Résumé : None.

Résumé : These two lectures will be dedicated to the identification and study of the first galaxies using clusters of galaxies as gravitational lenses. I will begin with a review around the present understanding on the formation of the first galaxies based on theoretical and observational considerations. The current state of the art will be presented and discussed regarding the constraints on the reionization process and the physical properties of  star-forming galaxies during the first billion years after the big bang. The use of cluster-lenses is expected to greatly improve the current landscape in this area. The relative efficiency of lensing and blank fields in the identification and study of the first galaxies will be discussed in details as a function of the main parameters, namely the redshift and properties of the distant sources, the redshift and properties of the lensing clusters, and the survey characteristics (i.e. area, depth...), focusing on current surveys. Finally, I will conclude with a discussion around future developments.

Bibliographie : Additional references will be included in the slides.

• "First Light in the Universe, Saas-Fee Advanced Courses" Number 36. Loeb, A.; Ferrara, A.; Ellis, R.S. 2008, ISBN 978-3-540-74163-3
• "In the beginning: the first sources of light and the reionization of the universe" Barkana & Loeb, Physics Reports, Volume 349, Issue 2, p. 125-238 (2001)
• "The First Galaxies" Bromm & Yoshida, Annual Review of Astronomy and Astrophysics, vol. 49, issue 1, pp. 373-407 (2011)
  
• "ALMA and the First Galaxies" Combes, F., in The First Stars and galaxies : Challenges for the next decade. AIP Conference Proceedings, Volume 1294, 9 (2010)
• "Cluster Lenses" Kneib J.P., & Natarajan, P., , "", The Astronomy and Astrophysics Review, Volume 19, 47 (2011)
  

Résumé : In these 2 lectures, I will present the topic of strong lensing and how it can be used to probe the high redshift Universe. I will start with an introduction of strong lensing and its key features in studying the distant Universe: magnification and source plane dilution. I will then explain how we do model strong lensing system with a detailed discussion of the constraints and the different techniques used. I will then explain how strong lensing has been used to count lensed galaxies and how we can uses lenses to probe the high redshift z>6 universe.

Bibliographie :
- Lens modeling

• Mellier et al 1993
• Kneib et al 1993, 1996
• Jullo et al 2007
• Coe et al 2010
• Kneib & Natarajan 2011

- Counting Lensed Galaxies

• Altieri et al 1999
• Blain et al 1999
• Metcalf et al 2003
  
• Coe et al 2010
• Knudsen et al 2008

- Distant Strong Lensed galaxies

• Ellis et al 2001
• Kneib et al 1993, 1996
• Kneib et al 2004
• Coe et al 2010
• Richard et al 2008
  

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Spatially resolved studies of lensed galaxies (pdf) Johan RICHARD, Centre de Recherche Astronomique de Lyon (CRAL), Université Lyon 1

Introduction on magnification of strongly-lensed galaxies and source reconstruction techniques Resolved morphology of lensed galaxies

Resolved kinematics of lensed galaxies Metallicity gradients

A kind of "Hands-on" Workshop: How to calculate Quasar Microlensing (tar ,pdf-1, pdf-2, pdf-3) - Joachim WAMBSGANSS

How to calculate Quasar Microlensing

Calculate Quasar Microlensing

Résumé : Hands-on exercises on using a hierarchical tree code for the calculation of quasar microlensing.
The participants need :

•  a computer/laptop with a FORTRAN compiler
• a graphics program, ideally IDL, but any graphics package that can handle FITS files will suffice

Bibliographie :

• "Gravitational lensing: numerical simulations with a hierarchical tree code", Wambsganss, Joachim, J. Comput. Appl. Math., Vol. 109, No. 1 - 2, p. 353 - 372 (1999)
• MICROLENS (a short hand-written manual of the microlensing code)

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A brief history of gravitational lensing - (pdf) - David VALLS-GABAUD, LERMA CNRS, Observatoire de Paris

Cosmological and astrophysical applications of vacuum quantum corrections (pdf) - Ilya L. SHAPIRO, Departamento de Fisica - ICE, Universidade Federal de Juiz de Fora

Résumé : The investigation of quantum correction to the action of gravity is a complicated problem, which is not completely resolved yet. At the same time, a set of simple assumptions such as covariance arguments, enable us to write down a general form of the quantum vacuum contributions up to a single free coefficient. It is interesting that the theory with such corrections is capable to explain the rotation curves in different types of galaxies without usual LCDM part. This fact gives some serious background to attempts to create an alternative cosmic concordance model with much smaller amount of WDM and dominating cosmological constant. The study of gravitational lensing in this model looks very promising and interesting task.

Bibliographie :

• "Galaxy rotation curves from General Relativity with quantum corrections", Davi C. Rodrigues, Patricio S. Letelier, Ilya L. Shapiro, JCAP 04 (2010) 020; DOI: 10.1088/1475-7516/2010/04/020; arXiv: 0911.4967.
• "Cosmic perturbations with running G and Lambda" Javier Grande, Joan Sola, Julio C. Fabris, Ilya L. Shapiro, Class. Quantum Grav. 27 (2010) 105004 (29pp). arXiv: 0911.4967
• "Testing DM warmness and quantity via the RRG model", Julio C. Fabris, Ilya L. Shapiro and Alan M. Velasquez-Toribio, Phys. Rev. D85 (2012) 023506; arXiv:1105.2275
  

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Geometric Scalar Gravity (pdf) - Mario NOVELLO, Centro Brasileiro de Pesquisas Fisicas (CBPF) & ICRA

Résumé : We review the previous theories of gravity associated to a scalar field. We present a new geometric theory that is able to circumvent all previous difficulties associated to scalar gravity.

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** Posters **

Improved lensing reconstruction with a non-parametric code (pdf) - Irene SENDRA, University of the Basque Country

Résumé : Based on the SLAP code (Sendra et al. 2005) we improve the lensing reconstruction of the mass in a galaxy cluster by integrating physical priors in the code that greatly help to increse the resolution of the solution and reduce the uncertainties. The new code is tested with simulated data (strong lensing) that mimics real data. We explore the improvements by comparing the solutions obtained with and without the new physical priors and discuss the limitations of the new code.

Bibliographie :

• ""Combined reconstruction of weak and strong lensing data with WSLAP", Sendra et al. MNRAS, 375, 958 ( 2007)
• "Non-parametric mass reconstruction of A1689 from strong lensing data with the Strong Lensing Analysis Package", Sendra et al. 2005, MNRAS, 362, 1247
• "Non-parametric inversion of strong lensing systems", Sendra et al. 2005, MNRAS, 360, 477

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A weak-lensing mass reconstruction of the large-scale filament feeding the massive galaxy cluster MACSJ0717.5+3745 (pdf)- Mathilde JAUZAC, Astrophysics and Cosmology Research Unit (ACRU), University of KwaZulu Natal , Durban (ZAF)

Résumé : MACSJ0717.5+3745 is an X-ray luminous cluster, at a redshift of z ~ 0.55. Previous analysis of the galaxy distribution in its surrounding field revealed the presence of an elongated structure which was thought to be a large-scale filament. By making a weak gravitational lensing analysis of this cluster and its surrounding field, we were able to report the first weak-lensing detection of a large-scale filament which funnels the matter onto the core of the cluster. Our analysis is based on a mosaic of 18 HST/ACS maps, ie an area of ~10×20 arcmin2. To test the consistency of our weak lensing analysis we first compared our results with the strong lensing analysis of Limousin et al. (2012) of the cluster core. The weak and strong lensing density profiles of the cluster core show a really good agreement. In terms of mass integrated in a radius of 500 kpc (given the same center), the strong lensing gives 1.06±0.03 1015 Modor, while the weak lensing gives 1.04±0.08 1015 Modor. The excellent agreement between both values and density profiles confirms the strength of our weak lensing analysis. Our analysis detects the MACSJ0717 filament within the 3 sigma detection contour of the lensing mass reconstruction, and underlines the importance of filaments for theoretical and numerical models of the mass distribution in the Cosmic Web. We measured a filament’s projected length of ~4.5 Mpc, and a mean density of 2.92±0.66 108 M⊙kpc-2. By complementing our imaging data with extensive spectroscopy of galaxies in the area, and applying plausible constraints concerning the structure’s geometry based on its galaxy velocity field, we construct a 3D model of the large-scale filament. Within this framework, we derive a three-dimensional length of the filament to be 18 Mpc. The filament’s de-projected density in terms of the critical density of the Universe is measured as 206±46, a value that lies at the very high end of the range predicted by numerical simulations.

Bibliographie :

• Ebeling et al., 2004, ApJ, 609, L49
  
• Ebeling et al., 2007, ApJ, 661, L33
• Jullo et al., 2007, New Journal of Physics, 9, 447
• Jullo & Kneib, 2009, MNRAS, 395, 1319
• Leauthaud et al., 2007, ApJS, 172, 219
• Leauthaud et al., 2010, ApJ, 709, 97
• Limousin et al., 2012, A&A, 544, 71
• Ma et al., 2008, ApJ, 684, 160
• Ma et al., 2009, ApJ, 693, L56
• Rhodes et al., 2000, ApJ, 172, 203

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Weak lensing mass mapping: Inverse and forward methods (pdf)- Eric JULLO, Laboratoire d'Astrophysique de Marseille (LAM)

Résumé : We compare the mass map reconstruction methods with Lenstool and in-painting, in forward and inverse methods respectively. We appy the methods to the massive cluster MACS0717.

Bibliographie :

• "COSMOS: Stochastic bias from measurements of weak lensing and galaxy clustering", Jullo E., Rhodes J., Kiessling A. , Taylor J.E., Massey R., Bergé J., Kneib J.-P., Scoville N., , arXiv :1202.6491
• "A Comprehensive View of a Strongly Lensed Planck-Associated Submillimeter Galaxy", Fu H., Jullo E.,  Cooray A., Bussman R.S., Ivison R.J, Perez-Fouron I., Djorgorovski S.G., Scoville N., Riechers D.A. et al., axXiv :1202.1829F
•  "Abell 370 revisited: refurbished Hubble imaging of the first strong lensing cluster", Richard J., Kneib J.-P., Limousin M., Edge A., Jullo E., MNRAS, 402,44 (2010)
•  "Cosmological constraints from strong gravitational lensing in clusters of galaxies", Jullo E., Natarajan P., Kneib J.-P., D’Aloisio A., Limousin M., Richard J., Schimd C., , Sience, 329, 924 (2010)
• "Strong Lensing as a Probe of the Mass Distribution Beyond the Einstein Radius. Mass & Light in SL2S J0544-0121, a Galaxy Group at z=0.35", Limousin M., Jullo E., Richard J., Cabanac R., Kneib J.-P., Gavazzi R., Soucail G., A&A, 524,95 (2009)
•  "Multiscale cluster lens mass mapping - I. Strong lensing modelling", Jullo E., Kneib J.-P., MNRAS, 395,1319 (2009)

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Strong lensing as a probe of the mass distribution beyond the Einstein radius. Mass and light in SL2SJ08544-0121, a galaxy group at z=0.35 (pdf)- Marceau LIMOUSIN, Laboratoire Astrophysique de Marseille (LAM)

Résumé : Strong lensing (SL) has been employed extensively to obtain accurate mass measurements within the Einstein radius, i.e. at the location of the multiply imaged systems used as constraints. I will show that SL can be used to probe mass distributions on scales much larger than the one defined by the Einstein radius. I will discuss this method on SL2SJ08544-0121, a galaxy group at redshift z=0.35. This group displays a bimodal light distribution with a strong lensing system located at one of the two luminosity peaks separated by  ~54 arcsec. The main arc and the counter-image of the strong lensing system are located at ~5 arcsec and ~8 arcsec from the lens galaxy centre. I will show that a simple elliptical isothermal potential cannot satisfactorily reproduce the strong lensing observations. However, with a mass model for the group built from its light-distribution, i obtain an accurate reproduction of the strong lensing observations, therefore setting constraints on the mass of the galaxy group as a whole. The SL only analysis hints that we are actually witnessing the merging of two galaxy  groups.
Using complementary data sets, spectroscopy of galaxy group members and Xray observations, i will show that the predictions from the SL only analysis are confirmed. This kind of analysis provides a quick and cheap way of probing the mass distribution of clusters and groups. This is particularly relevant in the context of forthcoming wide field surveys, which will yield thousands of strong lenses.

Bibliographie :

• "Strong lensing as a probe of the mass distribution beyond the Einstein radius. Mass and light in SL2S J08544-0121, a galaxy group at z = 0.35", Limousin, M.; Jullo, E.; Richard, J.; Cabanac, R.; Suyu, S. H.; Halkola, A.; Kneib, J.-P.;Gavazzi, R.; Soucail, G., Astron. Astrophys. 524, A95 (2010) ; ar Xiv: 0906.4118
• "Probing the slope of cluster mass profile with gravitational Einstein rings: application to Abell 1689", Tu, H.; Limousin, M.; Fort, B.; Shu, C. G.; Sygnet, J. F.; Jullo, E.; Kneib, J. P.; Richard, J., MNRAS 386,3,1169  (2008) ; arXiv: 0710.2246

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Cosmography with strong lensing systems - joint analysis (pdf) - Beata MALEC, Copernicus Center for Interdisciplinary Studies

Résumé : A key issue of contemporary cosmology is the problem of currently accelerating expansion of the Universe. The nature of this phenomenon is one of the most outstanding problems of physics and astronomy today. Its origin may be attributed to either unknown exotic material component with negative pressure - so called Dark Energy (DE), to infra red modification of gravity at cosmological scale or requires to relax the assumption of homogeneity of the Universe. It should be pointed out that the strength of modern cosmology (which now enterd stage dubbed the era of precision cosmology) lies in consistency across independent pieces of evidence rather than in single, crucial experiment. We approach to this subject from phenomenological point of view. In this spirit we perform a cosmographic analysis using several cosmological probes such as Type Ia Supernovae (Union2 compilation), data from Cosmic Microwave Background (WMAP7), Baryon Acoustic Oscillation (BAO) and strongly gravitationally lensed systems (combined data sets from SLACS and LSD surveys) and Gamma Ray Bursts. These tests falls into two distinct cathegories. The first one makes use of the angular diameter distance, and refers to the so called standard rulers. Here we have strong lensing systems, shift parameter R from CMB and BAO scales. The second uses the luminosity distance and then we deal with standard (or rather standarizable) candles. Here we deal with SN Ia and GRB. The two distance concepts, although theoretically related to each other, in practice have different systematic uncertainties and different parameter degeneracies.Hence their joint analysis is more restrictive in the parameter space. We considered several cosmological scenarios of dark energy, widely discussed in current literature. We also address the question which model is the best with information-theoretic criteria: the Akaike Criterion (AIC) and Bayesian Information Criterion (BIC).

Bibliographie :

• M. Biesiada, Phys. Rev. D, 73, 023006 (2006)
• C. Grillo, M. Lombardi, G. Bertin, Astron. Astrophys., 477, 397 (2008)
• M. Biesiada, B. Malec, A. Piorkowska, Res. Astron. Astrophys., 11, 641 (2011)
• L.V.E. Koopmans, T. Treu, A.S. Bolton, S. Burles, L.A. Moustakas, Astrohys.J.,  649, 599 (2006)
• R. Amanullah et al, Astrophys.J.716, 712, (2010)
• B. Reid et al, M.N.R.A.S. 404, 60 (2010)
• E. Komatsu et al, Astrophys.J.Sup. 192, 18 (2011)

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Effect of Non-linear structure and Baryons in Shear Power Spectrum (pdf) - Sanghamitra DEB, Argonne National Laboratory

Résumé : The Cosmic Shear Power Spectrum (CSPS) probes the growth and distribution of matter using the deflection of light by the web of large scale structure in the universe . Future and ongoing surveys such as DES, LSST and EUCLID will measure the CSPS at angular scales as small as an arcminute. In order to interpret the results and compute the cosmological parameters we need accurate prediction of the 3D matter power spectrum at non-linear scales. We will describe our approach based on the Coyote Universe Emulator that has been shown to predict the three dimensional dark matter power spectrum to percent level accuracy down to the non-linear scales relevant for lensing. Small scales are also dominated by baryonic matter which are not captured in N-body gravity only simulations. We will also explore modeling baryons using semi-analytic approaches and the corresponding biases in the Shear Power Spectrum.

Bibliographie :

•  Heitmann, K., Higdon, D., White, M., Habib, S., Williams, B. J., Lawrence, E., & Wagner, C. 2009, ApJ, 705, 156
• Heitmann, K., White, M., Wagner, C., Habib, S., & Higdon, D. 2010, ApJ, 715, 104
• Heitmann et. al. 2012, in preparation
• Hu, W. 1999, ApJ, 522, L21
• Lawrence, E., Heitmann, K., White, M., Higdon, D., Wagner, C., Habib, S., & Williams, B. 2010, ApJ, 713, 1322
• Schneider, P., van Waerbeke, L., Mellier, Y., Jain, B., Seitz, S., & Fort, B. 1998, A&A, 333, 767
• Semboloni, E., Hoekstra, H., Schaye, J., van Daalen, M. P., & McCarthy, I. G. 2011, MNRAS, 417, 2020
•  Zentner, A. R., Rudd, D. H., & Hu, W. 2008, Phys. Rev. D, 77, 043507

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Prospects for constraining Dark Energy and Early Universe with the B modes of CMB polarization (pdf) - Claudia ANTOLINI, SISSA/ISAS

Résumé : We investigate the constraining power of the CMB in the light of modern observations, focusing on the expectations from forthcoming satellite and sub-orbital (polarization oriented) experiments. In particular, we study their constraining capabilities concerning the physics of the early Universe and the onset of acceleration through the B modes polarization spectrum as a tool for inquiring primordial gravitational waves and the lensing peak.

Bibliographie :

• ""Dark Energy records in lensed cosmic microwave background", V. Acquaviva, C. Baccigalupi, Phys. Rev. D 74, 103510 (2006)
• "Estimating the tensor-to-scalar ratio and the effect of residual foreground contamination", Y. Fantaye et al JCAP08(2011)001
• "CMB lensing reconstruction in the presence of diffuse polarized foregrounds", Y. Fantaye et al arXiv:1207.0508v1

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Translations in Relative Locality (ppt) - Niccolò LORET, Università degli Studi di Roma 'La Sapienza'

Résumé : In this talk we will try to introduce the analysis of cosmological observables as a suitable arena for Relative Locality phenomenology. One of the fundamental aspects of General Relativity is that two different observers on two different hypersurfaces describe spacetime with two distinct sets of coordinates, and, thus, they give different coordinatizations of the same spacetime. Relative Locality is a relativistic theory that implements systematic nonlocalities that can emerge in many different approaches to the problem of Quantum Gravity. In this theory, locality is no longer absolute, as codified in a novel way to mathematically express translations between the two hypersurfaces. We will give an explicit example of signal analysis and related phenomenology on cosmological observables, with relative locality spacetime metric, mathematically modelized on kappa-Minkowski deformed spacetime transformations.

Bibliographie :

• G.Amelino-Camelia, J.Lukierski, A.Nowicki, Act.Phys.Pol. 4, Vol 29 (1998)
• G.Amelino-Camelia, L.Freidel, J.Kowalski-Glikman, L.Smolin, Phys. Rev. D 84, 084010 (2011)
• J. Magueijo, L.Smolin, Class. Quantum Grav. 21, 1725 (2004)
• G.Amelino-Camelia, N.Loret, G.Rosati, Phys. Lett. B 700, 150-156 (2011)
• G.Amelino-Camelia, N.Loret, G.Mandanici, F.Mercati, Int J. Mod. Phys. D 19, 2385-2392 (2010)
• G.Amelino-Camelia, N.Loret, L.Barcaroli, work in progress

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Constraints on variation of fundamental constants from Cosmology (pdf) - Eloisa MENEGONI, University of Rome Sapienza

Résumé : In about six refereed papers [7][10][12][13][14][15], I investigated the value of nature’s fundamental couplings in the early universe, considering possible deviations from the current standard values. A time varying fine structure constant can leave an imprint on CMB anisotropies by changing the time of recombination and the size of the acoustic horizon at photon-electron decoupling (see [1],[2],[3],[4]). The CMB datasets have been extensively used to constrain α by parametraizing a variation in the fine structure constant as Δα = (α - α0)∕α0, where α0 is the standard, local value and α is the value during the recombination process[5],[6]. By performing a MCMC analysis and using WMAP-5 years data, and I found α∕α0 = 0.998 ± 0.021 at 68% c.l., the constraints are much tighter if you also include all the CMB data plus a prior on the value of Hubble constant, in this case I found α∕α0 = 1.001 ± 0.007 [7].
By including early dark energy component [11], the variations of the fine structure constant using WMAP-7 years data and HST data give α∕α0 = 0.963 ± 0.044, Ωe < 0.064 and for the coupling ζ < 0.047 at 95%c.l.. By performing a Fisher matrix analysis and using Planck and CMBPol experimental specifications I found better and strong constraints on the parameter: for Planck σ(α∕α0) = 0.0012, σ(Ωe) = 0.0036, σ(ζ) < 0.0012 and the results for CMBPol σ(α∕α0) = 0.00025, σ(Ωe) = 0.0015 and σ(ζ) < 0.00022 [12].

Bibliographie :

• [1] Steen Hannestad. Phys.Rev. D60 (1999) 023515 DOI: 10.1103/PhysRevD.60.023515 Cite as: arXiv:astro-ph/9810102v2 .
• [2]   Manoj Kaplinghat, Robert J. Scherrer, Michael S. Turner. Phys.Rev. D60 (1999) 023516 DOI: 10.1103/PhysRevD.60.023516 Cite as: arXiv:astro-ph/9810133v2
• [3]   R.A. Battye, R. Crittenden, J. Weller. Phys.Rev. D63 (2001) 043505 DOI: 10.1103/PhysRevD.63.043505 Cite as: arXiv:astro-ph/0008265v1
• [4]   P.P. Avelino, S. Esposito, G. Mangano, C.J.A.P. Martins, A. Melchiorri, G. Miele, O. Pisanti, G. Rocha, P.T.P. Viana. Phys.Rev.D64:103505,2001 DOI: 10.1103/PhysRevD.64.103505 Report number: DAMTP-2001-13, DSF-5-2001 Cite as: arXiv:astro-ph/0102144v4.
• [5]   C.J.A.P.Martins , A. Melchiorri , G. Rocha , R. Trotta , P.P. Avelino , P. Viana . Phys.Lett.B585:29-34,2004 DOI: 10.1016/j.physletb.2003.11.080 Report number: DAMTP-2003-13 Cite as: arXiv:astro-ph/0302295v2.
• [6]   G. Rocha (Cambridge, CAUP), R. Trotta (Geneva), C.J.A.P. Martins (CAUP, Cambridge, IAP), A. Melchiorri (Oxford), P.P. Avelino (Porto), P.T.P. Viana (CAUP). NewAstron.Rev.47:863-869,2003 DOI: 10.1016/j.newar.2003.07.018 Cite as: arXiv:astro-ph/0309205v1.
• [7]   Eloisa Menegoni, Silvia Galli, James Bartlett, Carlos J. A. P. Martins, Alessandro Melchiorri. Phys.Rev.D80:087302,2009 DOI: 10.1103/PhysRevD.80.087302 Cite as: arXiv:0909.3584v1 [astro-ph.CO].
• [8]   P. Loren-Aguilar, E. Garcia-Berro, J. Isern, Yu.A. Kubyshin. Class.Quant.Grav.20:3885-3896,2003 DOI: 10.1088/0264-9381/20/18/302 Cite as: arXiv:astro-ph/0309722v1.
• [9]   E. Garcia-Berro, J. Isern and Y. A. Kubyshin,. Astron. Astrophys. Rev. 14, 113 (2007).
• [10]   C.J.A.P. Martins, Eloisa Menegoni, Silvia Galli, Gianpiero Mangano, Alessandro Melchiorri. Phys.Rev.D82:023532,2010 DOI: 10.1103/PhysRevD.82.023532 Cite as: arXiv:1001.3418v3 [astro-ph.CO].
• [11]   Erminia Calabrese, Roland de Putter, Dragan Huterer, Eric V. Linder, Alessandro Melchiorri. Phys.Rev.D83:023011,2011 DOI: 10.1103/PhysRevD.83.023011 Cite as: arXiv:1010.5612v1 [astro-ph.CO].
•  [12]   Erminia Calabrese, Eloisa Menegoni, C.J.A.P. Martins, Alessandro Melchiorri, Graca Rocha. Phys.Rev.D84:023518,2011 DOI: 10.1103/PhysRevD.84.023518 Cite as: arXiv:1104.0760v1 [astro-ph.CO].
• [13]   2009 ”‘Constraints on the dark energy equation of state in presence of a varying fine structure constant”’ (IJMPD, International Journal of Modern Physics D, Volume 19, Issue 04, pp. 507-512 2010). E. Menegoni, S. Pandolfi, S. Galli, M. Lattanzi, A. Melchiorri.
• [14]   ”The Fine Structure Constant and the CMB Damping Scale”, Eloisa Menegoni, Maria Archidiacono, Erminia Calabrese, Silvia Galli, C. J. A. P. Martins, Alessandro Melchiorri. Cite as: arXiv:1202.1476v1 [astro-ph.CO].
• [15]   ”Future constraints on variations of the fine structure constant from combined CMB and weak lensing measurements” Matteo Martinelli, Eloisa Menegoni, Alessandro Melchiorri. Cite as: arXiv:1202.4373v2 [astro-ph.CO].

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Cluster detection in the Next Generation Virgo Cluster Survey (NGVS) (pdf) - Rossella LICITRA, Observatoire de Paris

Résumé : We present recent results on the stellar evolution in cluster galaxies from z~1 to present from the Next Generation Virgo Cluster Survey. Our survey covers 104 sq. deg. centered on the Virgo cluster with deep CFHT/Megacam imaging in five band passes. We detect background clusters with dedicated methods based on the search of red galaxy and photometric redshift overdensities. We analyze galaxy stellar population evolution in clusters from z~1 to present using scaling relations, such as the color-magnitude relation.

Bibliographie :

• Coupon, J.,  Ilbert, O., Kilbinger, M., et al. 2009, A&A, 500, 981
• Ferrarese, L., Côté, P., Cuillandre, J., et al., 2012, ApJ, 200, 4
• Holder, G., Haiman, Z., & Mohr, J., 2001, ApJ, 560, L111

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The Three-Dimensional Shapes of Galaxy Clusters (pdf)- Marceau LIMOUSIN, Laboratoire Astrophysique de Marseille (LAM)

Résumé : While clusters of galaxies are considered as one of the most important cosmological probes, the standard spherical modelling of the dark matter and the intracluster medium is only a rough approximation. Indeed, it is well established both theoretically and observationally that galaxy clusters are much better approximated as triaxial objects. However, investigating the asphericity of galaxy clusters is still in its infancy.
I will review this topic which is currently gathering a growing interest from the cluster community. i will begin by introducing the triaxial geometry, then discuss the topic of deprojection and demonstrate the need for combining different probes of the cluster's potential, and finally review the different works that have been addressing these issues.
Then i will present a general parametric framework intended to simultaneously fit complementary data sets (X-ray, Sunyaev Zel'dovich and lensing data), and show an illustration on galaxy cluster Abell 1689.
I will show that, for strong lensing clusters, a triaxial model generally allows to lower the inferred value of the concentration parameter compared to a spherical analysis. This may alleviate tensions regarding, e.g., the over-concentration problem. However, i will stress that predictions from numerical simulations rely on a spherical analysis of triaxial halos.
Since triaxial analyses will have a growing importance in the observational side,  I advocate the need for simulations to be analysed in the very same way, allowing reliable and meaningful comparisons. Besides, methods and algorithms intended to derive the three dimensional shape of galaxy clusters should be extensively tested on simulated multi-wavelength observations in order to quantify the limitations of the triaxial model, which still represents an approximation  of what a real galaxy cluster might be.

Bibliographie :

• ""Triaxiality, principal axis orientation and non-thermal pressure in Abell 383 ", A. Morandi, M. Limousin, MNRAS 421,3147(2012)
• "Unveiling the Three-dimensional Structure of Galaxy Clusters: Resolving the Discrepancy Between X-ray and Lensing Masses", A. Morandi, K. Pedersen, M. Limousin, Astrophys.J. 713, 491(2010)
• "Reconstructing the Triaxiality of the Galaxy Cluster A1689: Solving the X-ray and Strong Lensing Mass Discrepancy", A. Morandi, K. Pedersen, M. Limousin, Astrophys. J. 729, 37 (2011)
•  "X-ray, lensing and Sunyaev Zel’dovich triaxial analysis of Abell 1835 out to R200", A. Morandi, M. Limousin, J. Sayers, S.R. Golwala, N.G. Czakon, E. Pierpaoli, S. Ameglio, MNRAS accepted, ArXiv:1111.6189 (2012)
• "Triaxiality and non-thermal gas pressure in Abell 1689", A. Morandi, M. Limousin, Y. Rephaeli, K. Umetsu , R. Barkana, T. Broadhurst, H. Dahle, MNRAS 416, 2567 (2011)
•  "Weak- and strong-lensing analyses of the triaxial matter distribution of Abell 1689", M. Sereno, K. Umetsu, MNRAS 416, 3187(2011)
• "Shape and orientation of the gas distribution in A1689", M. Sereno, S. Ettori, A. Baldi, MNRAS 419, 2646 (2012)
• "Measuring the Three-dimensional Structure of Galaxy Clusters. II. Are Clusters of Galaxies Oblate or Prolate?", M. Sereno, E. De Filippis, G. Longo, M.W. Bautz, Astrophys. J. 645,170 (2006)

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Efficient Cosmic Shear Analysis with COSEBIs (pdf) - Marika ASGARI, Royal Observatory Edinburgh

Résumé : Gravitational lensing is one of the leading tools in understanding the dark side of the Universe. The need for accurate, efficient and effective methods which are able to extract this information along with other cosmological parameters from cosmic shear data is ever growing. COSEBIs, Complete Orthogonal Sets of E-/B-Integrals, is a recently developed statistical measure that encompasses the complete E-/B-mode separable information contained in the shear correlation functions measured on a finite angular range. Aims. The aim of the present work is to test the properties of this newly developed statistics for a higher-dimensional parameter space and to generalize and test it for shear tomography. Methods. We use Fisher analysis to study the effectiveness of COSEBIs. We show our results in terms of figure-of-merit quantities, based on Fisher matrices. Results. We find that a relatively small number of COSEBIs modes is always enough to saturate to the maximum information level. This number is always smaller for 'logarithmic COSEBIs' than for 'linear COSEBIs', and also depends on the number of redshift bins, the number and choice of cosmological parameters, as well as the survey characteristics. Conclusions. COSEBIs provide a very compact way of analyzing cosmic shear data, i.e., all the E-/B-mode separable second-order statistical information in the data is reduced to a small number of COSEBIs modes. Furthermore, with this method the arbitrariness in data binning is no longer an issue since the COSEBIs modes are discrete. Finally, the small number of modes also implies that covariances, and their inverse, are much more conveniently obtainable, e.g., from numerical simulations, than for the shear correlation functions themselves.

Bibliographie :

• "Cosmic shear tomography and efficient data compression using COSEBIs", Asgari, M.; Schneider, P.; Simon, P., Astronomy & Astrophysics, Volume 542, id.A122 (2012), arXiv:1201.2669
• "COSEBIs: Extracting the full E-/B-mode information from cosmic shear correlation functions",  Schneider, P.; Eifler, T.; Krause, E., Astronomy and Astrophysics, Volume 520, id.A116 (2010), arXiv:1002.2136

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Galaxy bias and BAO tracers, combining weak lensing and halo occupation distribution (pdf) - Johan COMPARAT, Laboratoire d'Astrophysique de Marseille

Résumé : The Baryon Acoustic Oscillation (BAO) feature in the power spectrum of galaxies can be used as a standard ruler to probe the accelerated expansion of the Universe. The current surveys covering a comoving volume sufficient to unveil the BAO scale are limited to redshift $z \lesssim 0.6$.

We study several galaxy selection schemes aiming at building an emission-line-galaxy (ELG) sample in the redshift range $0.6<z<1.7$, that would be suitable for future BAO studies i.e. a highly biased galaxy sample.

We analyze six galaxy selections at the redshifts 0.3, 0.5, 0.7, 0.8, 1, 1.2 using the two observables, the angular galaxy clustering, and the weak lensing. We combine the angular clustering analysis with state of the art halo occupation distribution models to derive the properties of the haloes these galaxies inhabit, in particular the galaxy bias on large scales. Then a weak lensing analysis (aperture statistics) is performed to extract the galaxy bias and its stochasticity as a function of the scale.

We apply this analysis on a dataset composed of the photometry of the deep coadd on Stripe 82 (225 deg$^2$) made by SDSS and of WISE infrared photometric band W1. We use the photometric redshift of the CFHT-LS W4 T0006 and from SDSS. Both analysis on the selections at $z=0.3$ and 0.5 are consistent, and are in agreement with previous studies on these tracers, which shows our approach is valid. On the next redshift bins, the galaxy biases obtained using the weak lensing observable and the bias obtained by the clustering analysis are consistent. It shows the galaxy populations selected are strongly biased. Thus a survey using such tracers of the mass field will guarantee a high significance detection of the BAO. This gives a strong support for these galaxy selections to be observed by future large spectroscopic BAO surveys.

Bibliographie :

• Anderson, L., Aubourg, E., Bailey, S., et al. 2012, ArXiv e-prints Annis, J., Soares-Santos, M., Strauss, M. A., et al. 2011, ArXive-prints
• Blake, C., Brough, S., Colless, M., et al. 2010, MNRAS , 406, 803 Cannon, R., Drinkwater, M., Edge, A., et al. 2006, MNRAS , 372,425
• Coupon, J., Ilbert, O., Kilbinger, M., et al. 2009, A&A , 500, 981 Coupon, J., Kilbinger, M., McCracken, H. J., et al. 2012, A&A ,542, A5
• Eisenstein, D. J., Annis, J., Gunn, J. E., et al. 2001, AJ , 122, 2267 Eisenstein, D. J., Zehavi, I., Hogg, D. W., et al. 2005, Astrophys.J. , 633, 560
• Ilbert, O., Arnouts, S., McCracken, H. J., et al. 2006, A&A , 457,841
• Jullo, E., Rhodes, J., Kiessling, A., et al. 2012, Astrophys. J. , 750,37
•  Kilbinger, M., Benabed, K., Cappe, O., et al. 2011, ArXiv e-prints Regnault, N., Conley, A., Guy, J., et al. 2009, A&A , 506, 999 Schneider, P., van Waerbeke, L., Mellier, Y., et al. 1998, A&A ,333, 767
• White, M., Blanton, M., Bolton, A., et al. 2011, Astrophys. J. ,728, 126

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Looking for high-z galaxies (z>6.5) behind the lensing cluster A2667 (pptx) - Nicolas LAPORTE, Institut de Recherche en Astrophysique et Planétologie (IRAP)

Résumé : We investigate the nature and the physical properties of z, Y and, J‐dropouts galaxies selected behind the lensing cluster A2667. This field is part of our project aimed at identifying z~7‐10 candidates accessible to spectroscopic studies, based on deep photometry with ESO/VLT HAWK‐I and FORS2 (zYJH and Ks‐band images, AB(3 sigma)~26‐27) on a sample of lensing clusters extracted from our multi‐wavelength combined surveys with SPITZER, HST, and Herschel. We have selected 1 J‐dropout, 8 Y‐drops and 1 z‐drops within the common field of ~33 arcmin2 (effective area once corrected for contamination and lensing dilution). All of them are detected in H and Ks bands in addition to J and/or IRAC 3.6/4.5, with H(AB)~23.4 to 26.5, and have modest magnification factors. Although best‐fit photometric redshifts place all these candidates at high‐z, the contamination by low‐z interlopers is estimated at 50‐75% level based on previous studies, and the comparison with the blank‐field WIRCAM Ultra‐Deep Survey (WUDS). The same result is obtained when photometric redshifts include a luminosity prior, allowing us to remove half of the original sample as likely z~1.7‐3 interlopers with young stellar pulsations and strong extinction. Two additional sources among the remaining sample could be identified at low‐z based on a detection on Herschel data. Another source, our J-drop candidate, was also removed from our original high-z sample using X-Shooter observations.  These low‐z interlopers are not well described by current templates given the large break, and cannot be easily identified based solely on optical and near‐IR photometry. Given the estimated dust extinction and high SFRs, some of them could be also detected in the IR or sub‐mm bands. After correction for likely contaminants, the observed counts at z>7.5 seem to be in agreement with an evolving LF. We are able to constraint the bright end of the LF at z~8 and 9 after correction for contamination and incompleteness. Our results are consistent with previous studies.

Bibliographie :

• "The bright end of the luminosity function at z ~ 9" Laporte et al., 2012, A&A, 2012, 542L...31L
•  "A peculiar galaxy appears at redshift 11: properties of a moderate-redshift interloper" Hayes, Laporte et al., 2012, MNRAS, 425L...19H
• "Far-infrared constraints on the contamination by dust-obscured galaxies of high-z dropout searches" Boone et al., 2011, A&A, 534A...124B
•  "Optical dropout galaxies lensed by the cluster A2667" Laporte, Pello et al., 2011, A&A, 531A...74L