Daniel Holz
· ProfessorUniversity of Chicago · Physics
Active 1956–2024
About
Daniel Holz received his undergraduate degree in physics from Princeton University, under the mentorship of John Wheeler. He completed his graduate work at the University of Chicago with Robert Wald, earning a PhD in Physics. Following his doctoral studies, he spent a year as a postdoctoral researcher at the Albert Einstein Institute (Max Planck Institute for Gravitational Physics) in Potsdam, Germany, as a member of the astrophysical relativity division. He further conducted postdoctoral research at the Kavli Institute for Theoretical Physics in Santa Barbara from 2000 to 2002, and then returned to Chicago as a Fellow at the Kavli Institute for Cosmological Physics. In 2004, Holz moved to the Los Alamos National Laboratory as a Richard Feynman Fellow in the theoretical astrophysics and particle physics groups, becoming a Staff Member in 2007. He joined the University of Chicago faculty in 2011. His research focuses on astrophysics and gravitational physics, contributing to the understanding of phenomena such as black holes and gravitational waves.
Research topics
- Physics
- Astrophysics
- Astronomy
- Computer Science
- Theoretical physics
- Quantum mechanics
- Mathematics
- Particle physics
- Classical mechanics
- Demography
- Operating system
- Telecommunications
- Mathematical analysis
- Optics
- Computational physics
- Condensed matter physics
Selected publications
Physical Review X · 2023 · 1600 citations
- Computer Science
- Physics
- Computer Science
The third Gravitational-Wave Transient Catalog contains 90 probable gravitational-wave candidates, including binary black holes, binary neutron stars, and black hole--neutron star binaries across a wide range of masses.
Cosmology with the Laser Interferometer Space Antenna
Living Reviews in Relativity · 2023 · 318 citations
- Physics
- Theoretical physics
- Astrophysics
Abstract The Laser Interferometer Space Antenna (LISA) has two scientific objectives of cosmological focus: to probe the expansion rate of the universe, and to understand stochastic gravitational-wave backgrounds and their implications for early universe and particle physics, from the MeV to the Planck scale. However, the range of potential cosmological applications of gravitational-wave observations extends well beyond these two objectives. This publication presents a summary of the state of the art in LISA cosmology, theory and methods, and identifies new opportunities to use gravitational-wave observations by LISA to probe the universe.
Physical review. D/Physical review. D. · 2022 · 33 citations
- Astronomy
- Physics
We present the first results from an all-sky all-frequency (ASAF) search for an anisotropic stochastic gravitational-wave background using the data from the first three observing runs of the Advanced LIGO and Advanced Virgo detectors. Upper limit maps on broadband anisotropies of a persistent stochastic background were published for all observing runs of the LIGO-Virgo detectors. However, a broadband analysis is likely to miss narrowband signals as the signal-to-noise ratio of a narrowband signal can be significantly reduced when combined with detector output from other frequencies. Data folding and the computationally efficient analysis pipeline, PyStoch, enable us to perform the radiometer map-making at every frequency bin. We perform the search at 3072 HEALPix equal area pixels uniformly tiling the sky and in every frequency bin of width $1/32\text{ }\text{ }\mathrm{Hz}$ in the range 20--1726 Hz, except for bins that are likely to contain instrumental artefacts and hence are notched. We do not find any statistically significant evidence for the existence of narrowband gravitational-wave signals in the analyzed frequency bins. Therefore, we place 95% confidence upper limits on the gravitational-wave strain for each pixel-frequency pair, the limits are in the range $(0.030\ensuremath{-}9.6)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}24}$. In addition, we outline a method to identify candidate pixel-frequency pairs that could be followed up by a more sensitive (and potentially computationally expensive) search, e.g., a matched-filtering-based analysis, to look for fainter nearly monochromatic coherent signals. The ASAF analysis is inherently independent of models describing any spectral or spatial distribution of power. We demonstrate that the ASAF results can be appropriately combined over frequencies and sky directions to successfully recover the broadband directional and isotropic results.
Cosmology with the Laser Interferometer Space Antenna
arXiv (Cornell University) · 2022 · 33 citations
- Physics
- Theoretical physics
- Astrophysics
The Laser Interferometer Space Antenna (LISA) has two scientific objectives of cosmological focus: to probe the expansion rate of the universe, and to understand stochastic gravitational-wave backgrounds and their implications for early universe and particle physics, from the MeV to the Planck scale. However, the range of potential cosmological applications of gravitational-wave observations extends well beyond these two objectives. This publication presents a summary of the state of the art in LISA cosmology, theory and methods, and identifies new opportunities to use gravitational-wave observations by LISA to probe the universe.
Target-of-opportunity Observations of Gravitational-wave Events with Vera C. Rubin Observatory
The Astrophysical Journal Supplement Series · 2022 · 50 citations
- Astronomy
- Physics
- Astrophysics
Abstract The discovery of the electromagnetic counterpart to the binary neutron star (NS) merger GW170817 has opened the era of gravitational-wave multimessenger astronomy. Rapid identification of the optical/infrared kilonova enabled a precise localization of the source, which paved the way to deep multiwavelength follow-up and its myriad of related science results. Fully exploiting this new territory of exploration requires the acquisition of electromagnetic data from samples of NS mergers and other gravitational-wave sources. After GW170817, the frontier is now to map the diversity of kilonova properties and provide more stringent constraints on the Hubble constant, and enable new tests of fundamental physics. The Vera C. Rubin Observatory’s Legacy Survey of Space and Time can play a key role in this field in the 2020s, when an improved network of gravitational-wave detectors is expected to reach a sensitivity that will enable the discovery of a high rate of merger events involving NSs (∼tens per year) out to distances of several hundred megaparsecs. We design comprehensive target-of-opportunity observing strategies for follow-up of gravitational-wave triggers that will make the Rubin Observatory the premier instrument for discovery and early characterization of NS and other compact-object mergers, and yet unknown classes of gravitational-wave events.
Physical review. D/Physical review. D. · 2022 · 60 citations
- Physics
- Astrophysics
- Astronomy
Results are presented of searches for continuous gravitational waves from 20 accreting millisecond x-ray pulsars with accurately measured spin frequencies and orbital parameters, using data from the third observing run of the Advanced LIGO and Advanced Virgo detectors. The search algorithm uses a hidden Markov model, where the transition probabilities allow the frequency to wander according to an unbiased random walk, while the $\mathcal{J}$-statistic maximum-likelihood matched filter tracks the binary orbital phase. Three narrow subbands are searched for each target, centered on harmonics of the measured spin frequency. The search yields 16 candidates, consistent with a false alarm probability of 30% per subband and target searched. These candidates, along with one candidate from an additional target-of-opportunity search done for SAX $\mathrm{J}1808.4\ensuremath{-}3658$, which was in outburst during one month of the observing run, cannot be confidently associated with a known noise source. Additional follow-up does not provide convincing evidence that any are a true astrophysical signal. When all candidates are assumed nonastrophysical, upper limits are set on the maximum wave strain detectable at 95% confidence, ${h}_{0}^{95%}$. The strictest constraint is ${h}_{0}^{95%}=4.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}26}$ from IGR $\mathrm{J}17062\ensuremath{-}6143$. Constraints on the detectable wave strain from each target lead to constraints on neutron star ellipticity and $r$-mode amplitude, the strictest of which are ${\ensuremath{\epsilon}}^{95%}=3.1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$ and ${\ensuremath{\alpha}}^{95%}=1.8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ respectively. This analysis is the most comprehensive and sensitive search of continuous gravitational waves from accreting millisecond x-ray pulsars to date.
Journal of High Energy Astrophysics · 2022 · 1153 citations
- Physics
- Astrophysics
- Theoretical physics
The standard Λ Cold Dark Matter (ΛCDM) cosmological model provides a good description of a wide range of astrophysical and cosmological data. However, there are a few big open questions that make the standard model look like an approximation to a more realistic scenario yet to be found. In this paper, we list a few important goals that need to be addressed in the next decade, taking into account the current discordances between the different cosmological probes, such as the disagreement in the value of the Hubble constant H0, the σ8–S8 tension, and other less statistically significant anomalies. While these discordances can still be in part the result of systematic errors, their persistence after several years of accurate analysis strongly hints at cracks in the standard cosmological scenario and the necessity for new physics or generalisations beyond the standard model. In this paper, we focus on the 5.0σ tension between the Planck CMB estimate of the Hubble constant H0 and the SH0ES collaboration measurements. After showing the H0 evaluations made from different teams using different methods and geometric calibrations, we list a few interesting new physics models that could alleviate this tension and discuss how the next decade's experiments will be crucial. Moreover, we focus on the tension of the Planck CMB data with weak lensing measurements and redshift surveys, about the value of the matter energy density Ωm, and the amplitude or rate of the growth of structure (σ8,fσ8). We list a few interesting models proposed for alleviating this tension, and we discuss the importance of trying to fit a full array of data with a single model and not just one parameter at a time. Additionally, we present a wide range of other less discussed anomalies at a statistical significance level lower than the H0–S8 tensions which may also constitute hints towards new physics, and we discuss possible generic theoretical approaches that can collectively explain the non-standard nature of these signals. Finally, we give an overview of upgraded experiments and next-generation space missions and facilities on Earth that will be of crucial importance to address all these open questions.
Physical review. D/Physical review. D. · 2021 · 109 citations
- Physics
- Astrophysics
We report results from searches for anisotropic stochastic gravitational-wave backgrounds using data from the first three observing runs of the Advanced LIGO and Advanced Virgo detectors. For the first time, we include Virgo data in our analysis and run our search with a new efficient pipeline called pystoch on data folded over one sidereal day. We use gravitational-wave radiometry (broadband and narrow band) to produce sky maps of stochastic gravitational-wave backgrounds and to search for gravitational waves from point sources. A spherical harmonic decomposition method is employed to look for gravitational-wave emission from spatially-extended sources. Neither technique found evidence of gravitational-wave signals. Hence we derive 95% confidence-level upper limit sky maps on the gravitational-wave energy flux from broadband point sources, ranging from ${F}_{\ensuremath{\alpha},\mathrm{\ensuremath{\Theta}}}<(0.013--7.6)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}\text{ }\text{ }\mathrm{erg}\text{ }{\mathrm{cm}}^{\ensuremath{-}2}\text{ }{\mathrm{s}}^{\ensuremath{-}1}\text{ }{\mathrm{Hz}}^{\ensuremath{-}1}$, and on the (normalized) gravitational-wave energy density spectrum from extended sources, ranging from ${\mathrm{\ensuremath{\Omega}}}_{\ensuremath{\alpha},\mathrm{\ensuremath{\Theta}}}<(0.57--9.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}\text{ }\text{ }{\mathrm{sr}}^{\ensuremath{-}1}$, depending on direction ($\mathrm{\ensuremath{\Theta}}$) and spectral index ($\ensuremath{\alpha}$). These limits improve upon previous limits by factors of 2.9--3.5. We also set 95% confidence level upper limits on the frequency-dependent strain amplitudes of quasimonochromatic gravitational waves coming from three interesting targets, Scorpius X-1, SN 1987A and the Galactic Center, with best upper limits range from ${h}_{0}<(1.7--2.1)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}25}$, a factor of $\ensuremath{\ge}2.0$ improvement compared to previous stochastic radiometer searches.
Physical review. D/Physical review. D. · 2021 · 749 citations
- Computer Science
- Physics
- Astrophysics
Gravitational waves enable tests of general relativity in the highly dynamical and strong-field regime. Using events detected by LIGO-Virgo up to 1 October 2019, we evaluate the consistency of the data with predictions from the theory. We first establish that residuals from the best-fit waveform are consistent with detector noise, and that the low- and high-frequency parts of the signals are in agreement. We then consider parametrized modifications to the waveform by varying post-Newtonian and phenomenological coefficients, improving past constraints by factors of $\ensuremath{\sim}2$; we also find consistency with Kerr black holes when we specifically target signatures of the spin-induced quadrupole moment. Looking for gravitational-wave dispersion, we tighten constraints on Lorentz-violating coefficients by a factor of $\ensuremath{\sim}2.6$ and bound the mass of the graviton to ${m}_{g}\ensuremath{\le}1.76\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}23}\text{ }\text{ }\mathrm{eV}/{c}^{2}$ with 90% credibility. We also analyze the properties of the merger remnants by measuring ringdown frequencies and damping times, constraining fractional deviations away from the Kerr frequency to $\ensuremath{\delta}{\stackrel{^}{f}}_{220}=0.0{3}_{\ensuremath{-}0.35}^{+0.38}$ for the fundamental quadrupolar mode, and $\ensuremath{\delta}{\stackrel{^}{f}}_{221}=0.0{4}_{\ensuremath{-}0.32}^{+0.27}$ for the first overtone; additionally, we find no evidence for postmerger echoes. Finally, we determine that our data are consistent with tensorial polarizations through a template-independent method. When possible, we assess the validity of general relativity based on collections of events analyzed jointly. We find no evidence for new physics beyond general relativity, for black hole mimickers, or for any unaccounted systematics.
Physical review. D/Physical review. D. · 2021 · 425 citations
- Physics
- Astrophysics
- Computational physics
We report results of a search for an isotropic gravitational-wave background (GWB) using data from Advanced LIGO's and Advanced Virgo's third observing run (O3) combined with upper limits from the earlier O1 and O2 runs. Unlike in previous observing runs in the advanced detector era, we include Virgo in the search for the GWB. The results of the search are consistent with uncorrelated noise, and therefore we place upper limits on the strength of the GWB. We find that the dimensionless energy density GW 5.8 10 -9 at the 95% credible level for a flat (frequency-independent) GWB, using a prior which is uniform in the log of the strength of the GWB, with 99% of the sensitivity coming from the band 20-76.6 Hz; GW f 3.4 10 -9 at 25 Hz for a power-law GWB with a spectral index of 2=3 (consistent with expectations for compact binary coalescences), in the band 20-90.6 Hz; and GW f 3.9 10 -10 at 25 Hz for a spectral index of 3, in the band 20-291.6 Hz. These upper limits improve over our previous results by a factor of 6.0 for a flat GWB, 8.8 for a spectral index of 2=3, and 13.1 for a spectral index of 3. We also search for a GWB arising from scalar and vector modes, which are predicted by alternative theories of gravity; we do not find evidence of these, and place upper limits on the strength of GWBs with these polarizations. We demonstrate that there is no evidence of correlated noise of magnetic origin by performing a Bayesian analysis that allows for the presence of both a GWB and an effective magnetic background arising from geophysical Schumann resonances. We compare our upper limits to a fiducial model for the GWB from the merger of compact binaries, updating the model to use the most recent datadriven population inference from the systems detected during O3a. Finally, we combine our results with observations of individual mergers and show that, at design sensitivity, this joint approach may yield stronger constraints on the merger rate of binary black holes at z 2 than can be achieved with individually resolved mergers alone.
Recent grants
From Single to Statistical:The Dawn of Gravitational-Wave Astrophysics and Cosmology
NSF · $70k · 2020–2022
From First Detections to Gravitational-Wave Astrophysics
NSF · $450k · 2017–2021
CAREER: Hearing and Seeing the Universe Through Multi-Messenger Astronomy
NSF · $600k · 2012–2017
From One to Many: Statistical Gravitational-Wave Astrophysics and Cosmology
NSF · $538k · 2021–2025
WoU-MMA: Collaborative Research: Gravitational wave cosmology with tidal Love numbers
NSF · $315k · 2020–2023
Frequent coauthors
- 945 shared
J. van den Brand
- 634 shared
A. Heidmann
- 563 shared
E. Chassande–Mottin
Laboratoire AstroParticule et Cosmologie
- 517 shared
T. Briant
Collège de France
- 511 shared
R. Frey
- 509 shared
T. Jacqmin
Laboratoire Kastler Brossel
- 488 shared
N. Arnaud
Université Paris-Saclay
- 479 shared
M. Wąs
Laboratoire d’Annecy de Physique des Particules
Labs
Education
B.A.
Princeton University
Ph.D.
University of Chicago
Awards & honors
- Richard Feynman Fellow at Los Alamos National Laboratory
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