CWRU PAT Coffee Agenda

Tuesdays 10:30 - 11:30 | Fridays 11:30 - 12:30

+1 First discoveries of z~6 quasars with the Kilo Degree Survey and VISTA Kilo-Degree Infrared Galaxy survey.

jtd55 +1

+1 Gravitational Lensing Analysis of the Kilo Degree Survey.

jtd55 +1

+1 The first and second data releases of the Kilo-Degree Survey.

aam80 +1

+1 Hypermagnetic Fields and Baryon Asymmetry from Pseudoscalar Inflation.

cad96 +1 aam80 +1

+1 On stars, galaxies and black holes in massive bigravity.

aam80 +1

+1 Nonlocal and quasi-local field theories.

aam80 +1

+1 Can galileons solve the muon problem?. - [UPDATED]

cad96 +1

+1 A Three-Dimensional Map of Milky-Way Dust.

jtd55 +1

Showing votes from 2015-07-03 12:30 to 2015-07-07 11:30 | Next meeting is Friday Jul 10th, 11:30 am.

users

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astro-ph.CO

  • First discoveries of z~6 quasars with the Kilo Degree Survey and VISTA Kilo-Degree Infrared Galaxy survey.- [PDF] - [Article]

    B. P. Venemans, G. A. Verdoes Kleijn, J. Mwebaze, E. A. Valentijn, E. Bañados, R. Decarli, J. T. A. de Jong, J. R. Findlay, K. H. Kuijken, F. La Barbera, J. P. McFarland, R. G. McMahon, N. Napolitano, G. Sikkema, W. J. Sutherland
     

    We present the results of our first year of quasar search in the on-going ESO public Kilo Degree Survey (KiDS) and VISTA Kilo-Degree Infrared Galaxy (VIKING) surveys. These surveys go up to 2 magnitudes fainter than other wide-field imaging surveys that uncovered predominantly very luminous quasars at z~6. This allows us to probe a more common, fainter population of z~6 quasars. From this first set of combined survey catalogues covering ~250 deg^2 we selected point sources down to Z_AB=22 that had a very red i-Z (i-Z>2.2) colour. After follow-up imaging and spectroscopy, we discovered four new quasars in the redshift range 5.8<z<6.0. The absolute magnitudes at a rest-frame wavelength of 1450 A are between -26.6 < M_1450 < -24.4, confirming that we can find quasars fainter than M^*, which at z=6 has been estimated to be between M^*=-25.1 and M^*=-27.6. The discovery of 4 quasars in 250 deg^2 of survey data is consistent with predictions based on the z~6 quasar luminosity function. We discuss various ways to push the candidate selection to fainter magnitudes and we expect to find about 30 new quasars down to an absolute magnitude of M_1450=-24. Studying this homogeneously selected faint quasar population will be important to gain insight into the onset of the co-evolution of the black holes and their stellar hosts.

  • Gravitational Lensing Analysis of the Kilo Degree Survey.- [PDF] - [Article]

    Konrad Kuijken, Catherine Heymans, Hendrik Hildebrandt, Reiko Nakajima, Thomas Erben, Jelte T.A. de Jong, Massimo Viola, Ami Choi, Henk Hoekstra, Lance Miller, Edo van Uitert, Alexandra Amon, Chris Blake, Margot Brouwer, Axel Buddendiek, Ian Fenech Conti, Martin Eriksen, Aniello Grado, Joachim Harnois-Déraps, Ewout Helmich, Ricardo Herbonnet, Nancy Irisarri, Thomas Kitching, Dominik Klaes, Francesco Labarbera, Nicola Napolitano, Mario Radovich, Peter Schneider, Cristóbal Sifón, Gert Sikkema, Patrick Simon, Alexandru Tudorica, Edwin Valentijn, Gijs Verdoes Kleijn, Ludovic van Waerbeke
     

    The Kilo-Degree Survey (KiDS) is a multi-band imaging survey designed for cosmological studies from weak lensing and photometric redshifts. It uses the ESO VLT Survey Telescope with its wide-field camera OmegaCAM. KiDS images are taken in four filters similar to the SDSS ugri bands. The best-seeing time is reserved for deep r-band observations that reach a median 5-sigma limiting AB magnitude of 24.9 with a median seeing that is better than 0.7arcsec. Initial KiDS observations have concentrated on the GAMA regions near the celestial equator, where extensive, highly complete redshift catalogues are available. A total of 101 survey tiles, one square degree each, form the basis of the first set of lensing analyses, which focus on measurements of halo properties of GAMA galaxies. 9 galaxies per square arcminute enter the lensing analysis, for an effective inverse shear variance of 69 per square arcminute. Accounting for the shape measurement weight, the median redshift of the sources is 0.53. KiDS data processing follows two parallel tracks, one optimized for galaxy shape measurement (for weak lensing), and one for accurate matched-aperture photometry in four bands (for photometric redshifts). This technical paper describes how the lensing and photometric redshift catalogues have been produced (including an extensive description of the Gaussian Aperture and Photometry pipeline), summarizes the data quality, and presents extensive tests for systematic errors that might affect the lensing analyses. We also provide first demonstrations of the suitability of the data for cosmological measurements, and explain how the shear catalogues were blinded to prevent confirmation bias in the scientific analyses. The KiDS shear and photometric redshift catalogues, presented in this paper, are released to the community through this http URL .

  • The first and second data releases of the Kilo-Degree Survey.- [PDF] - [Article]

    Jelte T. A. de Jong, Gijs A. Verdoes Kleijn, Danny R. Boxhoorn, Hugo Buddelmeijer, Massimo Capaccioli, Fedor Getman, Aniello Grado, Ewout Helmich, Zhuoyi Huang, Nancy Irisarri, Konrad Kuijken, Francesco LaBarbera, John P. McFarland, Nicola R. Napolitano, Mario Radovich, Gert Sikkema, Edwin A. Valentijn, Kor G. Begeman, Massimo Brescia, Stefano Cavuoti, Ami Choi, Oliver-Mark Cordes, Giovanni Covone, Massimo Dall'Ora, Hendrik Hildebrandt, Giuseppe Longo, Reiko Nakajima, Maurizio Paolillo, Emanuella Puddu, Agatino Rifatto, Crescenzo Tortora, Edo van Uitert, Axel Buddendiek, Joachim Harnois-Déraps, Thomas Erben, Martin B. Eriksen, Catherine Heymans, Henk Hoekstra, Benjamin Joachimi, Thomas D. Kitching, Dominik Klaes, Léon V. E. Koopmans, Fabian Köhlinger, Nivya Roy, Cristóbal Sifon, et al. (4 additional authors not shown)
     

    The Kilo-Degree Survey (KiDS) is an optical wide-field imaging survey carried out with the VLT Survey Telescope and the OmegaCAM camera. KiDS will image 1500 square degrees in four filters (ugri), and together with its near-infrared counterpart VIKING will produce deep photometry in nine bands. Designed for weak lensing shape and photometric redshift measurements, the core science driver of the survey is mapping the large-scale matter distribution in the Universe back to a redshift of ~0.5. Secondary science cases are manifold, covering topics such as galaxy evolution, Milky Way structure, and the detection of high-redshift clusters and quasars. KiDS is an ESO Public Survey and dedicated to serving the astronomical community with high-quality data products derived from the survey data, as well as with calibration data. Public data releases will be made on a yearly basis, the first two of which are presented here. For a total of 148 survey tiles (~160 sq.deg.) astrometrically and photometrically calibrated, coadded ugri images have been released, accompanied by weight maps, masks, source lists, and a multi-band source catalog. A dedicated pipeline and data management system based on the Astro-WISE software system, combined with newly developed masking and source classification software, is used for the data production of the data products described here. The achieved data quality and early science projects based on the data products in the first two data releases are reviewed in order to validate the survey data. Early scientific results include the detection of nine high-z QSOs, fifteen candidate strong gravitational lenses, high-quality photometric redshifts and galaxy structural parameters for hundreds of thousands of galaxies. (Abridged)

  • Hypermagnetic Fields and Baryon Asymmetry from Pseudoscalar Inflation.- [PDF] - [Article]

    Mohamed M. Anber, Eray Sabancilar
     

    We show that maximally helical hypermagnetic fields produced during pseudoscalar inflation can generate the observed baryon asymmetry of the universe via the B+L anomaly in the Standard Model. We find that most of the parameter space of pseudoscalar inflation that explains the cosmological data leads to baryon overproduction, hence the models of natural inflation are severely constrained. We also point out a connection between the baryon number and topology of the relic magnetic fields. Both the magnitude and sign of magnetic helicity can be detected in future diffuse gamma ray data. This will be a smoking gun evidence for a link between inflation and the baryon asymmetry of the Universe.

  • On stars, galaxies and black holes in massive bigravity.- [PDF] - [Article]

    Jonas Enander, Edvard Mortsell
     

    In this paper we study the phenomenology of stars and galaxies in massive bigravity. We give parameter conditions for the existence of viable star solutions when the radius of the star is much smaller than the Compton wavelength of the graviton. If these parameter conditions are not met, we constrain the ratio between the coupling constants of the two metrics, in order to give viable conditions for e.g. neutron stars. For galaxies, we put constraints on both the Compton wavelength of the graviton and the conformal factor and coupling constants of the two metrics. The relationship between black holes and stars, and whether the former can be formed from the latter, is discussed. We argue that the different asymptotic structure of stars and black holes makes it unlikely that black holes form from the gravitational collapse of stars in massive bigravity.

astro-ph.HE

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astro-ph.GA

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astro-ph.IM

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gr-qc

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hep-ph

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hep-th

  • BRST invariance in Coulomb gauge QCD.- [PDF] - [Article]

    A. Andrasi, J. C. Taylor
     

    In the Coulomb gauge, the Hamiltonian of QCD contains terms of order h^2, identified by Christ and Lee, which are non-local but instantaneous. The question is addressed how these terms fit in with BRST invariance. Our discussion is confined to the simplest, O(g^4), example.

  • Nonlocal and quasi-local field theories.- [PDF] - [Article]

    E. T. Tomboulis
     

    We investigate nonlocal field theories, a subject that has attracted some renewed interest in connection with nonlocal gravity models. We study, in particular, scalar theories of interacting delocalized fields, the delocalization being specified by nonlocal integral kernels. We distinguish between strictly nonlocal and quasi-local (compact support) kernels and impose conditions on them to insure UV finiteness and unitarity of amplitudes. We study the classical initial value problem for the partial integro-differential equations of motion in detail. We give rigorous proofs of the existence but accompanying loss of uniqueness of solutions due to the presence of future, as well as past, "delays," a manifestation of acausality. In the quantum theory we derive a generalization of the Bogoliubov causality condition equation for amplitudes, which explicitly exhibits the corrections due to nonlocality. One finds that, remarkably, for quasi-local kernels all acausal effects are confined within the compact support regions. We briefly discuss the extension to other types of fields and prospects of such theories.

hep-ex

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quant-ph

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other

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