\u3ci\u3eThe Center of the World\u3c/i\u3e

A body of water is often seen as a serene place of relaxation, but just under the surface, aquatic life bustle around. This creative narrative will spark your imagination into having you believe that you are placed in the shoes of a wandering student as you encounter this great entity, known as the Bryant Pond. This journey will allow you to free your mind, and let it wander as you get lost in your own imagination. Have you ever wondered how certain things came to be, such as out-of-place objects in an environment that could have naturalistically been put there, but has a very small probability of actually being real nature? The Bryant Pond is located at the center of the university campus, and is an eye-catcher as you meander around. The pond acts as a waypoint for students, allowing them to navigate the campus with ease. Surrounding the pond are various forms of the environment, ranging from trees, to grass, to weeds and reeds around the perimeter of the pond. Since the pond is a secluded area inside of the campus, how did aquatic marine life come to be in this sort of environment with no connecting bodies of water? This would allow nothing to get in or out, unless an outside factor was to come into play. Fish swim around in the pond, and that draws the question on how they got there since there are no bodies of water connecting. Birds could have been the primary individuals that caused the influx of these marine creatures through transporting eggs in their feathers, or us humans could have planted them there to reconstruct a replica pond. Knowing and “Understanding the way that fish are dispersed in remote bodies of water is important for the maintenance of biodiversity”[1], and it can expand the wildlife that lives on Bryant’s campus. Maybe the bigger question is, what relationship do we have with the environment, and what do we do to appreciate what it has provided for us? [1] “Dispersal of Fish Eggs by Water Birds – Just a Myth?” ScienceDaily. ScienceDaily, February 19, 2018. https://www.sciencedaily.com/releases/2018/02/180219103258.htm

Neutrinos from Fallback onto Newly Formed Neutron Stars

In the standard supernova picture, type Ib/c and type II supernovae are powered by the potential energy released in the collapse of the core of a massive star. In studying supernovae, we primarily focus on the ejecta that makes it beyond the potential well of the collapsed core. But, as we shall show in this paper, in most supernova explosions, a tenth of a solar mass or more of the ejecta is decelerated enough that it does not escape the potential well of that compact object. This material falls back onto the proto-neutron star within the first 10-15 seconds after the launch of the explosion, releasing more than 1e52erg of additional potential energy. Most of this energy is emitted in the form of neutrinos and we must understand this fallback neutrino emission if we are to use neutrino observations to study the behavior of matter at high densities. Here we present both a 1-dimensional study of fallback using energy-injected, supernova explosions and a first study of neutrino emission from fallback using a suite of 2-dimensional simulations.Comment: 30 pages (including 10 figures), submitted to ApJ, comments welcom

The Observational Signatures of Primordial Pair-Instability Supernovae

Massive Population III stars from 140 - 260 solar masses ended their lives as pair-instability supernovae (PISNe), the most energetic thermonuclear explosions in the universe. Detection of these explosions could directly constrain the primordial IMF for the first time, which is key to the formation of the first galaxies, early cosmological reionization, and the chemical enrichment of the primeval IGM. We present radiation hydrodynamical calculations of Pop III PISN light curves and spectra performed with the RAGE code. We find that the initial radiation pulse due to shock breakout from the surface of the star, although attenuated by the Lyman-alpha forest, will still be visible by JWST at z ~ 10 - 15, and possibly out to z ~ 20 with strong gravitational lensing. We have also studied metal mixing at early stages of the explosion prior to breakout from the surface of the star with the CASTRO AMR code and find vigorous mixing in primordial core-collapse explosions but very little in PISNe. This implies that the key to determining progenitor masses of the first cosmic explosions is early spectroscopy just after shock breakout, and that multidimensional mixing is crucial to accurate low-mass Pop III SNe light curves and spectra.Comment: 4 pages, 3 figures, proceedings of Deciphering the Ancient Universe with Gamma-Ray Bursts, Kyoto, Japan, April 19 - 23, 201

The Formation of Rapidly Rotating Black Holes in High Mass X-ray Binaries

High mass X-ray binaries (HMXRBs) like Cygnus X-1, host some of the most rapidly spinning black holes (BHs) known to date, reaching spin parameters $a \gtrsim 0.84$. However, there are several effects that can severely limit the maximum BH spin parameter that could be obtained from direct collapse, such as tidal synchronization, magnetic core-envelope coupling and mass loss. Here we propose an alternative scenario where the BH is produced by a {\it failed} supernova (SN) explosion that is unable to unbind the stellar progenitor. A large amount of fallback material ensues, whose interaction with the secondary naturally increases its overall angular momentum content, and therefore, the spin of the BH when accreted. Through SPH hydrodynamic simulations, we studied the unsuccessful explosion of a $8M_{\odot }$ pre-SN star in a close binary with a $12M_{\odot}$ companion with an orbital period of $\approx1.2$ days, finding that it is possible to obtain a BH with a high spin parameter $a\gtrsim0.8$ even when the expected spin parameter from direct collapse is $a \lesssim 0.3$. This scenario also naturally explains the atmospheric metal pollution observed in HMXRB stellar companions.Comment: 6 pages, 4 figure

Modeling Emission from the First Explosions: Pitfalls and Problems

Observations of the explosions of Population III (Pop III) stars have the potential to teach us much about the formation and evolution of these zero-metallicity objects. To realize this potential, we must tie observed emission to an explosion model, which requires accurate light curve and spectra calculations. Here, we discuss many of the pitfalls and problems involved in such models, presenting some preliminary results from radiation-hydrodynamics simulations.Comment: 6 pages, 3 figures, proceedings of 'The First Stars and Galaxies: Challenges for the Next Decade", Austin, TX, March 8-11, 201