The 2-point angular correlation function w(θ) (2PACF), where θ is the angular separation between pairs of galaxies, provides the transversal Baryon Acoustic Oscillation (BAO) signal almost model-independently. In this paper we use 409,337 luminous red galaxies in the redshift range z = [0.440, 0.555] obtained from the tenth data release of the Sloan Digital Sky Survey (SDSS DR10) to estimate θBAO(z) from the 2PACF at six redshift shells. Since noise and systematics can hide the BAO signature in the w − θ plane, we also discuss some criteria to localize the acoustic bump. We identify two sources of model-dependence in the analysis, namely, the value of the acoustic scale from Cosmic Microwave Background (CMB) measurements and the correction in the θBAO(z) position due to projection effects. Constraints on the dark energy equation-of-state parameter w(z) from the θBAO(z) diagram are derived, as well as from a joint analysis with current CMB measurements. We find that the standard ΛCDM model as well as some of its extensions are in good agreement with these θBAO(z) measurements. * Electronic address: gabriela@on.br † Electronic address: bernui@on.br ‡ Electronic address: micolbenetti@on.br § Electronic address: jcarvalho@on.br ¶ Electronic address: alcaniz@on.br 1 The acoustic scale is defined as rs = ∞ z d cs(z) H(z) dz, where z d ≈ 1070 is the redshift of the drag epoch and cs(z) is the sound speed of the photon-baryon fluid. arXiv:1507.08972v2 [astro-ph.CO]
Following a quasi model-independent approach we measure the transversal BAO mode at high redshift using the two-point angular correlation function (2PACF). The analyses done here are only possible now with the quasar catalogue from the twelfth data release (DR12Q) from the Sloan Digital Sky Survey, because it is spatially dense enough to allow the measurement of the angular BAO signature with moderate statistical significance and acceptable precision. Our analyses with quasars in the redshift interval z ∈ [2.20, 2.25] produce the angular BAO scale θ BAO = 1.77 • ± 0.31 • with a statistical significance of 2.12 σ (i.e., 97% confidence level), calculated through a likelihood analysis performed using the theoretical covariance matrix sourced by the analytical power spectra expected in the ΛCDM concordance model. Additionally, we show that the BAO signal is robust -although with less statistical significance-under diverse bin-size choices and under small displacements of the quasars' angular coordinates. Finally, we also performed cosmological parameter analyses comparing the θ BAO predictions for wCDM and w(a)CDM models with angular BAO data available in the literature, including the measurement obtained here, jointly with CMB data. The constraints on the parameters Ω M , w 0 and w a are in excellent agreement with the ΛCDM concordance model.
The Javalambre-Physics of the Accelerating Universe Astrophysical Survey (J-PAS) will scan thousands of square degrees of the northern sky with a unique set of 56 filters using the dedicated 2.55m JST at the Javalambre Astrophysical Observatory. Prior to the installation of the main camera (4.2 deg 2 field-of-view with 1.2 Gpixels), the JST was equipped with the JPAS-Pathfinder, a one CCD camera with a 0.3 deg 2 field-of-view and plate scale of 0.23 arcsec pixel −1 . To demonstrate the scientific potential of J-PAS, the JPAS-Pathfinder camera was used to perform miniJPAS, a ∼1 deg 2 survey of the AEGIS field (along the Extended Groth Strip). The field was observed with the 56 J-PAS filters, which include 54 narrow band (NB, FWHM ∼ 145 Å) and two broader filters extending to the UV and the near-infrared, complemented by the u, g, r, i SDSS broad band (BB) filters. In this miniJPAS survey overview paper, we present the miniJPAS data set (images and catalogs), as we highlight key aspects and applications of these unique spectro-photometric data and describe how to access the public data products. The data parameters reach depths of mag AB 22 − 23.5 in the 54 narrow band filters and up to 24 in the broader filters (5σ in a 3 aperture). The miniJPAS primary catalog contains more than 64, 000 sources detected in the r band and with matched photometry in all other bands. This catalog is 99% complete at r = 23.6 (r = 22.7) mag for point-like (extended) sources. We show that our photometric redshifts have an accuracy better than 1% for all sources up to r = 22.5, and a precision of ≤ 0.3% for a subset consisting of about half of the sample. On this basis, we outline several scientific applications of our data, including the study of spatially-resolved stellar populations of nearby galaxies, the analysis of the large scale structure up to z ∼ 0.9, and the detection of large numbers of clusters and groups. Sub-percent redshift precision can also be reached for quasars, allowing for the study of the large-scale structure to be pushed to z > 2. The miniJPAS survey demonstrates the capability of the J-PAS filter system to accurately characterize a broad variety of sources and paves the way for the upcoming arrival of J-PAS, which will multiply this data by three orders of magnitude. For reference, the miniJPAS data and associated value added catalogs are publicly available http://archive.cefca.es/catalogues/minijpas-pdr201912.
The Baryon Acoustic Oscillations (BAO) imprinted a characteristic correlation length in the large-scale structure of the universe that can be used as a standard ruler for mapping out the cosmic expansion history. Here, we discuss the application of the angular two-point correlation function, w(θ ), to a sample of luminous red galaxies of the Sloan Digital Sky Survey (SDSS) and derive two new measurements of the BAO angular scale at z = 0.235 and z = 0.365. Since noise and systematics may hinder the identification of the BAO signature in the w − θ plane, we also introduce a potential new method to localize the acoustic bump in a model-independent way. We use these new measurements along with previous data to constrain cosmological parameters of dark energy models and to derive a new estimate of the acoustic scale r s .
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