Samuroff, S;
Mandelbaum, R;
Blazek, J;
Campos, A;
Maccrann, N;
Zacharegkas, G;
Amon, A;
... Pieres, A; + view all
(2023)
The Dark Energy Survey Year 3 and eBOSS: constraining galaxy intrinsic alignments across luminosity and colour space.
Monthly Notices of the Royal Astronomical Society
, 524
(2)
pp. 2195-2223.
10.1093/mnras/stad2013.
(In press).
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Abstract
We present direct constraints on galaxy intrinsic alignments (IAs) using the Dark Energy Survey Year 3 (DES Y3), the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), and its precursor, the Baryon Oscillation Spectroscopic Survey (BOSS). Our measurements incorporate photometric red sequence (redMaGiC) galaxies from DES with median redshift z ∼0.2-1.0, luminous red galaxies from eBOSS at z ∼0.8, and also an SDSS-III BOSS CMASS sample at z ∼0.5. We measure two-point IA correlations, which we fit using a model that includes lensing, magnification, and photometric redshift error. Fitting on scales 6 Mpc h-1 < rp < 70 Mpc h-1, we make a detection of IAs in each sample, at 5σ-22σ (assuming a simple one-parameter model for IAs). Using these red samples, we measure the IA-luminosity relation. Our results are statistically consistent with previous results, but offer a significant improvement in constraining power, particularly at low luminosity. With this improved precision, we see detectable dependence on colour between broadly defined red samples. It is likely that a more sophisticated approach than a binary red/blue split, which jointly considers colour and luminosity dependence in the IA signal, will be needed in future. We also compare the various signal components at the best-fitting point in parameter space for each sample, and find that magnification and lensing contribute of the total signal. As precision continues to improve, it will certainly be necessary to account for these effects in future direct IA measurements. Finally, we make equivalent measurements on a sample of emission-line galaxies from eBOSS at z ∼0.8. We constrain the non-linear alignment amplitude to be (|A1| < 0.78 at 95 per cent CL).
| Type: | Article |
|---|---|
| Title: | The Dark Energy Survey Year 3 and eBOSS: constraining galaxy intrinsic alignments across luminosity and colour space |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/stad2013 |
| Publisher version: | https://doi.org/10.1093/mnras/stad2013 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | gravitational lensing: weak – galaxies: statistics – cosmological parameters – cosmology: observations |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10175563 |
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