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The CCAPP Symposium 2009

 

Talk Abstracts

Francis Halzen -- "IceCube-First Light" (PPT)

Monday, October 12, 9:10 - 9:55am

After reviewing the rationale for building kilometer-scale neutrino detectors, we discuss the status of IceCube. The partially deployed detector collects more than 100 atmospheric neutrinos per day above a threshold of 100 GeV. Like atmospheric muons, they provide a calibration beam for the instrument although muons have also revealed interesting structures in the arrival directions of Galactic cosmic rays. We will summarize the status of the search for cosmic neutrinos, neutrinos from gamma ray bursts and for neutrinos produced by the annihilation of dark matter particles.

Terri Brandt -- "Ballooning for High Energy Cosmic Rays" (PDF)

Monday, October 12, 9:55 - 10:15am

With four balloon flights around the Antarctic continent, the Cosmic Ray Energetics And Mass (CREAM) experiment, has collected over 100 days of high energy cosmic ray data. Designed to measure individual nuclei from protons through Iron at energies of 10^12 - 10^15 eV, CREAM has extended individual spectral measurements of Carbon and Oxygen and has provided some of the highest energy, highest statistics measurements of the Boron to Carbon and Nitrogen to Oxygen ratios to date. These allow better constraints on the propagation index and Nitrogen abundance in cosmic rays' source(s). Further flights, including a fifth presently in preparation, are increasing our statistics and energy reach and enabling primary spectra and secondary to primary ratios of the less abundant cosmic ray nuclei.

Kohta Murase -- "Ultrahigh-energy photons as a probe of the highest-energy cosmic-ray sources" (PDF)

Monday, October 12, 10:15 - 10:35am

The origin of ultrahigh-energy cosmic rays (UHECRs) has been one of the biggest mysteries in astrophysics. There are two ways to identify the sources: examining the arrival directions of UHECRs, and hunting neutrinos and photons produced via hadronic interactions between cosmic rays and ambient photons and nucleons. The latter is more crucial especially if the sources are transient. We show that ultrahigh-energy (above 10 EeV) photons can be the most useful probe of nearby UHECR sources. Their detections directly suggest UHECR accelerators, and give us useful information on the uncertain cosmic radio background and cosmic magnetic fields. Furthermore, they may allow us a stringent test of possible Lorentz-invariance violation that is often predicted in quantum gravity theories. Such ultrahigh-energy signals might be detected by Auger and future JEM-EUSO, along with GeV-TeV signals that could be accompanied.

Peter Meszaros -- "GRB as sources of VHE gamma-rays, cosmic rays and neutrinos" (PDF)

Monday, October 12, 11:10 - 11:55am

TBA

Michael Stamatikos -- "Multi-Messenger GRB Astrophysics" (PPT)

Monday, October 12, 11:55am - 12:15pm

Gamma-ray Bursts (GRBs) are relativistic cosmological beacons of transient high energy radiation whose afterglows span the electromagnetic spectrum. Theoretical expectations of correlated neutrino emission position GRBs at an astrophysical nexus for a metamorphosis in our understanding of the Cosmos. This new dawn in the era of experimental (particle) astrophysics and cosmology is afforded by current facilities enabling the novel astronomy of high energy neutrinos, in concert with unprecedented electromagnetic coverage. In that regard, GRBs represent a compelling scientific theme that may facilitate fundamental breakthroughs in the context of Swift, Fermi and IceCube. Scientific synergy will be achieved by leveraging the combined sensitivity of contemporaneous ground-based and satellite observatories, thus optimizing their collective discovery potential. Hence, the advent of GRB multi-messenger astronomy may cement an explicit connection to fundamental physics, via nascent cosmic windows, throughout the next decade.

Asaf Pe'er -- "Radio Quiet AGNs as Possible Sources of Ultra-high Energy Cosmic Rays" (PPT)

Monday, October 12, 12:15 - 12:35pm

Active galactic nuclei (AGNs) have been one of the most widely discussed sources of ultrahigh-energy cosmic rays (UHECRs). The recent results of Pierre Auger observatory (PAO) have indicated a possible composition change of UHECRs above ~10^{18.5} eV towards heavy nuclei. I will show that if indeed UHECRs are largely heavy nuclei, then nearby radio quiet AGNs can be viable sources of UHECRs. I derive constraints on the acceleration sites which enable acceleration of UHECRs to 10^{20} eV without suffering losses. I show that the acceleration of UHECRs and the survival of energetic heavy nuclei are possible in the parsec scale weak jets that are typically observed in these objects, the main energy loss channel being photodisintegration. On this scale, energy dissipation by shock waves resulting from interactions inside a jet or of the jet with surrounding material are expected, which may accelerate the particles up to very high energies. I will discuss the possible contribution of radio-quiet AGNs to the observed UHECR flux, and show that the required energy production rate in UHECRs by a single object could be as low as ~10^{39.5} erg/s, which is less than a percent of the bolometric luminosity, and thus energetically consistent. I discuss consequences of this model, the main one being the difficulty in detecting energetic secondaries ($\gamma$-rays and neutrinos) from the same sources.

Douglas Bergman -- "Recent Result from HiRes" (PPT)

Monday, October 12, 2:00 - 2:20pm

I will present the latest results from the High Resolution Fly's Eye experiment. I will present our stereo measurement of the UHECR spectrum; our measurement of UHECR spectrum using average depth of shower maximum and the width of the distribution; and our measurement of the correlation of cosmic ray arrival direction with the local large-scale structure of the universe.

Hajime Takami -- "Possible correlation between the highest energy cosmic rays and their sources" (PDF)

Monday, October 12, 2:20 - 2:40pm

Although Pierre Auger Observatory found the correlation between the arrival directions of the highest energy cosmic rays (HECRs) and matter distribution in local Universe, the origin of the HECRs is still unclear. One reason is their deflection by Galatic and extragalactic magnetic fields. We calculate the propagation of the highest energy protons (HEPs) in magnetized Galactic space and investigate possible correlation between the protons and their sources in local Universe. We show thatthe error of cross-correlation function adopted in this study is sufficiently small by accumulating 200 events. We also find that the correlation is not disturbed largely in many cases after 200 events accumulation and positive signals of the correlation are significantly expected at angular scale of 3-5?. Only in the cases of the northern sky with axisymmetric spiral structures of GMF, the cross-correlation functions are consistent with no correlation or have very low significance even if the correlation is positive at small angular scale. Conversely, no observation of the correlation within this scale implies no field reversal of GMF outside the solar system. Finally, we draw the possible source directions of recently published data of the Pierre Auger Observatory (PAO) assuming the composition to be purely protons and irons, and demonstrate that the pure-iron assumption may break the correlation of the PAO data with the large-scale structure of local Universe.

Shunsaku Horiuchi -- "The production of ultra-high energy cosmic rays in the early epochs of radio-loud AGNs" (PDF)

Monday, October 12, 2:40 - 3:00pm

The origin of the highest energy cosmic rays observed, reaching 10^20 eV in energy, has been an outstanding question in high-energy astrophysics. While cosmic rays likely originate from extragalactic accelerators, there is an urgent lack of highly-energetic counterparts. This may be circumvented if acceleration is assumed transient, i.e., acceleration occurs over a time duration that is short compared to the typical time it takes the charged particles to propagate to the Earth. Gamma-ray bursts and AGN activities are prime examples. In this presentation I discuss the transient production of cosmic rays, focusing on the early epochs of radio-loud AGNs, i.e., compact symmetric objects (CSOs). The evolutionary model of CSOs into powerful radio-loud AGNs (e.g. FRII) suggests that CSO activity lasts ~10^4 yrs, making it transient in duration. I discuss the CSO as potential sources of cosmic rays, by addressing acceleration and escape of high-energy cosmic rays in young CSOs.

Brian Baughman -- "Relative Fluxes in Backtracked Ultra High Energy Cosmic Rays" (PDF)

Monday, October 12, 3:00 - 3:40pm

Tracking Ultra High Energy Cosmic Rays through models of the Galactic magnetic field can provide information on both the nature of UHECR sources and properties of the true Galactic magnetic field. Forward tracking UHECRs to the Earth requires significant computational time since most particles generated will not lie on paths intersecting the Earth as such many backtrack particles from Earth. Backtracking, while greatly reducing the required computational time, treats the Earth as a unique point; presented here are the results of simulations studying the effects of small translations of the detector point. The results indicate that small translations of the Earth's position can induce up to a 20% effect on relative fluxes from point sources across the sky.

Gary Hill -- "IceCube Overview" (PPT)

Monday, October 12, 4:10 - 4:30pm

The IceCube detector commenced construction in 2005. As of 2009, the detector is about three-quarters complete, nearing the goal of a kilometre-scale effective area for neutrino-induced muon detection. The detector is already the world's most sensitive instrument for the probing of neutrinos from high-energy processes in the far distant universe. In this talk, we will review the progress so far in the analysis of data looking for point-like and diffuse sources of neutrinos.

Rasha Abbasi -- "Large Scale Cosmic Ray Anisotropy Wtih IceCube" (PDF)

Monday, October 12, 4:30 - 4:50pm

IceCube is a neutrino observatory located at the geographical South Pole. In two years the km^3 detector is expected to be completed. At the moment it is taking data with 59 deployed strings, when completed it will comprise 80-strings plus 6 additional strings for the low energy array Deep Core. The strings are deployed in the deep ice between 1,450 and 2,450 meters depth, each string containing 60 optical sensors. During the year of 2007-2008 data were collected with 22 deployed strings. In this talk I will present the search reporting the measurement of 0.06% of large scale anisotropy. The data used in the large scale anisotropy analysis contains ~4.3 billion downward going muon events with a median energy per nucleon of ~14 TeV and a median angular resolution of 3 degrees. The energy dependence of this anisotropy at median energies of 12 TeV and 126 TeV is also presented in this work. The observed anisotropy has an unknown origin and we will discuss various possible explanations. Studies of the anisotropy could further enhance the understanding of the structure of the galactic magnetic field and possible cosmic ray sources.

Andrew Zentner -- "New Perspectives on Indirect, Astrophysical Dark Matter Limits" (PDF)

Monday, October 12, 4:50 - 5:10pm

High-Energy neutrinos from the annihilation of dark matter captured within the Sun have been considered a relatively clean, indirect probe of dark matter physics. This probe is sensitive to the dark matter-proton cross section so it can be used to cross-check direct searches, and does not rely on a large annihilation cross section in order to be observed in near-term experiments such as IceCube. I will consider a modification of the standard scenario. Dark matter that interacts strongly with itself as has been proposed in several contexts. I show that viable models of self-interacting dark matter can lead to large boosts in the expected neutrino flux from the Sun, though not from the Earth and not in direct detection. Thus, an anomalously large neutrino flux from the Sun is a signpost of self-interacting dark matter. I will also consider the consequences of a significant dark matter self-interaction for other indirect dark matter searches, such as high energy gamma-rays or neutrinos from the Galactic Center. Lastly, I will consider the possibilities for indirect signatures of particle dark matter in stars other than the Sun. I will show that other stars can provide interesting constraints on standard WIMP scenarios and modifications of the WIMP scenario that aim, in particular, to reconcile the DAMA observations of annual modulation.

Katie Richardson-McDaniel -- "Prospects of Indirect Sneutrino Dark Matter Detection with IceCube" (PDF)

Monday, October 12, 5:10 - 5:30pm

A U(1)_B-L extension of the MSSM provides a potential scalar dark matter (DM) candidate: the right-handed sneutrino. The sneutrino can be distinguished from traditional DM candidates via indirect detection in the IceCube neutrino telescope. In this talk I discuss the prospects of the detection of the neutrino signal from sneutrino dark matter annihilation in both the Sun and the Earth and compare them to the mSUGRA case. I will also address the possibility of a model independent analysis of neutrino flavor composition using the IceCube detector.

Carsten Rott -- "Indirect Searches for Dark Matter with IceCube" (PDF)

Monday, October 12, 5:30 - 5:50pm

TBA

Marco Cirelli -- "Seeing signs of Dark Matter in Cosmic Rays?" (PDF)

Tuesday, October 13, 9:00 - 9:45am

Dark Matter constitutes more that 80% of the total amount of matter in the Universe, yet almost nothing is known about its nature. A powerful investigation technique is that of searching for the products of annihilations of Dark Matter particles in the galactic halo, on top of the ordinary cosmic rays. Recent data from the PAMELA satellite and a number of balloon experiment have reported unexpected excesses in the measured fluxes of cosmic rays. Are these the first direct evidences for Dark Matter? If yes, which DM models and candidates can explain these anomalies and what do they imply for future searches?

Hasan Yuksel -- "Origin of the Cosmic Electron/Positron Excess"

Tuesday, October 13, 9:45 - 10:05am

TBA

Matt Kistler -- "High-energy Electrons, Positrons, and Gamma Rays from Geminga" (PDF)

Tuesday, October 13, 10:05 - 10:25am

Observations by Milagro have revealed extended, multi-TeV gamma-ray emission arising from the nearby Geminga pulsar. We will discuss the implications of this discovery for the cosmic-ray spectrum measured at Earth, particularly the GeV "positron excess" of much recent acclaim, and how this may be evidence of the first "direct" detection of a cosmic-ray source.

Patrick Smith -- "Prospects for Measuring the Cosmic-Ray Proton Spectrum" (PDF)

Tuesday, October 13, 10:25 - 10:45am

The Fermi Gamma-Ray Space Telescope was launched in June 2008 and the onboard Large Area Telescope (LAT) has been collecting data since August of that same year. The LAT is currently being used to study a wide range of science topics in high-energy astrophysics, one of which is the study of high-energy cosmic rays. The LAT has recently demonstrated its ability to measure cosmic-ray electrons, and the Fermi LAT Collaboration has published a measurement of the high-energy cosmic-ray electron spectrum in the 20 GeV to 1 TeV energy range. This talk will discuss the prospects for using the LAT to perform a similar analysis to measure cosmic-ray proton events. The instrument response for cosmic-ray protons will be characterized and an assessment of the potential to measure the cosmic-ray proton energy spectrum will be presented.

Jennifer Siegal-Gaskins -- "Gamma-rays from annihilation to charged leptons in Milky Way substructure" (PDF)

Tuesday, October 13, 11:10 - 11:30am

Dark matter annihilation in Milky Way subhalos could be a significant contributor to the local cosmic-ray electron and positron fluxes. I'll first demonstrate that in Sommerfeld models the local annihilation rate in substructure can be larger than in the smooth halo, and then discuss the observational consequences of annihilation in substructure accounting for the measured cosmic-ray fluxes. In particular, the inverse-Compton scattering of the electrons and positrons injected from substructure on the CMB produces nearly- isotropic diffuse gamma-ray emission at a level comparable to the diffuse background measured by Fermi. In addition, I'll show how HESS cosmic-ray electron measurements can constrain these scenarios by placing upper limits on TeV internal bremsstrahlung gamma-rays from annihilation to charged leptons.

Tim Linden -- "The morphology of the dark matter haze with self-consistent diffusion models" (PDF)

Tuesday, October 13, 11:30 - 11:50am

There is currently a significant effort to observe indirect evidence of dark matter annihilation in our galaxy. One interesting finding was an unexpected synchrotron haze (the "WMAP haze") with a similar intensity and morphology to those predicted by dark matter models. This finding may also be connected to another recent puzzle in cosmic ray physics: the excess of high energy positrons reported by the Pamela satellite. We evaluate a wide variety of well motivated dark matter particle physics setups as well as cosmic ray propagation models, and compare the simulated dark matter driven synchrotron signal against the observed WMAP haze. Further analyzing several reasonable dark matter fits to the WMAP haze, we determine the expected inverse-Compton scattering and positron/electron signals which should be detectable by cutting edge forthcoming Fermi and Pamela observations.

Savvas Koushiappas -- "Galactic substructure and high-energy neutrinos" (PDF)

Tuesday, October 13, 11:50am - 12:10pm

The presence of galactic substructure gives rise to a time-varying capture rate of WIMPs by the Sun and the Earth. This implies time variation in the annihilation rate and resulting energetic neutrino flux. Due to the time lag between the capture and annihilation rates, the energetic neutrino flux is determined by the density of dark matter in the Solar System's past trajectory, rather than the local density. The signature of such an effect may be sought in the ratio of the direct-to indirect-detection rates.

Adam Bradley -- "LUX_0.1: The Engineering Prototype" (PDF)

Tuesday, October 13, 12:10 - 12:30pm

LUX is a new dark matter search experiment to be carried out in the renewed underground laboratory at the Homestake (SD) old gold mine. The detector’s large size supports effective internal shielding from natural radioactivity of the surrounding materials and environment. The LUX detector consists of a cylindrical vessel containing 350 kg of liquid xenon (LXe) cooled down using a novel cryogenic system. We tested a small-scale four PMT prototype utilizing over 300 gm of active xenon, installed in the full-sized cryostat. We report the efficiency of a unique internal heat exchanger and liquid level stabilizer system, with standard gas phase purification with a heated getter, which allows for very high flow purification without requiring large cooling power. A stable LXe surface is required for good energy resolution and we report on data from the prototype. Such a system is required for multi-ton scale up.

Gary Bernstein -- "The power of weak gravitational lensing and galaxy clustering surveys" (PDF)

Tuesday, October 13, 2:00 - 2:45pm

I will review the concepts of weak gravitational lensing and its use to constrain dark energy and departures from general relativity, with an emphasis on the substantial gains from combining a weak lensing survey with a large spectroscopic galaxy redshift survey. I will also describe the state of the art in observational methods and the technical challenges facing proposed future experiments.

Szymon Kozlowski -- "OGLE View on Dark Matter in the Galactic Halo"

Tuesday, October 13, 2:45 - 3:05pm

If dark matter was clumpy and could form dark stellar mass objects, these would cause an observable microlensing effect of stars inside the nearby external Galaxies (Magellanic Clouds, M31). I has been demonstrated that the majority of dark matter is not in a form of stellar mass compact objects, but also that some part of the microlensing signal is due to dark matter. I will review recent findings by the OGLE group. Our conclusion is that the microlensing signal observed towards the Magellanic Clouds can be entirely explained by self-lensing, ie., foreground stars microlensing background stars, with no contribution from dark matter.

Tim Eifler -- "Optimized E/B mode decomposition for cosmic shear" (PDF)

Tuesday, October 13, 3:05 - 3:25pm

In recent years weak lensing by the large-scale structure of the Universe, called cosmic shear, has become a valuable probe in cosmology. Large upcoming surveys such as KIDS, Pan-STARRS, DES, LSST, JDEM, and Euclid will improve the quality of cosmic shear data significantly, making it an ideal probe to constrain Dark Energy. In order to obtain cosmological parameters from these high precision data properly, there remain issues to be addressed. On the observational side, systematic errors, mainly from insufficient PSF-correction, must be reduced, and a possible contribution to the shear signal coming from intrinsic alignment or shape-shear correlation must be excluded. On the theoretical side, we need accurate predictions for P_delta(k) and precise statistical methods to infer cosmological parameters. In this talk I review the basics of cosmic shear focusing on the properties of its second-order measures. Commonly used methods to decompose E- and B-modes in cosmic shear, namely the aperture mass dispersion and the E/B-mode shear correlation function, suffer from incomplete knowledge of the two-point correlation function (2PCF) on very small and/or very large scales. The ring statistics, the most recently developed cosmic shear measure, improves on this issue and is able to decompose E- and B-modes using a 2PCF measured on a finite interval. I explain advantages and problems of the ring statistics and present the first shear signal measurement using the ring statistics on data from the CFHTLS survey. In addition, I discuss how the ring statistics can be further optimized with respect to cosmological information.

Jonathan Bird -- "Radial Mixing in Galactic Disks: The Effects of Disk Structure and Satellite Bombardment" (PPT)

Tuesday, October 13, 4:00 - 4:20pm

TBA

Michael Mortonson -- "Testing generic predictions of dark energy" (PDF)

Tuesday, October 13, 4:20 - 4:40pm

The cosmological distance-redshift relation and the growth of large-scale structure are linked by their mutual dependence on the expansion rate of the universe. With measured distances and redshifts to a variety of objects in hand, we can predict the rate of structure growth that we should observe at the same redshifts. Different assumptions about dark energy properties, the spatial curvature of the universe, and the theory of gravity lead to different predictions for growth from the same set of distance measurements. Direct observations of the growth of structure can therefore test various models of dark energy, curvature, and gravity. I will present growth predictions from distance observations for several broad classes of dark energy models, assuming that general relativity is valid on all scales. I will then describe an application of these predictions to measuring the curvature of the universe with minimal dependence on dark energy evolution.

Mandeep Gill -- "Weak lensing tests on DES cluster simulation" (PPTx)

Tuesday, October 13, 4:40 - 5:00pm

TBA

David Schlegel -- "Baryon Oscillation Spectroscopic Surveys (BOSS and BigBOSS)" (PDF)

Wednesday, October 14, 9:00 - 9:45am

The Baryon Oscillation Spectroscopic Survey (BOSS) is a Stage III dark energy experiment beginning this year. I will describe the current status of baryon acoustic oscillation (BAO) results as standard rulers for dark energy, and the design goals of t he five years from 2009-2014, we will map 1.5 million galaxies at z<0.7. A simultaneous survey of 160,000 QSOs will map the hydrogen gas in absorption at redshifts 2.3 < z < 3. BOSS will provide the definitive measurement of the low redshift (z<0.7) BAO scale, and it will pioneer a powerful new method of measuring BAO at high redshift. BigBOSS is a proposed Stage IV experiment that would extend this map to 50 million galaxies over 24,000 deg^2. I will this proposed survey and its technical status.

Mat Pieri -- "Insights into the Enrichment of the Intergalactic Medium from SDSS" (PDF)

Wednesday, October 14, 9:45 - 10:05am

Mechanical feedback is a crucial component of our understanding of galaxy formation and evolution. Metals in the Intergalactic Medium (IGM) provide a valuable tracer of this feedback and is easiest to observe in the Lyman alpha forest at 2<z<3. Since the arrival the Keck, researchers have become dependent on the high resolution spectra for the measurement of this enrichment. We have used a wealth of data which has been as yet unmined: the Sloan Digital Sky Survey sample of QSO spectra.

We have used new pixel correlation techniques to place constraints on Omega_oxygen at precision comparable with a large sample of high resolution spectra. Data of this nature and quantity also allow us to produce a completely new observable: a restframe spectrum of Lyman alpha absorbers. Not only is this spectrum a novel window on the IGM it reveals as yet unseen species in the IGM. These metal lines represent a potential contaminant to the BOSS baryon acoustic oscillation (BAO) measurement and so these results will be crucial for a reliable measurement of BAO in the Lyman alpha forest. BOSS spectra will provide a boost in the precision of these measurements.

Eduardo Rozo -- "Cosmological Constraints from the maxBCG Cluster Catalog"

Wednesday, October 14, 10:05 - 10:25am

The maxBCG cluster catalog is a volume limited cluster catalog of optically selected clusters drawn from the SDSS photometric data. We present the constraints that the observed cluster abundance function places on cosmological parameters, and demonstrate that these results are in excellent agreement and competitive with X-ray cluster abundance measurements. As in X-ray studies, our errors are dominated by systematic uncertainties, and we will discuss ongoing efforts to mitigate these. The lessons learned here should prove to be an invaluable stepping stone for upcoming photometric surveys such as the Dark Energy Survey (DES).

Chris Orban -- "Self-similar Bumps and Wiggles: Isolating the Evolution of the BAO Peak with Power-law Initial Conditions" (PPT)

Wednesday, October 14, 11:00 - 11:20am

A challenging theoretical neccessity for the next generation of surveys is the ability to precisely model the non-linear gravitational evolution of the baryon acoustic oscillations (BAO) signature in the galaxy distribution. In this study, rather than using standard LambdaCDM initial conditions, we simplify the problem to that of a powerlaw correlation function with a bump. This allows us to use self-similar scaling as a test for numerical artifacts associated with the finite box size or numerical resolution. We isolate the evolution of the BAO bump by running cosmological N-body simulations with these initial conditions, measuring the autocorrelation function, and dividing out the "background" linear-theory powerlaw. We then measure the shift of the BAO peak, and compare the evolution of the bump with the predictions of a variety of methods used in the literature to model the behavior of the BAO signature. Results are presented for both Omega_m = 1.0, Omega_DE = 0.0 (which when coupled with these initial conditions is a universe which evolves with self-similarly) and also for the more realistic case of low Omega_m, Omega_Lambda > 0. Implications for measuring the BAO signature with large-scale structure surveys are discussed.

Kyler Kuehn -- "Prospects for the Dark Energy Survey" (PDF) (PPT)

Wednesday, October 14, 11:20 - 11:40am

The forthcoming Dark Energy Survey (DES), will observe nearly 1/4 of the southern sky; its primary mission is to determine with unprecedented precision the time-independent and time-dependent factors of the equation of state of Dark Energy (w_0 and w_a, respectively). Several complementary methods of analysis will be used to provide constraints on the values of w_0 and w_a; we will describe the cosmological significance of a number of possible results that DES could obtain for these values. We will also provide an update on the current design and construction status of DES, and we will briefly highlight several ancillary astrophysical questions that the deep, large-area Dark Energy Survey can help to answer in the course of its planned five year lifetime.

Eric Grashorn -- "An Overview of ANITA" (PPT)

Wednesday, October 14, 11:40am - 12:00pm

The ANITA (ANtarctic Impulsive Transient Antenna) experiment is a balloon-borne, broadband antenna array flown over the Antarctic continent. It is designed to detect radio Cherenkov emission from UHE astrophysical neutrino (\unit[E$>10^{12}$]{MeV}) interactions in the ice below. ANITA~1 completed a 35 day flight during the Austral summer of 2006-2007. ANITA~2, with increased sensitivity over ANITA~1, was launched December 20, 2008 and flew for 30 days. Initial analysis of ANITA~1 data shows that no neutrino candidates were detected with no physics background. In the absences of a signal, an upper limit was set on the high energy neutrino flux that begins to eliminate the highest cosmogenic neutrino models.

Risa Wechsler -- "Recent Insights and Current Puzzles in Galaxy Formation" (PDF)

Wednesday, October 14, 2:00 - 2:45pm

TBA

Haojing Yan -- "Galaxy Formation in the Early Universe" (PPT)

Wednesday, October 14, 2:45 - 3:05pm

The new deep data obtained by the Wide Field Camera 3 recently installed to the Hubble Space Telescope have revealed a large number of faint galaxy candidates at very high redshifts (z>7 and beyond). This new result and its implication to galaxy formation in the early universe will be discussed.

Stelios Kazantzidis -- "Coevolution of Galaxies & Supermassive Black Holes: A Key to Fundamental Physics and Galaxy Formation"

Wednesday, October 14, 3:05 - 3:25pm

In recent years, compelling dynamical evidence has indicated that supermassive black holes (SMBHs) are ubiquitous in galactic nuclei. According to the currently favored cold dark matter cosmological model, structures in the Universe grow through a complex process of continuous mergers and accretion of smaller systems. Thus, the hierarchical buildup of SMBHs by massive seed black holes present at the center of protogalaxies and the formation as natural consequences in any hierarchical cosmogony. Upcoming gravitational wave detection experiments such as the Laser Interferometer Space Antenna will be able to detect emission from coalescing SMBH binaries essentially to the edge of the observable Universe and provide a test of General Relativity as well as constraints on galaxy formation theories. The available observational data also reveal the existence of a remarkably tight correlation between the mass of the SMBH and the stellar velocity dispersion of the host galaxy spheroid, suggesting a fundamental connection between the growth of SMBHs and the assembly of galaxies. Numerical simulations constitute the most powerful tool for elucidating these issues. In this talk, I will investigate the coevolution of SMBHs and their host galaxies using high-resolution supercomputer simulations of galaxy mergers. In the process, I will emphasize the importance of SMBHs in offering new insights in fundamen our understanding of the processes of galaxy formation and evolution.

Pascal Vaudrevange -- "On the Eta problem and freeze-out in inflationary cosmology" (PDF)

Wednesday, October 14, 4:00 - 4:20pm

TBA

Matthias Dietrich -- "High-Redshift Quasars: Probing Early Star Formation" (PPT)

Wednesday, October 14, 4:20 - 4:40pm

To study star formation activity in juvenile galaxies in the early universe, high redshift quasars can be utilized as important probes. The rich emission line spectrum holds information about the gas chemical composition, i.e. the enrichment history, as well as about the mass of the super-massive black hole. For a sample of about 25 quasars at redshifts of about 3 < z < 5 ultraviolet, optical, and near-infrared spectra are analyzed

i. to estimate nuclear gas metallicities
ii. to probe the differential metal enrichment timescale between iron and alpha-elements at these early epochs indicated by the FeII UV / MgII line ratio, and
iii. to measure the mass of the super-massive central black hole (SMBH).

The quasars show at enhanced solar metallicities (~5 times solar) in their broad emission-line region and no indication of a metallicity evolution up to redshifts z = 5. The measured FeII UV / MgII ratios range from 3 to 5, typical for high redshift quasars, with a weighted mean of about 4. However, there is a marginal indication for a weak tendency for a lower mean ratio at z > 4.7. The estimated masses of the SMBHs are in the range of several times 109 M_sol. In concert, the gas metallicity, the FeII UV / MgII ratio, and model-based estimated time scales for enriching the gas and the growth time to assemble these super-massive black holes suggest that a major episode of star formation and the main growth of the black hole occurs roughly contemporaneously beginning at redshifts z = 10 and beyond.

 

Poster Abstracts

"Anisotropy Signatures of Millisecond Pulsars in Diffuse Gamma Ray Emission"

Rebecca Reesman (Ohio State, Physics)

We explore the possible contribution of unresolved millisecond pulsars (MSPs) to the high-latitude diffuse gamma-ray emission and examine the anisotropy properties of this source class. The presence of a signal from dark matter annihilation in Galactic subhalos in the diffuse gamma-ray background is expected to induce a modulation in the anisotropy energy spectrum. We examine whether the contribution from MSPs could interfere with a dark matter detection by producing a similar feature. We find that even if all millisecond pulsars share the same energy spectrum, as dark matter particles do, their features in the anisotropy energy spectrum only present a problem for detecting dark matter for dark matter particles with masses less than a few tens of GeV.

"Indirect WIMP search for the Sun and the galactic center in Super-Kamiokande"

Takayuki Tanaka (Najoya University)

We perform the indirect WIMP search using upward going muons(upmu) in Super-Kamiokande. We used from SK-I to SK-III dataset(3149.2 days) for this analysis. This search was done for the direction of the Sun and Galactic center. For the search of the Sun,no significant event excess was observed, and limit of WIMP induced upmu flux and limit of SD cross section was obtained. For the search of the Galactic center, no significant excess was observed. We calculated the limit of upmu flux.

"A Method for Establishing Constraints on Galactic Magnetic Field Models Using Data from Ultra High Energy Cosmic Rays"

Michael Sutherland (Ohio State, Physics)

Ultra high energy cosmic rays (UHECRs) are deflected by magnetic fields during their propagation. Different theoretical parametrisations of the Galactic magnetic field (GMF) are examined using a numerical tool which simulates their propagation through models of these fields. A method is presented for constraining the possible parameter space of GMF models for a given set of assumptions concerning the UHECR source distribution and composition.

"Multimessenger search for point sources: ultra-high energy cosmic rays and neutrinos"

Jelena Petrovic (Nikhef)

The origin of ultra-high energy cosmic rays (UHECRs) and neutrinos is still a mystery. Hadronic acceleration theory suggests that they should originate in the same sources (astrophysical or cosmological), together with gamma-rays. While gamma-rays have been linked to astrophysical sources, no point source of UHECRs or neutrinos have been found so far. In this paper, the multimessenger combination of UHECRs and neutrinos as a new approach to the high energy particle point source search is suggested. A statistical method for cross-correlation of UHECR and neutrino data sets is proposed. By obtaining the probability density function of number of neutrino events within chosen angular distance from observed UHECRs, the number of neutrino events in the vicinity of observed UHECRs, necessary to claim a discovery with a chosen significance, can be calculated. Different angular distances (bin sizes) are considered due to the unknown deflection of cosmic rays in galactic and intergalactic magnetic fields. Possible observed correlation of the arrival directions of UHECRs and neutrinos would provide a strong indication of hadronic acceleration theory. Correlation of both types of messengers with the location of certain sets of observed astrophysical objects would indicate sites of acceleration. Any systematic offset in arrival directions between UHECRs and neutrinos may shed more light on magnetic field deflection of cosmic rays.

"Measurement of Radio Frequency Attenuation in Deep Polar Ice Using IceCube's RF extension"

Eric Suchyta (OSU)

Astrophysical high energy neutrinos carry valuable information about their sources, and they are key to understanding the origins of high-energy cosmic rays. These high-energy neutrinos can be detected in-ice through coherent radio Cherenkov emission from neutrino induced showers. This has spurred a great interest in large-scale radio detectors that could be built as an extension to IceCube. AURA (Askaryan Under-ice Radio Array) is an experimental effort that is currently operating 5 in-ice radio frequency (RF) clusters (200 MHz - 1000 MHz) between depths of 300 m to 1300 m below the surface of the ice at the IceCube site. It's objective is to test technology and methods for a future array towards the detection of neutrinos >10^18 . A large variety of test data has been taken by the AURA array. We present a method to measure the radio attenuation length in the ice.

"Large Scale Structure in Modified Gravity"

David Jacobs (CWRU)

Coined as Generalized Einstein-Aether theory, this modification to standard gravity invokes a fixed-norm vector field with non-cannonical kinetic structure to explain the accelerated expansion and growth of large scale structure without the need for dark matter or dark energy.

"Degree Scale Anomalies in the CMB: Localizing the dip in the first peak to the north ecliptic pole"

Amanda Yoho (CWRU)

Noticeable deviations from the prediction of the fiducial LCDM cosmology are found in the angular power spectrum of the CMB. Besides large-angle anomalies, the WMAP 1st year data revealed a dip in the power spectra at l ~ 200, which was more evident in the ecliptic poles region. Using the latest WMAP 3-year data release, we study the intensity and spatial distribution of this feature in order to unveil its origin and its implications for the cosmological parameters. We show that in both first and third year WMAP data there is a substantial suppression of the first Doppler peak in a region near the north ecliptic pole. Currently, work is being done to determine the statistical significance of the dip, and to extend this analysis to the WMAP 5-year data.

"Using Reconstruction Uncertainty in an Active DeepCore Veto"

Jim Davis (OSU)

The IceCube neutrino observatory is currently being built at the south pole, and will consist of ~4800 digital optical modules (DOMs) deployed in one cubic kilometer of ice. The DeepCore low energy extension will be completed in 2010 with 13 strings, and will lower the detection threshold from 100 to ~10 GeV. The primary background, atmospheric muons, can be rejected by reconstructing a particle track and determining the likelihood that it began within the detector volume. The possibility of incorporating an estimate of track uncertainty into the rejection algorithm is investigated.

 

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