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  • Undergraduate Poster Abstracts
  • Astronomy/Astrophysics

    FRI-905 STUDYING DARK MATTER/BARYON INTERACTIONS AND THEIR EFFECTS ON THE DISTRIBUTION OF MASS IN GALAXIES

    • Cam Trujillo ;
    • Jillian Bellovary ;

    FRI-905

    STUDYING DARK MATTER/BARYON INTERACTIONS AND THEIR EFFECTS ON THE DISTRIBUTION OF MASS IN GALAXIES

    Cam Trujillo1, Jillian Bellovary2.

    1Humboldt State University, Arcata, CA, 2Vanderbilt University, Nashville, TN.

    We investigated the time development of a previously studied sample of a cosmological, high-resolution, smooth-particle-hydrodynamic N-body simulation, including a Milky-Way-like galaxy and several dwarf galaxies. For the first time, using a novel nonparametric approach to calculate dark matter halo concentrations in cosmological simulations, we addressed the cusp vs. core discrepancy between dark-matter-only simulations and those containing baryonic matter. Comparing the time-evolution of the parametrically derived DM-halo concentration with the time-evolution of the inner slope of the DM-density profile, and cross referencing it with new values for concentration calculated in volume space, we have gained new insight into the development of cores. There seems to be an interesting correlation between the inner slope of the density profile and the unique DM-halo concentration calculated in volume space. Their values and their progressions were shown in most cases to differ significantly from those calculated parametrically. Further research into these differences and their implications is certainly needed.

    THU-904 STUDYING THE CORRELATION BETWEEN MAGNETIC ACTIVITY AND ACOUSTIC MODES DETECTION IN SOLAR-LIKE STARS OBSERVED BY KEPLER

    • Netsha Santiago-Gonzalez ;
    • Savita Mathur ;

    THU-904

    STUDYING THE CORRELATION BETWEEN MAGNETIC ACTIVITY AND ACOUSTIC MODES DETECTION IN SOLAR-LIKE STARS OBSERVED BY KEPLER

    Netsha Santiago-Gonzalez1, Savita Mathur2.

    1Universidad de Puerto Rico en Cayey, Cayey, PR, 2Research Center for Extrasolar Planetary Systems, Space Science Institute, Boulder, CO.

    Asteroseismology consists of studying the properties of acoustic waves propagating in the stars. Thanks to missions like Kepler, it has proved to be a very powerful tool for studying the interior of stars and inferring their fundamental parameters: mass, radius, and age. The main goal of the mission was to look for exoplanets in the habitable-zone of their host stars, but asteroseismology also played an important role in characterizing the stars. Previous studies showed that magnetic activity suppresses acoustic modes while it is also crucial to better determine the limits of the habitable zones. The purpose of this project was to measure the surface rotation periods and magnetic activity levels of solar-like stars using the Kepler photometric observations to see whether there was a correlation between the detection of acoustic modes and the magnetic activity level of the stars. The sample studied by Chaplin et al., actually contained red giant stars and classical pulsators that could lead to misinterpretations. We redid the analysis with a better-known sample consisting of 1,245 stars without detected oscillations. We determined the rotation periods of the stars using 2 methods: wavelet analysis and autocorrelation, as described in García et al. We found 857 stars with reliable rotation periods, and we computed their magnetic indexes, Sph. As expected, preliminary analysis showed that this sample of stars without detected oscillations seem to have larger magnetic indexes than the stars with oscillations in García et al.

    FRI-904 X-RAY ANALYSIS OF ACTIVE GALACTIC NUCLEI IN CLUSTERS FROM THE DARK ENERGY SURVEY

    • Erica Bufanda ;
    • Tesla Jeltema ;
    • Devon Hollowood ;
    • Eli Rykoff ;
    • Eduardo Rozo ;

    FRI-904

    X-RAY ANALYSIS OF ACTIVE GALACTIC NUCLEI IN CLUSTERS FROM THE DARK ENERGY SURVEY

    Erica Bufanda1, Tesla Jeltema2, Devon Hollowood1, Eli Rykoff3, Eduardo Rozo3.

    1University of California, Santa Cruz, Santa Cruz, CA, 2Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, Santa Cruz, CA, 3SLAC National Accelerator Laboratory, Menlo Park, CA.

    We use Chandra X-ray images combined with optical information from the redMaPPer catalog of clusters of galaxies detected by the Dark Energy Survey (DES) to analyze the evolution of active galactic nuclei (AGN) and their host galaxies in large-scale structures. Recent research has shown that the presence of AGN in clusters is a function of redshift and cluster richness. Our purpose is to investigate these correlations and what this implies for the evolution of AGN in clusters. We accumulated a sample of 141 AGN in 659 clusters at 0.2 < z < 1 using an IDL-matching program that matches the optical positions of galaxies in clusters detected in early data from the DES redMaPPer cluster member catalog v. 6.2.12 with the X-ray positions of detected point sources in 93 different Chandra X-ray observations. We investigated the AGN fraction as a function of richness and redshift with a luminosity threshold of 1043 ergs/sec and selective richness and redshift cuts. We found that AGN in clusters of all richnesses increase by a factor of 8.8 from redshift 0.2 to 1. The high redshift AGN fraction is greater than the low redshift AGN fraction at 5σ. This is consistent with Martini et al’s, findings. In addition, the AGN fraction does not seem to have any significant dependence on cluster richness. Future work involves a recalculation of the AGN fraction and a reanalysis of our cluster AGN sample with the most current DES redMaPPer cluster catalog.

    THU-905 SATURN'S THERMAL EMISSION VARIANCES AT THE 5.1-5.2 µM WAVELENGTHS

    • Sara Gutierrez ;
    • Glenn Orton ;

    THU-905

    SATURN'S THERMAL EMISSION VARIANCES AT THE 5.1-5.2 µM WAVELENGTHS

    Sara Gutierrez1, Glenn Orton2.

    1University of California, Berkeley, Berkeley, CA, 2NASA Jet Propulsion Laboratory, Pasadena, CA.

    Near-infrared analyses of planetary atmospheres provide key information on their time-varying characteristics, allowing scientists to gain understanding of their evolution. Our goal is to confirm seasonal variances of Saturn’s thermal emissions and report the radiative impact of a large storm. The study of atmospheric clouds' variations will support the visible-infrared mapping spectrometer (VIMS) scattered observations from the Cassini Solstice Mission orbits 213-219. The observations of Saturn were taken at 5.1-μm and 5.2-μm wavelengths with the infrared telescope facility (IRTF) in Hawaii over 14 years, giving long-term information on cloud levels in the convectively dominated troposphere. We analyzed radiation levels of the ground-based infrared images at specific latitudes and over the entire planet on smaller time scales. Extensive scaling and correction methods allow us to support and compare our 3 analyses with space-based observations. Our analysis presents general trends of increasing thermal radiation values in the northern hemisphere and decreasing values in the southern hemisphere. As well, we report the increased brightness during and after the great storm of 2010-2011 at approximately 30° north latitude. The research will allow scientists to predict and constrain future atmospheric structures of Saturn around the 2-3 bar pressure level.