Browsing by Autor "David J. Brooks"

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Backlighting extended gas halos around luminous red galaxies: Kinematic Sunyaev-Zel’dovich effect from DESI Y1 and ACT data
(American Physical Society, 2025) Bernardita Ried Guachalla; Emmanuel Schaan; Boryana Hadzhiyska; Simone Ferraro; J. Aguilar; S. P. Ahlen; Nicholas Battaglia; D. Bianchi; Richard Bond; David J. Brooks
The gas density profile around galaxies, shaped by feedback and affecting the galaxy lensing signal, is imprinted on the cosmic microwave background (CMB) by the kinematic Sunyaev-Zel'dovich effect (kSZ). We precisely measure this effect ($S/N\ensuremath{\approx}10$) via velocity stacking with 825,283 spectroscopically confirmed luminous red galaxies (LRG) from the Dark Energy Spectroscopic Instrument Year 1 (DESI Y1) survey, which overlap with the Atacama Cosmology Telescope (ACT) Data Release 6 temperature maps over $\ensuremath{\ge}4,000\text{ }\text{ }{\mathrm{deg}}^{2}$. We explore the kSZ dependence with various galaxy parameters and find no significant trend with redshift but clear trends with stellar mass and absolute magnitude in $g$, $r$, and $z$ bands. Our analysis suggests that the gas extends beyond the dark matter halo (99.5% confidence level, i.e., probability to exceed $(\mathrm{PTE})=0.005$). We find a tentative preference for hydrodynamical simulation models with stronger feedback that drives gas further out (Illustris $z=0.5$, $\mathrm{PTE}=0.37$) over weaker-feedback cases (IllustrisTNG $z=0.8$, $\mathrm{PTE}=0.045$), though with limited statistical significance. In all cases, a free multiplicative amplitude was fit to the simulated profiles, and further modeling work is required to firm up these conclusions. We find consistency between kSZ profiles around spectroscopic and photometric LRG, with comparable statistical power, thus increasing our confidence in the photometric analysis. Additionally, we present the first kSZ measurement around the DESI Y1 bright galaxy sample (BGS) and the emission-line galaxies (ELG) whose features match qualitative expectations. Finally, we forecast $S/N\ensuremath{\sim}50$ for future stacked kSZ measurements using data from the ACT, the DESI Y3, and the Rubin Observatory. These measurements will serve as an input for galaxy formation models and baryonic uncertainties in galaxy lensing.
Detection of the large-scale tidal field with galaxy multiplet alignment in the DESI Y1 spectroscopic survey
(Oxford University Press, 2024) C Lamman; Daniel J. Eisenstein; J. E. Forero-Romero; J. Aguilar; S. P. Ahlen; S. Bailey; D. Bianchi; David J. Brooks; T. Claybaugh; Axel de la Macorra
ABSTRACT We explore correlations between the orientations of small galaxy groups, or ‘multiplets’, and the large-scale gravitational tidal field. Using data from the Dark Energy Spectroscopic Instrument (DESI) Y1 survey, we detect the intrinsic alignment (IA) of multiplets to the galaxy-traced matter field out to separations of $100\,h^{-1}$ Mpc. Unlike traditional IA measurements of individual galaxies, this estimator is not limited by imaging of galaxy shapes and allows for direct IA detection beyond redshift $z=1$. Multiplet alignment is a form of higher order clustering, for which the scale-dependence traces the underlying tidal field and amplitude is a result of small-scale ($\lt 1h^{-1}$ Mpc) dynamics. Within samples of bright galaxies, luminous red galaxies (LRG) and emission-line galaxies, we find similar scale-dependence regardless of intrinsic luminosity or colour. This is promising for measuring tidal alignment in galaxy samples that typically display no IA. DESI’s LRG mock galaxy catalogues created from the A bacusS ummitN-body simulations produce a similar alignment signal, though with a 33 per cent lower amplitude at all scales. An analytic model using a non-linear power spectrum (NLA) only matches the signal down to 20 $h^{-1}$ Mpc. Our detection demonstrates that galaxy clustering in the non-linear regime of structure formation preserves an interpretable memory of the large-scale tidal field. Multiplet alignment complements traditional two-point measurements by retaining directional information imprinted by tidal forces, and contains additional line-of-sight information compared to weak lensing. This is a more effective estimator than the alignment of individual galaxies in dense, blue, or faint galaxy samples.
Spectroscopic search for optical emission lines from dark matter decay
(American Physical Society, 2024) Hanyue Wang; Daniel J. Eisenstein; J. Aguilar; S. P. Ahlen; S. Bailey; David J. Brooks; T. Claybaugh; Axel de la Macorra; Peter Doel; J. E. Forero-Romero
We search for narrow-line optical emission from dark matter decay by stacking dark-sky spectra from the Dark Energy Spectroscopic Instrument (DESI) at the redshift of nearby galaxies from DESI's Bright Galaxy and Luminous Red Galaxy samples. Our search uses regions separated by 5 to 20 arcsec from the centers of the galaxies, corresponding to an impact parameter of approximately 50 kpc. No unidentified spectral line shows up in the search, and we place a line flux limit of ${10}^{\ensuremath{-}19}\text{ }\text{ }\mathrm{ergs}/\mathrm{s}/{\mathrm{cm}}^{2}/{\mathrm{arcsec}}^{2}$ on emissions in the wavelength range of $2000--9000\stackrel{\ensuremath{\circ}}{\mathrm{A}}$. This places the tightest constraints yet on the two-photon decay of dark matter in the mass range of 5 to 12 eV, with a particle lifetime exceeding $3\ifmmode\times\else\texttimes\fi{}{10}^{25}\text{ }\text{ }\mathrm{s}$. This detection limit also implies that the line surface brightness contributed from all dark matter along the line of sight is at least 2 orders of magnitude lower than the measured extragalactic background light (EBL), ruling out the possibility that narrow optical-line emission from dark matter decay is a major source of the EBL.
Updated cosmological constraints on axion dark energy with DESI
(American Physical Society, 2025) L. Arturo Ureña–López; F. Lozano-Rodríguez; J. O. Román-Herrera; José Edgar Madriz Aguilar; S. P. Ahlen; D. Bianchi; David J. Brooks; T. Claybaugh; Axel de la Macorra; Arjun Dey
We present updated constraints on the parameters of an axion dark energy model, for which we took into account the properties of its characteristic potential and its full cosmological evolution. We show that the values of the axion parameters appear sufficiently constrained by the data, including the latest DESI DR1, and are consistent with the theoretical expectations of a field mass ${m}_{a}$ in the ultralight regime $\mathrm{log}({m}_{a}{c}^{2}/\mathrm{eV})\ensuremath{\simeq}\ensuremath{-}32.60\ifmmode\pm\else\textpm\fi{}0.12$, and an effective energy scale ${f}_{a}$ close to the reduced Planck energy $\mathrm{log}({f}_{a}/{M}_{\mathrm{Pl}})\ensuremath{\simeq}\ensuremath{-}0.28\ifmmode\pm\else\textpm\fi{}0.19$. Our results also support the idea of dynamical dark energy, although Bayesian evidence still favors the phenomenological dark energy model ${w}_{0}{w}_{a}$ over the axion dark energy, with the Bayes factor indicating moderate and weak strength of the evidence, respectively, when the models are compared to the cosmological constant $\mathrm{\ensuremath{\Lambda}}$. However, the results suggest that axion dark energy remains a well-motivated model and its parameters may be better constrained if the upcoming DESI data show further evidence for dynamical dark energy.