Abstracts
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"Cosmological Imprints of f(R) Gravity"
In my talk, I will explain possible observational signatures of f(R) gravity. I will present the results of analytical and numerical analysis of equation of state (EoS) parameter for effective dark energy and matter density fluctuations in f(R) gravity. It is found that EoS parameter exhibits phantom crossing and the growth index of density fluctuations evolves nonmonotonically with time and depends on scale. Furthermore, the matter power spectrum is enhanced in f(R) gravity compared with LCDM model. I will also show that the enhancement of the matter power spectrum naturally realizes a scale dependent galaxy bias, which is
favored by the observational data from LRG samples. |
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"Circumstellar Disk Composition and Evolution"
This talk will discuss circumstellar disks as the birthplaces of planetary systems. Observations of the composition of dust over the transition from protoplanetary to debris disks teach us about the evolution of disks, the timescales for planet formation within them, and the processes that determine planetary compositions. In particular, I will show visual and
near-infrared multicolor imaging and mid-infrared spectroscopy of disks and discuss evidence for carbon rich chemistries in some, as well as evidence that planets may be modifying their environments. |
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"HETDEX Update"
We will provide an update on the HETDEX project, including the status
of the HET Wide Field Upgrade, VIRUS, and the science preparation
for dark energy and other science. |
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"High Resolution Imaging of the Sunyaev-Zel'dovich Effect in Galaxy Clusters"
Galaxy clusters are the most massive gravitationally bound objects in the
universe and, as such, are extensively used as cosmological
probes. These systems are usually assumed to be relaxed & spherical
to simplify the analyses. High angular resolution X-ray and, now,
Sunyaev-Zel'dovich Effect (SZE) measurements often reveal striking deviations
from equilibrium. These signatures convey information about the physical
processes in, and history of, the Intra-Cluster Medium, and can bias and
degrade results from large scale SZE surveys. The GBT is now engaged
in a systematic survey of SZ clusters at high angular resolution using
MUSTANG. I will present results from this ongoing campaign, describe
our plans for further observations, and discuss future directions. |
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"Exploration of the Circum-Galactic Medium at High Redshifts"
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. |
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"The Influence of Structure Formation on the Interpretation of Dark Matter Experiments"
Cosmological structure formation gives rise to a distribution of dark matter that is set by the complex process of hierarchical assembly. Dark matter experiments are inextricably linked to the details of this cosmological structure formation. I will discuss current work on quantifying the effects of structure formation on the interpretation of dark matter experiments. More specifically, I will focus on small-scale structure and how it influences the expected rates in direct, indirect and energetic neutrino experiments. |
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"Tracing Recent Mass Accretion in the Milky Way Halo"
We expect the outer halo of our Galaxy to an irregular and lumpy
place, made of recently-accreted dark matter subhalos and their
stellar populations. These tracer stars retain dynamical information
about the mass and density of the subhalos they came from, as well as
information about the star formation histories of those halos before
accretion. I will discuss what we have learned about the prevalence
and properties of substructure in the Milky Way halo from the radial
velocity and chemical abundance data from the SEGUE survey. |
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"Star Formation and Early Phases of Evolution: from the Stellar Initial Mass Function to the Properties of Young Stellar Objects"
Understanding the stellar initial mass function (IMF), i.e. the
distribution of stars per mass interval, is a major issue in
stellar astrophysics, with a direct impact on galaxy light,
mass and chemical evolution, and has been a domain of
intense research since the pioneering work of Salpeter in 1955.
In the first part of this talk, I will briefly describe a new, analytical
theory of the IMF, based on the modern gravo-turbulent picture
of star formation. |
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"Planet Formation in Dusty Disks Around Young Stars"
In their initial stages of formation planets should interact with the
accretion disk surrounding the newborn star, clearing the material
around themselves and leaving behind an observational signature in the
form of clearings in the disk. Stars with inner holes in
their disks have been detected and are labeled as transitional objects.
A few years ago, Spitzer identified a new class of "pre-transitional
disks" which have gaps rather than holes - they have an inner disk, a
gap, and an outer disk. In several cases, millimeter imaging has
confirmed the cavities in (pre-)transitional disks previously inferred
from SED modeling. Infrared variability has also been found to be a
common phenomenon in such objects. Physical mechanisms that have been
presented to explain disk clearing can be tested with these
observations; forming planets emerge as the most likely explanation. |
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