Search

Your search keyword '"LSST"' showing total 8 results
Start Over Descriptor "LSST" Topic dark energy
8 results on '"LSST"'

1. Probing the Dark Universe at the Pixel-Level in Large-Scale Surveys

Author

Broughton, Alexander Morris

Subjects
Physics, Astrophysics, astrophysics, cosmology, dark energy, dark matter, LSST, weak-lensing
Abstract

Future astrophysical surveys will provide unprecedented datasets in both scale and precision for testing our most concordant theories of dark matter and dark energy. For the first time, the confidence of our understanding of the components of the Universe will be limited by systematic uncertainties rather than the statistical precision we can achieve. Improved modeling of measurement biases in survey data is necessary to achieve the theory-constraining power of ambitious future astrophysical surveys. Recent in-lab, on-sky, and simulated experiments offer opportunities to investigate coherence between systematic and phenomenological observables and invent new techniques to differentiate them. This thesis details my contribution to measuring the Dark Universe, and it is structured in two parts. The first part of this thesis improves template modeling of the foreground gamma-ray emission in the Galactic plane in 12 years of Fermi-LAT data. This has implications for the observed excess \gray{} emission near the Galactic center, which was previously associated with dark matter. We compare the likelihood of observing gamma-ray emission from cold hydrogen gas clouds using models derived from spectral line emission maps of abundant ($^{12}\mathrm{CO}$) and rare ($^{13}\mathrm{CO}$) tracer molecules. Using this approach, the rare tracer predicts previously unmodeled gamma-ray emission at $47\sigma$ significance, localized to the pixels around the densest regions, where emission is undercounted due to reabsorption along the line-of-sight. We also identify unassociated point-like sources in the Galactic plane which were previously smoothed out by re-absorption consistent with peaked gas structure as well as point-like gas structure which could have been mistaken for millisecond pulsars by earlier works. We further utilize a convolutional neural network (CNN) to try to predict the $^{13}\mathrm{CO}$ distribution in the same region, which could prove useful to predict the $^{13}\mathrm{CO}$ distribution in data-poor regions such as the Galactic center. The second part of this thesis develops a correction for the observed size-magnitude relation of stars, which are used calibrate observables for the Legacy Survey of Space and Time (LSST). The brighter-fatter effect results in distorted images of bright calibration stars, creating a flux-dependent point spread function (PSF) that if left unmitigated, could make up a large fraction of the error budget in Stage IV weak-lensing (WL) surveys such as the Legacy Survey of Space and Time (LSST). Using data from the LSST camera, we compare the BFE in flat field and star images and test the ability of scalar correction methods to mitigate it. We observe that the BFE evolves anisotropically as a function of flux due to higher-order BFEs which were previously assumed to be negligible by a commonly used correction technique. We also find that poor assumptions of the correction result in unphysical violations of flux conservation in the images at the O(0.01\%) level. Based on these analyses, we then propose a new, unbiased correction methodology to account for these effects. With these improvements we can correct on average 95\% of the total effect in the sensors we tested. We use these results to predict the impact of these previously unmodeled effects on sensitive observables of inferred cosmological outcomes and advise data processing strategies to limit the impact of the effects on LSST science pathways.

Published
2024

2. Galaxy Cluster Centralization Utilizing Weak Gravitational Lensing of High Redshift, z>0.4, Galaxy Clusters

Author

Santana, Rebecca

Subjects
Astrophysics, Astronomy, Physics, galaxy clusters, gravitational lensing, weak lensing, high redshift, centralization, centroid, dark matter, cosmology, dark energy, LSST
Abstract

As more wide-angle, large-scale, all-sky surveys become available so do opportunities forsignificant advancements into our understanding of the Universe through the study offormation and evolution of structure and testing cosmological models. It is important toaddress the systematic errors of weak lensing measurements as statistical errors improve,especially those that are planned as part of an automated process such as pipelines for theVera Rubin Observatory’s Legacy Survey of Space and Time. I obtained and analyzedimages from 14 Hubble Space Telescope Advanced Camera for Surveys Wide FieldCamera galaxy clusters spanning redshifts from 0.4 to 0.9 to identify potential galaxycluster centroids and determine the optimal centroid usage based on observable indicators.I utilized the Principal Component Analysis method on individual exposures to describethe point spread function and the KSB+ method to correct the galaxy shapes and measurethe shear. I then performed a bootstrap resampling analysis to identify the weak lensingcentroid for each cluster. I compared this centroid with the brightest cluster galaxy (BCG),light and X-ray centroids to determine which centroid was optimal. I also searched forobservable markers indicating when it is beneficial to use which centroid. My analysis ofthe survey suggests the BCG as the better choice of center compared to light or X-raycentroids, but is still offset from the mass centroid at a statistically significant level in anumber of the clusters. I found no clear indicator within my research of an ideal centroidchoice.

Published
2024

4. Euclid preparation: I. The Euclid Wide Survey

Author

Scaramella, R., Amiaux, J., Mellier, Y., Burigana, C., Carvalho, C.S., Cuillandre, J.-C., Da Silva, A., Derosa, A., Dinis, J., Maiorano, E., Maris, M., Tereno, I., Laureijs, R., Boenke, T., Buenadicha, G., Dupac, X., Gaspar Venancio, L.M., Gómez-Álvarez, P., Hoar, J., Lorenzo Alvarez, J., Racca, G.D., Saavedra-Criado, G., Schwartz, J., Vavrek, R., Schirmer, M., Aussel, H., Azzollini, R., Cardone, V.F., Cropper, M., Ealet, A., Garilli, B., Gillard, W., Granett, B.R., Guzzo, L., Hoekstra, H., Jahnke, K., Kitching, T., Maciaszek, T., Meneghetti, M., Miller, L., Nakajima, R., Niemi, S.M., Pasian, F., Percival, W.J., Pottinger, S., Sauvage, M., Scodeggio, M., Wachter, S., Zacchei, A., Aghanim, N., Amara, A., Auphan, T., Auricchio, N., Awan, S., Balestra, A., Bender, R., Bodendorf, C., Bonino, D., Branchini, E., Brau-Nogue, S., Brescia, M., Candini, G.P., Capobianco, V., Carbone, C., Carlberg, R.G., Carretero, J., Casas, R., Castander, F.J., Castellano, M., Cavuoti, S., Cimatti, A., Cledassou, R., Congedo, G., Conselice, C.J., Conversi, L., Copin, Y., Corcione, L., Costille, A., Courbin, F., Degaudenzi, H., Douspis, M., Dubath, F., Duncan, C.A.J., Dusini, S., Farrens, S., Ferriol, S., Fosalba, P., Fourmanoit, N., Frailis, M., Franceschi, E., Franzetti, P., Fumana, M., Gillis, B., Giocoli, C., Grazian, A., Grupp, F., Haugan, S.V.H., Holmes, W., Hormuth, F., Hudelot, P., Kermiche, S., Kiessling, A., Kilbinger, M., Kohley, R., Kubik, B., Kümmel, M., Kunz, M., Kurki-Suonio, H., Lahav, O., Ligori, S., Lilje, P.B., Lloro, I., Mansutti, O., Marggraf, O., Markovic, K., Marulli, F., Massey, R., Maurogordato, S., Melchior, M., Merlin, E., Meylan, G., Mohr, J.J., Moresco, M., Morin, B., Moscardini, L., Munari, E., Nichol, R.C., Padilla, C., Paltani, S., Peacock, J., Pedersen, K., Pettorino, V., Pires, S., Poncet, M., Popa, L., Pozzetti, L., Raison, F., Rebolo, R., Rhodes, J., Rix, H.-W., Roncarelli, M., Rossetti, E., Saglia, R., Schneider, P., Schrabback, T., Secroun, A., Seidel, G., Serrano, S., Sirignano, C., Sirri, G., Skottfelt, J., Stanco, L., Starck, J.L., Tallada-Crespí, P., Tavagnacco, D., Taylor, A.N., Teplitz, H.I., Toledo-Moreo, R., Torradeflot, F., Trifoglio, M., Valentijn, E.A., Valenziano, L., Verdoes Kleijn, G.A., Wang, Y., Welikala, N., Weller, J., Wetzstein, M., Zamorani, G., Zoubian, J., Andreon, S., Baldi, M., Bardelli, S., Boucaud, A., Camera, S., Di Ferdinando, D., Fabbian, G., Farinelli, R., Galeotta, S., Graciá-Carpio, J., Maino, D., Medinaceli, E., Mei, S., Neissner, C., Polenta, G., Renzi, A., Romelli, E., Rosset, C., Sureau, F., Tenti, M., Vassallo, T., Zucca, E., Baccigalupi, C., Balaguera-Antolínez, A., Battaglia, P., Biviano, A., Borgani, S., Bozzo, E., Cabanac, R., Cappi, A., Casas, S., Castignani, G., Colodro-Conde, C., Coupon, J., Courtois, H.M., Cuby, J., de la Torre, S., Desai, S., Dole, H., Fabricius, M., Farina, M., Ferreira, P.G., Finelli, F., Flose-Reimberg, P., Fotopoulou, S., Ganga, K., Gozaliasl, G., Hook, I.M., Keihanen, E., Kirkpatrick, C.C., Liebing, P., Lindholm, V., Mainetti, G., Martinelli, M., Martinet, N., Maturi, M., McCracken, H.J., Metcalf, R.B., Morgante, G., Nightingale, J., Nucita, A., Patrizii, L., Potter, D., Riccio, G., Sánchez, A.G., Sapone, D., Schewtschenko, J.A., Schultheis, M., Scottez, V., Teyssier, R., Tutusaus, I., Valiviita, J., Viel, M., Vriend, W., Whittaker, L., Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Istituto di Astrofisica Spaziale e Fisica cosmica - Bologna (IASF-Bo), Istituto Nazionale di Astrofisica (INAF), Université de Lisbonne, Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), European Space Astronomy Centre (ESAC), Agence Spatiale Européenne = European Space Agency (ESA), Centre d'étude spatiale des rayonnements (CESR), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Institut de Physique des 2 Infinis de Lyon (IP2I Lyon), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Centre de Calcul de l'IN2P3 (CC-IN2P3), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), AUTRES, Département d'Astrophysique (ex SAP) (DAP), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Dipartimento di Fisica e Scienze della Terra [Ferrara], Università degli Studi di Ferrara (UniFE), University of California [Merced], University of California, Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Scaramella, R., Amiaux, J., Mellier, Y., Burigana, C., Carvalho, C. S., Cuillandre, J. -C., Da Silva, A., Derosa, A., Dinis, J., Maiorano, E., Maris, M., Tereno, I., Laureijs, R., Boenke, T., Buenadicha, G., Dupac, X., Gaspar Venancio, L. M., G??mez-??lvarez, P., Hoar, J., Lorenzo Alvarez, J., Racca, G. D., Saavedra-Criado, G., Schwartz, J., Vavrek, R., Schirmer, M., Aussel, H., Azzollini, R., Cardone, V. F., Cropper, M., Ealet, A., Garilli, B., Gillard, W., Granett, B. R., Guzzo, L., Hoekstra, H., Jahnke, K., Kitching, T., Maciaszek, T., Meneghetti, M., Miller, L., Nakajima, R., Niemi, S. M., Pasian, F., Percival, W. J., Pottinger, S., Sauvage, M., Scodeggio, M., Wachter, S., Zacchei, A., Aghanim, N., Amara, A., Auphan, T., Auricchio, N., Awan, S., Balestra, A., Bender, R., Bodendorf, C., Bonino, D., Branchini, E., Brau-Nogue, S., Brescia, M., Candini, G. P., Capobianco, V., Carbone, C., Carlberg, R. G., Carretero, J., Casas, R., Castander, F. J., Castellano, M., Cavuoti, S., Cimatti, A., Cledassou, R., Congedo, G., Conselice, C. J., Conversi, L., Copin, Y., Corcione, L., Costille, A., Courbin, F., Degaudenzi, H., Douspis, M., Dubath, F., Duncan, C. A. J., Dusini, S., Farrens, S., Ferriol, S., Fosalba, P., Fourmanoit, N., Frailis, M., Franceschi, E., Franzetti, P., Fumana, M., Gillis, B., Giocoli, C., Grazian, A., Grupp, F., Haugan, S. V. H., Holmes, W., Hormuth, F., Hudelot, P., Kermiche, S., Kiessling, A., Kilbinger, M., Kohley, R., Kubik, B., K??mmel, M., Kunz, M., Kurki-Suonio, H., Lahav, O., Ligori, S., Lilje, P. B., Lloro, I., Mansutti, O., Marggraf, O., Markovic, K., Marulli, F., Massey, R., Maurogordato, S., Melchior, M., Merlin, E., Meylan, G., Mohr, J. J., Moresco, M., Morin, B., Moscardini, L., Munari, E., Nichol, R. C., Padilla, C., Paltani, S., Peacock, J., Pedersen, K., Pettorino, V., Pires, S., Poncet, M., Popa, L., Pozzetti, L., Raison, F., Rebolo, R., Rhodes, J., Rix, H. -W., Roncarelli, M., Rossetti, E., Saglia, R., Schneider, P., Schrabback, T., Secroun, A., Seidel, G., Serrano, S., Sirignano, C., Sirri, G., Skottfelt, J., Stanco, L., Starck, J. L., Tallada-Cresp??, P., Tavagnacco, D., Taylor, A. N., Teplitz, H. I., Toledo-Moreo, R., Torradeflot, F., Trifoglio, M., Valentijn, E. A., Valenziano, L., Verdoes Kleijn, G. A., Wang, Y., Welikala, N., Weller, J., Wetzstein, M., Zamorani, G., Zoubian, J., Andreon, S., Baldi, M., Bardelli, S., Boucaud, A., Camera, S., Di Ferdinando, D., Fabbian, G., Farinelli, R., Galeotta, S., Graci??-Carpio, J., Maino, D., Medinaceli, E., Mei, S., Neissner, C., Polenta, G., Renzi, A., Romelli, E., Rosset, C., Sureau, F., Tenti, M., Vassallo, T., Zucca, E., Baccigalupi, C., Balaguera-Antol??nez, A., Battaglia, P., Biviano, A., Borgani, S., Bozzo, E., Cabanac, R., Cappi, A., Casas, S., Castignani, G., Colodro-Conde, C., Coupon, J., Courtois, H. M., Cuby, J., de la Torre, S., Desai, S., Dole, H., Fabricius, M., Farina, M., Ferreira, P. G., Finelli, F., Flose-Reimberg, P., Fotopoulou, S., Ganga, K., Gozaliasl, G., Hook, I. M., Keihanen, E., Kirkpatrick, C. C., Liebing, P., Lindholm, V., Mainetti, G., Martinelli, M., Martinet, N., Maturi, M., Mccracken, H. J., Metcalf, R. B., Morgante, G., Nightingale, J., Nucita, A., Patrizii, L., Potter, D., Riccio, G., S??nchez, A. G., Sapone, D., Schewtschenko, J. A., Schultheis, M., Scottez, V., Teyssier, R., Tutusaus, I., Valiviita, J., Viel, M., Vriend, W., Whittaker, L., Department of Physics, Research Program in Systems Oncology, Helsinki Institute of Physics, Gomez-Alvarez, P., Kummel, M., Tallada-Crespi, P., Gracia-Carpio, J., Balaguera-Antolinez, A., De La Torre, S., and Sanchez, A. G.

Subjects
Space vehicle, [PHYS.ASTR.IM]Physics [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Cosmology and Nongalactic Astrophysics (astro-ph.CO), space vehicle, space vehicles, surveys, methods, numerical, dark energy, dark matter, brightness, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Surveys, power spectrum, space mission, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], numerical , dark energy, dark matter [space vehicles, surveys, methods], Dark energy, magnitudes, Dark matter, survey, sky, Instrumentation and Methods for Astrophysics (astro-ph.IM), numerical [Methods], model, Methods: numerical, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Space vehicles, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, 115 Astronomy, Space science, universe, Space and Planetary Science, [SDU]Sciences of the Universe [physics], lsst, astro-ph.CO, method, Surveys, Methods: numerical, Astrophysics - Instrumentation and Methods for Astrophysics, astro-ph.IM, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Euclid is an ESA mission designed to constrain the properties of dark energy and gravity via weak gravitational lensing and galaxy clustering. It will carry out a wide area imaging and spectroscopy survey (EWS) in visible and near-infrared, covering roughly 15,000 square degrees of extragalactic sky on six years. The wide-field telescope and instruments are optimized for pristine PSF and reduced straylight, producing very crisp images. This paper presents the building of the Euclid reference survey: the sequence of pointings of EWS, Deep fields, Auxiliary fields for calibrations, and spacecraft movements followed by Euclid as it operates in a step-and-stare mode from its orbit around the Lagrange point L2. Each EWS pointing has four dithered frames; we simulate the dither pattern at pixel level to analyse the effective coverage. We use up-to-date models for the sky background to define the Euclid region-of-interest (RoI). The building of the reference survey is highly constrained from calibration cadences, spacecraft constraints and background levels; synergies with ground-based coverage are also considered. Via purposely-built software optimized to prioritize best sky areas, produce a compact coverage, and ensure thermal stability, we generate a schedule for the Auxiliary and Deep fields observations and schedule the RoI with EWS transit observations. The resulting reference survey RSD_2021A fulfills all constraints and is a good proxy for the final solution. Its wide survey covers 14,500 square degrees. The limiting AB magnitudes ($5\sigma$ point-like source) achieved in its footprint are estimated to be 26.2 (visible) and 24.5 (near-infrared); for spectroscopy, the H$_\alpha$ line flux limit is $2\times 10^{-16}$ erg cm$^{-2}$ s$^{-1}$ at 1600 nm; and for diffuse emission the surface brightness limits are 29.8 (visible) and 28.4 (near-infrared) mag arcsec$^{-2}$., Comment: 43 pages, 51 figures, submitted to A&A

Published
2021
Full Text
View/download PDF

5. Cosmologie et supernovas Ia : influence des vitesses propres et recherche d'anisotropies avec LSST

Author

Ciulli, Alexandre, Laboratoire de Physique de Clermont (LPC), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Université Clermont Auvergne [2017-2020], Philippe Gris, and Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)

Subjects
Simulations, Univers, Supernovas, LSST, SNIa, Amas de galaxies, Galaxy clusters, Astrophysics, Cosmology, Qualité astrométrique, Photometric quality, Supernovae, Universe, Qualité photométrique, Dark energy, Anisotropies, Vitesses propres, Phenomenology, Astrometric quality, Énergie noire, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Phénoménologique, Astrophysique, Cosmologie, Peculiar velocities
Abstract

Type Ia supernovae (SNIa) are transient objects, which remains observable in the optical for a period of a few months, and whose luminosity at its maximum is comparable to that of a whole galaxy. They represent, once standardized (i.e. corrected for their main variabilities), an excellent distance indicator and, in 1998, provided the first evidence for the acceleration of the expansion of the Universe. This thesis investigates three points in the cosmological SNIa pipeline:First, we focused on the data processing and the quality of the images for the Large Synoptic Survey Telescope (LSST), that will provide data for a number of cosmological observables, including the observation of SNIa. In preparation for LSST (which will start operations in 2020), we carried out a similar data processing strategy on images from a previous survey (deep field of CFHT) and compared to the required parameters of LSST. A dispersion slightly higher than that required was obtained. For photometry, although this excess is small, the sources of this dispersion remain to be understood. For astrometry, the obtained quality is likely to be sufficient when simultaneous astrometry fitting will be implemented.In a second moment, we propose a method to correct the effect of peculiar velocities of SNIa inside galaxy clusters. Indeed, these velocities ​​are more important in the clusters of galaxies, because of the gravitational interactions, and the measurement of the cosmological redshift related to the expansion of the Universe. These peculiar velocities were corrected using a sample of 145 SNIa with a low spectral shift (0.005

Published
2018

6. Cosmology and Type Ia Supernovae : influence of peculiar velocities and anisotropies

Author

Ciulli, Alexandre, Laboratoire de Physique de Clermont (LPC), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Université Clermont Auvergne [2017-2020], and Philippe Gris

Subjects
Simulations, Univers, Supernovas, LSST, SNIa, Amas de galaxies, Galaxy clusters, Astrophysics, Cosmology, Qualité astrométrique, Photometric quality, Supernovae, Universe, Qualité photométrique, Dark energy, Anisotropies, Vitesses propres, Phenomenology, Astrometric quality, Énergie noire, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Phénoménologique, Astrophysique, Cosmologie, Peculiar velocities
Abstract

Type Ia supernovae (SNIa) are transient objects, which remains observable in the optical for a period of a few months, and whose luminosity at its maximum is comparable to that of a whole galaxy. They represent, once standardized (i.e. corrected for their main variabilities), an excellent distance indicator and, in 1998, provided the first evidence for the acceleration of the expansion of the Universe. This thesis investigates three points in the cosmological SNIa pipeline:First, we focused on the data processing and the quality of the images for the Large Synoptic Survey Telescope (LSST), that will provide data for a number of cosmological observables, including the observation of SNIa. In preparation for LSST (which will start operations in 2020), we carried out a similar data processing strategy on images from a previous survey (deep field of CFHT) and compared to the required parameters of LSST. A dispersion slightly higher than that required was obtained. For photometry, although this excess is small, the sources of this dispersion remain to be understood. For astrometry, the obtained quality is likely to be sufficient when simultaneous astrometry fitting will be implemented.In a second moment, we propose a method to correct the effect of peculiar velocities of SNIa inside galaxy clusters. Indeed, these velocities ​​are more important in the clusters of galaxies, because of the gravitational interactions, and the measurement of the cosmological redshift related to the expansion of the Universe. These peculiar velocities were corrected using a sample of 145 SNIa with a low spectral shift (0.005

Published
2018

7. Určování parametrů temné energie a modifikované gravitace v rámci projektu LSST

Author

Vraštil, Michal, Prouza, Michal, and Heyrovský, David

Subjects
temná energie, chameleonní gravitace, cosmology, simulation, LSST, dark energy, kosmologie, simulace, modifikovaná gravitace, modified gravity, chameleon gravity, DESC
Abstract

Temnáenergietvořícípřibližně70%hmotyvesmíruz·stávájednouznejvětšch záhad moderní fyziky. K pochopení její podstaty jsou potřeba přesná kosmolog- ická měření. Jedním z projekt· zkoumající tuto exotickou formu hmoty bude i Large Synoptic Survey Telescope, který pom·že potvrdit či vyvrátit standardní kosmologický model (ΛCDM). Pro úspěch projektu je potřeba prozkoumat r·zné teorie temné energie. Jednou z alternativních teoríí vysvětlujících urychlenou expanzi vesmíru je tzv. chameleoní gravitace. Chameleon je nové skalární pole s hmotou závisející na okolní hustotě. V hustých prostředích jako je například Sluneční soustava získává pole velkou hmotu a propaguje se pouze na malých vzdálenostech díky čemuž m·že uniknout standardním test·m gravitace. V prá- ci mimo jiné studujeme chování chameleoního pole v okolí hvězd a v galaxiích. Ukazujeme také za jakých okolností je toto pole možné detekovat pomocí spek- troskopických měření a slabého čočkování.

Published
2015

8. Large imaging surveys for cosmology: cosmic magnification and photometric calibration

Author

Boucaud, Alexandre, Boucaud, Alexandre, APC - Cosmologie, AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Université Paris-Diderot - Paris VII, James G. Bartlett(bartlett@apc.univ-paris7.fr), James G. Bartlett, Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Physique Corpusculaire et Cosmologie - Collège de France (PCC), Collège de France (CdF)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Collège de France (CdF)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.ASTR.CO] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], [SDU.ASTR.CO]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], LSST, gravitational lensing, Astrophysics::Instrumentation and Methods for Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, cosmologie, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], photometric calibration, 13. Climate action, amplification cosmique, [PHYS.ASTR.CO] Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], étalonnage de la photométrie, énergie noire, cosmic magnification, dark energy, cosmology, lentilles gravitationnelles
Abstract

This thesis work focuses on the use of deep, wide field surveys to extract new cosmological information. Precise photometry plays a large role in this quest, through the determination of photometric redshifts and the propagation of photometric errors into the cosmological results. This is a unifying theme which effectively ties both parts of the thesis together. After a general review of cosmology and the measurements that support the ΛCDM model, and a description of the Large Synoptic Survey Telescope (LSST), the first part of this work deals with the influence of the variation of main atmospheric constituents on ground-based photometry, focusing particularly on the LSST site at Cerro Pachón, Chile. We process all recent available data on ozone, water vapor and aerosols to construct a long-term atmospheric simulation and estimate quantitatively how the spatial and temporal gradients of these constituents would affect LSST calibration process. The second part of this work starts with a theoretical description of gravitational lensing, concentrating on the weak lensing aspect. After discussing the advantages and difficulties of cosmic shear measurements, we explore the use of cosmic magnification, together with the redshift tomography enabled by the LSST, to constrain cosmological models. We find that cosmic magnification covariance is beset by intrinsic clustering but nevertheless represents a useful probe of galaxy bias and dark energy that complements cosmic shear, and which can increase the robustness of cosmological constraints from lensing surveys., Ce travail de thèse se focalise sur l'usage de grands sondages pour extraire de l'information sur la cosmologie. Une photométrie de précision joue un rôle clé dans cette quête à travers la détermination de redshifts photométriques ainsi que la propagation des erreurs dans les résultats cosmologiques ; thème unissant les deux parties de cette thèse. Après une revue de la cosmologie et des mesures favorisant le modèle ΛCDM, ainsi qu'une description du Large Synoptic Survey Telescope (LSST), la première partie de ce travail se porte sur l'étude de la variation des principaux constituants de l'atmosphère sur la photométrie au sol, au niveau du site du LSST à Cerro Pachón, au Chili. Nous utilisons des données récentes sur l'ozone, la vapeur d'eau et les aérosols pour en construire une simulation de longue durée et estimer quantitativement l'influence des gradients spatiaux et temporels de ces constituants sur la procédure de la calibration du LSST. La deuxième partie de ce travail débute par une description théorique de l'effet de lentille gravitationnelle, avec un accent sur le lentillage faible. Après une comparaison des avantages et inconvénients inhérents aux mesures de cisaillement cosmique, nous explorons l'utilisation de l'amplification cosmique conjointement à la séparation tomographique en redshift permise par le LSST afin de contraindre les modèles. Nous trouvons que l'amplification cosmique, bien qu'affectée par le clustering intrinsèque, représente une sonde prometteuse du biais des galaxies et de l'énergie noire, complémentaire au cisaillement cosmique, et qui augmente la robustesse des contraintes cosmologiques provenant des mêmes relevés.

Published
2013

Catalog

Books, media, physical & digital resources
See catalog results