Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

The DESI DR1 Peculiar Velocity Survey: global zero-point and $H_0$ constraints

A. Carr, C. Howlett, A. J. Amsellem, Tamara M. Davis, K. Said, D. Parkinson, A. Palmese, J. Aguilar, S. Ahlen, J. Bautista, S. BenZvi, D. Bianchi, C. Blake, D. Brooks, T. Claybaugh, A. Cuceu, A. de la Macorra, P. Doel, K. Douglass, S. Ferraro, J. E. Forero-Romero, E. Gaztañaga, S. Gontcho A Gontcho, G. Gutierrez, H. K. Herrera-Alcantar, K. Honscheid, D. Huterer, M. Ishak, R. Joyce, A. G. Kim, D. Kirkby, A. Kremin, O. Lahav, C. Lamman, M. Landriau, L. Le Guillou, M. E. Levi, M. Manera, A. Meisner, R. Miquel, J. Moustakas, S. Nadathur, W. J. Percival, F. Prada, I. Pérez-Ràfols, F. Qin, C. Ross, G. Rossi, E. Sanchez, D. Schlegel, H. Seo, D. Sprayberry, G. Tarlé, R. J. Turner, B. A. Weaver, P. Zarrouk, R. Zhou, H. Zou

TL;DR

This paper uses the DESI DR1 Peculiar Velocity data to calibrate FP and TF distances via a global zero-point anchored to external distance calibrators, primarily Pantheon+ SN Ia (SH0ES) with cross-checks from SBF and other tracers. By expanding calibrator overlap through a merged galaxy-group catalog, the study achieves a large, statistically powerful H0 measurement while accounting for systematic uncertainties from the zero-point, sample selection, and calibrator covariance. The fiducial SN Ia–calibrated result is H0 = 73.7 ± 1.1 km s^-1 Mpc^-1 (stat.+syst.), with SN+SBF providing a consistent, slightly tighter constraint; overall, the DESI PV approach offers a competitive, independent path to a local H0 typically aligned with the SH0ES value, and it holds promise for percent-level precision with future data and calibrators.

Abstract

The Dark Energy Spectroscopic Instrument (DESI) in its first Data Release (DR1) already provides more than 100,000 galaxies with relative distance measurements. The primary purpose of this paper is to perform the calibration of the zero-point for the DESI Fundamental Plane and Tully-Fisher relations, which allows us to measure the Hubble constant, $H_0$. This sample has a lower statistical uncertainty than any previously used to measure $H_0$, and we investigate the systematic uncertainties in absolute calibration that could limit the accuracy of that measurement. We improve upon the DESI Early Data Release Fundamental Plane $H_0$ measurement by a) using a group catalog to increase the number of calibrator galaxies and b) investigating alternative calibrators in the nearby universe. Our baseline measurement calibrates to the SH0ES/Pantheon+ type Ia supernovae, and finds $H_0=73.7\pm 0.06\;(\text{stat.})\pm 1.1\;(\text{syst.})$ km s$^{-1}$ Mpc$^{-1}$. Calibrating to surface brightness fluctuation (SBF) distances yields a similar $H_0$. We explore measurements using other calibrators, but these are currently less precise since the overlap with DESI peculiar velocity tracers is much smaller. In future data releases with an even larger peculiar velocity sample, we plan to calibrate directly to Cepheids and the tip of the red giant branch, which will enable the uncertainty to decrease towards a percent-level measurement of $H_0$. This will provide an alternative to supernovae as the Hubble flow sample for $H_0$ measurements.

The DESI DR1 Peculiar Velocity Survey: global zero-point and $H_0$ constraints

TL;DR

This paper uses the DESI DR1 Peculiar Velocity data to calibrate FP and TF distances via a global zero-point anchored to external distance calibrators, primarily Pantheon+ SN Ia (SH0ES) with cross-checks from SBF and other tracers. By expanding calibrator overlap through a merged galaxy-group catalog, the study achieves a large, statistically powerful H0 measurement while accounting for systematic uncertainties from the zero-point, sample selection, and calibrator covariance. The fiducial SN Ia–calibrated result is H0 = 73.7 ± 1.1 km s^-1 Mpc^-1 (stat.+syst.), with SN+SBF providing a consistent, slightly tighter constraint; overall, the DESI PV approach offers a competitive, independent path to a local H0 typically aligned with the SH0ES value, and it holds promise for percent-level precision with future data and calibrators.

Abstract

The Dark Energy Spectroscopic Instrument (DESI) in its first Data Release (DR1) already provides more than 100,000 galaxies with relative distance measurements. The primary purpose of this paper is to perform the calibration of the zero-point for the DESI Fundamental Plane and Tully-Fisher relations, which allows us to measure the Hubble constant, . This sample has a lower statistical uncertainty than any previously used to measure , and we investigate the systematic uncertainties in absolute calibration that could limit the accuracy of that measurement. We improve upon the DESI Early Data Release Fundamental Plane measurement by a) using a group catalog to increase the number of calibrator galaxies and b) investigating alternative calibrators in the nearby universe. Our baseline measurement calibrates to the SH0ES/Pantheon+ type Ia supernovae, and finds km s Mpc. Calibrating to surface brightness fluctuation (SBF) distances yields a similar . We explore measurements using other calibrators, but these are currently less precise since the overlap with DESI peculiar velocity tracers is much smaller. In future data releases with an even larger peculiar velocity sample, we plan to calibrate directly to Cepheids and the tip of the red giant branch, which will enable the uncertainty to decrease towards a percent-level measurement of . This will provide an alternative to supernovae as the Hubble flow sample for measurements.

Paper Structure

This paper contains 30 sections, 14 equations, 13 figures.

Table of Contents

  1. Introduction
  2. DESI and the DESI Peculiar Velocity Survey
  3. The Dark Energy Spectroscopic Instrument
  4. The DESI peculiar velocity program
  5. DESI PV targeting and selection cuts
  6. Calibrators
  7. Calibrating with SNe Ia
  8. Calibrating with Coma
  9. Calibrating with masers, Cepheids, and SBF
  10. Distances to Galaxy groups
  11. Comparison of galaxies in groups vs all galaxies
  12. Zero-pointing process
  13. The Tully-Fisher Relation
  14. The Fundamental Plane Relation
  15. Zero-pointing TF and FP simultaneously
  16. ...and 15 more sections

Figures (13)

  • Figure 1: Example of how we combine group catalogs to discover calibrators that are in the same group as DESI PV galaxies. Taking Lim group 2dFGRS 949 (orange circles in the left panel) as the initial group that contains one of our DESI PV galaxies (step 3), the SDSS group (green circles) was found to overlap (step 4), and then 2dFGRS 4889 was linked (step 6). The final group is defined as all galaxies discovered in the process (pink circles in the right panel). If any galaxy in the final group has a known distance, we can use it to calibrate the entire group and any PV galaxies in it (yellow crosses in the right panel). The background image is from the DESI Legacy Survey viewer, and the ellipses are for visualization only. To distinguish the galaxies that appear in multiple groups in the left panel, the individual symbols are offset from the center of the galaxy. The group identifiers are internal to the Lim catalog (a '+' denotes our expanded definition).
  • Figure 2: Distributions of TF distance indicators in groups (green) and in the full sample (gray). There is no evidence of a difference between the populations.
  • Figure 3: Distributions of FP distance indicators in groups (orange) and in the full sample (gray). The mean difference is significant enough to warrant correction back to the full sample mean.
  • Figure 4: The difference between FP and TF $\eta$ in each group containing at least one of each type of galaxy. Individual $\eta$ differences are in pink, and the binned, weighted averages are in black. There is no significant trend with redshift. The black dashed line shows the average difference/offset.
  • Figure 5: "Hubble Diagram" in $\eta$, which shows Hubble residuals as a function of redshift. We expect it to be flat in $z$, and centered on 0 when we use the same fiducial cosmology as was used to generate the catalogs.
  • ...and 8 more figures