Physics & Astronomy Nuclear Science Seminar

Title: From massive gravity to RATs: ultra-light dark matter phenomenology with atom interferometers

Abstract: Atom interferometers offer exceptional sensitivity to ultra-light dark matter (ULDM)  through their precise measurement of phenomena acting on atoms. Previous work has established their capability to detect scalar and vector ULDM, but their potential for detecting spin-2 ULDM has until recently remained unexplored. In this talk I will introduce the sensitivity of atom interferometers to ULDM and focus on novel research for spin-2 models derived from several frameworks for massive gravity: a Lorentz-invariant Fierz-Pauli case and two Lorentz-violating scenarios. Coherent oscillations of the spin-2 ULDM field induce a measurable phase shift through three distinct channels: coupling of the scalar mode to atomic energy levels, and vector and tensor effects that modify the propagation of atoms and light. Atom interferometers uniquely probe all of these effects, while providing sensitivity to a different mass range from laser interferometers. These results demonstrate an exciting new theory target for atom interferometers and other quantum sensors to explore. I will also discuss challenges faced by these experiments from environmental noise, including atmospheric phenomena and local human and animal activity.

Date:
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Location:
CP 179
Event Series:

Physics & Astronomy Astro Seminar

Title: A novel view of the Milky Way disk and outer Solar system

Abstract: Combining big survey data with advanced statistical analysis is a fruitful approach to new discoveries. I will present two examples.   (1) One is a new mapping technique to provide for the first time a clear and flat view of the phase space of Milky Way disk. Applying it to Gaia data, we found sharp new structures with order-of-unity contrast in number density and metallicity. It opens a new window to study galactic dynamics, calling for theoretical explanation and observational search for similar structures in other disk galaxies.  (2) Another example is a new algorithm searching for moving objects from imaging survey. Applying it to cosmological surveys, I found a dwarf planet with the widest orbit in the Solar system, which places an interesting challenge to the Planet Nine / Planet X hypothesis.

Date:
-
Location:
CP 303
Event Series:

Physics & Astronomy Astro Seminar

Title: Warm ionized gas filaments in non-central early-type galaxies

Abstract: Filamentary multiphase gas is nearly ubiquitously found within the brightest cluster galaxies (BCG) of cool-core clusters and is likely related to the feeding and feedback of their supermassive black holes. Determining how such filaments form is crucial to understanding the interplay between baryon cycling, active galactic nucleus (AGN) feedback, and the evolution of early-type galaxies (ETG). However, BCGs account for only a small percentage of all ETGs and their gaseous atmospheres are thought to be strongly influenced by the extreme, dense cluster environments in which they reside. In this talk, I will present the results of our multiwavelength analysis of 126 nearby ETGs that sit outside of the immediate cores of galaxy groups and clusters (hereafter “non-central” ETGs) - which aims to bridge our current understanding of filamentary multiphase gas formation to the greater ETG population. Using archival VLT-MUSE observations, we find that 54 of these non-central ETGs have detected warm ionized gas. 35 out of these 54 sources host warm gas in the form of rotating disks, while the remaining 19 host filamentary warm gas - resemblant of that observed in BCGs. I will discuss how the MUSE data, in tandem with archival Chandra X-ray observations, allows us to infer that the warm filaments originate from the cooling, thermally-unstable hot halos. Furthermore, I will share the results of our emission line analysis that probe the ionizing mechanisms capable of powering the warm filaments.

Date:
-
Location:
CP 303
Event Series:
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