Physics Commons^™

Exploring The Dynamics Of Tilted, Truncated Accretion Disks, José L. Montés, Chris Fragile, Deepika Bollimpalli, Matthew Liska

Journal of the South Carolina Academy of Science

Tilted accretion disks are theoretically not uncommon in stellar mass black hole systems. The dynamics of tilted disks display interesting physical behaviors that could explain certain observational phenomena such as quasi-periodic oscillations. We present results of recent numerical simulations of tilted, truncated accretion disks around rotating black holes. Our simulations model systems composed of a thick inner torus surrounded by a thin outer disk and were run with the goal of investigating the behaviors of the torus because of the exchange of angular momentum between it and the outer disk. Multiple simulations produced surprising results, such as the potential tearing …

Sub-Torque-Balance Upper Limits On Continuous Gravitational Waves From Scorpius X-1, A. G. Abac, I. Abouelfettouh, Teviet Creighton, Mario C. Diaz, Raul Alberto Espinosa Perez, J. Lawrence, Francisco Llamas Villarreal, Miriam Ramos Arevalo, Soma Mukherjee, Gaukhar Nurbek, Volker Quetschke, Wenhui Wang

Physics & Astronomy Faculty Publications

We present the results of a search for continuous gravitational waves (GWs) from the low-mass X-ray binary Scorpius X-1 using LIGO data from the first part of the fourth LIGO–Virgo–KAGRA observing run. By applying the resampling version of the cross-correlation pipeline to search for signal frequencies f0 between 25 and 200 Hz (corresponding to neutron star spin frequencies of 12.5–100 Hz for GWs due to triaxiality, or ∼15–20 to ∼120–150 Hz for GWs due to r-modes), we are able to achieve longer coherence times than before, and for the first time set upper limits below the standard torque …

Detector Orientation Matters: Consequences For Gravitational-Wave Background Detectability, Nelson Christensen, Joseph D. Romano, Mairi Sakellariadou, Jishnu Suresh

Physics & Astronomy Faculty Publications

Cross-correlation searches for gravitational-wave backgrounds depend on the geometrical configuration (physical separation and relative orientation) of the detectors comprising the network. Applying standard techniques to a few simple examples, we illustrate how the relative orientation of a pair of Earth-based L-shaped laser interferometers can drastically impact the detectability of both isotropic and anisotropic gravitational-wave backgrounds.

Where Are Linearized Gauge Invariants Encoded For Plane Waves In Linearized Gravity, Ramesh Radhakrishnan, David Mcnutt, Delaram Mirfendereski, Eric Davis, William Julius, Gerald Cleaver

Physics & Astronomy Faculty Publications

In this work we will investigate the structures of invariants within the class of plane waves in linearized General Relativity, to introduce a new approach to determine the linearized gauge invariants encoding the polarization of the plane waves. The Newman–Penrose (NP) formalism is traditionally used to analyze the polarization content of gravitational waves, while the gauge-invariant Bardeen formalism provides a complementary description based on the irreducible scalar, vector, and tensor perturbations of the metric. We will apply the Bardeen formalism to compute all scalar, vector, and tensor gauge-invariant variables explicitly and verify that only the two transverse–traceless tensor modes survive. …

Addressing Leakage And Mode Suppression In Angular Power Spectrum Estimation For Gravitational-Wave Backgrounds Using Pulsar Timing Arrays, Deepali Agarwal, Joseph D. Romano, Yacine Ali-Haïmoud, Tristan L. Smith

Physics & Astronomy Faculty Publications

Mapping gravitational-wave background (GWB) anisotropy with pulsar timing arrays (PTAs) is affected by harmonic space mode suppression and mode coupling arising from an array’s nonuniform sky response. Due to computational limitations, one must truncate spherical harmonic expansions at a finite multipole for recovery, ℓrec max, often chosen to equal ℓ𝑁pair max ≡int⁢[√𝑁pair−1], where 𝑁pair ≡𝑁psr⁢(𝑁psr −1)/2 is the number of distinct pulsar pairs in an array comprised of 𝑁psr pulsars. This choice is motivated by the counting argument that cross-correlations provide at most 𝑁pair independent pieces of information for a single frequency bin. Here, we explicitly obtain the multipole value …

K 1-6 Is A Photoionised Interstellar Medium Nebula Shaped By A Fast-Moving Hot White Dwarf In A Triple System, Jaroslav Merc, David Jones, Ana Escorza, Henri M. J. Boffin, Nicole Reindl, Michael Abdul-Masih, Thomas Masseron, Paulina Sowicka, Jan Kára, Jorge Jorge García-Rojas

Physics & Astronomy Faculty Publications

Aims. K 1-6 has long been classified as a planetary nebula (PN) hosting a binary central star; however, it has remained poorly studied due to its faintness. The central star exhibits pronounced photometric variability whose origin is still unclear. We present a comprehensive characterisation of the K 1-6 system, including the physical properties of its stellar components and the nature of the surrounding nebulosity.

Methods. We conducted a multi-wavelength analysis combining optical and UV spectroscopy obtained with the Gran Telescopio Canarias, the Telescopio Nazionale Galileo, the Nordic Optical Telescope, and the Hubble Space Telescope. We also present long-term multi-band ground- …

Cedar: Investigating The Mesosphere And Lower Thermosphere Neutral Temperature And Winds Responses To Geomagnetic Storms Equatorward Of The Auroral Zone, Tao Yuan

Funded Research Records

No abstract provided.

Enhanced Cooper Pairing Via Random Matrix Phonons In Superconducting Grains, Andrey Grankin, Mohammad Hafezi, Victor Galitski

Physics & Astronomy Faculty Publications

There is rich experimental evidence that granular superconductors and superconducting films often exhibit a higher transition temperature 𝑇𝑐 than that in bulk samples of the same material. This Letter suggests that this enhancement hinges on random matrix phonons mediating Cooper pairing more efficiently than bulk phonons. We develop the Eliashberg theory of superconductivity in chaotic grains, calculate the random phonon spectrum, and solve the Eliashberg equations numerically. Self-averaging of the effective electron-phonon coupling constant is noted, which allows us to fit the numerical data with analytical results based on a generalization of the Berry conjecture. The key insight is that …

Temperature Predictions With Zncuins/Zns Quantum Dots, Reu/Fri Program Physics And Astronomy, Amber Banks

Student Works

For hundreds of years, humans have built thermometers based on the principles of thermal expansion and contraction. In the modern world, there is a need to scale down our thermometers to monitor cellular reactions, both within the human body and within artificial organ chips. Lewis et al. (2020) introduces a nanoscale thermometer based on the thermal expansion of CdTe quantum dots. When ex panded, these dots exhibit systematic changes in photoluminescence (PL) which are recognized by a neural network as an increase in temperature. Our research builds upon the framework of Lewis et al. (2020), testing its feasibility with ZnCuInS/ZnS …

Field-Like- And Self-Spin-Orbit Torques In Magnetic Multilayer Films, Kyle Jeffrey Peterson

Electronic Theses and Dissertations

Spin-orbit torques (SOTs) have been realized as an energy efficient mechanism to manipulate and drive magnetization dynamics in magnetic multilayer films. Their damping-like and field-like components provide distinct pathways for controlling the magnetization, enabling switching, sustaining magneto-oscillations, and driving domain-wall motion with potential applications in nonvolatile memory, spin-based logic, and microwave signal generation. However, the accurate quantification and interpretation of these torques remains complicated by experimental sensitivity, the co-symmetry of the Oersted field and the effective field due to the field-like torque, and assumptions regarding the material layers from which the torques originate. The body of work set forth in …

Gw240925 And Gw250207: Astrophysical Calibration Of Gravitational Wave Detectors, A. G. Abac, I. Abouelfettouh, F. Acernese, Teviet Creighton, Mario C. Diaz, Raul Alberto Espinosa Perez, J. Lawrence, Francisco Llamas Villarreal, Soma Mukherjee, Gaukhar Nurbek, Volker Quetschke, Miriam Ramos Arevalo, Wenhui Wang

Physics & Astronomy Faculty Publications

GW240925 and GW250207 are two loud gravitational-wave signals from binary black hole coalescences observed with network signal-to-noise ratios ∼32 and ∼69, respectively, by the LIGO Hanford-LIGO Livingston-Virgo network. Gravitational-wave signals from coalescing binaries have characteristic phase and amplitude evolution predicted by general relativity. These signal waveforms, together with measured instrumental calibration uncertainties, are used to infer source parameters. However, for sufficiently loud detections, it is possible to constrain the calibration of the detectors directly using the signals themselves. We present the first informative astrophysical measurements of gravitational-wave detector calibration. For GW240925, we verify the inference of Hanford calibration from the …

Characterization Of An Ambe Tagged Neutron Source For A 30-Ton Wbls Detector, Rylee Grover

Discovery Day - Daytona Beach

Understanding the detection capabilities of water-based liquid scintillator (WbLS) is critical for its deployment in next-generation neutrino detectors such as THEIA and Phase II of the Deep Underground Neutrino Experiment (DUNE). This study focuses on the characterization and alignment testing of an Americium-Beryllium (AmBe) radioactive neutron source. We plan to dope the 30-ton WbLS detector at Brookhaven National Laboratory (BNL) with Gadolinium (Gd) to improve neutron detection capabilities. This will be tested by the implementation of an AmBe source as a calibration metric. The AmBe source emits neutrons coincident with a 4.4 MeV gamma ray, making it possible to perform …

M.O.D.U.S. Modular Optical Design Using Specular Film, Mario Gutierrez, Robert Thibodeau, Emma Show, Desiree Robinson, Lingyuan Meng, Sean Martin, Conner Beeson

Discovery Day - Daytona Beach

High-quality parabolic mirrors, which are vital components in reflecting telescopes, are typically bulky, costly, and highly fragile. This experiment explores the feasibility of using specular Class B Mylar as an unconventional, lightweight, and cost-effective alternative. This approach could enable new telescope designs by greatly reducing weight and manufacturing expenses, while also opening options for potential adaptability.   This approach involves using Mylar, a flexible, reflective style of plastic. The mylar is formed into a concave mirror by stretching a sheet over a chamber and depressurizing one side to force the sheet into the necessary curved shape. Multiple designs are being created …

String-Of-Pearls Measurements Of Supersonic Plasma Jets Using Magnetospheric Multiscale Satellites, Amelia Koth

Discovery Day - Daytona Beach

High-energy supersonic plasma jets form when the solar wind, which is a flow of charged particles from the Sun, slows down as it encounters Earth’s magnetic shield. Occasionally, the solar wind remains at supersonic speeds as it enters this region. This forms plasma jets that propagate toward Earth; these jets can carry strong magnetic fields, drive magnetic reconnection, and potentially initiate substorms that lead to auroral activity.   Previously studied plasma jets occurred when the interplanetary magnetic field (IMF) points southward. In contrast, this study focuses on northward IMF conditions, which are less understood, yet still capable of producing supersonic jets. …

Gwtc-4.0: Constraints On The Cosmic Expansion Rate And Modified Gravitational-Wave Propagation, A. G. Abac, I. Abouelfettouh, Teviet Creighton, Mario C. Diaz, Raul Alberto Espinosa Perez, J. Lawrence, Francisco Llamas Villarreal, Soma Mukherjee, Volker Quetschke, Miriam Ramos Arevalo, Wenhui Wang

Physics & Astronomy Faculty Publications

We analyze data from 142 of the 218 gravitational-wave (GW) sources in the fourth LIGO-Virgo-KAGRA Collaboration (LVK) Gravitational-Wave Transient Catalog (GWTC-4.0) to estimate the Hubble constant H0 jointly with the population properties of merging compact binaries. We measure the luminosity distance and redshifted masses of GW sources directly; in contrast, we infer GW source redshifts statistically through (i) location of features in the compact object mass spectrum and merger rate evolution, and (ii) identifying potential host galaxies in the GW localization volume. Probing the relationship between source luminosity distances and redshifts obtained in this way yields constraints on cosmological parameters. …

Measuring Cosmic Expansion From Early To Late Times Using Quasars, Galaxies, & Local Supernovae, Rajeev Vaisakh

Physics Theses and Dissertations

This dissertation investigates the evolution of cosmic expansion across a wide redshift ($z$) range by combining measurements from quasars \& galaxies in the distant universe $(z > 0.8)$ with those obtained from stripped-core collapse supernovae observations from the nearby universe $(z < 0.1)$. Using the DESI spectroscopic survey, we analyze large-scale clustering from quasars over $0.8 < z < 2.1$ and emission line galaxies over $0.8 < z < 1.6$, contributing to DESI DR2 BAO and full-shape measurements of cosmic expansion and structure growth. Combined with BBN in flat $\Lambda$CDM, DESI DR2 BAO gives $H_0 = 68.51 \pm 0.58$ km s$^{-1}$ Mpc$^{-1}$, while combinations of DESI BAO with CMB and supernova data show a preference for evolving dark energy, with representative constraints such as $w_0 = -0.752 \pm 0.057$ and $w_a = -0.86^{+0.23}_{-0.20}$ for DESI+CMB+DESY5. Using the ROTSE-III Supernova Survey and the expanding photosphere method (EPM), we measure distances to a sample of six supernovae for which the thermal phase can be clearly identified. This analysis focuses on testing whether reliable EPM distances can be obtained for this population. The resulting distances will eventually be compared with independent estimates from the literature. Establishing consistency with these external measurements represents an important step toward applying this methodology to larger samples, with the eventual goal of using ROTSE supernova distances to provide an independent measurement of the local Hubble constant.

Tellurium Selenide Quantum Wires Synthesized By Pulsed Laser Ablation In Liquids, Rajendra Subedi, Francisco Ruiz-Zepeda, Iono Hill, Geraldine Hallais, Etienne Herth, Gregory Guisbiers

Faculty Scholarship

Tellurium–selenide (TexSe1-x) binary alloys are promising chalcogenide systems with tunable optoelectronic properties, yet their synthesis in quantumly confined one-dimensional forms remains limited. Here, we report the synthesis of TexSe1-x quantum wires (QWs) via a two-step pulsed laser ablation in liquids (PLAL) approach, enabling surfactant-free formation of alloyed nanostructures under non-equilibrium conditions. A tellurium colloid is first generated and subsequently exposed to selenium ablation, promoting in-situ alloying through repeated plasma-bubble interactions at high repetition rate. The resulting QWs exhibit an average diameter of ~17 ± 4 nm and a length of ~475 ± 46 nm. Structural and chemical analyses (XRD, Raman, …

Mining Time Series Shapelets And Association Rules For Solar Flare Prediction, Drew Watson

All Graduate Theses and Dissertations, Fall 2023 to Present

Solar flares are the largest explosions in the solar system; they are caused by changes in the Sun’s magnetic field. Strong solar flares can disrupt power systems, damage satellites, and interfere with radio communication, so improving flare prediction is important. This thesis develops a way to predict severe solar flares while also helping researchers understand why those predictions are made. The approach looks for short patterns in solar magnetic field data that are linked to future flare activity. It then studies how these patterns appear together and in what order they happen over time. By doing this, the research not …

Emergent De Sitter Expansion And Closed Topology From The Cosmic Fabric Model As An Open Thermodynamic System: Resolving The Negative Bulk Modulus Paradox, T G. Tenev, C B. Ward, T F. Tenev, M F. Horstemeyer

Faculty Publications and Presentations

The Cosmic Fabric Model establishes a continuum-mechanics isomorphism to General Relativity by representing physical space as an elastic three-dimensional hyperplate embedded in a four-dimensional spatial bulk. Reproducing vacuum kinematics requires a vanishing P-wave modulus, which in turn implies a negative bulk modulus—an apparent thermodynamic instability in a closed system. This paradox is resolved by recasting the framework as an open system: the instability is not pathological but instead drives cosmic expansion. In this interpretation, the observable universe is a lower-energy solid formed through continuous solidification from a higher-dimensional precursor fluid. Using multiplicative kinematics from finite-growth mechanics, the model shows that …

A New Likely Pulsar Binary In 47 Tucanae From Continuum Searches, Thomas Maccarone, Alessandro Paduano, Arash Bahramian, Liliana E. Rivera Sandoval, Jay Strader, James C. A. Miller-Jones, Angiraben D. Mahida, Craig O. Heinke, Laura Chomiuk

Physics & Astronomy Faculty Publications

We present evidence that the X-ray source 47 Tuc W41, long considered to be an X-ray source powered by coronal activity, is actually a redback pulsar binary. The source continually shows LX = 3 × 10³¹ erg s⁻¹ (0.5–10 keV), which is well in excess of the coronal saturation limit for active binaries in quiescence, but is consistent with the intrabinary shock observed in redback pulsars, as is its photon index of Γ = 1.4 ± 0.1. In addition, using deep data from the Australia Telescope Compact Array, we show that W41 is a faint (9.8 ± 1.4μJy …

Quantum Control Of Qubits And Qudits In Neutral Atom Systems, Sri Datta Vikas Buchemmavari

Physics & Astronomy ETDs

This dissertation explores control of neutral atom quantum systems across multiple levels of abstraction, from atomic physics to system-level fault tolerance, using optimal control to improve performance. First, we propose a Rydberg entangling gate based on dressing with only the qubit control field; an interaction energy near the Rabi frequency benefits both gate speed and Rydberg decay. Second, with Sandia National Laboratories, we show that leakage errors in neutral atom systems can be converted to atom loss errors and detected using two entangling gates with an auxiliary atom, where a SWAP-based leakage detection unit outperforms the standard design. Next, we …

Extending The Discovery Space Of Tess: Probing Underexplored Exoplanet Populations, Mallory L. Harris

Physics & Astronomy ETDs

This dissertation investigates how cold exoplanets can be identified despite the strong observational bias of exoplanet surveys toward short-period systems. Planets at wider orbital separations remain comparatively poorly constrained, limiting tests of planetary-system formation and the prevalence of outer architectures beyond compact systems. To address this gap, I use two complementary approaches. First, I develop a transit-search pipeline for TESS Full-Frame Images that identifies both isolated and repeated transit-like signals around nearby M dwarfs and characterizes the dominant false-positive classes that limit sensitivity in this regime. I then present TOI-904 c, the coldest planet discovered by TESS around an M …

An Investigation Of Tess M&Ms And The Occurrence Rate Of Transiting Circumbinary Planets, Dominic Oddo

Physics & Astronomy ETDs

Circumbinary planets (CBPs) are worlds which orbit two stars simultaneously. CBPs are excellent tests of the tenacity of planet formation, but are difficult to detect. The space-based NASA Transiting Exoplanet Survey Satellite (TESS) mission is a nearly all-sky survey designed to detect exoplanets transiting nearby stars. In this dissertation, I analyze the performance of TESS by comparing to the photometric precision of the ESA CHEOPS mission. Then, I define a catalog of low-mass eclipsing binaries (M&Ms), which are the best sources to search for CBPs. I describe my custom transit search methodology and apply it to the M&M catalog. I …

Measurements And Studies For Rare Event Searches Using Directional Detectors, Elizabeth Tilly

Physics & Astronomy ETDs

Measuring topology and initial direction of low-energy (keV-MeV) particle tracks is interesting to rare-event searches. While directional dark matter searches have been one of the largest drivers for R&D for low-energy directional detectors, this work is interested in its application to Migdal searches. The Migdal effect—a nuclear recoil and an electron recoil sharing a vertex—has been used as a detection channel for low-mass dark matter but has only recently been measured. Low-energy directional detectors are ideal to measure the canonic Migdal topology. This dissertation discusses 3D reconstruction algorithms developed for the Migdal In Galactic Dark mAtter expLoration (MIGDAL) experiment and …

Exploring The Role Of A Mushy, Crustal Compliant Region In Volcano Deformation, Grant A. Block

Physics & Astronomy ETDs

Volcanoes are both creative and destructive forces that have shaped and continue to shape our world from early geologic time to the present day. Continued study of volcanic processes not only better prepares us for monitoring volcanic hazards but also allows us to better understand processes fundamental to Earth as we know it, such as the generation of the atmosphere and accretion of the continents. This dissertation focuses on an integral part of volcanic processes: the trans-crustal magmatic transport system. Specifically, we investigate regions of these transport systems where magma pools in melt-rich lenses within broader regions of low melt-fraction, …

New Distance Distributions Of Asymptotic Giant Branch Stars And Their Role In Tracing Galactic Structure, Rajorshi Bhattacharya

Physics & Astronomy ETDs

Asymptotic giant branch (AGB) stars are among the final evolutionary stages of low- and intermediate-mass stars and among the most luminous cool stellar populations in the Milky Way (MW). Their strong infrared emission allows them to be observed through regions of high interstellar extinction, making them useful tracers of the inner MW. However, their use is limited by unreliable distances because many are dust-obscured and variable, while geometric parallaxes are often unavailable or uncertain. This thesis develops statistical distance-estimation methods for large samples of oxygen-rich AGB stars. The resulting distances broadly agree with literature estimates, supporting their statistical reliability for …

Directed Searches For Gravitational Waves From Ultralight Vector Boson Clouds Around Merger Remnant And Galactic Black Holes During The First Part Of The Fourth Ligo-Virgo-Kagra Observing Run, A. G. Abac, I. Abouelfettouh, Teviet Creighton, Mario C. Diaz, Raul Alberto Espinosa Perez, J. Lawrence, Francisco Llamas Villarreal, Soma Mukherjee, Volker Quetschke, Miriam Ramos Arevalo, Wenhui Wang

Physics & Astronomy Faculty Publications

We present the first directed searches for long-transient and continuous gravitational waves from ultralight vector boson clouds around known black holes (BHs). We use LIGO data from the first part of the fourth LIGO-Virgo-KAGRA observing run. The searches target two distinct types of BHs and use two new semicoherent methods: hidden Markov model (HMM) tracking for the remnant BHs of the mergers GW230814_230901 and GW231123_135430 (referred to as GW230814 and GW231123 in this study) and a dedicated method using the Band Sampled Data (BSD) framework for the galactic BH in the Cygnus X-1 binary system. Without finding evidence of a …

Iron-Decorated Graphene Nanoplatelets Produced By Atmospheric-Pressure Ferrocene Pyrolysis As Nano-Additives For Cement Mortars, Harutyun Gyulasaryan, Manoj Chhetri, Karen S. Martirosyan, Nelli Muradyan, Hovsep Hoveyan, Manuk Barseghyan, Aram Manukyan

Physics & Astronomy Faculty Publications

This study examines iron-based graphene nanoplatelets (Fe-GNPs), synthesized through a modified ferrocene pyrolysis route, as hybrid nano-additives for cement mortars. The nanomaterial was characterized by scanning electron microscopy, X-ray diffraction, Brunauer–Emmett–Teller surface area analysis, and thermogravimetric analysis, confirming a graphitic carbon network decorated with crystalline α-Fe nanoparticles. Mortars containing 0.001, 0.01, 0.05, and 0.1 wt.% Fe-GNPs, with and without surfactant-assisted ultrasonication, were tested in flexure and compression after 7 and 28 days of curing. The results showed a clear concentration-dependent response, with 0.01 wt.% yielding the highest strength gains. At 28 days, this dosage increased flexural strength by 14.5% without …

Search For Planetary-Mass Ultracompact Binaries Using Data From The First Part Of The Ligo–Virgo–Kagra Fourth Observing Run, A. G. Abac, I. Abouelfettouh, Teviet Creighton, Mario C. Diaz, Raul Alberto Espinosa Perez, J. Lawrence, Francisco Llamas Villarreal, Soma Mukherjee, Volker Quetschke, Miriam Ramos Arevalo, Wenhui Wang

Physics & Astronomy Faculty Publications

We present a search for gravitational waves from inspiraling, planetary-mass ultracompact binaries using data from the first part of the fourth observing run of LIGO, Virgo, and KAGRA. Finding no evidence of such systems, we determine the maximum distance reach for such objects and their merger rate densities. Then, we identify classes of primordial black hole mass distributions for which these rate limits can be translated into relevant constraints on the mass distribution of primordial black holes, assuming that they are all composed of dark matter, in the mass range [10−6,10−3]⁢𝑀⊙. Our constraints for the class of primordial black hole …

Gwtc-4.0: Population Properties Of Merging Compact Binaries, A. G. Abac, I. Abouelfettouh, Teviet Creighton, Mario C. Diaz, Raul Alberto Espinosa Perez, J Lawrence, Francisco Llamas Villarreal, Soma Mukherjee, Volker Quetschke, Wenhui Wang

Physics & Astronomy Faculty Publications

We detail the population properties of binary neutron star, neutron star–black hole binary, and binary black hole mergers using 158 events from the cumulative Gravitational-Wave Transient Catalog 4.0. The black hole primary mass distribution consists of a power-law-like continuum that steepens above 35 M⊙ with overdensities at 10 M⊙ and 35 M⊙. Binary black holes with primary masses near 10 M⊙ are more likely to have less massive secondaries, with a mass ratio distribution peaking at  q=0.74+0.13−0.13, potentially a signature of stable mass transfer during binary evolution. Black hole spins are inferred to be nonextremal, with …