Assembly bias from nuisance to probe II: Salvaging linear clustering from DESI and SDSS data
Abstract
Galactic conformity is usually interpreted as a signature of assembly-biased galaxy occupation. We investigate whether compensated combinations of galaxy correlations can recover the linear matter correlation-function shape on scales where ordinary clustering becomes nonlinear. Using colour-selected DESI BGS and SDSS MGS samples, we measure conformity and compensated statistics in projection and redshift space, and compare them with MTNG, FLAMINGO, and MDPL2-SAG simulations. We find that the DESI conformity monopole, projected conformity, and compensated correlations follow the linear matter shape to substantially smaller separations than ordinary colour-selected clustering. The agreement is clearest for dense DESI samples with central-primary selection, although the dependence on primary selection varies with scale and statistic. Projected conformity resembles the unprojected linear matter correlation function more closely than its projected counterpart, consistent with an effective response concentrated at small line-of-sight separations. The conformity quadrupole is strongly suppressed, as expected from cancellation of the leading Kaiser terms. SDSS shows similar but noisier behaviour, while simulations reproduce the main trends with model-dependent amplitudes. These results suggest that compensated statistics can suppress nonlinear clustering contributions while retaining linear matter information, although residual nonlinear effects require calibration before precision cosmological applications. (Abridged)
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BibTeX
@misc{padilla2026assembly,
title = {{Assembly bias from nuisance to probe II: Salvaging linear clustering from DESI and SDSS data}},
author = {Nelson Padilla and Dante Paz and Iván Lacerna},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2608.26262},
eprint = {2608.26262},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.26262},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Assembly bias from nuisance to probe II: Salvaging linear clustering from DESI and SDSS data
AU - Nelson Padilla
AU - Dante Paz
AU - Iván Lacerna
PY - 2026
DA - 2026/10/30
PB - arXiv
DO - 10.48550/arxiv.2608.26262
UR - https://arxiv.org/abs/2608.26262
AB - Galactic conformity is usually interpreted as a signature of assembly-biased galaxy occupation. We investigate whether compensated combinations of galaxy correlations can recover the linear matter correlation-function shape on scales where ordinary clustering becomes nonlinear. Using colour-selected DESI BGS and SDSS MGS samples, we measure conformity and compensated statistics in projection and redshift space, and compare them with MTNG, FLAMINGO, and MDPL2-SAG simulations. We find that the DESI conformity monopole, projected conformity, and compensated correlations follow the linear matter shape to substantially smaller separations than ordinary colour-selected clustering. The agreement is clearest for dense DESI samples with central-primary selection, although the dependence on primary selection varies with scale and statistic. Projected conformity resembles the unprojected linear matter correlation function more closely than its projected counterpart, consistent with an effective response concentrated at small line-of-sight separations. The conformity quadrupole is strongly suppressed, as expected from cancellation of the leading Kaiser terms. SDSS shows similar but noisier behaviour, while simulations reproduce the main trends with model-dependent amplitudes. These results suggest that compensated statistics can suppress nonlinear clustering contributions while retaining linear matter information, although residual nonlinear effects require calibration before precision cosmological applications. (Abridged)
ER -