### Session K4: Cosmology and Galactic Structure and Formation

Chair: Drew Milsom, University of Arizona
Room: UA Student Union Copper

 Saturday, October 22, 2011 8:30AM - 8:42AM K4.00001: Summer 2011 VERITAS Observations of Blazar BL Lac Spencer Hatch BL Lacertae (BL Lac) is a nearby (z $\sim$ .0688) active galaxy with strong optical polarization and variability, as well as a non-thermal emission spectrum. It is also the prototype of a whole class of blazars known as BL Lac objects'' which share similar polarization and variability properties. Some objects belonging to this class have been identified as very-high energy (VHE) emitters (E $>$ 0.1TeV), while BL Lac has remained an unconfirmed source of VHE gamma-ray emission until recently. In late May 2011, the Fermi Large Area Telescope reported observing BL Lac in a high gamma-ray state, which led to a brief multi-wavelength campaign involving several institutions, including the Very Energetic Radiation Imaging Telescope Array System (VERITAS) in southern Arizona. VERITAS observed BL Lac for a total of nine hours over the course of several weeks, from late May to early July. Standard analysis has yielded little evidence for gamma-ray emission from BL Lac, with the very notable exception of a gamma-ray outburst on the evening of June 28th. In this talk I will give some background on the growing field of gamma-ray astronomy, as well as discuss recent observations of BL Lac by VERITAS in the late 2011 observing season. Saturday, October 22, 2011 8:42AM - 8:54AM K4.00002: Correlation Between the Effective Neutrino Number and Curvature Aaron Smith Cosmological data seems to favor models with more than three neutrinos. This talk focuses on recent discussion regarding additional sterile neutrinos and neutrino mass constraints in cosmology. We present a theoretical argument for correlation between the number of effective neutrinos and the curvature of the universe, which is confirmed by statistical analysis. Saturday, October 22, 2011 8:54AM - 9:06AM K4.00003: Stellar Archeology : Chemical Compositions and Kinematics Bayard Stringer , Bruce Carney The $\Lambda$-CDM model of cosmology predicts a hierarchical formation mechanism of galaxies, with smaller units accreting to construct larger ones. The detection of merger events in external galaxies is well known, and the detection and analysis of merger remnants in the Milky Way is a key component in piecing together the history of our home galaxy. Statistical analyses of stellar kinematics in the solar neighborhood reveal much kinematic structure in the Galactic disk, but it is not readily apparent whether this structure is extragalactic or dynamical in origin. The most prominent structures are quickly identified as well known moving groups of stars such as the Hercules, Sirius, and Hyades stellar streams. Additionally, a subset of kinematically selected stars observed at McDonald Observatory are members of a stellar stream putatively identified by Amina Helmi as part of a merger remnant. A semi-automated, high resolution spectral analysis is applied to 504 F and G dwarf stars, and the results are amenable to Kolmogorov-Smirnov membership hypothesis testing. In all four cases, the kinematic streams have chemistries roughly consistent with the Galactic disk trends, although the statistical analyses suggest some subtle differences. Saturday, October 22, 2011 9:06AM - 9:18AM K4.00004: A recipe for seeds: Growing SMBHs from PBHs James Chisholm In models of the early universe where a spectrum of large density perturbations are produced in the radiation dominated era (such as some models of inflation), primordial black holes (PBHs) are generically produced if the perturbation is sufficiently large. Due to the spatial clustering properties of the underlying density perturbation, the PBHs possess increased clustering and evolve to form gravitationally bound clusters. Under certain conditions, these clusters undergo core collapse to form a more massive, central black hole. In this talk I will examine the possibility that these collapsed PBH clusters may serve as the seeds of Supermassive Black Holes found at the centers of galaxies today, as well as observational signatures that distinguish it from other methods of creating SMBH seeds. Saturday, October 22, 2011 9:18AM - 9:30AM K4.00005: Classification of Galaxies in the Clowes-Campusano Large Quasar Group Drake Ranquist , Lutz Haberzettl The large-scale structure of galaxy clusters gives us greater understanding about the formation and evolution of galaxies. One such structure is found within the Clowes- Campusano Large Quasar Group (LQG). This LQG has two sheet-like clusters of galaxies at $z \sim 0.8$ and $z \sim1.3$. We identify and classify the galaxies in these regions by using color selection techniques. This allows us to differentiate between the star forming galaxies, the Lyman break galaxies and the redder, more evolved galaxies. By doing so, the environmental parameters within the LQGs will facilitate more accurate models of galaxy and quasar formation.