scholarly journals Baryon acoustic oscillations with the cross-correlation of spectroscopic and photometric samples

2013 ◽  
Vol 433 (1) ◽  
pp. 730-739 ◽  
Author(s):  
Atsushi J. Nishizawa ◽  
Masamune Oguri ◽  
Masahiro Takada
Keyword(s):  
Cross Correlation ◽  
Acoustic Oscillations ◽  
Baryon Acoustic Oscillations ◽  
The Cross

scholarly journals Baryon acoustic oscillations from the complete SDSS-III Lyα-quasar cross-correlation function at z = 2.4

2017 ◽  
Vol 608 ◽  
pp. A130 ◽  
Author(s):  
Hélion du Mas des Bourboux ◽  
Jean-Marc Le Goff ◽  
Michael Blomqvist ◽  
Nicolás G. Busca ◽  
Julien Guy ◽  
...  
Keyword(s):  
Correlation Function ◽  
Cross Correlation ◽  
Peak Position ◽  
Sloan Digital Sky Survey ◽  
Acoustic Oscillations ◽  
Microwave Background ◽  
Λcdm Model ◽  
Auto Correlation Function ◽  
Baryon Acoustic Oscillations ◽  
The Cross

We present a measurement of baryon acoustic oscillations (BAO) in the cross-correlation of quasars with the Lyα-forest flux transmission at a mean redshift of z = 2.40. The measurement uses the complete Sloan Digital Sky Survey (SDSS-III) data sample: 168 889 forests and 234 367 quasars from the SDSS data release DR12. In addition to the statistical improvement on our previous study using DR11, we have implemented numerous improvements at the analysis level enabling a more accurate measurement of this cross-correlation. We have also developed the first simulations of the cross-correlation that allow us to test different aspects of our data analysis and to search for potential systematic errors in the determination of the BAO peak position. We measure the two ratios DH(z = 2.40) /rd = 9.01 ± 0.36 and DM(z = 2.40) /rd = 35.7 ± 1.7, where the errors include marginalization over the non-linear velocity of quasars and the cross-correlation of metals and quasars, among other effects. These results are within 1.8σ of the prediction of the flat-ΛCDM model describing the observed cosmic microwave background anisotropies. We combine this study with the Lyα-forest auto-correlation function, yielding DH(z = 2.40) /rd = 8.94 ± 0.22 and DM(z = 2.40) /rd = 36.6 ± 1.2, within 2.3σ of the same flat-ΛCDM model.

scholarly journals Baryon acoustic oscillations at z = 2.34 from the correlations of Lyα absorption in eBOSS DR14

2019 ◽  
Vol 629 ◽  
pp. A85 ◽  
Author(s):  
Victoria de Sainte Agathe ◽  
Christophe Balland ◽  
Hélion du Mas des Bourboux ◽  
Nicolás G. Busca ◽  
Michael Blomqvist ◽  
...  
Keyword(s):  
Correlation Function ◽  
Cross Correlation ◽  
Companion Paper ◽  
Sloan Digital Sky Survey ◽  
Acoustic Oscillations ◽  
Angular Diameter Distance ◽  
Quasar Spectra ◽  
Sky Survey ◽  
Baryon Acoustic Oscillations ◽  
First Time

We measure the imprint of primordial baryon acoustic oscillations (BAOs) in the correlation function of Lyα absorption in quasar spectra from the Baryon Oscillation Spectroscopic Survey (BOSS) and the extended BOSS (eBOSS) in Data Release 14 (DR14) of the Sloan Digital Sky Survey (SDSS)-IV. In addition to 179 965 spectra with absorption in the Lyman-α (Lyα) region, we use Lyα absorption in the Lyman-β region of 56 154 spectra for the first time. We measure the Hubble distance, DH, and the comoving angular diameter distance, DM, relative to the sound horizon at the drag epoch rd at an effective redshift z = 2.34. Using a physical model of the correlation function outside the BAO peak, we find DH(2.34)/rd = 8.86 ± 0.29 and DM(2.34)/rd = 37.41 ± 1.86, within 1σ from the flat-ΛCDM model consistent with CMB anisotropy measurements. With the addition of polynomial “broadband” terms, the results remain within one standard deviation of the CMB-inspired model. Combined with the quasar-Lyα cross-correlation measurement presented in a companion paper, the BAO measurements at z = 2.35 are within 1.7σ of the predictions of this model.

scholarly journals Quasar-Lyman α forest cross-correlation from BOSS DR11: Baryon Acoustic Oscillations

2014 ◽  
Vol 2014 (05) ◽  
pp. 027-027 ◽  
Author(s):  
Andreu Font-Ribera ◽  
David Kirkby ◽  
Nicolas Busca ◽  
Jordi Miralda-Escudé ◽  
Nicholas P. Ross ◽  
...  
Keyword(s):  
Cross Correlation ◽  
Acoustic Oscillations ◽  
Baryon Acoustic Oscillations

scholarly journals Variations of the Low l Solar Acoustic Spectrum Correlated with the Activity Cycle

1990 ◽  
Vol 121 ◽  
pp. 349-355 ◽  
Author(s):  
P.L. Pallé ◽  
C. Régulo ◽  
T. Roca Cortés
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Cross Correlation ◽  
Power Spectra ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Frequency Variation ◽  
Acoustic Oscillations ◽  
Solar Cycle Variation ◽  
The Cross

AbstractSolar cycle variation of the frequencies and of the power of solar acoustic oscillations are investigated. Integrated sunlight data from 1977 to 1988 obtained at the Observatorio del Teide (Izaña, Tenerife), using a resonant scattering spectrophotometer, is analyzed in 60 day time strings and their power spectra are calculated from 2 to 3.8 mHz. To study the frequency variation, each power spectrum is cross-correlated with the one corresponding to the 1981 series and the shifts of the centroids of the cross-correlation peaks are calculated. The results show a clear variation in frequency of the cross-correlation peaks of −0.37 ± 0.04 μHz peak to peak as solar activity cycle goes from maximum to minimum. Moreover, this effect is found to depend on the l value of the modes, being absent for l = 0 and of 0.42 ± 0.06 μHz for l = 1. These results can be interpreted as an amplitude modulation between modes of the same multiplet, probably as a consequence of the action of strong magnetic fields. As low l modes penetrate deeply into the Sun’s interior, these observations suggest changes in its structure correlated with the solar activity cycle. When the power of the modes is calculated, using the same series as before, and its change along the solar cycle is studied, a variation of ~ 40% is found, the power being higher when solar activity is at its minimum. If this effect is independent of the l value of the p-modes, the results can be interpreted in terms of a change in the efficiency of the excitation mechanism of such modes. Indeed, if turbulent convection is such a mechanism, a change in the characteristic size of the granulation would account for the observed effect. Alternatively, another explanation could be a selective change in the efficiency of the excitation and/or damping mechanisms of the l ≤ 3 modes in front of other l value modes.

scholarly journals Baryon acoustic oscillations in the projected cross-correlation function between the eBOSS DR16 quasars and photometric galaxies from the DESI Legacy Imaging Surveys

2021 ◽  
Vol 503 (2) ◽  
pp. 2562-2582
Author(s):  
Pauline Zarrouk ◽  
Mehdi Rezaie ◽  
Anand Raichoor ◽  
Ashley J Ross ◽  
Shadab Alam ◽  
...  
Keyword(s):  
Correlation Function ◽  
Cross Correlation ◽  
Angular Distance ◽  
Photometric Data ◽  
Cross Correlation Function ◽  
Network Approach ◽  
Acoustic Oscillations ◽  
Neural Network Approach ◽  
Baryon Acoustic Oscillations ◽  
Line Galaxy

ABSTRACT We search for the baryon acoustic oscillations in the projected cross-correlation function binned into transverse comoving radius between the SDSS-IV DR16 eBOSS quasars and a dense photometric sample of galaxies selected from the DESI Legacy Imaging Surveys. We estimate the density of the photometric sample of galaxies in this redshift range to be about 2900 deg−2, which is deeper than the official DESI emission line galaxy selection, and the density of the spectroscopic sample is about 20 deg−2. In order to mitigate the systematics related to the use of different imaging surveys close to the detection limit, we use a neural network approach that accounts for complex dependences between the imaging attributes and the observed galaxy density. We find that we are limited by the depth of the imaging surveys that affects the density and purity of the photometric sample and its overlap in redshift with the quasar sample, which thus affects the performance of the method. When cross-correlating the photometric galaxies with quasars in the range 0.6 ≤ z ≤ 1.2, the cross-correlation function can provide better constraints on the comoving angular distance DM (6 per cent precision) compared to the constraint on the spherically averaged distance DV (9 per cent precision) obtained from the autocorrelation. Although not yet competitive, this technique will benefit from the arrival of deeper photometric data from upcoming surveys that will enable it to go beyond the current limitations we have identified in this work.

scholarly journals Insights to enhance the examination of tool marks in human cartilage

2021 ◽  
Author(s):  
Matthias Weber ◽  
Anja Niehoff ◽  
Markus A. Rothschild
Keyword(s):  
Light Microscope ◽  
Cross Correlation ◽  
Costal Cartilage ◽  
Correlation Coefficients ◽  
Human Cartilage ◽  
Cut Marks ◽  
Tool Marks ◽  
The Cross ◽  
Cleaning Methods ◽  
The Individual

AbstractThis work deals with the examination of tool marks in human cartilage. We compared the effectiveness of several cleaning methods on cut marks in porcine cartilage. The method cleaning by multiple casts achieved the significantly highest scores (P = 0.02). Furthermore, we examined the grain-like elevations (dots) located on casts of cut cartilage. The results of this study suggest that the casting material forms these dots when penetrating cartilage cavities, which are areas where the strong collagen fibres leave space for the chondrocytes. We performed fixation experiments to avoid this, without success. In addition, 31 casting materials were compared regarding contrast under light-microscope and 3D tool marks scanner. Under the light-microscope, brown materials achieved significantly higher values than grey (P = 0.02) or black (P = 0.00) whereas under the 3D scanner, black materials reached higher contrast values than grey (P = 0.04) or brown (P = 0.047). To compare the accuracy and reproducibility of 6 test materials for cartilage, we used 10 knives to create cut marks that were subsequently scanned. During the alignment of the individual signals of each mark, the cross-correlation coefficients (Xmax) and lags (LXmax) were calculated. The signals of the marks in agarose were aligned with significantly fewer lags and achieved significantly higher cross-correlation coefficients compared to all tested materials (both P = 0.00). Moreover, we determined the cross-correlation coefficients (XC) for known-matches (KM) per material. Agarose achieved significantly higher values than AccuTrans®, Clear Ballistics™, and gelatine (all P = 0.00). The results of this work provide valuable insights for the forensic investigation of marks in human costal cartilage.

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