Monday, April 21
Theoretical Astrophysics Center Seminar
Location: UCB – B5 Hearst Field Annex, 12:10 p.m.
Speaker: Melissa Graham & Josiah Schwab (UCB)
Title: “Physical Explanations for the Observed Diversity in Type IA Supernovae”
Location: UCB – 402 Old Le Conte, 2:30 p.m.
Speaker: Satoshi Shirai (UCB)
Title: “Flavor and Minimal SUSY GUT”
Physics Department Colloquium
Location: UCB – 1 Le Conte Hall, 4:15 p.m.
Speaker: James Sethna (Cornell)
Title: “Sloppy Models, Differential Geometry, and How Science Works”
Tuesday, April 22
Berkeley Cosmology Seminars
Location: UCB – Hearst Field Annex B1, 1:10 p.m. (also videoconferenced to LBNL 50-5026)
Speaker: Leonardo Senatore (Stanford)
Title: “The Effective Field Theory of Large Scale Structures”
Abstract: After discussing briefly some implications for Inflation after BICEP2, I will focus on Large Scale Structures surveys, as they promise to be the next leading probe of cosmological information. It is therefore crucial to reliably predict their observables. The Effective Field Theory of Large Scale Structures (EFTofLSS) provides a manifestly convergent perturbation theory for the weakly non-linear regime of dark matter, where correlation functions are computed in an expansion of the wavenumber k of a mode over the wavenumber associated with the non-linear scale k_nl. Since most of the information is contained at high wavenumbers, it is necessary to compute higher order corrections to correlation functions. I will present the predictions of the EFTofLSS up to 2-loops. We find that it matches to percent accuracy the non-linear matter power spectrum up to k~0.6 h/Mpc, requiring just one unknown coupling constant that needs to be fit to observations. Given that Standard Perturbation Theory stops converging at k~0.1 h/Mpc, our results demonstrate the possibility of accessing a factor of order 200 more dark matter quasi-linear modes than naively expected. If the remaining observational challenges to accessing these modes can be addressed with similar success, our results show that there is tremendous potential for large scale structure surveys to explore the primordial universe.
Location: UCB – 402 Old Le Conte, 3:40 p.m.
Speaker: Jaime Varela (UCB)
Title: “Semi-Classical Field Theory as Decoherence Free Spaces”
Physics Research Progress Meeting- no RPM today
Wednesday, April 23
Weekly BOSS lunch
Location: LBNL - outside
Particle Theory Seminar – no seminar today
String Group Meeting – no meeting today
Location: LBNL, INPA Room 50-5026, 3:30 p.m.
Thursday, April 24
Weekly Astronomy Lunch
Location: UCB, 210 Wheeler, 12:30 p.m.
Speakers: • Omar Bromberg: Direct Observation Evidence for the Collapsar Model in Gamma-ray Bursts and How to Really Tell a Long Burst From a Short One
• James McBride: Bent Jets Reveal a Stripped Interstellar Medium in NGC 1272
• Lucio Mayer: Orbital Decåy of Massive Black Hole Binaries in a Clumpy Interstellar Medium
Location: UCB, 2 LeConte Hall, 4:00 p.m.
Speaker: Lucio Mayer (ETH Zurich)
Title: “Formation Pathways for Massive BH Seeds and their Subsequent Evolution as Massive Black Holes Binaries in Gas-Rich Galaxy Mergers”
Abstract: The emergence of bright Quasars as early as z > ~ 7 strongly suggests the existence of a rapid pathway to form supermassive black holes. Conventional models based on the growth of light BH seeds from primordial Population III stars have difficulties in explaining such a rapid assembly. As a result, models in which massive BH seeds form by direct gas collapse in protogalaxies have received significant attention in the last few years. In the most common variants such models rely on fairly idealized thermodynamical conditions of gas flows in protogalaxies, such as suppression of cooling via dissociation of molecular hydrogen and metal-free gas in order to suppress fragmentation. We have recently developed a novel formation scenario that does not rely on any of such restrictive conditions (Mayer et al. 2010, Nature, 466, 1082). It is based on mergers between the most massive, already metal enriched protogalaxies at z < ~ 10, in which gas inflows in excess of 10^4 Mo/yr can arise in less than 10^5 yr following the merger. The latter give rise to supermassive, gravitationally unstable nuclear clouds with masses in excesse of 10^8 Mo. These are likely precursors of massive BH seeds that could form after a short supermassive star and/or a quasi-star phase. I will show new simulations which confirm this scenario further using more sophisticated radiative cooling , highligthing the role of gravitoturbulence in achieving prominent inflows while minimizing the effect of fragmentation and star formation in the nuclear gas. Using the Millenium simulations combined with the latest semi-analytical galaxy formation models with black hole growth we compare our scenario with a Pop III-based scenario. We find specific signatures of massive BH seeds formed by our direct collapse in the clustering and morphology of the host galaxies at both high and low redshift. Our model is so far the only one consistent with very recent determinations of the accreting SMBH population in dropout galaxies at z~6-8.
Location: LBNL, INPA Common Room, 50-5026, 4:00 p.m.
Speaker: Laura Gladstone (U. of Wisconsin-Madison)
Title: “Neutrino Oscillations with IceCube”
Abstract: The IceCube Neutrino Observatory at the South Pole can detect particles in a wide energy range, extending down as low as 10 GeV. This makes IceCube sensitive to studies of the neutrino mixing angle theta23 by observing atmospheric neutrinos from the opposite hemisphere. We use likelihood event reconstructions to find the energy and direction of the observed particles, and several oscillation search methods are already showing promising results.
Physics Research Progress Meeting – no RPM today
Friday, April 25
Location: LBNL – INPA Common Room (50-5026), 12:00 p.m.
Speaker: Igor Ostrovskiy (Stanford)
Title: “Gean4: “Search for Majorana Neutrinos with the First Two Years of EXO-200 Data”
April 29 - 1:10 p.m. (Cosmology-BCCP)
Speaker: Charlie Conroy, UCSC
Location: UCB, Hearst Field Annex, B1 (also videoconferenced to 50-5026)
Title: “Extragalactic Archeology””
Abstract: One of the primary avenues for understanding the formation and evolution of galaxies is through studying their stellar populations. A new generation of population synthesis tools that we have been developing are now capable of measuring an unprecedented amount of information from high quality spectra of galaxies. In this talk, I will present results from an ongoing program aimed at measuring the stellar initial mass function, ages, and detailed elemental abundance patterns of early-type galaxies over the interval 0 < z < 1. Constraints on the abundances of the alpha, iron peak, and neutron capture elements offer the promise of reconstructing the detailed star formation histories of these now dormant galaxies. By measuring the evolution of these quantities through cosmic time, we are gaining fresh insights into the assembly histories of galaxies. The techniques we are developing will enable `extragalactic chemical tagging’ and, more generally, will open up the low resolution universe for detailed study.