Still Thursday. Two more days of work this week, but it felt like Friday yesterday. Arman cooked a very nice dinner for all of us (Teppei, Hayin, Fred, me) last night.
INPA LBL
DeepCore and beyond - a phase approach toward precision megaton neutrino detectors
Darren Grant
* atmospheric neutrinos: produced in the collision of primarily cosmic rays (typically protons) with nuclei (N, O, etc) in the upper atmosphere. This creates a shower of hadrons, mostly pions, which decay into a muon and muon anti-neutrino. The muons decay to an electron, muon neutrino, and an electron anti-neutrino: 2 to 1 muon to electron neutrino ratio produced (some modification necessary).
* atmospheric neutrino detection: Super-K detects atmospheric neutrinos interaction with H and O in the 22.5 kT mass of water, reactions "fully contained" in the detector volume. Neutrino flavor tagged by detecting and identifying the final state lepton (muon or electron). Low energy (E < 1 GeV) neutrinos typically react by quasi-elastic scattering, with only the lepton visible. At higher energies, the final state muon or electrons is often accompanied by a pion or numerous hadrons (deep inelastic scattering). To properly associate the event with the neutrino type, select events with a single Cherenkov ring. "Partially contained" events are usually (98%) muons, since only muons have such great penetrating power. Muon ring sharp, electron ring more fuzzy (due to e- shower).
* evidence of neutrino oscillations in atmospheric neutrinos: (1) predicted muon/electron neutrino ratio has anomaly, (2) up-down asymmetry in high-E muon neutrinos, when we expect the high-E CR flux distribution to be symmetric (low-E CR's are affected by earth's magnetic field), (3) upward-going muons: the rate of low and high-E events were in poor agreement with the standard prediction, but in good agreement with a hypothesis of neutrino oscillations.
DeepCore: low energy extension to the IceCube Neutrino Observatory, fiducial volume up to 35 MT, energy threshold as low as 10GeV. Use of IceCube array as the active veto for cosmic ray muons to achieve a pure neutrino sample. New physics: atmospheric neutrino oscillations, indirect DM searches.
Possible to achieve lower detector energy thresholds and higher precision measurements in deep ice with more "infill". Two-phase approach of infill considered. First: similar to DeepCore, 10MT wth <1GeV sensitivity--improved sensitivity for indirect WIMP searches, atmospheric neutrinos, Galactic center point sources, proton decay searches. Second: few MT fiducial with 10 MeV threshold for large-scale physics program that includes proton decay, SNe neutrinos, and future long-baseline efforts.
Current status of DeepCore, 1st year data, simulation results, feasibility sutides for new arrays.
1107.2401
Interaction between dark matter sub-halos & galactic gaseous disk
Kannan, Maccio, Pasquali, Moster, Walter
Origin of observed holes and shells in H I distribution of galaxies: Intraction of DM sub-halos with gas disk (an idea). High-resolution hydro sims show pure DM sub-halos impacting galactic disk cannot produce holes, but result in high density regions in the disk. Sub-halos containing a small amount of gas (few percent gas mass fraction) can displace the gas in disk and form holes and shells. Size and lifetime dependent on density, halo gas mass, impact velocity. 1e8 M_sun can create a kpc scale hole. Also register an increased SFR at the rim of the hole, as also seen in observations. Number of predicted holes falls short compared to observations. DM halo impact is not the major channel through wich holes are formed.
1107.2516
Real-time, fast radio transient searches with GPU de-dispersion
Magro, Karastergiou, Salvini, Mort, Dulwich, Adami
Identification and discovery of fast radio transients throught blind-search surveys requires a large amount of processing power, ~O(N^3). GPUs can be used for fast transient discorvy in real-time.
1107.2542
An effective theory of accelerated expansion
Jiminez, Talavera, Verde
Effective theory of inflation and DE. How many (free) parameters are needed to broadly capture the physics of a theory describine cosmic acceleration? What are the physical interpretation of the parameters? There are 5 independent parameters, one can be constrained via general relativity tests; the other 4 by observing H(z). Need accurate measurement for H(z).
* Interesting-sounding paper.
1010.5250
The signatures of large-scale temperature and intensity fluctaions in the lyman-alpha forest
McQuinn, Hernquist, Lidz, Zaldarriaga
Reionization processes produce large-scale temperature fluctations in the intergalactic medium. Study consequences of inhomogeneous heating for the Ly-alpha forest--it's subtle, and doesn't show up in usual statisitcs. But earlier analysis were not sensitive to 3d modes with >30 comoving Mpc/h wavelengths, scales where temperature fluctuations are likely to be largest. Find physically motivated temperature models can alter 3D power specrum of the Ly-alpha forest at order unity level at k<0.1 Mpc^{-1}, easily detectable with BOSS. Fluctuation in the intensity of the UV BG can also alter P_F significantly. Can constrain models for the sources of the ionizing background. At higher z, potentially detect the thermal imprint of hydrogen reionization.
1103.5378
The flare-energy distributions generated by kink-unstable ensembles of zero-net-current coronal loops
Bareford, Browning, Van der Linden
* nano-flares can heat the corona to a million degrees K.
1106.5790
Stable heating of cluster cooling flows by CR streaming
Fujita, Ohira
* CR from AGN produces Alfven waves instability that heat the cooling flow in clusters.
1107.2155
The XENON 100 Dark Matter experiment
XENON100 collaboration
* time projection chamber: particle detected invented by Nygren at LBL. Consists of a gas-filled cylindrical chamber with multi-wire proportional chambers (MWPC) as endplates. Electric field along the cylinder radial direction, magnetic field along the cylinder axis. z coordinage determined by measuring the drift time from the ionization event to the MWPC at the end. Anode wires in the azimuthal direction, which provides information on the radial coordinate r.
Liquid Xe in a TPC to measure Xe nuclear recoils from WIMPs. Detector design, performance results from commissioning and first science runs. 62kg for LXe, surrounded by 99kg of LXe veto, instrumented by PMTs inside the liquid or Xe gas. LXe target in low-radioactivity stainless steel vessel, embedded in a pasive radiation shield. Installed in Gran Sasso (underground); has 100 live-days DM search. Design goal: detect WIMP-nucleon scattering of sigma=2e-45 cm^2 for a 100 GeV WIMP.
1107.2213
Weak lensing tomography with orthognal polynomials
Schaefer, Heisenberg
WL shear tomography with LOS weighting with a set of special orthogonal polynomials (TaRDiS). Each polynomial projects out statistically independent information; combination of multiple polynomials lifts degeneracies. Assumption of a reference cosmology is needed for the construction of the polynomials (!).
* It's like tomography, except that it doesn't use a top-hat. It uses TaRDiS polynomials.
1107.2258
Beyond Einstein: Cosmologcal test of model independent modified gravity
Thomas
Add Galaxy cluters to the observables and examine whether they can improve the constraints on the modified gravity parameters: Planck CMB, SZ cluster, DES WL survey. Cluster counts improves the constraints.
1107.2112
Symmetryon cosmology
Hinterbichler, Khoury, Levy, Matas
Symmetron: scalar field in the dark sector, where coupling to matter depends on the ambient matter density. Decoubled and screened in regions of high density (satisfies local constraint on gravity), but couples with gravitational strength in regions of low density. Derive the cosmological expansion history in the presence of a symmetron field, through inflation, radiation, and matter-dominated epochs. The scalar field reaches symmetry-breaking vacuum by the present epoch. Still needs cosmological constant to drive late-time cosmic acceleration.
1107.2316
Odyssey 2: A mission toward Neptune and Triton to test GR
Lenoir, et al
* Eddington parameter: "gamma", which is a straightforward paramaeterization of the amount of deflection of light bya gravitational source; equal to 1 for GR. Best constrained of the 10 post-Newtonian parameters.
Odyssey 2 proposed for M3 mission for Cosmic Vision 2015-2025. Aims at Neptune and Triton. Two sets of objectives: (1) perform a set of gravitation experiments at the Solar system scale; measure the Eddington parameter; investigate the navigation anomalies during fly-bys. These require Electrostatic accelerometer with a rotating stage, radio-science, and laser ranging. (2) enhance our knowledge of Neptune and Triton. Need: camera, spectrometer, dust and particle etectors, magnetometer. Obtain: gravity field, atmosphere and magnetosphere of the two bodies, surface geology of Triton, nature of planetary rings around Neptune.
1107.1714
Impacts of Dark Stars on Reionization and signatures in the CMB
Scott, Venkatesan, Roebber, Gondolo, Pierpaoli, Holder
Possible impacts of dark stars in reionization and CMB: if dark stars capture large amounts of dark matter via nuclear scattering, reionzation can be substantially delayed, decreasing integrated optical depth to last scattering. These effects can be constrained from WMAP7 data, but are degenerate with astrophysical uncertainties.
1107.1716
Do baryons trace dark matter in the early universe?
Grin, Dore, Kamionkowski
BBN and galaxy clusters allows compensated isocurvature perturbations to be as large as ~10%. They can modulate the power spectrum of CMB fluctuations. Observable in B modes in CMB polarization. Calculate the magnitude of this effect, describe the observability.
* any two-field inflationary picture would generically produce some iso-curvature; above scenario just happened to be poorly constrained. Can use CMB to learn more (don't need 21cm). Considers the case where the dominant perturbations are still adiabatic.
1107.1789
Cosmology today-a brief review
Cervantes-Cota, Smoot
Breif review of the standard model of cosmology. FRW at different epochs, comological lengths, physical processes necessary to understand the early and very early universe, and observations of it.
1107.1916
Where will supersymmetric DM first be seen?
Gao, Frenk, Jenkins, Springel, White
If dark matter consists of supersymmetric particles, then annihilation signals should come rom haloes. More signals from nearby rich clusters, just as clean as local dSph's. Signal mostly from subhalos. Fermi may be able to resolve them. Promising clusters: Coma and Fornax, but need better detection algorithms, since the signal is expected to be weak.
1107.1715
Global fits to the cMSSM including the first LHC and XENON100 data
Bertone, Cerdeno, Fornasa, Ruiz de Austri, Strege, Trotta
cMSSM: constrained minimal supersymmetric standard model, constrained using ATLAS, CMS at LHC, and XENON100. Conseequences for neutralino DM studied, rules out Focus Point region, from particle astrophysics.
1107.1477
Herschel detects a massive dust reservoir in Supernova 1987A
Matsuura et al
Far IR and submillimiter observations of SN 1987A in LMC. Observations show presence of a population of cold dust grains radiating at 17-23K at 220 L_sun; SED and intensity implies dust mass of 0.4-0.7 M_sun. This must be the SN ejecta, which requires efficient precipitation of all refractory material into dust. Implies SNe can produce the large dust masses detected in young galaxies at very high z.
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