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Articles 1 - 30 of 184
Full-Text Articles in Physics
Dynamical Architectures Of S-Type Transiting Planets In Binaries. I. Target Selection Using Hipparcos And Gaia Proper Motion Anomalies, J. Zhang, L. M. Weiss, D. Huber, Eric L.N. Jensen, T. D. Brandt, K. Collins, D. M. Conti, H. Isaacson, P. Lewin, G. Marino, B. Massey, F. Murgas, E. Palle, D. J. Radford, H. M. Relles, G. Srdoc, C. Stockdale, T.-G. Tan, G. Wang
Dynamical Architectures Of S-Type Transiting Planets In Binaries. I. Target Selection Using Hipparcos And Gaia Proper Motion Anomalies, J. Zhang, L. M. Weiss, D. Huber, Eric L.N. Jensen, T. D. Brandt, K. Collins, D. M. Conti, H. Isaacson, P. Lewin, G. Marino, B. Massey, F. Murgas, E. Palle, D. J. Radford, H. M. Relles, G. Srdoc, C. Stockdale, T.-G. Tan, G. Wang
Physics & Astronomy Faculty Works
The effect of stellar multiplicity on planetary architecture and orbital dynamics provides an important context for exoplanet demographics. We present a volume-limited catalog of up to 300 pc of 66 stars hosting planets and planet candidates from Kepler, K2, and TESS with significant Hipparcos-Gaia proper motion anomalies, which indicates the presence of companions. We assess the reliability of each transiting planet candidate using ground-based follow-up observations, and find that the TESS Objects of Interest (TOIs) with significant proper anomalies show nearly four times more false positives due to eclipsing binaries compared to TOIs with marginal proper anomalies. In addition, we …
Novel Integrated Sachs-Wolfe Effect From Early Dark Energy, Tristan L. Smith, J. T. Giblin Jr., M. Amin, M. Gerhardinger, E. Florio, M. Cerep, S. Daniels
Novel Integrated Sachs-Wolfe Effect From Early Dark Energy, Tristan L. Smith, J. T. Giblin Jr., M. Amin, M. Gerhardinger, E. Florio, M. Cerep, S. Daniels
Physics & Astronomy Faculty Works
We study the nonlinear effects of minimally coupled, massless, cosmological scalar fields on the cosmic microwave background (CMB). These fields can exhibit postrecombination parametric resonance and subsequent nonlinear evolution leading to novel contributions to the gravitational potential. We compute the resulting contributions to the CMB temperature anisotropies through the time variation of the gravitational potential (i.e., the integrated Sachs-Wolfe (ISW) effect). We find that fields that constitute 5% of the total energy density and become dynamical at zc ≃ 104 can produce marginally observable ISW signals at multipoles ℓ ≃ 2000. Fields that become dynamical at earlier times …
Comparative Analysis Of Interacting Stepped Dark Radiation, N. Schöneberg, G. F. Abellán, T. Simon, A. Bartlett, Y. Patel, Tristan L. Smith
Comparative Analysis Of Interacting Stepped Dark Radiation, N. Schöneberg, G. F. Abellán, T. Simon, A. Bartlett, Y. Patel, Tristan L. Smith
Physics & Astronomy Faculty Works
Models that address both the Hubble and S8 tensions with the same mechanism generically cause a prerecombination suppression of the small scale matter power spectrum. Here we focus on two such models. Both models introduce a self-interacting dark radiation fluid scattering with dark matter, which has a step in its abundance around some transition redshift. In one model, the interaction is weak and with all of the dark matter whereas in the other it is strong but with only a fraction of the dark matter. The weakly interacting case is able to address both tensions simultaneously and provide a …
Separated Twins Or Just Siblings? A Multiplanet System Around An M Dwarf Including A Cool Sub-Neptune, M. Harris, D. Dragomir, I. Mireles, K. A. Collins, S. Ulmer-Moll, S. B. Howell, K. G. Stassun, G. Zhou, C. Ziegler, F. Bouchy, C. Briceño, D. Charbonneau, K. I. Collins, G. Fűűrész, N. M. Guerrero, J. M. Jenkins, Eric L.N. Jensen, M. H. K. Kristiansen, N. Law, M. Lendl, A. W. Mann, H. P. Osborn, S. N. Quinn, G. R. Ricker, R. P. Schwarz, S. Seager, E. B. Ting, R. Vanderspek, D. Watanabe, J. N. Winn
Separated Twins Or Just Siblings? A Multiplanet System Around An M Dwarf Including A Cool Sub-Neptune, M. Harris, D. Dragomir, I. Mireles, K. A. Collins, S. Ulmer-Moll, S. B. Howell, K. G. Stassun, G. Zhou, C. Ziegler, F. Bouchy, C. Briceño, D. Charbonneau, K. I. Collins, G. Fűűrész, N. M. Guerrero, J. M. Jenkins, Eric L.N. Jensen, M. H. K. Kristiansen, N. Law, M. Lendl, A. W. Mann, H. P. Osborn, S. N. Quinn, G. R. Ricker, R. P. Schwarz, S. Seager, E. B. Ting, R. Vanderspek, D. Watanabe, J. N. Winn
Physics & Astronomy Faculty Works
We report the discovery of two TESS sub-Neptunes orbiting the early M dwarf TOI-904 (TIC 261257684). Both exoplanets, TOI-904 b and c, were initially observed in TESS Sector 12 with twin sizes of 2.426 (+0.163)/(-0.157) and 2.167 (+0.130)/(-0.118) R⊕, respectively. Through observations in five additional sectors in the TESS primary mission and the first and second extended missions, the orbital periods of the planets were measured to be 10.887 ± 0.001 and 83.999 ± 0.001 days, respectively. Reconnaissance radial velocity measurements (taken with EULER/CORALIE and SMARTS/CHIRON) and high-resolution speckle imaging with adaptive optics (obtained from SOAR/HRCAM and Gemini …
Assessing The Robustness Of Sound Horizon-Free Determinations Of The Hubble Constant, Tristan L. Smith, V. Poulin, T. Simon
Assessing The Robustness Of Sound Horizon-Free Determinations Of The Hubble Constant, Tristan L. Smith, V. Poulin, T. Simon
Physics & Astronomy Faculty Works
The Hubble tension can be addressed by modifying the sound horizon (rs) before recombination, triggering interest in early universe estimates of the Hubble constant, H0, independent of rs. Constraints on H0 from an rs-free analysis of the full shape BOSS galaxy power spectra within Λ CDM were recently reported and used to comment on the viability of physics beyond Λ CDM. Here we demonstrate that rs-free analyses with current data depend on both the model and the priors placed on the cosmological parameters, such that Λ CDM analyses …
Magnetic-Field-Driven Director Configuration Transitions In Radial Nematic Liquid Crystal Droplets, S. Ettinger, C. G. Slaughter, S. H. Parra, J. M. Kikkawa, Peter J. Collings, A. G. Yodh
Magnetic-Field-Driven Director Configuration Transitions In Radial Nematic Liquid Crystal Droplets, S. Ettinger, C. G. Slaughter, S. H. Parra, J. M. Kikkawa, Peter J. Collings, A. G. Yodh
Physics & Astronomy Faculty Works
We study the director configurations of nematic liquid crystal (NLC) droplets with homeotropic anchoring in a magnetic field and report observation of a magnetic-field-driven transition from a deformed radial to an axial-with-defect configuration. Magnetic-field-induced transitions in NLC droplets differ fundamentally from the traditional planar Freedericksz transition due to the spherical droplet geometry and resulting topological defect. This transition has been studied theoretically, but the director configurations and mechanism of defect evolution in an applied magnetic field have yet to be observed experimentally. To this end, we combine polarized optical microscopy with a variable electromagnet (≤ 1 T) for continuous observation …
Development And Reliability Analysis Of A Split-Administration Test Of The Math Epistemic Games Survey, Stephen Hackler, E. Elliott, M. Eichenlaub, A. M. Sweeney
Development And Reliability Analysis Of A Split-Administration Test Of The Math Epistemic Games Survey, Stephen Hackler, E. Elliott, M. Eichenlaub, A. M. Sweeney
Physics & Astronomy Faculty Works
The increasing and diversifying student enrollments in introductory physics courses make reliable, valid, and usable instruments for measuring student skills and gains ever more important. In introductory physics, in addition to teaching facts about mechanics, we also seek to teach our students the skills of “thinking like a physicist,” or expertise in and intuition for physical problem solving. How and when these expert, intuitive problem-solving skills emerge during a STEM education, or what the most effective teaching methods might be, are not certain. A facile survey to measure students’ “physics-thinking” skills in a pretest and post-test format is therefore desirable …
Development And Reliability Analysis Of A Split-Administration Test Of The Math Epistemic Games Survey, Stephen Hackler, E. Elliott, M. Eichenlaub, Alison M. Sweeney
Development And Reliability Analysis Of A Split-Administration Test Of The Math Epistemic Games Survey, Stephen Hackler, E. Elliott, M. Eichenlaub, Alison M. Sweeney
Physics & Astronomy Faculty Works
The increasing and diversifying student enrollments in introductory physics courses make reliable, valid, and usable instruments for measuring student skills and gains ever more important. In introductory physics, in addition to teaching facts about mechanics, we also seek to teach our students the skills of “thinking like a physicist,” or expertise in and intuition for physical problem solving. How and when these expert, intuitive problem-solving skills emerge during a STEM education, or what the most effective teaching methods might be, are not certain. A facile survey to measure students’ “physics-thinking” skills in a pretest and post-test format is therefore desirable …
Consistency Of Effective Field Theory Analyses Of The Boss Power Spectrum, T. Simon, P. Zhang, V. Poulin, Tristan L. Smith
Consistency Of Effective Field Theory Analyses Of The Boss Power Spectrum, T. Simon, P. Zhang, V. Poulin, Tristan L. Smith
Physics & Astronomy Faculty Works
We assess the robustness of Λ cold dark matter (Λ CDM) results from the full-shape analysis of BOSS power spectrum using the one-loop prediction of the effective field theory of large-scale structure (EFTofLSS). In former EFT analyses, the two public likelihoods pybird and class-pt lead to results in agreement only at the 1σ level, which may appear unsatisfactory given that they are derived from the same BOSS dataset and the same theory model. To identify the origin of the difference, we perform a thorough comparison of the various analyses choices made between the two pipelines. We find that most …
Updated Constraints From The Effective Field Theory Analysis Of The Boss Power Spectrum On Early Dark Energy, T. Simon, P. Zhang, V. Poulin, Tristan L. Smith
Updated Constraints From The Effective Field Theory Analysis Of The Boss Power Spectrum On Early Dark Energy, T. Simon, P. Zhang, V. Poulin, Tristan L. Smith
Physics & Astronomy Faculty Works
Analyses of the full shape of the Baryon Oscillation Spectroscopic Survey (BOSS) DR12 power spectrum using the one-loop prediction from the effective field theory of large-scale structures (EFTBOSS) have led to new constraints on extensions to the Λ cold dark matter model, such as early dark energy (EDE), which has been suggested as a resolution to the “Hubble tension.” In this paper, we reassess the constraining power of the EFTBOSS on EDE in light of a correction to the normalization of BOSS window functions. Overall we find that constraints from EFTBOSS on EDE are weakened and represent a small change …
Development Of A Biaxial Apparatus For Jamming Profiles Of Photoelastic Granular Media, H. Zheng, G. Dai, Cacey Stevens Bester, M. Wang, D. Wang
Development Of A Biaxial Apparatus For Jamming Profiles Of Photoelastic Granular Media, H. Zheng, G. Dai, Cacey Stevens Bester, M. Wang, D. Wang
Physics & Astronomy Faculty Works
We describe a two-dimensional biaxial apparatus that is used to conduct the experimental study of the jamming of granular media. The setup is designed based on the photoelastic imaging technique, which allows us to detect force-bearing contacts among particles, calculate the pressure on each particle according to the mean squared intensity gradient method, and compute contact forces on each particle [T. S. Majmudar and R. P. Behringer, Nature 435, 1079–1082 (2005)]. Particles float in a density-matched solution to avoid basal friction during experiments. We can compress (uniaxially or biaxially) or shear the granular system by an entangled comb geometry by …
Nonharmonic Contributions To The High-Temperature Phonon Thermodynamics Of Cr, C. M. Bernal-Choban, Hillary L. Smith, C. N. Saunders, D. S. Kim, D. L. Abernathy, B. Fultz
Nonharmonic Contributions To The High-Temperature Phonon Thermodynamics Of Cr, C. M. Bernal-Choban, Hillary L. Smith, C. N. Saunders, D. S. Kim, D. L. Abernathy, B. Fultz
Physics & Astronomy Faculty Works
Phonon densities of states (DOSs) of body-centered cubic chromium were measured by time-of-flight inelastic neutron scattering at temperatures up to 1493 K. Density functional theory calculations with both quasiharmonic (QH) and anharmonic (AH) methods were performed at temperatures above the Néel temperature. Features in the phonon DOSs decrease in energy (soften) substantially with temperature. A Born–von Kármán analysis using fits to the experimental DOSs reveals a softening of almost 17% of the high-transverse phonon branch between 330 and 1493 K. The low-transverse branch changes by approximately half this amount. The AH calculations capture the observed behavior of the two transverse …
Was Entropy Conserved Between Bbn And Recombination?, A. C. Sobotka, A. L. Erickcek, Tristan L. Smith
Was Entropy Conserved Between Bbn And Recombination?, A. C. Sobotka, A. L. Erickcek, Tristan L. Smith
Physics & Astronomy Faculty Works
We test the assumption of entropy conservation between big bang nucleosynthesis and recombination by considering a massive particle that decays into a mixture of photons and other relativistic species. We employ Planck temperature and polarization anisotropies, COBE/FIRAS spectral distortion bounds, and the observed primordial deuterium abundance to constrain these decay scenarios. If between 56% and 71% of the decaying particle’s energy is transferred to photons, then Neff at recombination is minimally altered, and Planck data alone allows for significant entropy injection. If photons are injected by the decay, the addition of spectral distortion bounds restricts the decay rate of …
Hydrogen Adsorption And Isotope Mixing On Copper-Functionalized Activated Carbons, C. M. Quine, Hillary L. Smith, C. C. Ahn, A. Hasse-Zamudio, D. A. Boyd, B. Fultz
Hydrogen Adsorption And Isotope Mixing On Copper-Functionalized Activated Carbons, C. M. Quine, Hillary L. Smith, C. C. Ahn, A. Hasse-Zamudio, D. A. Boyd, B. Fultz
Physics & Astronomy Faculty Works
High-specific surface area (SSA) carbons were functionalized with copper nanoclusters and evaluated as potential hydrogen storage materials. The adsorption and desorption behaviors of the copper-functionalized material and pristine high-SSA carbon are compared between 77 and 400 K using adsorption isotherms up to 10 MPa and by temperature-programmed desorption of isotopic hydrogen. The high-SSA activated carbon with copper nanoclusters exhibited two desorption behaviors. (1) A desorption peak at 120 K, which was associated with physisorption on carbon, and (2) a desorption peak at 310 K, which was associated with a chemisorption process involving copper. The desorption from copper was strongly dependent …
Jammed Solids With Pins: Thresholds, Force Networks, And Elasticity, Andy L. Zhang , '22, S. A. Ridout, Celia Parts , '22, Aarushi Sachdeva , '24, Cacey Stevens Bester, K. Vollmayr-Lee, B. C. Utter, T. Brzinski, Amy Lisa Graves
Jammed Solids With Pins: Thresholds, Force Networks, And Elasticity, Andy L. Zhang , '22, S. A. Ridout, Celia Parts , '22, Aarushi Sachdeva , '24, Cacey Stevens Bester, K. Vollmayr-Lee, B. C. Utter, T. Brzinski, Amy Lisa Graves
Physics & Astronomy Faculty Works
The role of fixed degrees of freedom in soft or granular matter systems has broad applicability and theoretical interest. Here we address questions of the geometrical role that a scaffolding of fixed particles plays in tuning the threshold volume fraction and force network in the vicinity of jamming. Our two-dimensional simulated system consists of soft particles and fixed “pins,” both of which harmonically repel overlaps. On the one hand, we find that many of the critical scalings associated with jamming in the absence of pins continue to hold in the presence of even dense pin latices. On the other hand, …
Hints Of Early Dark Energy In Planck, Spt, And Act Data: New Physics Or Systematics?, Tristan L. Smith, M. Lucca, V. Poulin, G. F. Abellan, L. Balkenhol, K. Benabed, S. Galli, R. Murgia
Hints Of Early Dark Energy In Planck, Spt, And Act Data: New Physics Or Systematics?, Tristan L. Smith, M. Lucca, V. Poulin, G. F. Abellan, L. Balkenhol, K. Benabed, S. Galli, R. Murgia
Physics & Astronomy Faculty Works
We investigate constraints on early dark energy (EDE) using ACT DR4, SPT-3G 2018, Planck polarization, and restricted Planck temperature data (at ℓσ preference (Δχ2= −16.2 for three additional degrees of freedom) for EDE over Λ CDM. The EDE contributes a maximum fractional energy density of fEDE(zc) = 0.163(+0.047)/(−0.04) at a redshift zc = 3357±200 and leads to a CMB inferred value of the Hubble constant H0 = 74.2(+1.9)/(−2.1) km/s/Mpc. We find that Planck and ACT DR4 data provide the majority of the improvement in χ2, and that the inclusion …
Frustration-Induced Diffusive Scattering Anomaly And Dimension Change In Fege₂, Y. Su, Hillary L. Smith, M. B. Stone, D. L. Abernathy, M. D. Lumsden, C. P. Adams, C. Li
Frustration-Induced Diffusive Scattering Anomaly And Dimension Change In Fege₂, Y. Su, Hillary L. Smith, M. B. Stone, D. L. Abernathy, M. D. Lumsden, C. P. Adams, C. Li
Physics & Astronomy Faculty Works
Magnetic frustration, arising from the competition of exchange interactions, has received great attention because of its relevance to exotic quantum phenomena in materials. In the current work, we report an unusual checkerboard-shaped scattering anomaly in FeGe₂, far from the known incommensurate magnetic satellite peaks, by inelastic neutron scattering. More surprisingly, such phenomenon appears as spin dynamics at low temperature, but it becomes prominent above Néel transition as elastic scattering. A model Hamiltonian that includes an intraplane next-nearest neighbor was proposed and such anomaly is attributed to the near-perfect magnetic frustration and the emergence of unexpected two-dimensional magnetic order in the …
Thermal Expansion And Phonon Anharmonicity Of Cuprite Studied By Inelastic Neutron Scattering And Ab Initio Calculations, C. N. Saunders, D. S. Kim, O. Hellman, Hillary L. Smith, N. J. Weadock, S. T. Omelchenko, G. E. Ganroth, C. M. Bernal-Choban, S. H. Lohaus, D. L. Abernathy, B. Fultz
Thermal Expansion And Phonon Anharmonicity Of Cuprite Studied By Inelastic Neutron Scattering And Ab Initio Calculations, C. N. Saunders, D. S. Kim, O. Hellman, Hillary L. Smith, N. J. Weadock, S. T. Omelchenko, G. E. Ganroth, C. M. Bernal-Choban, S. H. Lohaus, D. L. Abernathy, B. Fultz
Physics & Astronomy Faculty Works
Inelastic neutron scattering measurements were performed with a time-of-flight chopper spectrometer to observe phonons in all parts of the Brillouin zone of a single crystal of cuprite Cu₂ O. We reduced the experimental data to phonon dispersions in the high-symmetry directions, and changes between 10 and 300 K are reported. In this paper, we show ab initio quasiharmonic (QH) and anharmonic (AH) calculations of phonon dispersions. We performed all AH calculations with a temperature-dependent effective potential method. Both QH and AH calculations account for the small negative thermal expansion of cuprite at low temperatures. However, the measured temperature-dependent phonon behavior …
Theory Of Director Fluctuations About A Hedgehog Defect In A Nematic Drop, O. Stenull, A. De La Cotte, S. Ettinger, Peter J. Collings, A. G. Yodh, T. C. Lubensky
Theory Of Director Fluctuations About A Hedgehog Defect In A Nematic Drop, O. Stenull, A. De La Cotte, S. Ettinger, Peter J. Collings, A. G. Yodh, T. C. Lubensky
Physics & Astronomy Faculty Works
We present calculations of eigenmode energies and wave functions of both azimuthal and polar distortions of the nematic director relative to a radial hedgehog trapped in a spherical drop with a smaller concentric spherical droplet at its core. All surfaces interior to the drop have perpendicular (homeotropic) boundary conditions. We also calculate director correlation functions and their relaxation times. Of particular interest is a critical mode whose energy, with fixed Frank constants, vanishes as the ratio μ = R₂/R₁ increases toward a critical value μc, where R₂ is the radius of the drop and …
Giant Director Fluctuations In Liquid Crystal Drops, A. De La Cotte, O. Stenull, S. Ettinger, Peter J. Collings, T. C. Lubensky, A. G. Yodh
Giant Director Fluctuations In Liquid Crystal Drops, A. De La Cotte, O. Stenull, S. Ettinger, Peter J. Collings, T. C. Lubensky, A. G. Yodh
Physics & Astronomy Faculty Works
We report the discovery and elucidation of giant spatiotemporal orientational fluctuations in nematic liquid crystal drops with radial orientation of the nematic anisotropy axis producing a central “hedgehog” defect. We study the spatial and temporal properties of the fluctuations experimentally using polarized optical microscopy, and theoretically, by calculating the eigenspectrum of the Frank elastic free energy of a nematic drop of radius R₂, containing a spherical central core of radius R₁ and constrained by perpendicular boundary conditions on all surfaces. We find that the hedgehog defect with radial orientation has a complex excitation spectrum with a single critical …
The International Pulsar Timing Array Second Data Release: Search For An Isotropic Gravitational Wave Background, J. Antoniadis, Z. Arzoumanian, S. Babak, M. Bailes, A.-S. Bak Nielsen, P. T. Baker, C. G. Bassa, B. Bécsy, A. Berthereau, M. Bonetti, A. Brazier, P. R. Brook, M. Burgay, S. Burke-Spolaor, R. N. Caballero, J. A. Casey-Clyde, A. Chalumeau, D. J. Champion, M. Charisi, S. Chatterjee, S. Chen, I. Cognard, J. M. Cordes, N. J. Cornish, F. Crawford, H. T. Cromartie, K. Crowter, S. Dai, M. E. Decesar, P. B. Demorest, G. Desvignes, T. Dolch, B. Drachler, M. Falxa, E. C. Ferrara, W. Fiore, E. Fonseca, J. R. Gair, N. Garver-Daniels, B. Goncharov, D. C. Good, E. Graikou, L. Guillemot, Y. J. Guo, J. S. Hazboun, G. Hobbs, H. Hu, K. Islo, G. H. Janssen, R. J. Jennings, A. D. Johnson, M. L. Jones, A. R. Kaiser, D. L. Kaplan, R. Karuppusamy, M. J. Keith, L. Z. Kelley, M. Kerr, J. S. Key, M. Kramer, M. T. Lam, W. G. Lamb, T. J. W. Lazio, K. J. Lee, L. Lentati, K. Liu, J. Luo, R. S. Lynch, A. G. Lyne, D. R. Madison, R. A. Main, R. N. Manchester, A. Mcewen, J. W. Mckee, M. A. Mclaughlin, M. B. Mickaliger, C. M. F. Mingarelli, C. Ng, D. J. Nice, S. Osłowski, A. Parthasarathy, T. T. Pennucci, B. B. P. Perera, D. Perrodin, A. Petiteau, N. S. Pol, N. K. Porayko, A. Possenti, S. M. Ransom, P. S. Ray, D. J. Reardon, C. J. Russell, S. Samajdar, L. M. Sampson, S. Sanidas, J. M. Sarkissian, K. Schmitz, L. Schult, A. Sesana, G. Shaifullah, R. M. Shannon, B. J. Shapiro-Albert, X. Siemens, J. Simon, Tristan L. Smith, L. Speri, R. Spiewak, I. H. Stairs, B. W. Stappers, D. R. Stinebring, J. K. Swiggum, S. R. Taylor, G. Theureau, C. Tiburzi, M. Vallisneri, E. Van Der Wateren, A. Vecchio, J. P. W. Verbiest, S. J. Vigeland, H. Wahl, J. B. Wang, J. Wang, L. Wang, C. A. Witt, S. Zhang, X. J. Zhu
The International Pulsar Timing Array Second Data Release: Search For An Isotropic Gravitational Wave Background, J. Antoniadis, Z. Arzoumanian, S. Babak, M. Bailes, A.-S. Bak Nielsen, P. T. Baker, C. G. Bassa, B. Bécsy, A. Berthereau, M. Bonetti, A. Brazier, P. R. Brook, M. Burgay, S. Burke-Spolaor, R. N. Caballero, J. A. Casey-Clyde, A. Chalumeau, D. J. Champion, M. Charisi, S. Chatterjee, S. Chen, I. Cognard, J. M. Cordes, N. J. Cornish, F. Crawford, H. T. Cromartie, K. Crowter, S. Dai, M. E. Decesar, P. B. Demorest, G. Desvignes, T. Dolch, B. Drachler, M. Falxa, E. C. Ferrara, W. Fiore, E. Fonseca, J. R. Gair, N. Garver-Daniels, B. Goncharov, D. C. Good, E. Graikou, L. Guillemot, Y. J. Guo, J. S. Hazboun, G. Hobbs, H. Hu, K. Islo, G. H. Janssen, R. J. Jennings, A. D. Johnson, M. L. Jones, A. R. Kaiser, D. L. Kaplan, R. Karuppusamy, M. J. Keith, L. Z. Kelley, M. Kerr, J. S. Key, M. Kramer, M. T. Lam, W. G. Lamb, T. J. W. Lazio, K. J. Lee, L. Lentati, K. Liu, J. Luo, R. S. Lynch, A. G. Lyne, D. R. Madison, R. A. Main, R. N. Manchester, A. Mcewen, J. W. Mckee, M. A. Mclaughlin, M. B. Mickaliger, C. M. F. Mingarelli, C. Ng, D. J. Nice, S. Osłowski, A. Parthasarathy, T. T. Pennucci, B. B. P. Perera, D. Perrodin, A. Petiteau, N. S. Pol, N. K. Porayko, A. Possenti, S. M. Ransom, P. S. Ray, D. J. Reardon, C. J. Russell, S. Samajdar, L. M. Sampson, S. Sanidas, J. M. Sarkissian, K. Schmitz, L. Schult, A. Sesana, G. Shaifullah, R. M. Shannon, B. J. Shapiro-Albert, X. Siemens, J. Simon, Tristan L. Smith, L. Speri, R. Spiewak, I. H. Stairs, B. W. Stappers, D. R. Stinebring, J. K. Swiggum, S. R. Taylor, G. Theureau, C. Tiburzi, M. Vallisneri, E. Van Der Wateren, A. Vecchio, J. P. W. Verbiest, S. J. Vigeland, H. Wahl, J. B. Wang, J. Wang, L. Wang, C. A. Witt, S. Zhang, X. J. Zhu
Physics & Astronomy Faculty Works
We searched for an isotropic stochastic gravitational wave background in the second data release of the International Pulsar Timing Array, a global collaboration synthesizing decadal-length pulsar-timing campaigns in North America, Europe, and Australia. In our reference search for a power-law strain spectrum of the form hc = A(f/1 yr⁻¹)α, we found strong evidence for a spectrally similar low-frequency stochastic process of amplitude A = 3.8 (+6.3)/(-2.5) × 10⁻¹⁵ and spectral index α = −0.5 ± 0.5, where the uncertainties represent 95 per cent credible regions, using information from the auto- and cross-correlation terms between …
Impact Of Introductory Physics For The Life Sciences In A Senior Biology Capstone Course, Benjamin D. Geller , '01, Jack Rubien , '20, Sara Hiebert Burch, Catherine Hirshfeld Crouch
Impact Of Introductory Physics For The Life Sciences In A Senior Biology Capstone Course, Benjamin D. Geller , '01, Jack Rubien , '20, Sara Hiebert Burch, Catherine Hirshfeld Crouch
Physics & Astronomy Faculty Works
A goal of introductory physics for life sciences (IPLS) curricula is to prepare students to effectively use physical models and quantitative reasoning in biological and medical settings. To assess whether this goal is being met, we conducted a longitudinal study of the impact of IPLS on student work in later biology and chemistry courses. We report here on one part of that study, a comparison of written responses by students with different physics backgrounds on a diffusion task administered in a senior biology capstone course. We observed differences in student reasoning that were found to be associated with prior or …
Assessing The Impact Of Introductory Physics For The Life Sciences On Students’ Ability To Build Complex Models, Benjamin D. Geller , '01, Maya Tipton , '24, Brandon Daniel-Morales , '24, Nikhil Tignor , '24, Calvin White , '24, Catherine Hirshfeld Crouch
Assessing The Impact Of Introductory Physics For The Life Sciences On Students’ Ability To Build Complex Models, Benjamin D. Geller , '01, Maya Tipton , '24, Brandon Daniel-Morales , '24, Nikhil Tignor , '24, Calvin White , '24, Catherine Hirshfeld Crouch
Physics & Astronomy Faculty Works
A central goal of introductory physics for the life sciences (IPLS) is to prepare students to use physics to model and analyze biological situations, a skill of increasing importance for their future studies and careers. Here we report our findings on life science students’ ability to carry out a sophisticated biological modeling task at the end of first-semester introductory physics. Some students were enrolled in a standard course (N = 34), and some in an IPLS course (N = 61); both courses were taught with active learning, used calculus, and included the same core physics concepts. Compared to …
Dark Energy At Early Times And Act Data: A Larger Hubble Constant Without Late-Time Priors, V. Poulin, Tristan L. Smith, A. Bartlett
Dark Energy At Early Times And Act Data: A Larger Hubble Constant Without Late-Time Priors, V. Poulin, Tristan L. Smith, A. Bartlett
Physics & Astronomy Faculty Works
Recent observations using the Atacama Cosmology Telescope (ACT) have provided ground-based cosmic microwave background (CMB) maps with higher angular resolution than the Planck satellite. These have the potential to put interesting constraints on models resolving the “Hubble tension.” In this paper we fit two models of early dark energy (EDE) (an increase in the expansion rate around matter/radiation equality) to the combination of ACT data with large-scale measurements of the CMB either from the WMAP or the Planck satellite (including lensing), along with measurements of the baryon acoustic oscillations and uncalibrated supernovae luminosity distance. We study a phenomenological axionlike potential …
Early Dark Energy Is Not Excluded By Current Large-Scale Structure Data, Tristan L. Smith, V. Poulin, J. L. Bernal, K. K. Boddy, M. Kamionkowski, R. Murgia
Early Dark Energy Is Not Excluded By Current Large-Scale Structure Data, Tristan L. Smith, V. Poulin, J. L. Bernal, K. K. Boddy, M. Kamionkowski, R. Murgia
Physics & Astronomy Faculty Works
We revisit the impact of early dark energy (EDE) on galaxy clustering using BOSS galaxy power spectra, analyzed using the effective field theory (EFT) of large-scale structure (LSS) and anisotropies of the cosmic microwave background (CMB) from Planck. Recent studies found that these data place stringent constraints on the maximum abundance of EDE allowed in the Universe. We argue here that their conclusions are a consequence of their choice of priors on the EDE parameter space, rather than any disagreement between the data and the model. For example, when considering EFT-LSS, CMB, and high-redshift supernovae data we find the …
Clustering And Halo Abundances In Early Dark Energy Cosmological Models, A. Klypin, V. Poulin, F. Prada, J. Primack, M. Kamionkowski, V. Avila-Reese, A. Rodriguez-Puebla, P. Behroozi, D. Hellinger, Tristan L. Smith
Clustering And Halo Abundances In Early Dark Energy Cosmological Models, A. Klypin, V. Poulin, F. Prada, J. Primack, M. Kamionkowski, V. Avila-Reese, A. Rodriguez-Puebla, P. Behroozi, D. Hellinger, Tristan L. Smith
Physics & Astronomy Faculty Works
Cold Dark Matter with cosmological constant (ΛCDM) cosmological models with early dark energy (EDE) have been proposed to resolve tensions between the Hubble constant H0=100h km ṡ−1Ṁpc−1 measured locally, giving h ≈ 0.73, and H0 deduced from Planck cosmic microwave background (CMB) and other early-Universe measurements plus ΛCDM, giving h ≈ 0.67. EDE models do this by adding a scalar field that temporarily adds dark energy equal to about 10 per cent of the cosmological energy density at the end of the radiation-dominated era at redshift z ∼ 3500. Here, we compare linear and non-linear predictions of a Planck-normalized ΛCDM …
On The Halo-Mass And Radial Scale Dependence Of The Lensing Is Low Effect, J. U. Lange, A. Leauthaud, S. Singh, H. Guo, R. Zhou, Tristan L. Smith, F.-Y. Cyr-Racine
On The Halo-Mass And Radial Scale Dependence Of The Lensing Is Low Effect, J. U. Lange, A. Leauthaud, S. Singh, H. Guo, R. Zhou, Tristan L. Smith, F.-Y. Cyr-Racine
Physics & Astronomy Faculty Works
The canonical Lambda cold dark matter (ΛCDM) cosmological model makes precise predictions for the clustering and lensing properties of galaxies. It has been shown that the lensing amplitude of galaxies in the Baryon Oscillation Spectroscopic Survey (BOSS) is lower than expected given their clustering properties. We present new measurements and modelling of galaxies in the BOSS LOWZ sample. We focus on the radial and stellar mass dependence of the lensing amplitude mismatch. We find an amplitude mismatch of around 35 per cent when assuming ΛCDM with Planck Cosmological Microwave Background (CMB) constraints. This offset is independent of halo mass and …
Insights Into Searches For Anisotropies In The Nanohertz Gravitational-Wave Background, Y. Ali-Haïmoud, Tristan L. Smith, C. M. F. Mingarelli
Insights Into Searches For Anisotropies In The Nanohertz Gravitational-Wave Background, Y. Ali-Haïmoud, Tristan L. Smith, C. M. F. Mingarelli
Physics & Astronomy Faculty Works
Within the next several years pulsar timing arrays (PTAs) are positioned to detect the stochastic gravitational-wave background (GWB) likely produced by the collection of inspiralling supermassive black holes binaries, and potentially constrain some exotic physics. So far most of the pulsar timing data analysis has focused on the monopole of the GWB, assuming it is perfectly isotropic. The natural next step is to search for anisotropies in the GWB. In this paper, we use the recently developed PTA Fisher matrix to gain insights into optimal search strategies for GWB anisotropies. For concreteness, we apply our results to the European Pulsar …
The First Three Seconds: A Review Of Possible Expansion Histories Of The Early Universe, R. Allahverdi, M. A. Amin, A. Berlin, N. Bernal, C. T. Byrnes, M. S. Delos, A. L. Erickcek, M. Escudero, D. G. Figueroa, K. Freese, T. Harada, D. Hooper, D. I. Kaiser, T. Karwal, K. Kohri, G. Krnjaic, M. Lewicki, K. D. Lozanov, V. Poulin, K. Sinha, Tristan L. Smith, T. Takahashi, T. Tenkanen, J. Unwin, V. Vaskonen, S. Watson
The First Three Seconds: A Review Of Possible Expansion Histories Of The Early Universe, R. Allahverdi, M. A. Amin, A. Berlin, N. Bernal, C. T. Byrnes, M. S. Delos, A. L. Erickcek, M. Escudero, D. G. Figueroa, K. Freese, T. Harada, D. Hooper, D. I. Kaiser, T. Karwal, K. Kohri, G. Krnjaic, M. Lewicki, K. D. Lozanov, V. Poulin, K. Sinha, Tristan L. Smith, T. Takahashi, T. Tenkanen, J. Unwin, V. Vaskonen, S. Watson
Physics & Astronomy Faculty Works
It is commonly assumed that the energy density of the Universe was dominated by radiation between reheating after inflation and the onset of matter domination 54,000 years later. While the abundance of light elements indicates that the Universe was radiation dominated during Big Bang Nucleosynthesis (BBN), there is scant evidence that the Universe was radiation dominated prior to BBN. It is therefore possible that the cosmological history was more complicated, with deviations from the standard radiation domination during the earliest epochs. Indeed, several interesting proposals regarding various topics such as the generation of dark matter, matter-antimatter asymmetry, gravitational waves, primordial …
Fisher Formalism For Anisotropic Gravitational-Wave Background Searches With Pulsar Timing Arrays, Y. Ali-Haïmoud, Tristan L. Smith, C. M. F. Mingarelli
Fisher Formalism For Anisotropic Gravitational-Wave Background Searches With Pulsar Timing Arrays, Y. Ali-Haïmoud, Tristan L. Smith, C. M. F. Mingarelli
Physics & Astronomy Faculty Works
Pulsar timing arrays (PTAs) are currently the only experiments directly sensitive to gravitational waves with decade-long periods. Within the next five to ten years, PTAs are expected to detect the stochastic gravitational-wave background (SGWB) collectively sourced by inspiraling supermassive black hole binaries. It is expected that this background is mostly isotropic, and current searches focus on the monopole part of the SGWB. Looking ahead, anisotropies in the SGWB may provide a trove of additional information on both known and unknown astrophysical and cosmological sources. In this paper, we build a simple yet realistic Fisher formalism for anisotropic SGWB searches with …