The DESI DR1 Peculiar Velocity Survey: Fundamental Plane Catalogue

arXiv:2512.03226 · astro-ph.CO, astro-ph.GA · Submitted 2026-08-21 · Read on arXiv

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Introduction to the show: ident: Astrophysics Radio. Generated commentary on the latest astrophysics papers.

Vera: Next we'll be talking about the paper "The DESI DR1 Peculiar Velocity Survey: Fundamental Plane Catalogue".

Jocelyn: The paper was written by the authors from Department of Physics "Aldo Pontremoli", University degli Studi di Milano and INAF-Osservatorio Astronomico di Brera and Centre for Astrophysics & Supercomputing, Swinburne University of Technology and Department of Physics & Astronomy, University College London and Korea Astronomy and Space Science Institute and Institute of Physics, Universidad Nacional Autónoma de México and Department of Astronomy & Astrophysics, University of Toronto and Department of Physics & Astronomy and Pittsburgh Particle Physics and Astrophysics, and Cosmology Center (PITT PACC), University of Pittsburgh and Department of Physics and Astronomy, Sejong University and Planck Collaboration and Department of Astronomy & Astrophysics, University of California and Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology and Departamento de Física, Universidad de los Andes and Observatorio Astronómico, Universidad de los Andes and Institut d’Estudis Espacials de Catalunya (IEEC) and Institute of Cosmology and Gravitation, University of Portsmouth and Institute of Space Sciences, ICE-CSIC and University of Virginia, Department of Astronomy and Fermi National Accelerator Laboratory and Center for Cosmology and Astroparticle Physics, The Ohio State University and Department of Physics, The Ohio State University and The Ohio State University and Department of Physics, University of Michigan and University of Michigan and Department of Physics, The University of Texas at Dallas and NSF NOIRLab (National Optical-Infrared Astronomy Research Laboratory) and Sorbonne Université, CNRS/IN2P3, Laboratoire de Physique Nucléaire et de Hautes Energies (LPNHE) and Department of Astronomy and Astrophysics, University of California and Department of Astronomy, The Ohio State University and Institució Catalana de Recerca i Estudis Avançats and Department of Physics and Astronomy, Siena University and IRFU, CEA, Université Paris-Saclay and Department of Physics and Astronomy, University of Waterloo and Perimeter Institute for Theoretical Physics and Waterloo Centre for Astrophysics, University of Waterloo and Space Sciences Laboratory, University of California and Instituto de Astrofísica de Andalucía (CSIC) and Departament de Física, EEBE, Universitat Politècnica de Catalunya.

Vera: Stay tuned as we take you through the paper and discuss its implications.

Summary and Key Findings: Vera: So, after discussing the initial scope, let's look at what "The DESI DR1 Peculiar Velocity Survey: Fundamental Plane Catalogue" actually found in terms of raw data.

Jocelyn: The core result is this massive catalogue containing ninety-eight thousand two hundred ninety-two unique early-type galaxies that have been measured using the Fundamental Plane relation.

Subrahmanyam: That volume is what really matters for us, because it gives us the statistical power to see patterns in motion that are invisible at smaller datasets.

Vera: And while we've got this massive sample, they achieved a precision of twenty-six percent random error in their distance measurements, which is competitive with previous surveys.

Jocelyn: That tells us that even though it’s a huge undertaking, the quality of the data is actually on par with established methods like those used in the SMAC sample or other early surveys.

Subrahmanyam: It's important to recognize that having a large sample size and maintaining high precision are two separate things, and they've managed to do both here.

Vera: It’s a huge step forward because of the sheer number of these detailed measurements in the local universe, increasing our total count by roughly twice as many as ever measured before this is released.

Jocelyn: I think that will immediately allow for some very strong comparisons when we look at how these galaxies are moving relative to each other.

Subrahmanyam: The paper' puts the number ninety-eight thousand two hundred ninety-two in bold, and that number speaks volumes about the scale of the data they’ve collected.

Improvements and Impact: Vera: Building on that large sample size, let’s talk about how this work improves upon previous surveys like Cosmicflows-four.

Jocelyn: The text suggests a major improvement in moving from having scattered snapshots to getting a single, high-resolution picture of cosmic evolution.

Subrahmanyam: It’s not just the quantity; we are using motion as a proxy for mass distribution, and this catalogue gives us much more reliable tracers than previous compilations.

Vera: The paper achieves a homogeneous dataset by cleaning up all the messy overlaps that used to plague earlier compilations like CosmicFlow-four.

Jocelyn: That homogenization is huge because it means we are comparing apples to apples, which is essential for accurate analysis of how galaxies move in relation to one another.

Subrahmanyam: The ability this gives us to constrain parameters like m or test general relativity across a much wider range of scales is unprecedented.

Vera: I think the most impactful change here is that we are setting up the future observational framework for dark energy studies with a robust, reliable set of measurements.

Jocelyn: It feels like moving from having scattered data to getting a single, high-resolution video of cosmic evolution, which is much more powerful for any subsequent analysis.

Subrahmanyam: This is about establishing a firm baseline that will be used by AI and other sophisticated models to understand the dynamics of the universe.

Methodology and Rigor: Vera: We’ve seen what this data looks like, but let's pivot now to the technical rigor behind it, specifically the quality control measures detailed in "The DESI DR1 Peculiar Velocity Survey: Fundamental Plane Catalogue."

Jocelyn: It’s crucial to understand that simply having a lot of data isn't enough; the reliability of every single point must be scrutinized, especially when measuring such tiny deviations from the expected smooth flow.

Subrahmanyam: The rigor in their validation process is what gives us confidence that these measurements are real, not just instrumental artifacts.

Vera: I was particularly impressed by the exhaustive detail on how they cleaned up and validated their measurements through quality control checks across analysis parameters.

Jocelyn: So, these detailed checks essentially build a kind of trust score for every single galaxy in the sample before we even start calculating any cosmological parameters.

Subrahmanyam: It means they didn't just run one analysis; they ran dozens, deliberately changing input assumptions to see if the core results remained stable.

Vera: The process of running these systematic checks is a way of testing for biases related to the redshift space distortions and making sure our interpretation is solid.

Jocelyn: And because this catalogue includes both FP and TF methods, we are able to test the assumption that gravity acts universally across all scales we observe.

Subrahmanyam: The way they’ve handled these systematic uncertainties ensures that this dataset isn't just a collection of numbers, but a trustworthy map of cosmic dynamics for the entire sample.

Conclusion and Wrap-Up: Vera: So, wrapping up our discussion on "The DESI DR1 Peculiar Velocity Survey: Fundamental Plane Catalogue," it’s clear that this represents a genuinely pivotal moment for observational cosmology.

Jocelyn: It really does; the sheer scale of this dataset gives us an unprecedented view into the dynamics of cosmic structure—it moves us beyond mere observation into actual measurement of cosmic forces.

Subrahmanyam: By quantifying these motions, we are essentially gaining a detailed history book of the universe written in motion itself.

Vera: And that capability allows us to constrain parameters related to dark energy and structure growth with a precision that was simply unattainable before this survey was completed.

Jocelyn: It truly solidifies the catalogue's role not just as a dataset, but as a highly specialized, dynamic tool for understanding the evolution of cosmic structure over billions of years.

Subrahmanyam: The potential applications for future surveys are immense, giving us a robust foundation to probe the nature and ultimate fate of our universe.

Vera: It’s been an incredibly illuminating conversation about how this data will guide our next steps in research.

Jocelyn: We are so excited to see how this catalogue is used by other teams in their own analyses.

Subrahmanyam: I am confident that the meticulous effort detailed in "The DESI DR1 Peculiar Velocity Survey: Fundamental Plane Catalogue" provides the necessary foundation for a deep, robust understanding of the cosmos.

Department of Physics "Aldo Pontremoli", University degli Studi di Milano · INAF-Osservatorio Astronomico di Brera · Centre for Astrophysics & Supercomputing, Swinburne University of Technology · Department of Physics & Astronomy, University College London · Korea Astronomy and Space Science Institute · Institute of Physics, Universidad Nacional Autónoma de México · Department of Astronomy & Astrophysics, University of Toronto · Department of Physics & Astronomy and Pittsburgh Particle Physics · Astrophysics, and Cosmology Center (PITT PACC), University of Pittsburgh · Department of Physics and Astronomy, Sejong University · Planck Collaboration · Department of Astronomy & Astrophysics, University of California · Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology · Departamento de Física, Universidad de los Andes · Observatorio Astronómico, Universidad de los Andes · Institut d’Estudis Espacials de Catalunya (IEEC) · Institute of Cosmology and Gravitation, University of Portsmouth · Institute of Space Sciences, ICE-CSIC · University of Virginia, Department of Astronomy · Fermi National Accelerator Laboratory · Center for Cosmology and Astroparticle Physics, The Ohio State University · Department of Physics, The Ohio State University · The Ohio State University · Department of Physics, University of Michigan · University of Michigan · Department of Physics, The University of Texas at Dallas · NSF NOIRLab (National Optical-Infrared Astronomy Research Laboratory) · Sorbonne Université, CNRS/IN2P3, Laboratoire de Physique Nucléaire et de Hautes Energies (LPNHE) · Department of Astronomy and Astrophysics, University of California · Department of Astronomy and Astrophysics, University of California · Department of Astronomy, The Ohio State University · Institució Catalana de Recerca i Estudis Avançats · Department of Physics and Astronomy, Siena University · IRFU, CEA, Université Paris-Saclay · Department of Physics and Astronomy, University of Waterloo · Perimeter Institute for Theoretical Physics · Waterloo Centre for Astrophysics, University of Waterloo · Space Sciences Laboratory, University of California · Instituto de Astrofísica de Andalucía (CSIC) · Departament de Física, EEBE, Universitat Politècnica de Catalunya

astro-ph.CO, astro-ph.GA

Submitted: 2026-08-21

Updated: 2026-08-24

Comments: 21 pages, 17 figures. Part of the batch release of the DESI PV DR1 results. Accepted by Publications of the Astronomical Society of Australia. Data will be released as a DESI VAC shortly

DOI: 10.1017/pasa.2026.10204

License: http://creativecommons.org/licenses/by/4.0/

Importance score: 8/100

The gist: The DESI DR1 Peculiar Velocity Survey: Fundamental Plane Catalogue presents a detailed study of peculiar velocity measurements in the local Universe using data from the first data release (DR1) of

Key concepts

Fundamental Plane relation: This is a relationship used to measure the distance of galaxies. The survey uses this relation to measure the peculiar velocity of galaxies, which helps scientists understand how they are moving relative to each other in the universe.
Peculiar Velocity Survey: This survey measures the motion of galaxies beyond their smooth cosmic flow. By quantifying these motions, researchers gain a detailed history book of the universe written in motion itself, allowing for measurements of cosmic forces.
Fundamental Plane Catalogue: This catalogue is a massive collection containing ninety-eight thousand two hundred ninety-two unique early-type galaxies measured using the Fundamental Plane. This large dataset provides statistical power to see patterns in motion that are difficult to find in smaller samples.
Homogenization: This process involves cleaning up messy overlaps in data from previous compilations, such as CosmicFlow-four. Achieving a homogeneous dataset is crucial because it ensures that comparisons between different galaxy motions are 'apples to apples' for accurate analysis.

Terminology

Fundamental Plane — 99× in this paper
Velocity Dispersion — 88× in this paper · explained in 2 episodes
Aperture — 25× in this paper · explained in 1 episode
Aperture Correction — 20× in this paper · explained in 1 episode
Consistency — 16× in this paper · explained in 3 episodes
Calibration — 14× in this paper · explained in 7 episodes
Clustering — 11× in this paper · explained in 2 episodes
alpha — 7× in this paper · explained in 1 episode
Dark Energy Spectroscopic Instrument — 4× in this paper
Department of Energy — 4× in this paper
Core — 2× in this paper · explained in 2 episodes
National Science Foundation — 2× in this paper
Beijing-Arizona Sky Survey — 1× in this paper
Bright Galaxy Survey — 1× in this paper
Degeneracy — 1× in this paper · explained in 3 episodes
Homogenization — 1× in this paper · explained in 2 episodes
Selection Bias — 1× in this paper · explained in 4 episodes

Summary

The DESI DR1 Peculiar Velocity Survey: Fundamental Plane Catalogue presents a detailed study of peculiar velocity measurements in the local Universe using data from the first data release (DR1) of the Dark Energy Spectroscopic Instrument (DESI).

Motivation and Context

Measurements of peculiar velocities are described as "a powerful tool to study the nature of dark energy at low (z < 0.1) redshifts. The paper notes that PV surveys are used to test our cosmological models through measurements of the local expansion rate, H0, and the structure growth rate, f σ8." Two primary distance indicators are utilized: the Fundamental Plane (FP) relation for early-type galaxies and the Tully-Fisher (TF) relation for late-type galaxies.

Sample Selection and Quality Control

The DESI DR1 catalogue contains FP-based distances and peculiar velocities for 98, 292 unique early-type galaxies. The sample selection follows a rigorous multi-stage process:

Initial Criteria: The primary selection is based on criteria used in the SDSS peculiar velocity analysis, including objects being spectroscopically classified as galaxies (SPECTYPE = 'GALAXY') and having a successful redshift measurement with "ZWARN = 0 and DELTACHI2 > 30."
Photometric Quality: The sample requires well-defined flux measurements ("FLUX>0) and positive photometric observations (NOBS>0").
Redshift Range: The sample is limited to the range where reliable measurements are possible: "0.0033 < z < 0.1."
Structural and Photometric Cuts: Further cuts ensure quality, including magnitude limits (e.g., "10.0 < mr < 18.0), color cuts to remove contaminants like green valley and blue cloud galaxies, and requiring the surface brightness profile fit to be the de Vaucouleurs profile or a Sérsic profile with ns > 2.5."
Consistency Checks: The paper performed several checks:
Magnitude Consistency (Section 3): The authors compared DECaLS and BASS/MzLS r-band magnitudes, finding an offset of mBASS/MzLS - mDECaLS = -0.018 ± 0.013, which was deemed consistent with zero and thus no magnitude offset correction was applied.
Velocity Dispersion Checks (Section 4): Three cuts were applied: a minimum velocity dispersion of σ = 50 km s-1, a maximum of σ = 420 km s-1, and requiring that the velocity dispersion error be greater than zero (delta sigma > 0).
Internal Consistency (Section 4.3): The authors analyzed deviations across different sky positions (HEALPix bins) and between bright/dark time observations, finding no noticeable patterns in the sky position variation.

** Methodology for Distance and Velocity Calculation**

The methodology involves fitting a 3D Gaussian Fundamental Plane model:

Fundamental Plane Parameters: The FP relation is defined as Re = a sigma 0 + b I e + c. The goal is to calculate the observed physical effective radius, r z, which differs from the true effective radius due to peculiar velocities.
Centralization of Velocity Dispersion: To use velocity dispersion (sigma) as a distance-independent parameter, an aperture correction is applied: s = (sigma) + alpha ap (theta e) - (8 theta ap). The fiducial value used was alpha afid = -0.06 plus or minus 0.03.
** Fitting the Model:** The model is fitted using a maximum likelihood method (Equation 12). After removing outliers (galaxies with p < 0.01), the the sample is reduced to 96,758 calibration galaxies.
** Log-Distance Ratios (eta):** The true intrinsic size (r t) is estimated by comparing the observed r z to-distance ratios: eta (d(z cmb) / d(z t)).
** Peculiar Velocity Calculation:** The peculiar velocity is derived from the log-distance ratio using the Carreres et al. (2023) estimator: (eta) = c 10 [(1 + z cmb) c-1 H(z cmb) d(z cmb)-1 / eta].

** Systematic Corrections and Bias Mitigation**

The authors addressed several potential systematic biases:

Group Richness (Section 5.2.3): A correlation between the richness of a group and the measured log-distance ratio was identified. A correction was applied using a piecewise linear function to account for this bias, which matched trends seen in SDSS data.
Evolution and Aperture Corrections (Section 6.1): The effects of the aperture correction (alpha) and the evolution correction (Q) on the log-distance-redshift tilt were analyzed. The fiducial values chosen— alpha fid = -0.06 plus or minus 0.03 and Q fid = 1.1 plus or minus 0.4 —were those that best flattened the log-distance-redshift tilt while staying within the published literature measurements.

** Results and Conclusion**

The study resulted in a large catalogue of distances, noting that DESI DR1 has "increased the total number of z < 0.1 FP distances ever measured by a factor of about 2. The resulting peculiar velocity errors are found to be comparable to previous surveys" at a precision of 26%.

The final output includes:

The FP catalogue containing 98,292 unique galaxies.
A subset (73,822) used for cosmological measurements after removing outliers.
A distribution of peculiar velocity errors that increases with redshift.

In summary, the DESI DR1 survey provides a substantial increase in the number of known Fundamental Plane distances, and the resulting catalogue is considered transformative for the field of peculiar velocities and cosmic cartography at low-redshift.

Improvements for AI systems

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Please provide the full text of the arXiv paper (PDF or LaTeX source) you wish me to analyze.

Once I have access to the scientific content, I will proceed with a rigorous analysis and provide only highly specific improvements structured as follows:

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Abstract

Measurements of peculiar velocities in the local Universe are a powerful tool to study the nature of dark energy at low (z < 0.1) redshifts. Here we present the largest single set of z<0.1 peculiar velocity measurements to date, obtained using the Fundamental Plane (FP) of galaxies in the first data release (DR1) of the Dark Energy Spectroscopic Instrument (DESI). We describe the photometric and spectroscopic selection criteria used to define the sample, as well as extensive quality control checks on the photometry and velocity dispersion measurements. Additionally, we perform detailed systematics checks for the many analysis parameters in our pipeline. Our DESI DR1 catalogue contains FP-based distances and peculiar velocities for 98,292 unique early-type galaxies, increasing the total number of z < 0.1 FP distances ever measured by a factor of about2. We achieve a precision of 26% random error in our distance measurements which is comparable to previous surveys. A series of companion DESI papers use the distances and peculiar velocities presented in this paper to measure cosmological parameters.