KICP Colloquia: 2010
DateTalk TitleSpeaker
January 6, 2010Attometer Astrophysics: Gravitational wave astronomy with LIGOSam Waldman, MIT
January 27, 2010The structure and evolution of obscured quasarsNadia Zakamska, Institute for Advanced Study
February 10, 2010Understanding the Diverse Explosions of Massive Stars: Supernovae, Gamma-Ray Bursts, and their Host GalaxiesMaryam Modjaz, UC Berkeley
February 17, 2010Feeding Gaseous Baryons to GalaxiesMary Putman, Columbia University
March 3, 2010Surveying the TeV Sky with Milagro and HAWCBrenda L Dingus, Los Alamos National Lab
April 7, 2010Oldies but Goodies: Old Hypervelocity Stars and RR Lyrae as Probes of the Inner and Outer Milky WayKollmeier Juna, Carnegie Institution of Washington
April 21, 2010Early Results from the South Pole TelescopeJohn Carlstrom, The University of Chicago
May 5, 2010Dark stars, or how dark matter can make a star shine: introduction and updatePaolo Gondolo, University of Utah
May 19, 2010Hydrogen and Helium ReionizationAdam A Lidz, University of Pennsylvania
October 20, 2010The Generation and Evolution of Cosmic Magnetic FieldsEllen Zweibel, U Wisconsin-Madison
November 3, 2010Coherent Neutrino-Nucleus Scattering: From Supernovas to ReactorsTodd Hossbach, Pacific Northwest National Laboratory
November 17, 2010Understanding the Cosmic Recombination EpochChristopher M Hirata, Caltech
December 1, 2010Exploration of the "Circum-galactic" Medium of Galaxies at High RedshiftChuck Steidel, Caltech

Attometer Astrophysics: Gravitational wave astronomy with LIGO
January 6, 2010 | RI 480 | 3:30 PM
Sam Waldman, MIT

The direct detection of gravitaitonal waves will provide a revolutionary new probe of the most energetic processes in the universe. The 4 km long LIGO interferometers have demonstrated the sub-attometer displacement sensitivity (< 10^{-18} m/ Hz^{1/2}) required to place upper limits on the neutron star/neutron star merger out beyond the Virgo galaxy cluster. Such mergers are thought to be the progenitors of short gamma-ray bursts and provide an ideal "golden event" signal for direct GW detection. An aggressive R&D program, Advanced LIGO, is underway to increase the interferometer stored power 30-fold (to 750 kW), develop new low noise readouts, and increase the detector sensitivity by an order of magnitude. In the next 5 years, Advanced LIGO will observe neutron star mergers and other gravitational wave events regularly, beginning a new era of gravitational astronomy.

The structure and evolution of obscured quasars
January 27, 2010 | RI 480 | 3:30 PM
Nadia Zakamska, Institute for Advanced Study

Quasars are among the most powerful objects in the Universe and are now thought to play an important role in galaxy evolution. Despite their extreme luminosity, the majority of all quasars have eluded detection through conventional methods until recently. In these objects, the active regions are embedded in clouds of gas and dust, making them faint at optical, ultraviolet and X-ray frequencies, quite unlike 'normal' quasars that are bright at these wavelengths. I will present a detailed study of such obscured quasars, describe the evolution of these objects and their host galaxies and review the current status of quasar demographics studies from multi-wavelength surveys.

Understanding the Diverse Explosions of Massive Stars: Supernovae, Gamma-Ray Bursts, and their Host Galaxies
February 10, 2010 | RI 480 | 3:30 PM
Maryam Modjaz, UC Berkeley

Long-duration gamma-ray bursts (GRBs) and Type Ib/c Supernovae (SN Ib/c) are two of nature's most magnificent explosions. Both can be seen over cosmological distances, and both are products of collapsing massive stars. While GRBs launch relativistic jets, SN Ib/c are core-collapse explosions whose massive progenitors have been stripped of their hydrogen and helium envelopes. Yet for over a decade, one of the key outstanding questions in astronomy is what conditions lead to each kind of explosion in massive stars. Determining the fate of massive stars is essential for using GRBs as star formation indicators over distances up to 13 billion light-years, and for mapping the chemical enrichment history of the universe.
I will present a number of comprehensive observational studies that probe the progenitor environments, their metallicities and the explosion conditions of SN with and without GRBs. Specifically, my benchmark study on the measured metallicities of SN with and without GRBs indicates that low metallicity (less than ~1/3 solar) might be the key factor for producing SN-GRBs, providing constraints on the theoretical predictions of GRB formation. Furthermore, I will discuss SN 2008D, which was discovered serendipitously in January 2008 with the NASA Swift satellite via its X-ray emission and has generated great interest amongst both observers and theorists. I will discuss the significance of this SN, whether it harbored a jet, and its implications for the SN-GRB connection. I will conclude with an outlook on how the most promising venues of research - using both existing facilities such as Magellan and innovative SN surveys, and also upcoming large-scale surveys such as LSST - will shed light on the diverse deaths of massive stars.

Feeding Gaseous Baryons to Galaxies
February 17, 2010 | RI 480 | 3:30 PM
Mary Putman, Columbia University

Galaxies like the Milky Way form stars throughout their lifetimes at rates that indicate a continuous fuel source is needed. I will discuss the evidence for this continual fueling with a focus on gas surrounding the Milky Way. In particular, the roles of existing cold halo clouds and the extended diffuse hot halo medium are discussed in the context of local and cosmological simulations of galaxy formation.

Surveying the TeV Sky with Milagro and HAWC
March 3, 2010 | RI 480 | 3:30 PM
Brenda L Dingus, Los Alamos National Lab

The deepest, wide field of view survey of the TeV sky has been performed with the Milagro observatory, probing the origin of Galactic cosmic rays through discovery of new Galactic gamma-ray sources, diffuse Galactic gamma-ray emission, and unexpected localized regions of hadronic cosmic rays. Milagro was located near Los Alamos, NM and was operated from 2000-2008. A next-generation version of this wide field of view, high duty cycle, water Cherenkov observatory is called HAWC. HAWC will be located near Puebla, Mexico at an elevation of 13,500' and will have 15 times the sensitivity of Milagro. I will discuss results from Miilagro and the expected contributions of HAWC.

Oldies but Goodies: Old Hypervelocity Stars and RR Lyrae as Probes of the Inner and Outer Milky Way
April 7, 2010 | RI 480 | 3:30 PM
Kollmeier Juna, Carnegie Institution of Washington

The Milky Way provides an opportunity for a close-up investigation of the complex processes of galaxy and star formation. I will discuss recent efforts to do this by using rare, but important, probes of these phenomena. In the first portion of the talk I will present results on hypervelocity stars primarily from the Sloan Digital Sky Survey. The distribution of these stars, in physical properties and in space, allows us to place interesting limits on star formation and dynamics at the Galactic Center as well as the possibility to constrain the shape of the Milky Way's dark matter halo. I will discuss progress we have made toward these goals. In the second portion of the talk, I will discuss how one can use RR Lyrae stars to probe the outer halo of the Milky Way and find new and distant substructures which are difficult to probe by other means. Our recent confirmation of a distant structure in RR Lyrae stars highlights the power of this approach to unraveling the outer halo and showcases exciting possibilities for future all-sky time-domain surveys.

Early Results from the South Pole Telescope
April 21, 2010 | RI 480 | 3:30 PM
John Carlstrom, The University of Chicago

Dark stars, or how dark matter can make a star shine: introduction and update
May 5, 2010 | RI 480 | 3:30 PM
Paolo Gondolo, University of Utah

The first stars in the universe may have shined due to dark matter annihilation instead of nuclear fusion. They were dark matter-powered stars, or for short Dark Stars. In this talk, I will report on the story of Dark Stars including recent developments: how they formed, evolved and might have died, and how they might be detected.

Hydrogen and Helium Reionization
May 19, 2010 | RI 480 | 3:30 PM
Adam A Lidz, University of Pennsylvania

A key period in our story of structure formation is the Epoch of Reionization (EoR), when early populations of galaxies and/or quasars formed, emitted ultraviolet light and ionized 'bubbles' of gas around them, eventually filling the entire volume of the intergalactic medium (IGM) with ionized gas. Reionization studies aim to determine the filling factor and size distribution of ionized bubbles during the EoR, which in turn constrain the properties of the first luminous sources. Current observations suggest that hydrogen is reionized sometime before z>~6 by star-forming galaxies. These sources should simultaneously singly ionize helium, but are unlikely to also doubly ionize it. Helium may be doubly-ionized only later on, perhaps near z~3, by bright quasars. I will describe efforts to theoretically model the Epochs of Hydrogen and Helium Reionization, and focus on some of their observational implications. First, I will forecast the prospects for learning about hydrogen reionization from upcoming 21 cm observations. I will then discuss an analysis of existing HI Ly-a forest data aimed at identifying signatures of helium reionization near z~3.

The Generation and Evolution of Cosmic Magnetic Fields
October 20, 2010 | RI 480 | 3:30 PM
Ellen Zweibel, U Wisconsin-Madison

Despite spectacular recent progress in cosmology, the origin of magnetic fields in the Universe remains unknown. I will review the evidence, emphasizing recent detections of extremely weak intergalactic fields, discuss the evolution of these fields over time, and talk about their effects on astrophysical processes.

Coherent Neutrino-Nucleus Scattering: From Supernovas to Reactors
November 3, 2010 | RI 480 | 3:30 PM
Todd Hossbach, Pacific Northwest National Laboratory

Coherent neutrino-nucleus scattering is a non-controversial prediction of the Standard Model of Particle Physics that has yet to be experimentally verified. In the first part of the talk I will discuss a new research effort to search for this elusive process at a spallation source using a small CsI(Na) detector. I will show how this detector can be easily scaled to a size relevant for studies of fundamental neutrino properties and discuss its potential as a supernova-neutrino detector. The second part of the talk will focus on exploiting the coherent scattering process and a new type of low-noise large-mass germanium detector to monitor the emission of antineutrinos from operating nuclear reactors. Details of this new germanium detector will be presented and I will discuss how this technology has allowed us to perform one of the most sensitive light-WIMP searches thus far.

Understanding the Cosmic Recombination Epoch
November 17, 2010 | RI 480 | 3:30 PM
Christopher M Hirata, Caltech

Exploration of the "Circum-galactic" Medium of Galaxies at High Redshift
December 1, 2010 | RI 480 | 3:30 PM
Chuck Steidel, Caltech

During the peak epoch of galaxy formation, the intergalactic medium is both the source of gas fueling star formation in forming galaxies, as well as the waste dump for the products of star formation and black hole accretion that are not retained by galaxies. By studying the "Circum-Galactic Medium", the region within a few hundred physical kpc of forming galaxies, one can begin to constrain the flow of baryons into and out of galaxies. At present, there is a puzzling discrepancy between observations and theoretical expectations whose resolution may be the key to unraveling the aspects of galaxy formation that are least well-understood.