The University of Florida Theoretical Astrophysics Seminar is held on Wednesdays at 1:45pm in Room 2165 of the New Physics Building, unless otherwise noted.

Fall 2019 Schedule

August 28: Evan Schneider (Princeton)

Title: The Origin of Multiphase Galaxy Outflows

Abstract:

Star-forming galaxies are often observed to host galactic winds - gas that is flowing out of the galaxy in phases ranging from cold molecular clouds to hot X-ray emitting plasma. While these multiphase outflows are routinely observed, theoretically constraining their origin and evolution has proven difficult. Explaining the prevalence and velocities of the cool ionized phase (T~10^4 K) in particular poses a challenge. In this talk, I will discuss a potential dual origin for this cool gas. Through a series of extremely high-resolution simulations run with the GPU-based Cholla code, I will show that in high star formation surface density systems, dense disk gas can be pushed out by the collective effect of clustered supernovae, explaining the low-velocity material. Subsequent shredding and mixing of these clouds creates gas with intermediate densities and temperatures that is prone to radiative cooling, allowing momentum to transfer between phases and producing high velocity cool gas. In addition to explaining the nature of outflows themselves, these multiphase winds could potentially be a source of the cool photo-ionized gas that is found in abundance in galaxy halos.

September 18: Aklant Bhowmick (UF)

Title: Clustering of quasars and high redshift galaxies: New frontiers for structure formation

Abstract:

Galaxy clustering from large scales (>20 Mpc) to small scales (<1 Mpc) serves as a key probe for the physics of non-linear structure and galaxy formation. At large scales, it enables us to probe the galaxy linear bias, which establishes the connection between galaxy properties with the properties of underlying haloes that correlate with the halo bias. At small scales, we can probe the halo substructure and how galaxies are distributed within it, and also look for possible signatures of hierarchical structure growth. In this talk, I will be presenting the recent results on the clustering statistics of two rare classes of objects in the observable universe, namely, high redshift (z > 7) galaxies and quasars (0 < z < 4) using two state of the art cosmological hydrodynamic simulations, BlueTides and MassiveBlackII. I will discuss how the simulation results compare with existing observational constraints, and prospects of detecting these objects in upcoming surveys.

October 9: Zachary Slepian (UF)

Title: Triangulating the Universe’s Contents, Laws, and Origin with Galaxy Correlation

Abstract:

The Universe is now in an epoch of accelerated expansion of space-time itself, presumed due to dark energy. 3D maps of the distribution of galaxies such as the Sloan Digital Sky Survey (SDSS) have yielded percent-level constraints on dark energy using the imprint of Baryon Acoustic Oscillations (BAO) as a standard ruler to map the Universe's expansion history. Dark Energy Spectroscopic Instrument (DESI; 2019-2024) will map 30 million galaxies (30X SDSS) to improve dark energy constraints by an order of magnitude.

The standard analysis approach for these surveys uses the clustering of galaxy pairs. However, fully exploiting the powerful DESI dataset will demand new ideas. The clustering of galaxy triplets—triangles—measured through the 3-Point Correlation Function (3PCF), offers a powerful new window on cosmic acceleration and dark energy. First, the BAO method can be used in the 3PCF exactly as it is already used with pairs, to sharpen our history of the Universe’s expansion. Second, the 3PCF offers information on the fidelity with which galaxies trace the underlying matter (galaxy biasing), enhancing their utility for cosmology. Third, the direction-dependent 3PCF enables probing modified gravity, another possible explanation for accelerated cosmic expansion. I will present a transformatively fast 3PCF algorithm, and demonstrate its use to make the first application of the BAO method to the 3PCF and place high-precision constraints on galaxy biasing. I will then show how the direction-dependent 3PCF can provide a complementary probe of modified gravity. I will close with further exciting 3PCF cosmology opportunities, such as constraining inflation and the neutrino mass, as well as a novel application to understand the physics of the turbulent interstellar medium as relevant for star formation.

October 23: Jeremiah Murphy (FSU)

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November 6: Dan D'Orazio (CfA)

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November 27: [Thanksgiving Week: No Seminar]

Dec 4: Chiara Mingarelli (Flatiron Institute)

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Other Events

Students may receive credit for attending the Astrophysics Seminar by registering for PHY 6391.