant star formation mode across cosmic time. Mass and energy feedback from these enormous clusters is inevitably responsible for shaping their host galaxies. In this talk, I will discuss the tight relationship between giant molecular clouds on small scales and galaxies on large scales and provide the first attempts to bring star formation and galaxy formation community together. On the one hand, the properties of YMCs and GMCs populations can be used to calibrate and help improve the current cosmological simulations. On the other hand, galaxy formation simulations provide the perfect initial conditions for the modeling GMCs in realistic environments. Finally, bringing together the collective wisdom from both galaxy and star formation, I will highlight some of my recent works on solving the mystery of the origin of globular cluster populations in the Universe.

Zoom Recording: https://uky.zoom.us/rec/share/gU3PD8lWcY7ckp8yX1hzar4ehA2fRStP3in6YZPpUFYvsIVbmRrsxNpoHvP3qCOw.8tPxhtnTxMA4vByE

Date:
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Location:
Zoom
Type of Event (for grouping events):

Probing Magnetic Field Morphology in Galaxy Clusters with the Gradient Technique

Magnetic fields in the intracluster medium (ICM) affect the structure and the evolution of galaxy
clusters. However, their properties are largely unknown, and measuring magnetic fields in galaxy
clusters is challenging, especially on large-scales outside of individual radio sources. Here we
probe the plane-of-the-sky orientation of magnetic fields in clusters using the intensity gradients.
The technique is a branch of the Gradient Technique (GT) that employs emission intensity maps
from turbulent gas. We utilize the Chandra X-ray images of the Perseus, M 87, Coma, and
A2597 galaxy clusters, and the VLA radio observations of the synchrotron emission from
Perseus. We find that the fields predominantly follow the sloshing arms in Perseus, which is in
agreement with numerical simulations. The GT-predicted magnetic field shows signatures of
magnetic draping around rising bubbles driven by supermassive black hole (SMBH) feedback in
the centers of cool-core clusters, as well as draping around substructures merging with the Coma
cluster.

Zoom Recording: https://uky.zoom.us/rec/share/mkGB72TcxVuohGMJ5EVwN282koaKcMinbki7FuSKX3UvAwcl4j22df-zG5VZJnS_.gnvslk37Wx91DbZZ

Date:
-
Location:
Zoom
Type of Event (for grouping events):

The Javalambre-Physics of the Accelerated Universe Astrophysical Survey, current status and preliminary results from the miniJPAS survey

The Javalambre-Physics of the Accelerated Universe Astrophysical Survey (J-PAS) is a narrow band, very wide field cosmological and astrophysical survey to be carried out from the Javalambre Astrophysical Observatory in Spain with a purpose-built, dedicated 2.5m telescope and a 5 sq.deg. 1.2Gpix camera. With first light obtained in June 2020, J-PAS plans to observe >8000sq.deg. of Northern Sky and measure sigma_z~0.003(1+z) photo-z for up to 9E7 LRG and ELG galaxies plus several million QSOs, sampling an effective volume of ~ 14 Gpc^3 up to z~1.3 reaching Stage IV radial BAO experiment. J-PAS is expected to detect ~7E5 galaxy clusters and groups, setting constraints on Dark Energy which rival those obtained from its BAO measurements. 

Thanks to the superb characteristics of the site (seeing ~0.7 arcsec), J-PAS is expected to obtain a deep, sub-arcsec multi-band image of the Northern sky, which combined with its unique photo-z precision will have an immense legacy value for almost all astrophysical areas. The key to the J-PAS potential is its innovative approach: a contiguous system of 54+2 filters with 145A width, placed 100A apart over a multi-degree FoV is a powerful "redshift machine", with the survey speed of a 4000 multiplexing low resolution spectrograph. Its commissioning camera, the PathFinder, has collected data since 2018 with all J-PAS filters of a variety of targets and fields, in particular of the AEGIS field (miniJPAS) as a proof of concept for photo-z depth and others. 

Here I will present the status of J-PAS, the main results of miniJPAS and how it impacts the expectations for J-PAS.

 

Zoom recording: https://uky.zoom.us/rec/share/F9E1ic1VTD7A1b0uY0c6sWNlWtCvII8N1eESjj8WC4UNIHGTzMJzxRa_mj3iIdnL.ay0DT-aSZ6MRRBTU

Date:
-
Location:
Zoom
Type of Event (for grouping events):

Modeling Dispersal of Giant Molecular Clouds by UV Radiation Feedback

Giant molecular clouds (GMCs) are the primary reservoir of cold molecular gas in the interstellar medium and sites of ongoing star formation. It has been known for decades that star formation efficiency (SFE) of GMCs is very low. While UV radiation feedback from massive stars are expected to play a crucial role in controlling the GMC lifetime and SFE, our theoretical understanding of how it actually works in turbulent, magnetized clouds remains incomplete. In this talk, I will report recent progress we made in modeling GMC destruction by UV radiation feedback. I will first briefly review the predictions made by 1D models about SFE, cloud lifetime, and importance of photoionization and radiation pressure in different star-forming environments. I will then present the results of radiation (magneto)hydrodynamic simulations of star-forming GMCs and discuss how turbulence and magnetic fields can change the picture. If time allows, I will also talk about ongoing efforts in modeling GMC evolution with all major forms of feedback processes (radiation/winds/SNe).

Date:
-
Location:
Zoom
Type of Event (for grouping events):

The Milky Way in its Extragalactic Context

In recent work, we have obtained improved measurements of the properties of the Milky Way and used the results to select a sample of Milky Way analog (MWA) galaxies from the Sloan Digital Sky Survey (SDSS) whose distributions of stellar mass and star formation rate match our Galaxy’s, incorporating all uncertainties. Relying on the Copernican assumption that the Milky Way should not be extraordinary, the colors and luminosities of the MWAs constrain the possible properties of our own Galaxy. This has enabled us to explore how our Galaxy fits in with the broader population; for instance, we can determine whether its properties are consistent with the power-law scaling relations exhibited by other spiral galaxies. The results have significant implications for the development of computational models of galaxy evolution in a cosmological context.  I will also describe follow-up work exploring the population of satellite galaxies in Milky Way-like dark matter halos.  It has been a long-standing puzzle why the Milky Way has considerably fewer satellite galaxies discovered to date than the typical number of satellite dark matter halos that would be found in a dark matter halo as massive as that which contains our Galaxy.  I will show that almost half of this ‘missing satellites’ problem can be explained by well-established ways in which our Galaxy’s dark matter halo is atypical.  Finally, if time allows I will also describe new work on the density profile of dark matter halos when mass within subhalos, which can often host individual galaxies, is not counted as part of the parent halo.  Widely-used profiles (such as Navarro Frenk and White) perform poorly at representing the smooth centrally-concentrated component of the halo, but there are simple functional forms which do better.

 

Zoom recording: https://uky.zoom.us/rec/play/58uXDQDw95A6o5P7owEDEwzb-X3PhCXv8WevwQSdhV…

Date:
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Location:
Zoom
Type of Event (for grouping events):

Tracing the physics of the neutral and ionized ISM with the HI-MaNGA survey

The HI-MaNGA survey is an HI (21cm line) follow-up program for the SDSS-IV MaNGA survey.  I will describe the HI-MaNGA survey, its progress to date, and future plans.  I will then present new results where we combine HI-MaNGA and MaNGA data to investigate how the global HI content of star-forming galaxies relates to the mean properties of their ISM derived from optical emission lines, including integrated equivalent width, metallicity, ionization parameter, and the relative strength of low-ionization lines such as [SII] and [OI]. This analysis allows us to understand if and how the properties of the ISM vary between the most gas-rich galaxies to the most gas-poor, and how such variations may affect their evolution.  I will also discuss how gas content relates to the nuclear ionizing source (e.g., Seyfert, LINER, HII regions) and whether we find any evidence that AGN contribute to gas deficiency in the galaxy population.

Zoom Recording: https://uky.zoom.us/rec/share/xGrDewYs7rui5ao4A-_hr_N5r8_c6mkGkiksm--I61WP-hQ8VhJn9HM8fTadgDUG.M9oUhbMc-oa1r2Nr

Date:
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Location:
Online by Zoom
Type of Event (for grouping events):

The role of binary star evolution and stochastic fluctuations in modeling stellar populations

I will discuss state of the art population synthesis models that improve on the following aspects with respect to most available models. (a) Treatment of the UV spectral range, including new evolutionary tracks and updated treatment of the ionizing radiation emitted by the stellar population. (b) Improved treatment of TP-AGB stars that dominate the NIR spectral range.  (c) Definition of new diagnostics to characterize the combined stellar and nebular emission and the cold ISM in galaxies. (d) The role of interacting binary stars on the integrated spectra of stellar populations will be discussed and compared with the effects produced by stochastic fluctuations in low mass populations. Single star models are available in a wide range of metallicity, from Z = 0 to Z = 0.06, and are ready to use to interpret the spectra of galaxies of any age at low and high redshift. Applications will be discussed.
Date:
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Location:
BL 339
Type of Event (for grouping events):

Dark Energy Survey Data at the Low Surface Brightness Regime: Diffuse Light in Galaxies and Galaxy Clusters

The enormous amount of data collected by the Dark Energy Survey (DES) provide a great opportunity to explore low surface brightness science topics, such as faint diffuse light in galaxies and galaxy clusters. In this talk, I will describe how we study diffuse intra-cluster light through stacking the images of hundreds of galaxy clusters from DES, reaching a surface brightness limit of 30 mag/arcsec^2, out to a radial distance of 1 Mpc from the cluster center. Despite their low surface brightness, our studies show that intra-cluster light is a significant component of the galaxy cluster stellar content. The stacking method has also been applied to characterizing the light profiles of luminous red galaxies, as well as studying the aureole component of the DES point spread function. Weak lensing and precision photometry calibration  methods may wish to consider these effects in the future.

Date:
-
Location:
BL 339
Type of Event (for grouping events):
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