About

Daniel M. Scolnic is an Associate Professor of Physics at Duke University, affiliated with the Trinity College of Arts & Sciences, and also holds a position in the Department of Electrical and Computer Engineering at the Pratt School of Engineering. His research focuses on using observational tools to measure the expansion history of the universe, aiming to answer fundamental questions such as the nature of dark energy. Scolnic's work involves analyzing Type Ia supernovae data, contributing to cosmological constraints and understanding cosmic expansion, isotropy, and structure growth. He has been actively involved in several significant projects, including the Dark Energy Survey supernova program and the Dark Energy Bedrock All-sky Supernova Program. His research has led to improved cosmological measurements and insights into evolving dark energy. Scolnic has also contributed to assessing the Vera Rubin Observatory’s ability to discover asteroid impactors, reflecting his broader interest in astrophysics and planetary defense. His academic background includes a Ph.D. from Johns Hopkins University and a B.S. from the Massachusetts Institute of Technology. He has received multiple grants supporting his research, including funding from NASA, the Department of Energy, and the Packard Foundation.

Research topics

• Physics
• Astronomy
• Astrophysics
• Computer Science
• Systems engineering
• Mathematical physics
• Particle physics
• Quantum mechanics
• Geodesy
• Statistics
• Optics
• Theoretical physics
• Computer graphics (images)
• Remote sensing
• Engineering
• Geology
• Geography

Selected publications

• The Dark Energy Survey supernova program: a reanalysis of cosmology results and evidence for evolving dark energy with an updated Type Ia supernova calibration

  Monthly Notices of the Royal Astronomical Society · 2026-04-01 · 2 citations

  preprintOpen access

  ABSTRACT We present improved cosmological constraints from a re-analysis of the Dark Energy Survey (DES) 5-year sample of Type Ia supernovae (DES-SN5YR). This re-analysis includes an improved photometric cross-calibration, recent white dwarf observations to cross-calibrate between DES and low-redshift surveys, retraining the salt3 light-curve model and fixing a numerical approximation in the host-galaxy colour law. Our fully recalibrated sample, which we call DES-Dovekie, comprises $\sim$1600 likely Type Ia SNe from DES and $\sim$200 low-redshift SNe from other surveys. With DES-Dovekie, we obtain $\Omega _{\rm m} = 0.330 \pm 0.015$ in flat Lambda-cold dark matter ($\Lambda$CDM) which changes $\Omega _{\rm m}$ by $-0.022$ compared to DES-SN5YR. Combining DES-Dovekie with cosmic microwave background data from Planck, Atacama Cosmology Telescope, and South Pole Telescope and the DESI DR2 measurements in a flat $w_0 w_a$CDM cosmology, we find $w_0 = -0.803 \pm 0.054$ and $w_a = -0.72 \pm 0.21$. Our results hold a significance of $3.2\sigma$, reduced from $4.2\sigma$ for DES-SN5YR, to reject the null hypothesis that the data are compatible with the cosmological constant. This significance is equivalent to a Bayesian model preference odds of approximately 5:1 in favour of the flat $w_0 w_a$CDM model. Using generally accepted thresholds for model preference, our updated data exhibits only a weak preference for evolving dark energy.

  PublisherDOI

• Dark Energy Survey: Implications for cosmological expansion models from the final DES baryon acoustic oscillation and supernova data

  Physical review. D/Physical review. D. · 2026-01-30 · 6 citations

  article

  International audience

  PublisherDOI

• Initial Characterization of Stellar Photometry of Roman Images from the OpenUniverse Simulations

  The Astronomical Journal · 2026-02-04

  articleOpen access

  Abstract NASA’s Nancy Grace Roman Space Telescope (Roman) will provide an opportunity to study dark energy with unprecedented precision and accuracy using several techniques, including measurements of high- z Type Ia Supernovae (SNe Ia; z ≲ 3.0) via the High-Latitude Time Domain Survey (HLTDS). In this work, we do an initial “benchmark” characterization of the photometric repeatability of stellar fluxes, which must be below 1% when sky noise is subdominant in order to enable a number of calibration requirements. Achieving this level of flux precision requires attention to Roman’s highly structured, spatially varying, undersampled point-spread function (PSF). In this work, we build a library of effective PSFs (ePSFs) compatible with the OpenUniverse HLTDS simulations. Using our library of ePSFs, we recover stellar flux to between 0.6% and 1.2% photometric precision, finding that redder bands perform better by this metric. We also find that flux recovery is improved by up to 20% when a chip (sensor chip assembly, SCA) is divided into eight sub-SCAs in order to account for the spatial variation of the PSF. With our optimized algorithm, we measure nonlinearity due to photometry (magnitude dependence) of ∣ s NL ∣ < 1.93 × 10 −3 dex −1 , which is still larger than stated requirements for detector effects and indicates that further work is necessary. We also measure the dependence of photometric residuals on stellar color and find the largest possible dependence in R062, implying a color-dependent PSF model may be needed. Finally, we characterize the detection efficiency function of each OpenUniverse Roman filter, which will inform future studies.

  PublisherDOI

• Measuring the Distances to Asteroids from One Observatory in One Night with Upcoming All-sky Telescopes

  The Planetary Science Journal · 2026-04-01

  preprintOpen access

  Abstract Upcoming telescopes like the Vera Rubin Observatory and the Argus Array will image large fractions of the sky multiple times per night, yielding numerous near-Earth object (NEO) discoveries. When asteroids are measured with short observation time windows, the dominant uncertainty in orbit construction is due to distance uncertainty to the NEO. One approach to recover distances is from topocentric parallax , which is a technique that leverages the rotation of the Earth, causing a small but detectable sinusoidal additive signal to the R.A. of the NEO following a period of 1 day. In this paper, we further develop and evaluate this technique to recover distances in as quickly as a single night. We first test the technique on synthetic data of 20 different asteroids ranging from ∼0.05 to ∼2.4 au. We modify previous algorithms and recover distances with uncertainties as low as the ∼4.0% level for more nearby objects (≲0.3 au) when assuming astrometric uncertainties of ∼0 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover> <mml:mrow> <mml:mo>.</mml:mo> </mml:mrow> <mml:mrow> <mml:mtext>″</mml:mtext> </mml:mrow> </mml:mover> </mml:math> 02. We then acquire our own observations of two asteroids within a single night and find we are able to recover distances to the 3% level. We also compare results with the Find_Orb software package and quantify the limitations of our method. We show with Find_Orb that for nearby asteroids, orbits are significantly better constrained when the topocentric parallax is measured with a diversity of observation hour angles rather than without this diversity.

  PublisherDOI

• TITAN DR1: An Improved, Validated, and Systematically-Controlled Recalibration of ATLAS Photometry toward Type Ia Supernova Cosmology

  ArXiv.org · 2025-12-26

  articleOpen access

  ATLAS (Asteroid Terrestrial Last Alert System) is a time-domain survey using four telescopes, covering the entire sky. It has observed over 10,000 spectroscopically confirmed Type Ia supernovae (SNe~Ia), with thousands of cosmology-grade light curves (to be released as TITAN DR1). To prepare this massive, low-redshift dataset for cosmology, we evaluate and cross-calibrate ATLAS forced photometry using tertiary stars from the DES (Dark Energy Survey) Y6 release. The 5000 deg$^2$ DES footprint overlaps regions both in and out of the PS1 (Pan-STARRS DR1) footprint, allowing tests of the primary calibrator for the ATLAS Refcat2 catalog. Initial offsets are at the $\sim$40 mmag scale. To improve this we determine $Δ$ zeropoint offsets for two cases: (1) pixel-to-pixel offsets within individual CCDs (reduced from $\sim$8 to $\sim$4 mmag RMS) and (2) chip-to-chip offsets across the 9 CCDs and filters (reduced from $\sim$17 to $\sim$3 mmag RMS). We also identify the largest systematic uncertainty as a transmission-function color dependence, requiring shifts in the assumed ATLAS filters at the $\sim$30 mmag level if uncorrected. We validate our calibration using (a) CALSPEC standards, (b) an independent tertiary catalog, and (c) distance moduli of cross-matched SNe~Ia, all showing improved consistency. Overall, we estimate combined calibration-related systematics at the $\sim$5--10 mmag level, supporting competitive cosmological constraints with the TITAN SN~Ia dataset.

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• The Hourglass Simulation: A Catalog for the Roman High-Latitude Time-Domain Core Community Survey

  ArXiv.org · 2025-06-05

  preprintOpen access

  We present a simulation of the time-domain catalog for the Nancy Grace Roman Space Telescope's High-Latitude Time-Domain Core Community Survey. This simulation, called the Hourglass simulation, uses the most up-to-date spectral energy distribution models and rate measurements for ten extra-galactic time-domain sources. We simulate these models through the design reference Roman Space Telescope survey: four filters per tier, a five day cadence, over two years, a wide tier of 19 deg$^2$ and a deep tier of 4.2 deg$^2$, with $\sim$20% of those areas also covered with prism observations. We find that a science-independent Roman time-domain catalog, assuming a S/N at max of &gt;5, would have approximately 21,000 Type Ia supernovae, 40,000 core-collapse supernovae, around 70 superluminous supernovae, $\sim$35 tidal disruption events, 3 kilonovae, and possibly pair-instability supernovae. In total, Hourglass has over 64,000 transient objects, 11 million photometric observations, and 500,000 spectra. Additionally, Hourglass is a useful data set to train machine learning classification algorithms. We show that SCONE is able to photometrically classify Type Ia supernovae with high precision ($\sim$95%) to a z &gt; 2. Finally, we present the first realistic simulations of non-Type Ia supernovae spectral-time series data from Roman's prism.

  PublisherOA PDFDOI

• phrosty: A difference imaging pipeline for Roman

  ArXiv.org · 2025-09-23 · 1 citations

  preprintOpen access

  NASA's Nancy Grace Roman Space Telescope (Roman) will provide an opportunity to study dark energy with unprecedented precision using several techniques, including measurements of Type Ia Supernovae (SNe Ia). Here, we present `phrosty` (PHotometry for ROman with SFFT for tYpe Ia supernovae): a difference imaging pipeline for measuring the brightness of transient point sources in the sky, primarily SNe Ia, using Roman data. `phrosty` is written in Python. We implement a GPU-accelerated version of the Saccadic Fast Fourier Transform (SFFT) method for difference imaging.

  PublisherOA PDFDOI

• Comparing the DES-SN5YR and Pantheon+ SN cosmology analyses: investigation based on ‘evolving dark energy or supernovae systematics’?

  Monthly Notices of the Royal Astronomical Society · 2025-07-07 · 26 citations

  articleOpen access

  ABSTRACT Recent cosmological analyses measuring distances of type Ia supernovae (SNe Ia) and baryon acoustic oscillations (BAO) have all given similar hints at time-evolving dark energy. To examine whether underestimated SN Ia systematics might be driving these results, Efstathiou (2025) compared overlapping SN events between Pantheon+ and DES-SN5YR (20 per cent SNe are in common), and reported evidence for an $\sim$0.04 mag offset between the low- and high-redshift distance measurements of this subsample of events. If this offset is arbitrarily subtracted from the entire DES-SN5YR sample, the preference for evolving dark energy is reduced. In this paper, we show that this offset is mostly due to different corrections for Malmquist bias between the two samples; therefore, an object-to-object comparison can be misleading. Malmquist bias corrections differ between the two analyses for several reasons. First, DES-SN5YR used an improved model of SN Ia luminosity scatter compared to Pantheon+ but the associated scatter-model uncertainties are included in the error budget. Secondly, improvements in host mass estimates in DES-SN5YR also affected SN standardized magnitudes and their bias corrections. Thirdly, and most importantly, the selection functions of the two compilations are significantly different, hence the inferred Malmquist bias corrections. Even if the original scatter model and host properties from Pantheon+ are used instead, the evidence for evolving dark energy from CMB, DESI BAO Year 1 and DES-SN5YR is only reduced from 3.9$\sigma$ to 3.3$\sigma$, consistent with the error budget. Finally, in this investigation, we identify an underestimated systematic uncertainty related to host galaxy property uncertainties, which could increase the final DES-SN5YR error budget by 3 per cent. In conclusion, we confirm the validity of the published DES-SN5YR results.

  PublisherOA PDFDOI

• mf342/Maryann-et-al.-2025: Version 1.0.0 – Published Manuscript Data and Code

  Zenodo (CERN European Organization for Nuclear Research) · 2025-12-20

  otherOpen access

  This release contains the finalized code, data products, Jupyter notebooks, and supporting files corresponding to Maryann et al. (2025), reflecting the version of the repository after completion of peer-review revisions. These materials reproduce the results presented in the manuscript "Measuring the Distances to Asteroids from One Observatory in One Night with Upcoming All-Sky Telescopes," (arXiv:2502.07881) including Figures 1–10 and Tables 1–3. This release has been archived in Zenodo and assigned a DOI to ensure long-term preservation and citability, and the DOI is referenced in the manuscript.

  PublisherDOI

• JAGB 2.0: Improved Constraints on the J-region Asymptotic Giant Branch–based Hubble Constant from an Expanded Sample of JWST Observations

  The Astrophysical Journal · 2025-07-16 · 11 citations

  articleOpen accessCorresponding

  Abstract The J-region asymptotic giant branch (JAGB) is an overdensity of stars in the near-infrared, attributed to carbon-rich AGB stars, and recently used as a standard candle for measuring extragalactic distances and the Hubble constant. Using JWST in Cycle 2, we extend JAGB measurements to six hosts of nine Type Ia supernovae (SNe Ia; NGC 2525, NGC 3147, NGC 3370, NGC 3447, NGC 5468, and NGC 5861), with two at D ∼ 40 Mpc, all calibrated by the maser host NGC 4258. We investigate the effects of incompleteness and are unable to recover a JAGB measurement for NGC 3147. We compile all JWST JAGB observations of SN Ia hosts, 15 galaxies hosting 18 SNe Ia, from the SH0ES and CCHP programs, and employ all literature measures. We find no significant mean difference between these distances and those from Hubble Space Telescope Cepheids, −0.03 ± 0.02 (stat.) ± 0.05 (sys.) mag. We find a difference of 0.11 ± 0.022 mag between JAGB mode measurements in the CCHP analyses of two fields in NGC 4258, a feature also seen in two SH0ES fields (see field-to-field variations in S. Li et al.), indicating significant variation of NGC 4258 JAGB measurements, which produce a large absolute calibration uncertainty. Variations are also seen in the shape of the JAGB luminosity function (LF) across galaxies so that different measures produce different values of the Hubble constant. We look for but do not (yet) find a standardizing relation between JAGB LF skew or color dependence and the apparent variation. Using the middle result of all JAGB measures to calibrate SNe Ia yields a Hubble constant of H 0 = 73.3 ± 1.4 (stat.) ± 2.0 (sys.) km s −1 Mpc −1 with the systematic dominated by apparent differences across the NGC 4258 calibrating fields or their measures.

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Frequent coauthors

• R. J. Foley

  268 shared

• Adam G. Riess

  Space Telescope Science Institute

  183 shared

• L. N. da Costa

  Laboratório Interinstitucional de e-Astronomia

  179 shared

• E. Bertin

  Orange (France)

  178 shared

• D. Gruen

  177 shared

• Dillon Brout

  Boston University

  173 shared

• A. Rest

  171 shared

• A. Carnero Rosell

  167 shared

Labs

• Cosmology & AstrophysicsPI

Awards & honors

• A Roman Project Infrastructure Team to Support Cosmological…
• Big Data and the Biggest Tension in Cosmology Research Princ…