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1. Constraining solar emission radius at 42 MHz during the 2024 total solar eclipse using a student-commissioned radio telescope

Author: Young, Olivia R., Dolch, Timothy E., Helmboldt, Joseph F., Mentrek, Christopher, Dartez, Louis P., Lam, Michael T., Fiscella, Sophia V. Sosa, Bretl, Evan, Joyce, Colin, Loock, Johannes, Meyer, Grace, Peltzer, Annabel, Petullo, Joseph, Reed, Parker, Sigtryggsson, Emerson, Bassett, Benjamin, Hawken, Andrew B., Heredia, Alejandro Z., Lettow, Paige, Lewis, Whit, Manna, Mikayla, Mirochnikoff, Nicholas, and Zemcov, Michael
Subjects: Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: Low-frequency solar radio emission is sourced in the solar corona, with sub-100 MHz radio emission largely originating from the $\sim$10$^{5}$\,$\mathrm{K}$ plasma around 2 optical radii. However, the region of emission has yet to be constrained at 35--45\,MHz due to both instrumentation limitations and the rarity of astronomical events, such as total solar eclipses, which allow for direct observational approaches. In this work, we present the results from a student-led project to commission a low-frequency radio telescope array situated in the path of totality of the 2024 total solar eclipse in an effort to probe the middle corona. The Deployable Low-Band Ionosphere and Transient Experiment (DLITE) is a low-frequency radio array comprised of four dipole antennas, optimized to observe at 35--45\,MHz, and capable of resolving the brightest radio sources in the sky. We constructed a DLITE station in Observatory Park, a dark sky park in Montville, Ohio. Results of observations during the total solar eclipse demonstrate that DLITE stations can be quickly deployed for observations and provide constraints on the radius of solar emission at our center observing frequency of 42\,MHz. In this work, we outline the construction of DLITE Ohio and the solar observation results from the total solar eclipse that transversed North America in April 2024.
Published: 2024

2. The NANOGrav 15 year Data Set: Removing pulsars one by one from the pulsar timing array

Author: Agazie, Gabriella, Anumarlapudi, Akash, Archibald, Anne M., Arzoumanian, Zaven, Baier, Jeremy G., Baker, Paul T., Becsy, Bence, Blecha, Laura, Brazier, Adam, Brook, Paul R., Burke-Spolaor, Sarah, Casey-Clyde, J. Andrew, Charisi, Maria, Chatterjee, Shami, Cohen, Tyler, Cordes, James M., Cornish, Neil J., Crawford, Fronefield, Cromartie, H. Thankful, Crowter, Kathryn, DeCesar, Megan E., Demorest, Paul B., Deng, Heling, Dey, Lankeswar, Dolch, Timothy, Ferrara, Elizabeth C., Fiore, William, Fonseca, Emmanuel, Freedman, Gabriel E., Gardiner, Emiko C., Garver-Daniels, Nate, Gentile, Peter A., Gersbach, Kyle A., Glaser, Joseph, Good, Deborah C., Guertin, Lydia, Gultekin, Kayhan, Hazboun, Jeffrey S., Jennings, Ross J., Johnson, Aaron D., Jones, Megan L., Kaiser, Andrew R., Kaplan, David L., Kelley, Luke Zoltan, Kerr, Matthew, Key, Joey S., Laal, Nima, Lam, Michael T., Lamb, William G., Larsen, Bjorn, Lazio, T. Joseph W., Lewandowska, Natalia, Liu, Tingting, Lorimer, Duncan R., Luo, Jing, Lynch, Ryan S., Ma, Chung-Pei, Madison, Dustin R., McEwen, Alexander, McKee, James W., McLaughlin, Maura A., McMann, Natasha, Meyers, Bradley W., Meyers, Patrick M., Middleton, Hannah, Mingarelli, Chiara M. F., Mitridate, Andrea, Moore, Christopher J., Ng, Cherry, Nice, David J., Ocker, Stella Koch, Olum, Ken D., Pennucci, Timothy T., Perera, Benetge B. P., Pol, Nihan S., Radovan, Henri A., Ransom, Scott M., Ray, Paul S., Romano, Joseph D., Runnoe, Jessie C., Saffer, Alexander, Sardesai, Shashwat C., Schmiedekamp, Ann, Schmiedekamp, Carl, Schmitz, Kai, Shapiro-Albert, Brent J., Siemens, Xavier, Simon, Joseph, Siwek, Magdalena S., Fiscella, Sophia V. Sosa, Stairs, Ingrid H., Stinebring, Daniel R., Stovall, Kevin, Susobhanan, Abhimanyu, Swiggum, Joseph K., Taylor, Stephen R., Turner, Jacob E., Unal, Caner, Vallisneri, Michele, Vecchio, Alberto, Vigeland, Sarah J., Wahl, Haley M., Witt, Caitlin A., Wright, David, and Young, Olivia
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: Evidence has emerged for a stochastic signal correlated among 67 pulsars within the 15-year pulsar-timing data set compiled by the NANOGrav collaboration. Similar signals have been found in data from the European, Indian, Parkes, and Chinese PTAs. This signal has been interpreted as indicative of the presence of a nanohertz stochastic gravitational wave background. To explore the internal consistency of this result we investigate how the recovered signal strength changes as we remove the pulsars one by one from the data set. We calculate the signal strength using the (noise-marginalized) optimal statistic, a frequentist metric designed to measure correlated excess power in the residuals of the arrival times of the radio pulses. We identify several features emerging from this analysis that were initially unexpected. The significance of these features, however, can only be assessed by comparing the real data to synthetic data sets. After conducting identical analyses on simulated data sets, we do not find anything inconsistent with the presence of a stochastic gravitational wave background in the NANOGrav 15-year data. The methodologies developed here can offer additional tools for application to future, more sensitive data sets. While this analysis provides an internal consistency check of the NANOGrav results, it does not eliminate the necessity for additional investigations that could identify potential systematics or uncover unmodeled physical phenomena in the data., Comment: 21 pages, 11 figures, 2 tables
Published: 2024

3. The NANOGrav 15 yr Data Set: Harmonic Analysis of the Pulsar Angular Correlations

Author: Agazie, Gabriella, Baier, Jeremy G., Baker, Paul T., Becsy, Bence, Blecha, Laura, Boddy, Kimberly K., Brazier, Adam, Brook, Paul R., Burke-Spolaor, Sarah, Burnette, Rand, Casey-Clyde, J. Andrew, Charisi, Maria, Chatterjee, Shami, Cohen, Tyler, Cordes, James M., Cornish, Neil J., Crawford, Fronefield, Cromartie, H. Thankful, DeCesar, Megan E., Demorest, Paul B., Deng, Heling, Dey, Lankeswar, Dolch, Timothy, Ferrara, Elizabeth C., Fiore, William, Fonseca, Emmanuel, Freedman, Gabriel E., Gardiner, Emiko C., Gersbach, Kyle A., Glaser, Joseph, Good, Deborah C., Gultekin, Kayhan, Hazboun, Jeffrey S., Jennings, Ross J., Johnson, Aaron D., Kaplan, David L., Kelley, Luke Zoltan, Key, Joey S., Laal, Nima, Lam, Michael T., Lamb, William G., Larsen, Bjorn, Lazio, T. Joseph W., Lewandowska, Natalia, Liu, Tingting, Luo, Jing, Lynch, Ryan S., Ma, Chung-Pei, Madison, Dustin R., McEwen, Alexander, McKee, James W., McLaughlin, Maura A., Meyers, Patrick M., Mingarelli, Chiara M. F., Mitridate, Andrea, Nay, Jonathan, Nice, David J., Ocker, Stella Koch, Olum, Ken D., Pennucci, Timothy T., Petrov, Polina, Pol, Nihan S., Radovan, Henri A., Ransom, Scott M., Ray, Paul S., Runnoe, Jessie C., Saffer, Alexander, Sardesai, Shashwat C., Schmitz, Kai, Siemens, Xavier, Simon, Joseph, Siwek, Magdalena S., Smith, Tristan L., Fiscella, Sophia V. Sosa, Stairs, Ingrid H., Stinebring, Daniel R., Susobhanan, Abhimanyu, Swiggum, Joseph K., Taylor, Jacob, Taylor, Stephen R., Turner, Jacob E., Unal, Caner, Vallisneri, Michele, van Haasteren, Rutger, Verbiest, Joris, Vigeland, Sarah J., Witt, Caitlin A., Wright, David, and Young, Olivia
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies, General Relativity and Quantum Cosmology
Abstract: Pulsar timing array observations have found evidence for an isotropic gravitational wave background with the Hellings-Downs angular correlations, expected from general relativity. This interpretation hinges on the measured shape of the angular correlations, which is predominately quadrupolar under general relativity. Here we explore a more flexible parameterization: we expand the angular correlations into a sum of Legendre polynomials and use a Bayesian analysis to constrain their coefficients with the 15-year pulsar timing data set collected by the North American Nanohertz Observatory for Gravitational Waves (NANOGrav). When including Legendre polynomials with multipoles $\ell \geq 2$, we only find a significant signal in the quadrupole with an amplitude consistent with general relativity and non-zero at the $\sim 95\%$ confidence level and a Bayes factor of 200. When we include multipoles $\ell \leq 1$, the Bayes factor evidence for quadrupole correlations decreases by more than an order of magnitude due to evidence for a monopolar signal at approximately 4 nHz which has also been noted in previous analyses of the NANOGrav 15-year data. Further work needs to be done in order to better characterize the properties of this monopolar signal and its effect on the evidence for quadrupolar angular correlations., Comment: 15 pages, 6 figures
Published: 2024

4. Galaxy Tomography with the Gravitational Wave Background from Supermassive Black Hole Binaries

Author: Chen, Yifan, Daniel, Matthias, D'Orazio, Daniel J., Mitridate, Andrea, Sagunski, Laura, Xue, Xiao, Agazie, Gabriella, Baier, Jeremy G., Baker, Paul T., Bécsy, Bence, Blecha, Laura, Brazier, Adam, Brook, Paul R., Burke-Spolaor, Sarah, Burnette, Rand, Casey-Clyde, J. Andrew, Charisi, Maria, Chatterjee, Shami, Cohen, Tyler, Cordes, James M., Cornish, Neil J., Crawford, Fronefield, Cromartie, H. Thankful, DeCesar, Megan E., Demorest, Paul B., Deng, Heling, Dey, Lankeswar, Dolch, Timothy, Ferrara, Elizabeth C., Fiore, William, Fonseca, Emmanuel, Freedman, Gabriel E., Gardiner, Emiko C., Gersbach, Kyle A., Glaser, Joseph, Good, Deborah C., Gültekin, Kayhan, Hazboun, Jeffrey S., Jennings, Ross J., Johnson, Aaron D., Kaplan, David L., Kelley, Luke Zoltan, Key, Joey S., Laal, Nima, Lam, Michael T., Lamb, William G., Larsen, Bjorn, Lazio, T. Joseph W., Lewandowska, Natalia, Liu, Tingting, Luo, Jing, Lynch, Ryan S., Ma, Chung-Pei, Madison, Dustin R., McEwen, Alexander, McKee, James W., McLaughlin, Maura A., Meyers, Patrick M., Mingarelli, Chiara M. F., Nice, David J., Ocker, Stella Koch, Olum, Ken D., Pennucci, Timothy T., Petrov, Polina, Pol, Nihan S., Radovan, Henri A., Ransom, Scott M., Ray, Paul S., Romano, Joseph D., Runnoe, Jessie C., Saffer, Alexander, Sardesai, Shashwat C., Schmitz, Kai, Siemens, Xavier, Simon, Joseph, Siwek, Magdalena S., Fiscella, Sophia V. Sosa, Stairs, Ingrid H., Stinebring, Daniel R., Susobhanan, Abhimanyu, Swiggum, Joseph K., Taylor, Jacob, Taylor, Stephen R., Turner, Jacob E., Unal, Caner, Vallisneri, Michele, van Haasteren, Rutger, Verbiest, Joris, Vigeland, Sarah J., Witt, Caitlin A., Wright, David, and Young, Olivia
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics, Astrophysics - Astrophysics of Galaxies, General Relativity and Quantum Cosmology, High Energy Physics - Phenomenology
Abstract: The detection of a stochastic gravitational wave background by pulsar timing arrays suggests the presence of a supermassive black hole binary population. Although the observed spectrum generally aligns with predictions from orbital evolution driven by gravitational wave emission in circular orbits, there is a discernible preference for a turnover at the lowest observed frequencies. This turnover could indicate a significant hardening phase, transitioning from early environmental influences to later stages predominantly influenced by gravitational wave emission. In the vicinity of these binaries, the ejection of stars or dark matter particles through gravitational three-body slingshots efficiently extracts orbital energy, leading to a low-frequency turnover in the spectrum. By analyzing the NANOGrav 15-year data, we assess how the gravitational wave spectrum depends on the initial inner galactic profile prior to disruption by binary ejections, accounting for a range of initial binary eccentricities. Our findings suggest a parsec-scale galactic center density around $10^6\,M_\odot/\textrm{pc}^3$ across most of the parameter space, offering insights into the environmental effects on black hole evolution and combined matter density near galaxy centers., Comment: 15 pages, 5 figures
Published: 2024

5. The NANOGrav 15 yr Data Set: Running of the Spectral Index

Author: Agazie, Gabriella, Anumarlapudi, Akash, Archibald, Anne M., Arzoumanian, Zaven, Baier, Jeremy George, Baker, Paul T., Bécsy, Bence, Blecha, Laura, Brazier, Adam, Brook, Paul R., Burke-Spolaor, Sarah, Casey-Clyde, J. Andrew, Charisi, Maria, Chatterjee, Shami, Cohen, Tyler, Cordes, James M., Cornish, Neil J., Crawford, Fronefield, Cromartie, H. Thankful, Crowter, Kathryn, DeCesar, Megan E., Demorest, Paul B., Deng, Heling, Dey, Lankeswar, Dolch, Timothy, Esmyol, David, Ferrara, Elizabeth C., Fiore, William, Fonseca, Emmanuel, Freedman, Gabriel E., Gardiner, Emiko C., Garver-Daniels, Nate, Gentile, Peter A., Gersbach, Kyle A., Glaser, Joseph, Good, Deborah C., Gültekin, Kayhan, Hazboun, Jeffrey S., Jennings, Ross J., Johnson, Aaron D., Jones, Megan L., Kaplan, David L., Kelley, Luke Zoltan, Kerr, Matthew, Key, Joey S., Laal, Nima, Lam, Michael T., Lamb, William G., Larsen, Bjorn, Lazio, T. Joseph W., Lewandowska, Natalia, Santos, Rafael R. Lino dos, Liu, Tingting, Lorimer, Duncan R., Luo, Jing, Lynch, Ryan S., Ma, Chung-Pei, Madison, Dustin R., McEwen, Alexander, McKee, James W., McLaughlin, Maura A., McMann, Natasha, Meyers, Bradley W., Meyers, Patrick M., Mingarelli, Chiara M. F., Mitridate, Andrea, Ng, Cherry, Nice, David J., Ocker, Stella Koch, Olum, Ken D., Pennucci, Timothy T., Perera, Benetge B. P., Pol, Nihan S., Radovan, Henri A., Ransom, Scott M., Ray, Paul S., Romano, Joseph D., Runnoe, Jessie C., Saffer, Alexander, Sardesai, Shashwat C., Schmiedekamp, Ann, Schmiedekamp, Carl, Schmitz, Kai, Schröder, Tobias, Shapiro-Albert, Brent J., Siemens, Xavier, Simon, Joseph, Siwek, Magdalena S., Fiscella, Sophia V. Sosa, Stairs, Ingrid H., Stinebring, Daniel R., Stovall, Kevin, Susobhanan, Abhimanyu, Swiggum, Joseph K., Taylor, Stephen R., Turner, Jacob E., Unal, Caner, Vallisneri, Michele, van Haasteren, Rutger, Vigeland, Sarah J., von Eckardstein, Richard, Wahl, Haley M., Witt, Caitlin A., Wright, David, and Young, Olivia
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics, General Relativity and Quantum Cosmology, High Energy Physics - Phenomenology
Abstract: The NANOGrav 15-year data provides compelling evidence for a stochastic gravitational-wave (GW) background at nanohertz frequencies. The simplest model-independent approach to characterizing the frequency spectrum of this signal consists in a simple power-law fit involving two parameters: an amplitude A and a spectral index \gamma. In this paper, we consider the next logical step beyond this minimal spectral model, allowing for a running (i.e., logarithmic frequency dependence) of the spectral index, \gamma_run(f) = \gamma + \beta \ln(f/f_ref). We fit this running-power-law (RPL) model to the NANOGrav 15-year data and perform a Bayesian model comparison with the minimal constant-power-law (CPL) model, which results in a 95% credible interval for the parameter \beta consistent with no running, \beta \in [-0.80,2.96], and an inconclusive Bayes factor, B(RPL vs. CPL) = 0.69 +- 0.01. We thus conclude that, at present, the minimal CPL model still suffices to adequately describe the NANOGrav signal; however, future data sets may well lead to a measurement of nonzero \beta. Finally, we interpret the RPL model as a description of primordial GWs generated during cosmic inflation, which allows us to combine our results with upper limits from big-bang nucleosynthesis, the cosmic microwave background, and LIGO-Virgo-KAGRA., Comment: 17 pages, 4 figures, 2 tables
Published: 2024

6. The NANOGrav 15 yr data set: Posterior predictive checks for gravitational-wave detection with pulsar timing arrays

Author: Agazie, Gabriella, Anumarlapudi, Akash, Archibald, Anne M., Arzoumanian, Zaven, Baier, Jeremy George, Baker, Paul T., Bécsy, Bence, Blecha, Laura, Brazier, Adam, Brook, Paul R., Burke-Spolaor, Sarah, Casey-Clyde, J. Andrew, Charisi, Maria, Chatterjee, Shami, Chatziioannou, Katerina, Cohen, Tyler, Cordes, James M., Cornish, Neil J., Crawford, Fronefield, Cromartie, H. Thankful, Crowter, Kathryn, DeCesar, Megan E., Demorest, Paul B., Deng, Heling, Dey, Lankeswar, Dolch, Timothy, Ferrara, Elizabeth C., Fiore, William, Fonseca, Emmanuel, Freedman, Gabriel E., Gardiner, Emiko C., Garver-Daniels, Nate, Gentile, Peter A., Gersbach, Kyle A., Glaser, Joseph, Good, Deborah C., Gültekin, Kayhan, Hazboun, Jeffrey S., Jennings, Ross J., Johnson, Aaron D., Jones, Megan L., Kaiser, Andrew R., Kaplan, David L., Kelley, Luke Zoltan, Kerr, Matthew, Key, Joey S., Laal, Nima, Lam, Michael T., Lamb, William G., Larsen, Bjorn, Lazio, T. Joseph W., Lewandowska, Natalia, Liu, Tingting, Lorimer, Duncan R., Luo, Jing, Lynch, Ryan S., Ma, Chung-Pei, Madison, Dustin R., McEwen, Alexander, McKee, James W., McLaughlin, Maura A., McMann, Natasha, Meyers, Bradley W., Meyers, Patrick M., Mingarelli, Chiara M. F., Mitridate, Andrea, Ng, Cherry, Nice, David J., Ocker, Stella Koch, Olum, Ken D., Pennucci, Timothy T., Perera, Benetge B. P., Pol, Nihan S., Radovan, Henri A., Ransom, Scott M., Ray, Paul S., Romano, Joseph D., Runnoe, Jessie C., Saffer, Alexander, Sardesai, Shashwat C., Schmiedekamp, Ann, Schmiedekamp, Carl, Schmitz, Kai, Shapiro-Albert, Brent J., Siemens, Xavier, Simon, Joseph, Siwek, Magdalena S., Fiscella, Sophia V. Sosa, Stairs, Ingrid H., Stinebring, Daniel R., Stovall, Kevin, Susobhanan, Abhimanyu, Swiggum, Joseph K., Taylor, Stephen R., Turner, Jacob E., Unal, Caner, Vallisneri, Michele, Vigeland, Sarah J., Wahl, Haley M., Witt, Caitlin A., Wright, David, and Young, Olivia
Subjects: Astrophysics - High Energy Astrophysical Phenomena, General Relativity and Quantum Cosmology
Abstract: Pulsar-timing-array experiments have reported evidence for a stochastic background of nanohertz gravitational waves consistent with the signal expected from a population of supermassive--black-hole binaries. Those analyses assume power-law spectra for intrinsic pulsar noise and for the background, as well as a Hellings--Downs cross-correlation pattern among the gravitational-wave--induced residuals across pulsars. These assumptions are idealizations that may not be realized in actuality. We test them in the NANOGrav 15 yr data set using Bayesian posterior predictive checks: after fitting our fiducial model to real data, we generate a population of simulated data-set replications, and use them to assess whether the optimal-statistic significance, inter-pulsar correlations, and spectral coefficients assume extreme values for the real data when compared to the replications. We confirm that the NANOGrav 15 yr data set is consistent with power-law and Hellings--Downs assumptions. We also evaluate the evidence for the stochastic background using posterior-predictive versions of the frequentist optimal statistic and of Bayesian model comparison, and find comparable significance (3.2\ $\sigma$ and 3\ $\sigma$ respectively) to what was previously reported for the standard statistics. We conclude with novel visualizations of the reconstructed gravitational waveforms that enter the residuals for each pulsar. Our analysis strengthens confidence in the identification and characterization of the gravitational-wave background as reported by NANOGrav., Comment: 20 pages, 14 Figures
Published: 2024

7. The NANOGrav 15 yr Data Set: Looking for Signs of Discreteness in the Gravitational-wave Background

Author: Agazie, Gabriella, Anumarlapudi, Akash, Archibald, Anne M., Arzoumanian, Zaven, Baier, Jeremy George, Baker, Paul T., Bécsy, Bence, Blecha, Laura, Brazier, Adam, Brook, Paul R., Brown, Lucas, Burke-Spolaor, Sarah, Casey-Clyde, J. Andrew, Charisi, Maria, Chatterjee, Shami, Cohen, Tyler, Cordes, James M., Cornish, Neil J., Crawford, Fronefield, Cromartie, H. Thankful, Crowter, Kathryn, DeCesar, Megan E., Demorest, Paul B., Deng, Heling, Dolch, Timothy, Ferrara, Elizabeth C., Fiore, William, Fonseca, Emmanuel, Freedman, Gabriel E., Garver-Daniels, Nate, Gentile, Peter A., Glaser, Joseph, Good, Deborah C., Gültekin, Kayhan, Hazboun, Jeffrey S., Jennings, Ross J., Johnson, Aaron D., Jones, Megan L., Kaiser, Andrew R., Kaplan, David L., Kelley, Luke Zoltan, Kerr, Matthew, Key, Joey S., Laal, Nima, Lam, Michael T., Lamb, William G., Larsen, Bjorn, Lazio, T. Joseph W., Lewandowska, Natalia, Liu, Tingting, Lorimer, Duncan R., Luo, Jing, Lynch, Ryan S., Ma, Chung-Pei, Madison, Dustin R., McEwen, Alexander, McKee, James W., McLaughlin, Maura A., McMann, Natasha, Meyers, Bradley W., Meyers, Patrick M., Mingarelli, Chiara M. F., Mitridate, Andrea, Natarajan, Priyamvada, Ng, Cherry, Nice, David J., Ocker, Stella Koch, Olum, Ken D., Pennucci, Timothy T., Perera, Benetge B. P., Pol, Nihan S., Radovan, Henri A., Ransom, Scott M., Ray, Paul S., Romano, Joseph D., Runnoe, Jessie C., Sardesai, Shashwat C., Schmiedekamp, Ann, Schmiedekamp, Carl, Schmitz, Kai, Shapiro-Albert, Brent, Siemens, Xavier, Simon, Joseph, Siwek, Magdalena S., Fiscella, Sophia V. Sosa, Stairs, Ingrid H., Stinebring, Daniel R., Stovall, Kevin, Susobhanan, Abhimanyu, Swiggum, Joseph K., Taylor, Stephen R., Turner, Jacob E., Unal, Caner, Vallisneri, Michele, Vigeland, Sarah J., Wahl, Haley M., Willson, London, Witt, Caitlin A., Wright, David, and Young, Olivia
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies
Abstract: The cosmic merger history of supermassive black hole binaries (SMBHBs) is expected to produce a low-frequency gravitational wave background (GWB). Here we investigate how signs of the discrete nature of this GWB can manifest in pulsar timing arrays through excursions from, and breaks in, the expected $f_{\mathrm{GW}}^{-2/3}$ power-law of the GWB strain spectrum. To do this, we create a semi-analytic SMBHB population model, fit to NANOGrav's 15 yr GWB amplitude, and with 1,000 realizations we study the populations' characteristic strain and residual spectra. Comparing our models to the NANOGrav 15 yr spectrum, we find two interesting excursions from the power-law. The first, at $2 \; \mathrm{nHz}$, is below our GWB realizations with $p$-value significance $p = 0.05$ to $0.06$ ($\approx 1.8 \sigma - 1.9 \sigma$). The second, at $16 \; \mathrm{nHz}$, is above our GWB realizations with $p = 0.04$ to $0.15$ ($\approx 1.4 \sigma - 2.1 \sigma$). We explore the properties of a loud SMBHB which could cause such an excursion. Our simulations also show that the expected number of SMBHBs decreases by three orders of magnitude, from $\sim 10^6$ to $\sim 10^3$, between $2\; \mathrm{nHz}$ and $20 \; \mathrm{nHz}$. This causes a break in the strain spectrum as the stochasticity of the background breaks down at $26^{+28}_{-19} \; \mathrm{nHz}$, consistent with predictions pre-dating GWB measurements. The diminished GWB signal from SMBHBs at frequencies above the $26~\mathrm{nHz}$ break opens a window for PTAs to detect continuous GWs from individual SMBHBs or GWs from the early universe., Comment: 13 pages, 8 figures, 2 appendices, in press at ApJ
Published: 2024
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8. The NANOGrav 15-year data set: Search for Transverse Polarization Modes in the Gravitational-Wave Background

Author: Agazie, Gabriella, Anumarlapudi, Akash, Archibald, Anne M., Arzoumanian, Zaven, Baier, Jeremy, Baker, Paul T., Bécsy, Bence, Blecha, Laura, Brazier, Adam, Brook, Paul R., Burke-Spolaor, Sarah, Burnette, Rand, Case, Robin, Casey-Clyde, J. Andrew, Charisi, Maria, Chatterjee, Shami, Cohen, Tyler, Cordes, James M., Cornish, Neil J., Crawford, Fronefield, Cromartie, H. Thankful, Crowter, Kathryn, DeCesar, Megan E., DeGan, Dallas, Demorest, Paul B., Dolch, Timothy, Drachler, Brendan, Ferrara, Elizabeth C., Fiore, William, Fonseca, Emmanuel, Freedman, Gabriel E., Garver-Daniels, Nate, Gentile, Peter A., Glaser, Joseph, Good, Deborah C., Gültekin, Kayhan, Hazboun, Jeffrey S., Jennings, Ross J., Johnson, Aaron D., Jones, Megan L., Kaiser, Andrew R., Kaplan, David L., Kelley, Luke Zoltan, Kerr, Matthew, Key, Joey S., Laal, Nima, Lam, Michael T., Lamb, William G., Lazio, T. Joseph W., Lewandowska, Natalia, Liu, Tingting, Lorimer, Duncan R., Luo, Jing, Lynch, Ryan S., Ma, Chung-Pei, Madison, Dustin R., McEwen, Alexander, McKee, James W., McLaughlin, Maura A., McMann, Natasha, Meyers, Bradley W., Mingarelli, Chiara M. F., Mitridate, Andrea, Natarajan, Priyamvada, Ng, Cherry, Nice, David J., Ocker, Stella Koch, Olum, Ken D., Pennucci, Timothy T., Perera, Benetge B. P., Pol, Nihan S., Radovan, Henri A., Ransom, Scott M., Ray, Paul S., Romano, Joseph D., Saffer, Alexander, Sardesai, Shashwat C., Schmiedekamp, Ann, Schmiedekamp, Carl, Schmitz, Kai, Shapiro-Albert, Brent J., Siemens, Xavier, Simon, Joseph, Siwek, Magdalena S., Stairs, Ingrid H., Stinebring, Daniel R., Stovall, Kevin, Sun, Jerry P., Susobhanan, Abhimanyu, Swiggum, Joseph K., Taylor, Jacob A., Taylor, Stephen R., Turner, E., Unal, Caner, Vallisneri, Michele, Vigeland, Sarah J., Wahl, Haley M., Witt, Caitlin A., and Young, Olivia
Subjects: General Relativity and Quantum Cosmology, Astrophysics - Astrophysics of Galaxies, Astrophysics - High Energy Astrophysical Phenomena
Abstract: Recently we found compelling evidence for a gravitational wave background with Hellings and Downs (HD) correlations in our 15-year data set. These correlations describe gravitational waves as predicted by general relativity, which has two transverse polarization modes. However, more general metric theories of gravity can have additional polarization modes which produce different interpulsar correlations. In this work we search the NANOGrav 15-year data set for evidence of a gravitational wave background with quadrupolar Hellings and Downs (HD) and Scalar Transverse (ST) correlations. We find that HD correlations are the best fit to the data, and no significant evidence in favor of ST correlations. While Bayes factors show strong evidence for a correlated signal, the data does not strongly prefer either correlation signature, with Bayes factors $\sim 2$ when comparing HD to ST correlations, and $\sim 1$ for HD plus ST correlations to HD correlations alone. However, when modeled alongside HD correlations, the amplitude and spectral index posteriors for ST correlations are uninformative, with the HD process accounting for the vast majority of the total signal. Using the optimal statistic, a frequentist technique that focuses on the pulsar-pair cross-correlations, we find median signal-to-noise-ratios of 5.0 for HD and 4.6 for ST correlations when fit for separately, and median signal-to-noise-ratios of 3.5 for HD and 3.0 for ST correlations when fit for simultaneously. While the signal-to-noise-ratios for each of the correlations are comparable, the estimated amplitude and spectral index for HD are a significantly better fit to the total signal, in agreement with our Bayesian analysis., Comment: 11 pages, 5 figures
Published: 2023

9. The NANOGrav 12.5-year data set: A computationally efficient eccentric binary search pipeline and constraints on an eccentric supermassive binary candidate in 3C 66B

Author: Agazie, Gabriella, Arzoumanian, Zaven, Baker, Paul T., Bécsy, Bence, Blecha, Laura, Blumer, Harsha, Brazier, Adam, Brook, Paul R., Burke-Spolaor, Sarah, Casey-Clyde, J. Andrew, Charisi, Maria, Chatterjee, Shami, Cheeseboro, Belinda D., Cohen, Tyler, Cordes, James M., Cornish, Neil J., Crawford, Fronefield, Cromartie, H. Thankful, DeCesar, Megan E., Demorest, Paul B., Dey, Lankeswar, Dolch, Timothy, Ellis, Justin A., Ferdman, Robert D., Ferrara, Elizabeth C., Fiore, William, Fonseca, Emmanuel, Freedman, Gabriel E., Garver-Daniels, Nate, Gentile, Peter A., Glaser, Joseph, Good, Deborah C., Gopakumar, Achamveedu, Gültekin, Kayhan, Hazboun, Jeffrey S., Jennings, Ross J., Johnson, Aaron D., Jones, Megan L., Kaiser, Andrew R., Kaplan, David L., Kelley, Luke Zoltan, Key, Joey S., Laal, Nima, Lam, Michael T., Lamb, William G., Lazio, T. Joseph W., Lewandowska, Natalia, Liu, Tingting, Lorimer, Duncan R., Luo, Jing, Lynch, Ryan S., Ma, Chung-Pei, Madison, Dustin R., McEwen, Alexander, McKee, James W., McLaughlin, Maura A., Meyers, Patrick M., Mingarelli, Chiara M. F., Mitridate, Andrea, Ng, Cherry, Nice, David J., Ocker, Stella Koch, Olum, Ken D., Pennucci, Timothy T., Pol, Nihan S., Radovan, Henri A., Ransom, Scott M., Ray, Paul S., Romano, Joseph D., Sardesai, Shashwat C., Schmitz, Kai, Siemens, Xavier, Simon, Joseph, Siwek, Magdalena S., Fiscella, Sophia V. Sosa, Spiewak, Renée, Stairs, Ingrid H., Stinebring, Daniel R., Stovall, Kevin, Susobhanan, Abhimanyu, Swiggum, Joseph K., Taylor, Stephen R., Turner, Jacob E., Unal, Caner, Vallisneri, Michele, Vigeland, Sarah J., Witt, Caitlin A., and Young, Olivia
Subjects: Astrophysics - High Energy Astrophysical Phenomena, General Relativity and Quantum Cosmology
Abstract: The radio galaxy 3C 66B has been hypothesized to host a supermassive black hole binary (SMBHB) at its center based on electromagnetic observations. Its apparent 1.05-year period and low redshift ($\sim0.02$) make it an interesting testbed to search for low-frequency gravitational waves (GWs) using Pulsar Timing Array (PTA) experiments. This source has been subjected to multiple searches for continuous GWs from a circular SMBHB, resulting in progressively more stringent constraints on its GW amplitude and chirp mass. In this paper, we develop a pipeline for performing Bayesian targeted searches for eccentric SMBHBs in PTA data sets, and test its efficacy by applying it on simulated data sets with varying injected signal strengths. We also search for a realistic eccentric SMBHB source in 3C 66B using the NANOGrav 12.5-year data set employing PTA signal models containing Earth term-only as well as Earth+Pulsar term contributions using this pipeline. Due to limitations in our PTA signal model, we get meaningful results only when the initial eccentricity $e_0<0.5$ and the symmetric mass ratio $\eta>0.1$. We find no evidence for an eccentric SMBHB signal in our data, and therefore place 95% upper limits on the PTA signal amplitude of $88.1\pm3.7$ ns for the Earth term-only and $81.74\pm0.86$ ns for the Earth+Pulsar term searches for $e_0<0.5$ and $\eta>0.1$. Similar 95% upper limits on the chirp mass are $(1.98 \pm 0.05) \times 10^9\,M_{\odot}$ and $(1.81 \pm 0.01) \times 10^9\,M_{\odot}$. These upper limits, while less stringent than those calculated from a circular binary search in the NANOGrav 12.5-year data set, are consistent with the SMBHB model of 3C 66B developed from electromagnetic observations., Comment: 27 Pages, 10 Figures, 1 Table, Accepted for publication in ApJ
Published: 2023
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10. How to Detect an Astrophysical Nanohertz Gravitational-Wave Background

Author: Bécsy, Bence, Cornish, Neil J., Meyers, Patrick M., Kelley, Luke Zoltan, Agazie, Gabriella, Anumarlapudi, Akash, Archibald, Anne M., Arzoumanian, Zaven, Baker, Paul T., Blecha, Laura, Brazier, Adam, Brook, Paul R., Burke-Spolaor, Sarah, Casey-Clyde, J. Andrew, Charisi, Maria, Chatterjee, Shami, Chatziioannou, Katerina, Cohen, Tyler, Cordes, James M., Crawford, Fronefield, Cromartie, H. Thankful, Crowter, Kathryn, DeCesar, Megan E., Demorest, Paul B., Dolch, Timothy, Ferrara, Elizabeth C., Fiore, William, Fonseca, Emmanuel, Freedman, Gabriel E., Garver-Daniels, Nate, Gentile, Peter A., Glaser, Joseph, Good, Deborah C., Gültekin, Kayhan, Hazboun, Jeffrey S., Hourihane, Sophie, Jennings, Ross J., Johnson, Aaron D., Jones, Megan L., Kaiser, Andrew R., Kaplan, David L., Kerr, Matthew, Key, Joey S., Laal, Nima, Lam, Michael T., Lamb, William G., Lazio, T. Joseph W., Lewandowska, Natalia, Littenberg, Tyson B., Liu, Tingting, Lorimer, Duncan R., Luo, Jing, Lynch, Ryan S., Ma, Chung-Pei, Madison, Dustin R., McEwen, Alexander, McKee, James W., McLaughlin, Maura A., McMann, Natasha, Meyers, Bradley W., Mingarelli, Chiara M. F., Mitridate, Andrea, Ng, Cherry, Nice, David J., Ocker, Stella Koch, Olum, Ken D., Pennucci, Timothy T., Perera, Benetge B. P., Pol, Nihan S., Radovan, Henri A., Ransom, Scott M., Ray, Paul S., Romano, Joseph D., Sardesai, Shashwat C., Schmiedekamp, Ann, Schmiedekamp, Carl, Schmitz, Kai, Shapiro-Albert, Brent J., Siemens, Xavier, Simon, Joseph, Siwek, Magdalena S., Fiscella, Sophia V. Sosa, Stairs, Ingrid H., Stinebring, Daniel R., Stovall, Kevin, Susobhanan, Abhimanyu, Swiggum, Joseph K., Taylor, Stephen R., Turner, Jacob E., Unal, Caner, Vallisneri, Michele, van Haasteren, Rutger, Vigeland, Sarah J., Wahl, Haley M., Witt, Caitlin A., and Young, Olivia
Subjects: General Relativity and Quantum Cosmology, Astrophysics - High Energy Astrophysical Phenomena
Abstract: Analysis of pulsar timing data have provided evidence for a stochastic gravitational wave background in the nHz frequency band. The most plausible source of such a background is the superposition of signals from millions of supermassive black hole binaries. The standard statistical techniques used to search for such a background and assess its significance make several simplifying assumptions, namely: i) Gaussianity; ii) isotropy; and most often iii) a power-law spectrum. However, a stochastic background from a finite collection of binaries does not exactly satisfy any of these assumptions. To understand the effect of these assumptions, we test standard analysis techniques on a large collection of realistic simulated datasets. The dataset length, observing schedule, and noise levels were chosen to emulate the NANOGrav 15-year dataset. Simulated signals from millions of binaries drawn from models based on the Illustris cosmological hydrodynamical simulation were added to the data. We find that the standard statistical methods perform remarkably well on these simulated datasets, despite their fundamental assumptions not being strictly met. They are able to achieve a confident detection of the background. However, even for a fixed set of astrophysical parameters, different realizations of the universe result in a large variance in the significance and recovered parameters of the background. We also find that the presence of loud individual binaries can bias the spectral recovery of the background if we do not account for them., Comment: 14 pages, 8 figures, version matching published paper
Published: 2023
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11. Fine tuning of CpG spatial distribution with DNA origami for improved cancer vaccination

Author: Zeng, Yang C., Young, Olivia J., Wintersinger, Christopher M., Anastassacos, Frances M., MacDonald, James I., Isinelli, Giorgia, Dellacherie, Maxence O., Sobral, Miguel, Bai, Haiqing, Graveline, Amanda R., Vernet, Andyna, Sanchez, Melinda, Mulligan, Kathleen, Choi, Youngjin, Ferrante, Thomas C., Keskin, Derin B., Fell, Geoffrey G., Neuberg, Donna, Wu, Catherine J., Mooney, David J., Kwon, Ick Chan, Ryu, Ju Hee, and Shih, William M.
Published: 2024
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12. The NANOGrav 12.5-year Data Set: Search for Gravitational Wave Memory

Author: Agazie, Gabriella, Arzoumanian, Zaven, Baker, Paul T., Bécsy, Bence, Blecha, Laura, Blumer, Harsha, Brazier, Adam, Brook, Paul R., Burke-Spolaor, Sarah, Burnette, Rand, Case, Robin, Casey-Clyde, J. Andrew, Charisi, Maria, Chatterjee, Shami, Cohen, Tyler, Cordes, James M., Cornish, Neil J., Crawford, Fronefield, Cromartie, H. Thankful, DeCesar, Megan E., DeGan, Dallas, Demorest, Paul B., Dolch, Timothy, Drachler, Brendan, Ellis, Justin A., Ferdman, Robert D., Ferrara, Elizabeth C., Fiore, William, Fonseca, Emmanuel, Freedman, Gabriel E., Garver-Daniels, Nate, Gentile, Peter A., Glaser, Joseph, Good, Deborah C., Gültekin, Kayhan, Hazboun, Jeffrey S., Jennings, Ross J., Johnson, Aaron D., Jones, Megan L., Kaiser, Andrew R., Kaplan, David L., Kelley, Luke Zoltan, Key, Joey S., Laal, Nima, Lam, Michael T., Lamb, William G., Lazio, T. Joseph W., Lewandowska, Natalia, Liu, Tingting, Lorimer, Duncan R., Luo, Jing, Lynch, Ryan S., Ma, Chung-Pei, Madison, Dustin R., McEwen, Alexander, McKee, James W., McLaughlin, Maura A., Meyers, Patrick M., Mingarelli, Chiara M. F., Mitridate, Andrea, Ng, Cherry, Nice, David J., Ocker, Stella Koch, Olum, Ken D., Pennucci, Timothy T., Pol, Nihan S., Ransom, Scott M., Ray, Paul S., Romano, Joseph D., Sardesai, Shashwat C., Schmitz, Kai, Siemens, Xavier, Simon, Joseph, Siwek, Magdalena S., Fiscella, Sophia V. Sosa, Spiewak, Renée, Stairs, Ingrid H., Stinebring, Daniel R., Stovall, Kevin, Sun, Jerry P., Swiggum, Joseph K., Taylor, Jacob, Taylor, Stephen R., Turner, Jacob E., Unal, Caner, Vallisneri, Michele, Vigeland, Sarah J., Wahl, Haley M., Witt, Caitlin A., and Young, Olivia
Subjects: General Relativity and Quantum Cosmology, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: We present the results of a Bayesian search for gravitational wave (GW) memory in the NANOGrav 12.5-yr data set. We find no convincing evidence for any gravitational wave memory signals in this data set (Bayes factor = 2.8). As such, we go on to place upper limits on the strain amplitude of GW memory events as a function of sky location and event epoch. These upper limits are computed using a signal model that assumes the existence of a common, spatially uncorrelated red noise in addition to a GW memory signal. The median strain upper limit as a function of sky position is approximately $3.3 \times 10^{-14}$. We also find that there are some differences in the upper limits as a function of sky position centered around PSR J0613$-$0200. This suggests that this pulsar has some excess noise which can be confounded with GW memory. Finally, the upper limits as a function of burst epoch continue to improve at later epochs. This improvement is attributable to the continued growth of the pulsar timing array., Comment: 29 pages, 5 figures
Published: 2023

13. The NANOGrav 15-year Gravitational-Wave Background Analysis Pipeline

Author: Johnson, Aaron D., Meyers, Patrick M., Baker, Paul T., Cornish, Neil J., Hazboun, Jeffrey S., Littenberg, Tyson B., Romano, Joseph D., Taylor, Stephen R., Vallisneri, Michele, Vigeland, Sarah J., Olum, Ken D., Siemens, Xavier, Ellis, Justin A., van Haasteren, Rutger, Hourihane, Sophie, Agazie, Gabriella, Anumarlapudi, Akash, Archibald, Anne M., Arzoumanian, Zaven, Blecha, Laura, Brazier, Adam, Brook, Paul R., Burke-Spolaor, Sarah, Bécsy, Bence, Casey-Clyde, J. Andrew, Charisi, Maria, Chatterjee, Shami, Chatziioannou, Katerina, Cohen, Tyler, Cordes, James M., Crawford, Fronefield, Cromartie, H. Thankful, Crowter, Kathryn, DeCesar, Megan E., Demorest, Paul B., Dolch, Timothy, Drachler, Brendan, Ferrara, Elizabeth C., Fiore, William, Fonseca, Emmanuel, Freedman, Gabriel E., Garver-Daniels, Nate, Gentile, Peter A., Glaser, Joseph, Good, Deborah C., Gültekin, Kayhan, Jennings, Ross J., Jones, Megan L., Kaiser, Andrew R., Kaplan, David L., Kelley, Luke Zoltan, Kerr, Matthew, Key, Joey S., Laal, Nima, Lam, Michael T., Lamb, William G., Lazio, T. Joseph W., Lewandowska, Natalia, Liu, Tingting, Lorimer, Duncan R., Lynch, Ryan S., Ma, Chung-Pei, Madison, Dustin R., McEwen, Alexander, McKee, James W., McLaughlin, Maura A., McMann, Natasha, Meyers, Bradley W., Mingarelli, Chiara M. F., Mitridate, Andrea, Ng, Cherry, Nice, David J., Ocker, Stella Koch, Pennucci, Timothy T., Perera, Benetge B. P., Pol, Nihan S., Radovan, Henri A., Ransom, Scott M., Ray, Paul S., Sardesai, Shashwat C., Schmiedekamp, Carl, Schmiedekamp, Ann, Schmitz, Kai, Shapiro-Albert, Brent J., Simon, Joseph, Siwek, Magdalena S., Stairs, Ingrid H., Stinebring, Daniel R., Stovall, Kevin, Susobhanan, Abhimanyu, Swiggum, Joseph K., Turner, Jacob E., Unal, Caner, Wahl, Haley M., Witt, Caitlin A., and Young, Olivia
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, General Relativity and Quantum Cosmology
Abstract: This paper presents rigorous tests of pulsar timing array methods and software, examining their consistency across a wide range of injected parameters and signal strength. We discuss updates to the 15-year isotropic gravitational-wave background analyses and their corresponding code representations. Descriptions of the internal structure of the flagship algorithms \texttt{Enterprise} and \texttt{PTMCMCSampler} are given to facilitate understanding of the PTA likelihood structure, how models are built, and what methods are currently used in sampling the high-dimensional PTA parameter space. We introduce a novel version of the PTA likelihood that uses a two-step marginalization procedure that performs much faster when the white noise parameters remain fixed. We perform stringent tests of consistency and correctness of the Bayesian and frequentist analysis software. For the Bayesian analysis, we test prior recovery, injection recovery, and Bayes factors. For the frequentist analysis, we test that the cross-correlation-based optimal statistic, when modified to account for a non-negligible gravitational-wave background, accurately recovers the amplitude of the background. We also summarize recent advances and tests performed on the optimal statistic in the literature from both GWB detection and parameter estimation perspectives. The tests presented here validate current and future analyses of PTA data., Comment: 30 pages, 10 figures, 1 table; Companion paper to "The NANOGrav 15-year Data Set: Evidence for a Gravitational-Wave Background"; For questions or comments, please email comments@nanograv.org
Published: 2023

14. The NANOGrav 15-year Data Set: Bayesian Limits on Gravitational Waves from Individual Supermassive Black Hole Binaries

Author: Agazie, Gabriella, Anumarlapudi, Akash, Archibald, Anne M., Arzoumanian, Zaven, Baker, Paul T., Bécsy, Bence, Blecha, Laura, Brazier, Adam, Brook, Paul R., Burke-Spolaor, Sarah, Case, Robin, Casey-Clyde, J. Andrew, Charisi, Maria, Chatterjee, Shami, Cohen, Tyler, Cordes, James M., Cornish, Neil, Crawford, Fronefield, Cromartie, H. Thankful, Crowter, Kathryn, DeCesar, Megan, Demorest, Paul B., Digman, Matthew C., Dolch, Timothy, Drachler, Brendan, Ferrara, Elizabeth C., Fiore, William, Fonseca, Emmanuel, Freedman, Gabriel, Garver-Daniels, Nathaniel, Gentile, Peter, Glaser, Joseph, Good, Deborah, Gültekin, Kayhan, Hazboun, Jeffrey, Hourihane, Sophie, Jennings, Ross, Johnson, Aaron D., Jones, Megan, Kaiser, Andrew R., Kaplan, David, Kelley, Luke Zoltan, Kerr, Matthew, Key, Joey, Laal, Nima, Lam, Michael, Lamb, William G., Lazio, T. Joseph W., Lewandowska, Natalia, Liu, Tingting, Lorimer, Duncan R., Luo, Jing Santiago, Lynch, Ryan S., Ma, Chung-Pei, Madison, Dustin, McEwen, Alexander, McKee, James W., McLaughlin, Maura, McMann, Natasha, Meyers, Bradley W., Meyers, Patrick M., Mingarelli, Chiara M. F., mitridate, andrea, natarajan, priya, Ng, Cherry, Nice, David, Ocker, Stella Koch, Olum, Ken, Pennucci, Timothy T., Perera, Benetge, Petrov, Polina, Pol, Nihan, Radovan, Henri A., Ransom, Scott, Ray, Paul S., Romano, Joseph, Sardesai, Shashwat C., Schmiedekamp, Ann, Schmiedekamp, Carl, Schmitz, Kai, Shapiro-Albert, Brent J., Siemens, Xavier, Simon, Joseph, Siwek, Magdalena, Stairs, Ingrid, Stinebring, Dan, Stovall, Kevin, Susobhanan, Abhimanyu, Swiggum, Joseph, Taylor, Jacob, Taylor, Stephen, Turner, Jacob E., Unal, Caner, Vallisneri, Michele, van Haasteren, Rutger, Vigeland, Sarah J., Wahl, Haley M., Witt, Caitlin, and Young, Olivia
Subjects: Astrophysics - High Energy Astrophysical Phenomena, General Relativity and Quantum Cosmology
Abstract: Evidence for a low-frequency stochastic gravitational wave background has recently been reported based on analyses of pulsar timing array data. The most likely source of such a background is a population of supermassive black hole binaries, the loudest of which may be individually detected in these datasets. Here we present the search for individual supermassive black hole binaries in the NANOGrav 15-year dataset. We introduce several new techniques, which enhance the efficiency and modeling accuracy of the analysis. The search uncovered weak evidence for two candidate signals, one with a gravitational-wave frequency of $\sim$4 nHz, and another at $\sim$170 nHz. The significance of the low-frequency candidate was greatly diminished when Hellings-Downs correlations were included in the background model. The high-frequency candidate was discounted due to the lack of a plausible host galaxy, the unlikely astrophysical prior odds of finding such a source, and since most of its support comes from a single pulsar with a commensurate binary period. Finding no compelling evidence for signals from individual binary systems, we place upper limits on the strain amplitude of gravitational waves emitted by such systems., Comment: 23 pages, 13 figures, 2 tables. Accepted for publication in Astrophysical Journal Letters as part of Focus on NANOGrav's 15-year Data Set and the Gravitational Wave Background. For questions or comments, please email comments@nanograv.org
Published: 2023
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15. The NANOGrav 15-year Data Set: Search for Anisotropy in the Gravitational-Wave Background

Author: Agazie, Gabriella, Anumarlapudi, Akash, Archibald, Anne M., Arzoumanian, Zaven, Baker, Paul T., Bécsy, Bence, Blecha, Laura, Brazier, Adam, Brook, Paul R., Burke-Spolaor, Sarah, Casey-Clyde, J. Andrew, Charisi, Maria, Chatterjee, Shami, Cohen, Tyler, Cordes, James M., Cornish, Neil J., Crawford, Fronefield, Cromartie, H. Thankful, Crowter, Kathryn, DeCesar, Megan E., Demorest, Paul B., Dolch, Timothy, Drachler, Brendan, Ferrara, Elizabeth C., Fiore, William, Fonseca, Emmanuel, Freedman, Gabriel E., Gardiner, Emiko, Garver-Daniels, Nate, Gentile, Peter A., Glaser, Joseph, Good, Deborah C., Gültekin, Kayhan, Hazboun, Jeffrey S., Jennings, Ross J., Johnson, Aaron D., Jones, Megan L., Kaiser, Andrew R., Kaplan, David L., Kelley, Luke Zoltan, Kerr, Matthew, Key, Joey S., Laal, Nima, Lam, Michael T., Lamb, William G., Lazio, T. Joseph W., Lewandowska, Natalia, Liu, Tingting, Lorimer, Duncan R., Luo, Jing, Lynch, Ryan S., Ma, Chung-Pei, Madison, Dustin R., McEwen, Alexander, McKee, James W., McLaughlin, Maura A., McMann, Natasha, Meyers, Bradley W., Mingarelli, Chiara M. F., Mitridate, Andrea, Ng, Cherry, Nice, David J., Ocker, Stella Koch, Olum, Ken D., Pennucci, Timothy T., Perera, Benetge B. P., Pol, Nihan S., Radovan, Henri A., Ransom, Scott M., Ray, Paul S., Romano, Joseph D., Sardesai, Shashwat C., Schmiedekamp, Ann, Schmiedekamp, Carl, Schmitz, Kai, Schult, Levi, Shapiro-Albert, Brent J., Siemens, Xavier, Simon, Joseph, Siwek, Magdalena S., Stairs, Ingrid H., Stinebring, Daniel R., Stovall, Kevin, Susobhanan, Abhimanyu, Swiggum, Joseph K., Taylor, Stephen R., Turner, Jacob E., Unal, Caner, Vallisneri, Michele, Vigeland, Sarah J., Wahl, Haley M., Witt, Caitlin A., and Young, Olivia
Subjects: Astrophysics - High Energy Astrophysical Phenomena, General Relativity and Quantum Cosmology
Abstract: The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has reported evidence for the presence of an isotropic nanohertz gravitational wave background (GWB) in its 15 yr dataset. However, if the GWB is produced by a population of inspiraling supermassive black hole binary (SMBHB) systems, then the background is predicted to be anisotropic, depending on the distribution of these systems in the local Universe and the statistical properties of the SMBHB population. In this work, we search for anisotropy in the GWB using multiple methods and bases to describe the distribution of the GWB power on the sky. We do not find significant evidence of anisotropy, and place a Bayesian $95\%$ upper limit on the level of broadband anisotropy such that $(C_{l>0} / C_{l=0}) < 20\%$. We also derive conservative estimates on the anisotropy expected from a random distribution of SMBHB systems using astrophysical simulations conditioned on the isotropic GWB inferred in the 15-yr dataset, and show that this dataset has sufficient sensitivity to probe a large fraction of the predicted level of anisotropy. We end by highlighting the opportunities and challenges in searching for anisotropy in pulsar timing array data., Comment: 19 pages, 11 figures; submitted to Astrophysical Journal Letters as part of Focus on NANOGrav's 15-year Data Set and the Gravitational Wave Background. For questions or comments, please email comments@nanograv.org
Published: 2023

16. The NANOGrav 15-year Data Set: Constraints on Supermassive Black Hole Binaries from the Gravitational Wave Background

Author: Agazie, Gabriella, Anumarlapudi, Akash, Archibald, Anne M., Baker, Paul T., Bécsy, Bence, Blecha, Laura, Bonilla, Alexander, Brazier, Adam, Brook, Paul R., Burke-Spolaor, Sarah, Burnette, Rand, Case, Robin, Casey-Clyde, J. Andrew, Charisi, Maria, Chatterjee, Shami, Chatziioannou, Katerina, Cheeseboro, Belinda D., Chen, Siyuan, Cohen, Tyler, Cordes, James M., Cornish, Neil J., Crawford, Fronefield, Cromartie, H. Thankful, Crowter, Kathryn, Cutler, Curt J., D'Orazio, Daniel J., DeCesar, Megan E., DeGan, Dallas, Demorest, Paul B., Deng, Heling, Dolch, Timothy, Drachler, Brendan, Ferrara, Elizabeth C., Fiore, William, Fonseca, Emmanuel, Freedman, Gabriel E., Gardiner, Emiko, Garver-Daniels, Nate, Gentile, Peter A., Gersbach, Kyle A., Glaser, Joseph, Good, Deborah C., Gültekin, Kayhan, Hazboun, Jeffrey S., Hourihane, Sophie, Islo, Kristina, Jennings, Ross J., Johnson, Aaron, Jones, Megan L., Kaiser, Andrew R., Kaplan, David L., Kelley, Luke Zoltan, Kerr, Matthew, Key, Joey S., Laal, Nima, Lam, Michael T., Lamb, William G., Lazio, T. Joseph W., Lewandowska, Natalia, Littenberg, Tyson B., Liu, Tingting, Luo, Jing, Lynch, Ryan S., Ma, Chung-Pei, Madison, Dustin R., McEwen, Alexander, McKee, James W., McLaughlin, Maura A., McMann, Natasha, Meyers, Bradley W., Meyers, Patrick M., Mingarelli, Chiara M. F., Mitridate, Andrea, Natarajan, Priyamvada, Ng, Cherry, Nice, David J., Ocker, Stella Koch, Olum, Ken D., Pennucci, Timothy T., Perera, Benetge B. P., Petrov, Polina, Pol, Nihan S., Radovan, Henri A., Ransom, Scott M., Ray, Paul S., Romano, Joseph D., Runnoe, Jessie C., Sardesai, Shashwat C., Schmiedekamp, Ann, Schmiedekamp, Carl, Schmitz, Kai, Schult, Levi, Shapiro-Albert, Brent J., Siemens, Xavier, Simon, Joseph, Siwek, Magdalena S., Stairs, Ingrid H., Stinebring, Daniel R., Stovall, Kevin, Sun, Jerry P., Susobhanan, Abhimanyu, Swiggum, Joseph K., Taylor, Jacob, Taylor, Stephen R., Turner, Jacob E., Unal, Caner, Vallisneri, Michele, Vigeland, Sarah J., Wachter, Jeremy M., Wahl, Haley M., Wang, Qiaohong, Witt, Caitlin A., Wright, David, and Young, Olivia
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics, General Relativity and Quantum Cosmology
Abstract: The NANOGrav 15-year data set shows evidence for the presence of a low-frequency gravitational-wave background (GWB). While many physical processes can source such low-frequency gravitational waves, here we analyze the signal as coming from a population of supermassive black hole (SMBH) binaries distributed throughout the Universe. We show that astrophysically motivated models of SMBH binary populations are able to reproduce both the amplitude and shape of the observed low-frequency gravitational-wave spectrum. While multiple model variations are able to reproduce the GWB spectrum at our current measurement precision, our results highlight the importance of accurately modeling binary evolution for producing realistic GWB spectra. Additionally, while reasonable parameters are able to reproduce the 15-year observations, the implied GWB amplitude necessitates either a large number of parameters to be at the edges of expected values, or a small number of parameters to be notably different from standard expectations. While we are not yet able to definitively establish the origin of the inferred GWB signal, the consistency of the signal with astrophysical expectations offers a tantalizing prospect for confirming that SMBH binaries are able to form, reach sub-parsec separations, and eventually coalesce. As the significance grows over time, higher-order features of the GWB spectrum will definitively determine the nature of the GWB and allow for novel constraints on SMBH populations., Comment: Accepted by Astrophysical Journal Letters as part of Focus on NANOGrav's 15-year Data Set and the Gravitational Wave Background. For questions or comments, please email comments@nanograv.org. Edited to fix two equation typos (Eq.13 & 21), and minor text typos
Published: 2023
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17. The NANOGrav 15-year Data Set: Search for Signals from New Physics

Author: Afzal, Adeela, Agazie, Gabriella, Anumarlapudi, Akash, Archibald, Anne M., Arzoumanian, Zaven, Baker, Paul T., Bécsy, Bence, Blanco-Pillado, Jose Juan, Blecha, Laura, Boddy, Kimberly K., Brazier, Adam, Brook, Paul R., Burke-Spolaor, Sarah, Burnette, Rand, Case, Robin, Charisi, Maria, Chatterjee, Shami, Chatziioannou, Katerina, Cheeseboro, Belinda D., Chen, Siyuan, Cohen, Tyler, Cordes, James M., Cornish, Neil J., Crawford, Fronefield, Cromartie, H. Thankful, Crowter, Kathryn, Cutler, Curt J., DeCesar, Megan E., DeGan, Dallas, Demorest, Paul B., Deng, Heling, Dolch, Timothy, Drachler, Brendan, von Eckardstein, Richard, Ferrara, Elizabeth C., Fiore, William, Fonseca, Emmanuel, Freedman, Gabriel E., Garver-Daniels, Nate, Gentile, Peter A., Gersbach, Kyle A., Glaser, Joseph, Good, Deborah C., Guertin, Lydia, Gültekin, Kayhan, Hazboun, Jeffrey S., Hourihane, Sophie, Islo, Kristina, Jennings, Ross J., Johnson, Aaron D., Jones, Megan L., Kaiser, Andrew R., Kaplan, David L., Kelley, Luke Zoltan, Kerr, Matthew, Key, Joey S., Laal, Nima, Lam, Michael T., Lamb, William G., Lazio, T. Joseph W., Lee, Vincent S. H., Lewandowska, Natalia, Santos, Rafael R. Lino dos, Littenberg, Tyson B., Liu, Tingting, Lorimer, Duncan R., Luo, Jing, Lynch, Ryan S., Ma, Chung-Pei, Madison, Dustin R., McEwen, Alexander, McKee, James W., McLaughlin, Maura A., McMann, Natasha, Meyers, Bradley W., Meyers, Patrick M., Mingarelli, Chiara M. F., Mitridate, Andrea, Nay, Jonathan, Natarajan, Priyamvada, Ng, Cherry, Nice, David J., Ocker, Stella Koch, Olum, Ken D., Pennucci, Timothy T., Perera, Benetge B. P., Petrov, Polina, Pol, Nihan S., Radovan, Henri A., Ransom, Scott M., Ray, Paul S., Romano, Joseph D., Sardesai, Shashwat C., Schmiedekamp, Ann, Schmiedekamp, Carl, Schmitz, Kai, Schröder, Tobias, Schult, Levi, Shapiro-Albert, Brent J., Siemens, Xavier, Simon, Joseph, Siwek, Magdalena S., Stairs, Ingrid H., Stinebring, Daniel R., Stovall, Kevin, Stratmann, Peter, Sun, Jerry P., Susobhanan, Abhimanyu, Swiggum, Joseph K., Taylor, Jacob, Taylor, Stephen R., Trickle, Tanner, Turner, Jacob E., Unal, Caner, Vallisneri, Michele, Verma, Sonali, Vigeland, Sarah J., Wahl, Haley M., Wang, Qiaohong, Witt, Caitlin A., Wright, David, Young, Olivia, and Zurek, Kathryn M.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics, General Relativity and Quantum Cosmology, High Energy Physics - Phenomenology
Abstract: The 15-year pulsar timing data set collected by the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) shows positive evidence for the presence of a low-frequency gravitational-wave (GW) background. In this paper, we investigate potential cosmological interpretations of this signal, specifically cosmic inflation, scalar-induced GWs, first-order phase transitions, cosmic strings, and domain walls. We find that, with the exception of stable cosmic strings of field theory origin, all these models can reproduce the observed signal. When compared to the standard interpretation in terms of inspiraling supermassive black hole binaries (SMBHBs), many cosmological models seem to provide a better fit resulting in Bayes factors in the range from 10 to 100. However, these results strongly depend on modeling assumptions about the cosmic SMBHB population and, at this stage, should not be regarded as evidence for new physics. Furthermore, we identify excluded parameter regions where the predicted GW signal from cosmological sources significantly exceeds the NANOGrav signal. These parameter constraints are independent of the origin of the NANOGrav signal and illustrate how pulsar timing data provide a new way to constrain the parameter space of these models. Finally, we search for deterministic signals produced by models of ultralight dark matter (ULDM) and dark matter substructures in the Milky Way. We find no evidence for either of these signals and thus report updated constraints on these models. In the case of ULDM, these constraints outperform torsion balance and atomic clock constraints for ULDM coupled to electrons, muons, or gluons., Comment: 74 pages, 31 figures, 4 tables; published in Astrophysical Journal Letters as part of Focus on NANOGrav's 15-year Data Set and the Gravitational Wave Background. For questions or comments, please email comments@nanograv.org
Published: 2023
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18. The NANOGrav 15-Year Data Set: Detector Characterization and Noise Budget

Author: Agazie, Gabriella, Anumarlapudi, Akash, Archibald, Anne M., Arzoumanian, Zaven, Baker, Paul T., Bécsy, Bence, Blecha, Laura, Brazier, Adam, Brook, Paul R., Burke-Spolaor, Sarah, Charisi, Maria, Chatterjee, Shami, Cohen, Tyler, Cordes, James M., Cornish, Neil J., Crawford, Fronefield, Cromartie, H. Thankful, Crowter, Kathryn, Decesar, Megan E., Demorest, Paul B., Dolch, Timothy, Drachler, Brendan, Ferrara, Elizabeth C., Fiore, William, Fonseca, Emmanuel, Freedman, Gabriel E., Garver-Daniels, Nate, Gentile, Peter A., Glaser, Joseph, Good, Deborah C., Guertin, Lydia, Gültekin, Kayhan, Hazboun, Jeffrey S., Jennings, Ross J., Johnson, Aaron D., Jones, Megan L., Kaiser, Andrew R., Kaplan, David L., Kelley, Luke Zoltan, Kerr, Matthew, Key, Joey S., Laal, Nima, Lam, Michael T., Lamb, William G., Lazio, T. Joseph W., Lewandowska, Natalia, Liu, Tingting, Lorimer, Duncan R., Luo, Jing, Lynch, Ryan S., Ma, Chung-Pei, Madison, Dustin R., Mcewen, Alexander, Mckee, James W., Mclaughlin, Maura A., Mcmann, Natasha, Meyers, Bradley W., Mingarelli, Chiara M. F., Mitridate, Andrea, Ng, Cherry, Nice, David J., Ocker, Stella Koch, Olum, Ken D., Pennucci, Timothy T., Perera, Benetge B. P., Pol, Nihan S., Radovan, Henri A., Ransom, Scott M., Ray, Paul S., Romano, Joseph D., Sardesai, Shashwat C., Schmiedekamp, Ann, Schmiedekamp, Carl, Schmitz, Kai, Shapiro-Albert, Brent J., Siemens, Xavier, Simon, Joseph, Siwek, Magdalena S., Stairs, Ingrid H., Stinebring, Daniel R., Stovall, Kevin, Susobhanan, Abhimanyu, Swiggum, Joseph K., Taylor, Stephen R., Turner, Jacob E., Unal, Caner, Vallisneri, Michele, Vigeland, Sarah J., Wahl, Haley M., Witt, Caitlin A., and Young, Olivia
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics, Astrophysics - Astrophysics of Galaxies, Astrophysics - Instrumentation and Methods for Astrophysics, General Relativity and Quantum Cosmology
Abstract: Pulsar timing arrays (PTAs) are galactic-scale gravitational wave detectors. Each individual arm, composed of a millisecond pulsar, a radio telescope, and a kiloparsecs-long path, differs in its properties but, in aggregate, can be used to extract low-frequency gravitational wave (GW) signals. We present a noise and sensitivity analysis to accompany the NANOGrav 15-year data release and associated papers, along with an in-depth introduction to PTA noise models. As a first step in our analysis, we characterize each individual pulsar data set with three types of white noise parameters and two red noise parameters. These parameters, along with the timing model and, particularly, a piecewise-constant model for the time-variable dispersion measure, determine the sensitivity curve over the low-frequency GW band we are searching. We tabulate information for all of the pulsars in this data release and present some representative sensitivity curves. We then combine the individual pulsar sensitivities using a signal-to-noise-ratio statistic to calculate the global sensitivity of the PTA to a stochastic background of GWs, obtaining a minimum noise characteristic strain of $7\times 10^{-15}$ at 5 nHz. A power law-integrated analysis shows rough agreement with the amplitudes recovered in NANOGrav's 15-year GW background analysis. While our phenomenological noise model does not model all known physical effects explicitly, it provides an accurate characterization of the noise in the data while preserving sensitivity to multiple classes of GW signals., Comment: 67 pages, 73 figures, 3 tables; published in Astrophysical Journal Letters as part of Focus on NANOGrav's 15-year Data Set and the Gravitational Wave Background. For questions or comments, please email comments@nanograv.org
Published: 2023
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19. The NANOGrav 15-year Data Set: Observations and Timing of 68 Millisecond Pulsars

Author: Agazie, Gabriella, Alam, Md Faisal, Anumarlapudi, Akash, Archibald, Anne M., Arzoumanian, Zaven, Baker, Paul T., Blecha, Laura, Bonidie, Victoria, Brazier, Adam, Brook, Paul R., Burke-Spolaor, Sarah, Bécsy, Bence, Chapman, Christopher, Charisi, Maria, Chatterjee, Shami, Cohen, Tyler, Cordes, James M., Cornish, Neil J., Crawford, Fronefield, Cromartie, H. Thankful, Crowter, Kathryn, DeCesar, Megan E., Demorest, Paul B., Dolch, Timothy, Drachler, Brendan, Ferrara, Elizabeth C., Fiore, William, Fonseca, Emmanuel, Freedman, Gabriel E., Garver-Daniels, Nate, Gentile, Peter A., Glaser, Joseph, Good, Deborah C., Gültekin, Kayhan, Hazboun, Jeffrey S., Jennings, Ross J., Jessup, Cody, Johnson, Aaron D., Jones, Megan L., Kaiser, Andrew R., Kaplan, David L., Kelley, Luke Zoltan, Kerr, Matthew, Key, Joey S., Kuske, Anastasia, Laal, Nima, Lam, Michael T., Lamb, William G., Lazio, T. Joseph W., Lewandowska, Natalia, Lin, Ye, Liu, Tingting, Lorimer, Duncan R., Luo, Jing, Lynch, Ryan S., Ma, Chung-Pei, Madison, Dustin R., Maraccini, Kaleb, McEwen, Alexander, McKee, James W., McLaughlin, Maura A., McMann, Natasha, Meyers, Bradley W., Mingarelli, Chiara M. F., Mitridate, Andrea, Ng, Cherry, Nice, David J., Ocker, Stella Koch, Olum, Ken D., Panciu, Elisa, Pennucci, Timothy T., Perera, Benetge B. P., Pol, Nihan S., Radovan, Henri A., Ransom, Scott M., Ray, Paul S., Romano, Joseph D., Salo, Laura, Sardesai, Shashwat C., Schmiedekamp, Carl, Schmiedekamp, Ann, Schmitz, Kai, Shapiro-Albert, Brent J., Siemens, Xavier, Simon, Joseph, Siwek, Magdalena S., Stairs, Ingrid H., Stinebring, Daniel R., Stovall, Kevin, Susobhanan, Abhimanyu, Swiggum, Joseph K., Taylor, Stephen R., Turner, Jacob E., Unal, Caner, Vallisneri, Michele, Vigeland, Sarah J., Wahl, Haley M., Wang, Qiaohong, Witt, Caitlin A., and Young, Olivia
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: We present observations and timing analyses of 68 millisecond pulsars (MSPs) comprising the 15-year data set of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav). NANOGrav is a pulsar timing array (PTA) experiment that is sensitive to low-frequency gravitational waves. This is NANOGrav's fifth public data release, including both "narrowband" and "wideband" time-of-arrival (TOA) measurements and corresponding pulsar timing models. We have added 21 MSPs and extended our timing baselines by three years, now spanning nearly 16 years for some of our sources. The data were collected using the Arecibo Observatory, the Green Bank Telescope, and the Very Large Array between frequencies of 327 MHz and 3 GHz, with most sources observed approximately monthly. A number of notable methodological and procedural changes were made compared to our previous data sets. These improve the overall quality of the TOA data set and are part of the transition to new pulsar timing and PTA analysis software packages. For the first time, our data products are accompanied by a full suite of software to reproduce data reduction, analysis, and results. Our timing models include a variety of newly detected astrometric and binary pulsar parameters, including several significant improvements to pulsar mass constraints. We find that the time series of 23 pulsars contain detectable levels of red noise, 10 of which are new measurements. In this data set, we find evidence for a stochastic gravitational-wave background., Comment: 90 pages, 74 figures, 6 tables; published in Astrophysical Journal Letters as part of Focus on NANOGrav's 15-year Data Set and the Gravitational Wave Background. For questions or comments, please email comments@nanograv.org
Published: 2023
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20. The NANOGrav 15-year Data Set: Evidence for a Gravitational-Wave Background

Author: Agazie, Gabriella, Anumarlapudi, Akash, Archibald, Anne M., Arzoumanian, Zaven, Baker, Paul T., Becsy, Bence, Blecha, Laura, Brazier, Adam, Brook, Paul R., Burke-Spolaor, Sarah, Burnette, Rand, Case, Robin, Charisi, Maria, Chatterjee, Shami, Chatziioannou, Katerina, Cheeseboro, Belinda D., Chen, Siyuan, Cohen, Tyler, Cordes, James M., Cornish, Neil J., Crawford, Fronefield, Cromartie, H. Thankful, Crowter, Kathryn, Cutler, Curt J., DeCesar, Megan E., DeGan, Dallas, Demorest, Paul B., Deng, Heling, Dolch, Timothy, Drachler, Brendan, Ellis, Justin A., Ferrara, Elizabeth C., Fiore, William, Fonseca, Emmanuel, Freedman, Gabriel E., Garver-Daniels, Nate, Gentile, Peter A., Gersbach, Kyle A., Glaser, Joseph, Good, Deborah C., Gultekin, Kayhan, Hazboun, Jeffrey S., Hourihane, Sophie, Islo, Kristina, Jennings, Ross J., Johnson, Aaron D., Jones, Megan L., Kaiser, Andrew R., Kaplan, David L., Kelley, Luke Zoltan, Kerr, Matthew, Key, Joey S., Klein, Tonia C., Laal, Nima, Lam, Michael T., Lamb, William G., Lazio, T. Joseph W., Lewandowska, Natalia, Littenberg, Tyson B., Liu, Tingting, Lommen, Andrea, Lorimer, Duncan R., Luo, Jing, Lynch, Ryan S., Ma, Chung-Pei, Madison, Dustin R., Mattson, Margaret A., McEwen, Alexander, McKee, James W., McLaughlin, Maura A., McMann, Natasha, Meyers, Bradley W., Meyers, Patrick M., Mingarelli, Chiara M. F., Mitridate, Andrea, Natarajan, Priyamvada, Ng, Cherry, Nice, David J., Ocker, Stella Koch, Olum, Ken D., Pennucci, Timothy T., Perera, Benetge B. P., Petrov, Polina, Pol, Nihan S., Radovan, Henri A., Ransom, Scott M., Ray, Paul S., Romano, Joseph D., Sardesai, Shashwat C., Schmiedekamp, Ann, Schmiedekamp, Carl, Schmitz, Kai, Schult, Levi, Shapiro-Albert, Brent J., Siemens, Xavier, Simon, Joseph, Siwek, Magdalena S., Stairs, Ingrid H., Stinebring, Daniel R., Stovall, Kevin, Sun, Jerry P., Susobhanan, Abhimanyu, Swiggum, Joseph K., Taylor, Jacob, Taylor, Stephen R., Turner, Jacob E., Unal, Caner, Vallisneri, Michele, van Haasteren, Rutger, Vigeland, Sarah J., Wahl, Haley M., Wang, Qiaohong, Witt, Caitlin A., and Young, Olivia
Subjects: Astrophysics - High Energy Astrophysical Phenomena, General Relativity and Quantum Cosmology
Abstract: We report multiple lines of evidence for a stochastic signal that is correlated among 67 pulsars from the 15-year pulsar-timing data set collected by the North American Nanohertz Observatory for Gravitational Waves. The correlations follow the Hellings-Downs pattern expected for a stochastic gravitational-wave background. The presence of such a gravitational-wave background with a power-law-spectrum is favored over a model with only independent pulsar noises with a Bayes factor in excess of $10^{14}$, and this same model is favored over an uncorrelated common power-law-spectrum model with Bayes factors of 200-1000, depending on spectral modeling choices. We have built a statistical background distribution for these latter Bayes factors using a method that removes inter-pulsar correlations from our data set, finding $p = 10^{-3}$ (approx. $3\sigma$) for the observed Bayes factors in the null no-correlation scenario. A frequentist test statistic built directly as a weighted sum of inter-pulsar correlations yields $p = 5 \times 10^{-5} - 1.9 \times 10^{-4}$ (approx. $3.5 - 4\sigma$). Assuming a fiducial $f^{-2/3}$ characteristic-strain spectrum, as appropriate for an ensemble of binary supermassive black-hole inspirals, the strain amplitude is $2.4^{+0.7}_{-0.6} \times 10^{-15}$ (median + 90% credible interval) at a reference frequency of 1/(1 yr). The inferred gravitational-wave background amplitude and spectrum are consistent with astrophysical expectations for a signal from a population of supermassive black-hole binaries, although more exotic cosmological and astrophysical sources cannot be excluded. The observation of Hellings-Downs correlations points to the gravitational-wave origin of this signal., Comment: 30 pages, 18 figures. Published in Astrophysical Journal Letters as part of Focus on NANOGrav's 15-year Data Set and the Gravitational Wave Background. For questions or comments, please email comments@nanograv.org
Published: 2023
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21. Redeveloping a CLEAN Deconvolution Algorithm for Scatter-Broadened Radio Pulsar Signals

Author: Young, Olivia and Lam, Michael
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Broadband radio waves emitted from pulsars are distorted and delayed as they propagate toward the Earth due to interactions with the free electrons that compose the interstellar medium, with lower radio frequencies being more impacted than higher frequencies. Multipath propagation in the interstellar medium results in both later times of arrival for the lower frequencies and causes the observed pulse to arrive with a broadened tail described via the pulse broadening function. We employ the CLEAN deconvolution technique to recover both the intrinsic pulse shape and pulse broadening function. This work expands upon previous descriptions of CLEAN deconvolution used in pulse broadening analyses by parameterizing the efficacy on simulated data and developing a suite of tests to establish which of a set of figures of merit lead to an automatic and consistent determination of the scattering timescale and its uncertainty. We compare our algorithm to simulations performed on cyclic spectroscopy estimates of the scattering timescale. We test our improved algorithm on the highly scattered millisecond pulsar J1903+0327, showing the scattering timescale to change over years, consistent with estimates of the refractive timescale of the pulsar.
Published: 2023

22. The NANOGrav 12.5-year Data Set: Bayesian Limits on Gravitational Waves from Individual Supermassive Black Hole Binaries

Author: Arzoumanian, Zaven, Baker, Paul T., Blecha, Laura, Blumer, Harsha, Brazier, Adam, Brook, Paul R., Burke-Spolaor, Sarah, Bécsy, Bence, Casey-Clyde, J. Andrew, Charisi, Maria, Chatterjee, Shami, Chen, Siyuan, Cordes, James M., Cornish, Neil J., Crawford, Fronefield, Cromartie, H. Thankful, DeCesar, Megan E., Demorest, Paul B., Dolch, Timothy, Drachler, Brendan, Ellis, Justin A., Ferrara, E. C., Fiore, William, Fonseca, Emmanuel, Freedman, Gabriel E., Garver-Daniels, Nathan, Gentile, Peter A., Glaser, Joseph, Good, Deborah C., Gültekin, Kayhan, Hazboun, Jeffrey S., Jennings, Ross J., Johnson, Aaron D., Jones, Megan L., Kaiser, Andrew R., Kaplan, David L., Kelley, Luke Zoltan, Key, Joey Shapiro, Laal, Nima, Lam, Michael T., Lamb, William G, Lazio, T. Joseph W., Lewandowska, Natalia, Liu, Tingting, Lorimer, Duncan R., Luo, Jing, Lynch, Ryan S., Madison, Dustin R., McEwen, Alexander, McLaughlin, Maura A., Mingarelli, Chiara M. F., Ng, Cherry, Nice, David J., Ocker, Stella Koch, Olum, Ken D., Pennucci, Timothy T., Pol, Nihan S., Ransom, Scott M., Ray, Paul S., Romano, Joseph D., Shapiro-Albert, Brent J., Siemens, Xavier, Simon, Joseph, Siwek, Magdalena, Spiewak, Renée, Stairs, Ingrid H., Stinebring, Daniel R., Stovall, Kevin, Swiggum, Joseph K., Sydnor, Jessica, Taylor, Stephen R., Turner, Jacob E., Vallisneri, Michele, Vigeland, Sarah J., Wahl, Haley M., Walsh, Gregory, Witt, Caitlin A., and Young, Olivia
Subjects: Astrophysics - Astrophysics of Galaxies, Astrophysics - High Energy Astrophysical Phenomena, General Relativity and Quantum Cosmology
Abstract: Pulsar timing array collaborations, such as the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), are seeking to detect nanohertz gravitational waves emitted by supermassive black hole binaries formed in the aftermath of galaxy mergers. We have searched for continuous waves from individual circular supermassive black hole binaries using the NANOGrav's recent 12.5-year data set. We created new methods to accurately model the uncertainties on pulsar distances in our analysis, and we implemented new techniques to account for a common red noise process in pulsar timing array data sets while searching for deterministic gravitational wave signals, including continuous waves. As we found no evidence for continuous waves in our data, we placed 95\% upper limits on the strain amplitude of continuous waves emitted by these sources. At our most sensitive frequency of 7.65 nanohertz, we placed a sky-averaged limit of $h_0 < $ $(6.82 \pm 0.35) \times 10^{-15}$, and $h_0 <$ $(2.66 \pm 0.15) \times 10^{-15}$ in our most sensitive sky location. Finally, we placed a multi-messenger limit of $\mathcal{M} <$ $(1.41 \pm 0.02) \times 10^9 M_\odot$ on the chirp mass of the supermassive black hole binary candidate 3C~66B., Comment: 22 pages, 12 figures. Accepted by ApJL
Published: 2023
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23. Toward a novel soft robotic system for minimally invasive interventions

Author: Barnes, Noah, Young, Olivia, Colton, Adira, Liu, Xiaolong, Janowski, Miroslaw, Gandhi, Dheeraj, Sochol, Ryan, Brown, Jeremy, and Krieger, Axel
Published: 2023
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24. Catch your breath: The protective role of the angiotensin AT2 receptor for the treatment of idiopathic pulmonary fibrosis

Author: Young, Olivia N., Bourke, Jane E., and Widdop, Robert E.
Published: 2023
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25. Non-detection of fast radio bursts from six gamma-ray burst remnants with possible magnetar engines

Author: Men, Yunpeng, Aggarwal, Kshitij, Li, Ye, Palaniswamy, Divya, Burke-Spolaor, Sarah, Lee, K. J., Luo, Rui, Demorest, Paul, Tendulkar, Shriharsh, Agarwal, Devansh, Young, Olivia, and Zhang, Bing
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The analogy of the host galaxy of the repeating fast radio burst (FRB) source FRB 121102 and those of long gamma-ray bursts (GRBs) and super-luminous supernovae (SLSNe) has led to the suggestion that young magnetars born in GRBs and SLSNe could be the central engine of repeating FRBs. We test such a hypothesis by performing dedicated observations of the remnants of six GRBs with evidence of having a magnetar central engine using the Arecibo telescope and the Robert C. Byrd Green Bank Telescope (GBT). A total of $\sim 20$ hrs of observations of these sources did not detect any FRB from these remnants. Under the assumptions that all these GRBs left behind a long-lived magnetar and that the bursting rate of FRB 121102 is typical for a magnetar FRB engine, we estimate a non-detection probability of $8.9\times10^{-6}$. Even though these non-detections cannot exclude the young magnetar model of FRBs, we place constraints on the burst rate and luminosity function of FRBs from these GRB targets., Comment: 6 pages, 3 figures, accepted for publication in MNRAS
Published: 2019
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26. GBTrans: A commensal search for radio pulses with the Green Bank twenty metre telescope

Author: Golpayegani, Golnoosh, Lorimer, Duncan R., Ellingson, Steven W., Agarwal, Devansh, Young, Olivia, Ghigo, Frank, Prestage, Richard, Rajwade, Kaustubh, McLaughlin, Maura A., and Mingyar, Michael
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: We describe GBTrans, a real-time search system designed to find fast radio bursts (FRBs) using the 20-m radio telescope at the Green Bank Observatory. The telescope has been part of the Skynet educational program since 2015. We give details of the observing system and report on the non-detection of FRBs from a total observing time of 503 days. Single pulses from four known pulsars were detected as part of the commensal observing. The system is sensitive enough to detect approximately half of all currently known FRBs and we estimate that our survey probed redshifts out to about 0.3 corresponding to an effective survey volume of around 124,000~Mpc$^3$. Modeling the FRB rate as a function of fluence, $F$, as a power law with $F^{-\alpha}$, we constrain the index $\alpha < 2.5$ at the 90% confidence level. We discuss the implications of this result in the context of constraints from other FRB surveys., Comment: 7 pages, 6 figures
Published: 2019
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27. Folate Receptor as a Biomarker and Therapeutic Target in Solid Tumors

Author: Young, Olivia, Ngo, Nealie, Lin, Leslie, Stanbery, Laura, Creeden, Justin Fortune, Hamouda, Danae, and Nemunaitis, John
Published: 2023
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28. Cargo Quantification of Functionalized DNA Origami for Therapeutic Application.

Author: Young, Olivia J., Dembele, Hawa, Rajwar, Anjali, Kwon, Ick Chan, Ryu, Ju Hee, Shih, William M., and Zeng, Yang C.
Subjects: *DNA folding, *MOLECULAR biology, *PEPTIDES, *NUCLEIC acids, *NANOPARTICLES
Abstract: In recent years, notable advances in nanotechnology‐based drug delivery have emerged. A particularly promising platform in this field is DNA origami‐based nanoparticles, which offer highly programmable surfaces, providing precise control over the nanoscale spacing and stoichiometry of various cargo. These versatile particles are finding diverse applications ranging from basic molecular biology to diagnostics and therapeutics. This growing interest creates the need for effective methods to quantify cargo on DNA origami nanoparticles. The study consolidates several previously validated methods focusing on gel‐based and fluorescence‐based techniques, including multiplexed quantification of protein, peptide, and nucleic acid cargo on these nanoparticles. In this work, how gel band intensity and nanodrop fluorescence readings can be used to quantify protein, peptide, and RNA cargo on a DNA origami nanoparticle is demonstrated. This work may serve as a valuable resource for groups of researchers keen on utilizing DNA origami‐based nanoparticles in therapeutic applications. [ABSTRACT FROM AUTHOR]
Published: 2024
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29. A universal glycoenzyme biosynthesis pipeline that enables efficient cell-free remodeling of glycans

Author: Jaroentomeechai, Thapakorn, Kwon, Yong Hyun, Liu, Yiwen, Young, Olivia, Bhawal, Ruchika, Wilson, Joshua D., Li, Mingji, Chapla, Digantkumar G., Moremen, Kelley W., Jewett, Michael C., Mizrachi, Dario, and DeLisa, Matthew P.
Published: 2022
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30. One-Piece 3D-Printed Pneumatic Catheter: Dual-Segment Design with Integrated Robotics Control for Endovascular Interventions

Author: Jiang, Shaopeng, primary, Di, Lingyun, additional, Barnes, Noah, additional, Qu, Hannah, additional, Young, Olivia, additional, Brown, Jeremy D., additional, Sochol, Ryan, additional, and Krieger, Axel, additional
Published: 2024
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31. An Approach for 3D Microprinting Soft Robotic Surgical Tools at 1.5 French Length Scales for Endovascular Interventions

Author: Felix, Bailey M., primary, Young, Olivia M., additional, Andreou, Jordi T., additional, Portwood, Nicholas, additional, Barvenik, Kieran J., additional, Barnes, Noah, additional, Weiss, Clifford R., additional, Bailey, Christopher R., additional, Gandhi, Dheeraj, additional, Janowski, Miroslaw, additional, Brown, Jeremy D., additional, Tubaldi, Eleonora, additional, Fuge, Mark, additional, Krieger, Axel, additional, and Sochol, Ryan D., additional
Published: 2024
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32. The role of peer support and patient navigation for empowerment in breast cancer survivors: implications for community cancer control

Author: Sleiman, Marcelo M., primary, Yockel, Mary Rose, additional, Fleischmann, Adina, additional, Silber, Elana, additional, Liu, Mingqian, additional, Young, Olivia, additional, Arumani, Sahana, additional, and Tercyak, Kenneth P., additional
Published: 2024
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33. Elevation‐dependent patterns of borer‐mediated snow‐gum dieback are associated with subspecies' trait differences and environmental variation

Author: Bryant, Callum, primary, Ball, Marilyn C., additional, Borevitz, Justin, additional, Brookhouse, Matthew T., additional, Carle, Hannah, additional, Cunningham, Pia, additional, Davey, Mei, additional, Davies, James, additional, Eason, Ashleigh, additional, Erskine, Joseph D., additional, Fuenzalida, Tomas I., additional, Grishin, Dmitry, additional, Harris, Rosalie, additional, Kriticos, Jessica, additional, Midson, Aaron, additional, Nicotra, Adrienne B., additional, Nshuti, Annabelle, additional, Ward‐Jones, Jessica, additional, Yau, Yolanda, additional, Young, Olivia, additional, and Bothwell, Helen, additional
Published: 2024
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34. Redeveloping a CLEAN Deconvolution Algorithm for Scatter-broadened Radio Pulsar Signals

Author: Young, Olivia, primary and Lam, Michael T., additional
Published: 2024
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35. Engineering orthogonal human O-linked glycoprotein biosynthesis in bacteria

Author: Natarajan, Aravind, Jaroentomeechai, Thapakorn, Cabrera-Sánchez, Marielisa, Mohammed, Jody C., Cox, Emily C., Young, Olivia, Shajahan, Asif, Vilkhovoy, Michael, Vadhin, Sandra, Varner, Jeffrey D., Azadi, Parastoo, and DeLisa, Matthew P.
Published: 2020
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36. Humans, monkeys, and diesel fumes; oh my!

Author: Karl, Katherine, Lamb, Nai, and Young, Olivia
Published: 2019
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37. A 3D-Microprinted Coaxial Nozzle for Fabricating Long, Flexible Microfluidic Tubing

Author: Young, Olivia M., primary, Felix, Bailey M., additional, Fuge, Mark D., additional, Krieger, Axel, additional, and Sochol, Ryan D., additional
Published: 2024
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38. Fabrication of Multilumen Microfluidic Tubing for Ex Situ Direct Laser Writing

Author: Felix, Bailey M., primary, Young, Olivia M., additional, Andreou, Jordi T., additional, Sarker, Sunandita, additional, Fuge, Mark D., additional, Krieger, Axel, additional, Weiss, Clifford R., additional, Bailey, Christopher R., additional, and Sochol, Ryan D., additional
Published: 2024
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39. DNA origami vaccine (DoriVac) nanoparticles improve both humoral and cellular immune responses to infectious diseases

Author: Zeng, Yang C., primary, Young, Olivia J., additional, Si, Longlong, additional, Ku, Min Wen, additional, Isinelli, Giorgia, additional, Rajwar, Anjali, additional, Jiang, Amanda, additional, Wintersinger, Chris M., additional, Graveline, Amanda R., additional, Vernet, Andyna, additional, Sanchez, Melinda, additional, Ryu, Ju Hee, additional, Kwon, Ick Chan, additional, Goyal, Girija, additional, Ingber, Donald E., additional, and Shih, William M., additional
Published: 2024
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40. Direct laser writing-enabled 3D printing strategies for microfluidic applications.

Author: Young, Olivia M., Xin Xu, Sarker, Sunandita, and Sochol, Ryan D.
Subjects: *THREE-dimensional printing, *MICROPHYSIOLOGICAL systems, *LABS on a chip, *LASERS, *RESEARCH personnel, *COMPUTER printers
Abstract: Over the past decade, additive manufacturing--or "three-dimensional (3D) printing"--has attracted increasing attention in the Lab on a Chip community as a pathway to achieve sophisticated system architectures that are difficult or infeasible to fabricate via conventional means. One particularly promising 3D manufacturing technology is "direct laser writing (DLW)", which leverages two-photon (or multiphoton) polymerization (2PP) phenomena to enable high geometric versatility, print speeds, and precision at length scales down to the 100 nm range. Although researchers have demonstrated the potential of using DLW for microfluidic applications ranging from organ on a chip and drug delivery to micro/nanoparticle processing and soft microrobotics, such scenarios present unique challenges for DLW. Specifically, microfluidic systems typically require macro-to-micro fluidic interfaces (e.g., inlet and outlet ports) to facilitate fluidic loading, control, and retrieval operations; however, DLW-based 3D printing relies on a micron-to-submicron-sized 2PP volume element (i.e., "voxel") that is poorly suited for manufacturing these larger-scale fluidic interfaces. In this Tutorial Review, we highlight and discuss the four most prominent strategies that researchers have developed to circumvent this trade-off and realize macro-to-micro interfaces for DLW-enabled microfluidic components and systems. In addition, we consider the possibility that--with the advent of next-generation commercial DLW printers equipped with new dynamic voxel tuning, print field, and laser power capabilities--the overall utility of DLW strategies for Lab on a Chip fields may soon expand dramatically. [ABSTRACT FROM AUTHOR]
Published: 2024
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41. Elevation-dependent patterns of snow-gum dieback are associated with subspecies’ trait differences and environmental variation

Author: Bryant, Callum, primary, Ball, Marilyn C., additional, Borevitz, Justin, additional, Brookhouse, Matthew T., additional, Carle, Hannah, additional, Cunningham, Pia, additional, Davey, Mei, additional, Davies, James, additional, Eason, Ashleigh, additional, Erskine, Joseph D., additional, Fuenzalida, Tomas I., additional, Grishin, Dmitry, additional, Harris, Rosalie, additional, Kriticos, Jessica, additional, Midson, Aaron, additional, Nicotra, Adrienne B., additional, Nshuti, Annabelle, additional, Ward-Jones, Jessica, additional, Yau, Yolanda, additional, Young, Olivia, additional, and Bothwell, Helen, additional
Published: 2023
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42. How to Detect an Astrophysical Nanohertz Gravitational Wave Background

Author: Bécsy, Bence, primary, Cornish, Neil J., additional, Meyers, Patrick M., additional, Kelley, Luke Zoltan, additional, Agazie, Gabriella, additional, Anumarlapudi, Akash, additional, Archibald, Anne M., additional, Arzoumanian, Zaven, additional, Baker, Paul T., additional, Blecha, Laura, additional, Brazier, Adam, additional, Brook, Paul R., additional, Burke-Spolaor, Sarah, additional, Casey-Clyde, J. Andrew, additional, Charisi, Maria, additional, Chatterjee, Shami, additional, Chatziioannou, Katerina, additional, Cohen, Tyler, additional, Cordes, James M., additional, Crawford, Fronefield, additional, Cromartie, H. Thankful, additional, Crowter, Kathryn, additional, DeCesar, Megan E., additional, Demorest, Paul B., additional, Dolch, Timothy, additional, Ferrara, Elizabeth C., additional, Fiore, William, additional, Fonseca, Emmanuel, additional, Freedman, Gabriel E., additional, Garver-Daniels, Nate, additional, Gentile, Peter A., additional, Glaser, Joseph, additional, Good, Deborah C., additional, Gültekin, Kayhan, additional, Hazboun, Jeffrey S., additional, Hourihane, Sophie, additional, Jennings, Ross J., additional, Johnson, Aaron D., additional, Jones, Megan L., additional, Kaiser, Andrew R., additional, Kaplan, David L., additional, Kerr, Matthew, additional, Key, Joey S., additional, Laal, Nima, additional, Lam, Michael T., additional, Lamb, William G., additional, W. Lazio, T. Joseph, additional, Lewandowska, Natalia, additional, Littenberg, Tyson B., additional, Liu, Tingting, additional, Lorimer, Duncan R., additional, Luo, Jing, additional, Lynch, Ryan S., additional, Ma, Chung-Pei, additional, Madison, Dustin R., additional, McEwen, Alexander, additional, McKee, James W., additional, McLaughlin, Maura A., additional, McMann, Natasha, additional, Meyers, Bradley W., additional, Mingarelli, Chiara M. F., additional, Mitridate, Andrea, additional, Ng, Cherry, additional, Nice, David J., additional, Ocker, Stella Koch, additional, Olum, Ken D., additional, Pennucci, Timothy T., additional, Perera, Benetge B. P., additional, Pol, Nihan S., additional, Radovan, Henri A., additional, Ransom, Scott M., additional, Ray, Paul S., additional, Romano, Joseph D., additional, Sardesai, Shashwat C., additional, Schmiedekamp, Ann, additional, Schmiedekamp, Carl, additional, Schmitz, Kai, additional, Shapiro-Albert, Brent J., additional, Siemens, Xavier, additional, Simon, Joseph, additional, Siwek, Magdalena S., additional, Sosa Fiscella, Sophia V., additional, Stairs, Ingrid H., additional, Stinebring, Daniel R., additional, Stovall, Kevin, additional, Susobhanan, Abhimanyu, additional, Swiggum, Joseph K., additional, Taylor, Stephen R., additional, Turner, Jacob E., additional, Unal, Caner, additional, Vallisneri, Michele, additional, van Haasteren, Rutger, additional, Vigeland, Sarah J., additional, Wahl, Haley M., additional, Witt, Caitlin A., additional, and Young, Olivia, additional
Published: 2023
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43. Is extreme body size in dogs associated with differing longevity and mortality in the UK?

Author: Pegram, Camilla, primary, Young, Olivia, additional, Brodbelt, David, additional, Church, David, additional, and O’Neill, Dan, additional
Published: 2020
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44. To an Always Knowing.

Author: Young, Olivia K.
Subjects: *GAZE, *BEREAVEMENT, *VIOLENCE against Black people, *ART history
Published: 2024
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45. Black Op Art

Author: Young, Olivia K., primary
Published: 2023
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46. The NANOGrav 15 yr Data Set: Constraints on Supermassive Black Hole Binaries from the Gravitational-wave Background

Author: Agazie, Gabriella, primary, Anumarlapudi, Akash, additional, Archibald, Anne M., additional, Baker, Paul T., additional, Bécsy, Bence, additional, Blecha, Laura, additional, Bonilla, Alexander, additional, Brazier, Adam, additional, Brook, Paul R., additional, Burke-Spolaor, Sarah, additional, Burnette, Rand, additional, Case, Robin, additional, Casey-Clyde, J. Andrew, additional, Charisi, Maria, additional, Chatterjee, Shami, additional, Chatziioannou, Katerina, additional, Cheeseboro, Belinda D., additional, Chen, Siyuan, additional, Cohen, Tyler, additional, Cordes, James M., additional, Cornish, Neil J., additional, Crawford, Fronefield, additional, Cromartie, H. Thankful, additional, Crowter, Kathryn, additional, Cutler, Curt J., additional, D’Orazio, Daniel J., additional, DeCesar, Megan E., additional, DeGan, Dallas, additional, Demorest, Paul B., additional, Deng, Heling, additional, Dolch, Timothy, additional, Drachler, Brendan, additional, Ferrara, Elizabeth C., additional, Fiore, William, additional, Fonseca, Emmanuel, additional, Freedman, Gabriel E., additional, Gardiner, Emiko, additional, Garver-Daniels, Nate, additional, Gentile, Peter A., additional, Gersbach, Kyle A., additional, Glaser, Joseph, additional, Good, Deborah C., additional, Gültekin, Kayhan, additional, Hazboun, Jeffrey S., additional, Hourihane, Sophie, additional, Islo, Kristina, additional, Jennings, Ross J., additional, Johnson, Aaron, additional, Jones, Megan L., additional, Kaiser, Andrew R., additional, Kaplan, David L., additional, Kelley, Luke Zoltan, additional, Kerr, Matthew, additional, Key, Joey S., additional, Laal, Nima, additional, Lam, Michael T., additional, Lamb, William G., additional, W. Lazio, T. Joseph, additional, Lewandowska, Natalia, additional, Littenberg, Tyson B., additional, Liu, Tingting, additional, Luo, Jing, additional, Lynch, Ryan S., additional, Ma, Chung-Pei, additional, Madison, Dustin R., additional, McEwen, Alexander, additional, McKee, James W., additional, McLaughlin, Maura A., additional, McMann, Natasha, additional, Meyers, Bradley W., additional, Meyers, Patrick M., additional, Mingarelli, Chiara M. F., additional, Mitridate, Andrea, additional, Natarajan, Priyamvada, additional, Ng, Cherry, additional, Nice, David J., additional, Ocker, Stella Koch, additional, Olum, Ken D., additional, Pennucci, Timothy T., additional, Perera, Benetge B. P., additional, Petrov, Polina, additional, Pol, Nihan S., additional, Radovan, Henri A., additional, Ransom, Scott M., additional, Ray, Paul S., additional, Romano, Joseph D., additional, Runnoe, Jessie C., additional, Sardesai, Shashwat C., additional, Schmiedekamp, Ann, additional, Schmiedekamp, Carl, additional, Schmitz, Kai, additional, Schult, Levi, additional, Shapiro-Albert, Brent J., additional, Siemens, Xavier, additional, Simon, Joseph, additional, Siwek, Magdalena S., additional, Stairs, Ingrid H., additional, Stinebring, Daniel R., additional, Stovall, Kevin, additional, Sun, Jerry P., additional, Susobhanan, Abhimanyu, additional, Swiggum, Joseph K., additional, Taylor, Jacob, additional, Taylor, Stephen R., additional, Turner, Jacob E., additional, Unal, Caner, additional, Vallisneri, Michele, additional, Vigeland, Sarah J., additional, Wachter, Jeremy M., additional, Wahl, Haley M., additional, Wang, Qiaohong, additional, Witt, Caitlin A., additional, Wright, David, additional, and Young, Olivia, additional
Published: 2023
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47. Modulation of Mitochondrial Metabolic Parameters and Antioxidant Enzymes in Healthy and Glaucomatous Trabecular Meshwork Cells with Hybrid Small Molecule SA-2

Author: Amankwa, Charles E., primary, Young, Olivia, additional, DebNath, Biddut, additional, Gondi, Sudershan R., additional, Rangan, Rajiv, additional, Ellis, Dorette Z., additional, Zode, Gulab, additional, Stankowska, Dorota L., additional, and Acharya, Suchismita, additional
Published: 2023
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48. The NANOGrav 15 yr Data Set: Bayesian Limits on Gravitational Waves from Individual Supermassive Black Hole Binaries

Author: Agazie, Gabriella, primary, Anumarlapudi, Akash, additional, Archibald, Anne M., additional, Arzoumanian, Zaven, additional, Baker, Paul T., additional, Bécsy, Bence, additional, Blecha, Laura, additional, Brazier, Adam, additional, Brook, Paul R., additional, Burke-Spolaor, Sarah, additional, Case, Robin, additional, Casey-Clyde, J. Andrew, additional, Charisi, Maria, additional, Chatterjee, Shami, additional, Cohen, Tyler, additional, Cordes, James M., additional, Cornish, Neil J., additional, Crawford, Fronefield, additional, Cromartie, H. Thankful, additional, Crowter, Kathryn, additional, DeCesar, Megan E., additional, Demorest, Paul B., additional, Digman, Matthew C., additional, Dolch, Timothy, additional, Drachler, Brendan, additional, Ferrara, Elizabeth C., additional, Fiore, William, additional, Fonseca, Emmanuel, additional, Freedman, Gabriel E., additional, Garver-Daniels, Nate, additional, Gentile, Peter A., additional, Glaser, Joseph, additional, Good, Deborah C., additional, Gültekin, Kayhan, additional, Hazboun, Jeffrey S., additional, Hourihane, Sophie, additional, Jennings, Ross J., additional, Johnson, Aaron D., additional, Jones, Megan L., additional, Kaiser, Andrew R., additional, Kaplan, David L., additional, Kelley, Luke Zoltan, additional, Kerr, Matthew, additional, Key, Joey S., additional, Laal, Nima, additional, Lam, Michael T., additional, Lamb, William G., additional, W. Lazio, T. Joseph, additional, Lewandowska, Natalia, additional, Liu, Tingting, additional, Lorimer, Duncan R., additional, Luo, Jing, additional, Lynch, Ryan S., additional, Ma, Chung-Pei, additional, Madison, Dustin R., additional, McEwen, Alexander, additional, McKee, James W., additional, McLaughlin, Maura A., additional, McMann, Natasha, additional, Meyers, Bradley W., additional, Meyers, Patrick M., additional, Mingarelli, Chiara M. F., additional, Mitridate, Andrea, additional, Ng, Cherry, additional, Nice, David J., additional, Ocker, Stella Koch, additional, Olum, Ken D., additional, Pennucci, Timothy T., additional, Perera, Benetge B. P., additional, Petrov, Polina, additional, Pol, Nihan S., additional, Radovan, Henri A., additional, Ransom, Scott M., additional, Ray, Paul S., additional, Romano, Joseph D., additional, Sardesai, Shashwat C., additional, Schmiedekamp, Ann, additional, Schmiedekamp, Carl, additional, Schmitz, Kai, additional, Shapiro-Albert, Brent J., additional, Siemens, Xavier, additional, Simon, Joseph, additional, Siwek, Magdalena S., additional, Stairs, Ingrid H., additional, Stinebring, Daniel R., additional, Stovall, Kevin, additional, Susobhanan, Abhimanyu, additional, Swiggum, Joseph K., additional, Taylor, Jacob, additional, Taylor, Stephen R., additional, Turner, Jacob E., additional, Unal, Caner, additional, Vallisneri, Michele, additional, van Haasteren, Rutger, additional, Vigeland, Sarah J., additional, Wahl, Haley M., additional, Witt, Caitlin A., additional, and Young, Olivia, additional
Published: 2023
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49. The NANOGrav 12.5 yr Data Set: Bayesian Limits on Gravitational Waves from Individual Supermassive Black Hole Binaries

Author: Arzoumanian, Zaven, primary, Baker, Paul T., additional, Blecha, Laura, additional, Blumer, Harsha, additional, Brazier, Adam, additional, Brook, Paul R., additional, Burke-Spolaor, Sarah, additional, Bécsy, Bence, additional, Casey-Clyde, J. Andrew, additional, Charisi, Maria, additional, Chatterjee, Shami, additional, Chen, Siyuan, additional, Cordes, James M., additional, Cornish, Neil J., additional, Crawford, Fronefield, additional, Cromartie, H. Thankful, additional, DeCesar, Megan E., additional, Demorest, Paul B., additional, Dolch, Timothy, additional, Drachler, Brendan, additional, Ellis, Justin A., additional, Ferrara, E. C., additional, Fiore, William, additional, Fonseca, Emmanuel, additional, Freedman, Gabriel E., additional, Garver-Daniels, Nathan, additional, Gentile, Peter A., additional, Glaser, Joseph, additional, Good, Deborah C., additional, Gültekin, Kayhan, additional, Hazboun, Jeffrey S., additional, Jennings, Ross J., additional, Johnson, Aaron D., additional, Jones, Megan L., additional, Kaiser, Andrew R., additional, Kaplan, David L., additional, Kelley, Luke Zoltan, additional, Key, Joey Shapiro, additional, Laal, Nima, additional, Lam, Michael T., additional, Lamb, William G, additional, W. Lazio, T. Joseph, additional, Lewandowska, Natalia, additional, Liu, Tingting, additional, Lorimer, Duncan R., additional, Luo, Jing, additional, Lynch, Ryan S., additional, Madison, Dustin R., additional, McEwen, Alexander, additional, McLaughlin, Maura A., additional, Mingarelli, Chiara M. F., additional, Ng, Cherry, additional, Nice, David J., additional, Ocker, Stella Koch, additional, Olum, Ken D., additional, Pennucci, Timothy T., additional, Pol, Nihan S., additional, Ransom, Scott M., additional, Ray, Paul S., additional, Romano, Joseph D., additional, Shapiro-Albert, Brent J., additional, Siemens, Xavier, additional, Simon, Joseph, additional, Siwek, Magdalena, additional, Spiewak, Renée, additional, Stairs, Ingrid H., additional, Stinebring, Daniel R., additional, Stovall, Kevin, additional, Swiggum, Joseph K., additional, Sydnor, Jessica, additional, Taylor, Stephen R., additional, Turner, Jacob E., additional, Vallisneri, Michele, additional, Vigeland, Sarah J., additional, Wahl, Haley M., additional, Walsh, Gregory, additional, Witt, Caitlin A., additional, and Young, Olivia, additional
Published: 2023
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50. The NANOGrav 15 yr Data Set: Observations and Timing of 68 Millisecond Pulsars

Author: Agazie, Gabriella, primary, Alam, Md Faisal, additional, Anumarlapudi, Akash, additional, Archibald, Anne M., additional, Arzoumanian, Zaven, additional, Baker, Paul T., additional, Blecha, Laura, additional, Bonidie, Victoria, additional, Brazier, Adam, additional, Brook, Paul R., additional, Burke-Spolaor, Sarah, additional, Bécsy, Bence, additional, Chapman, Christopher, additional, Charisi, Maria, additional, Chatterjee, Shami, additional, Cohen, Tyler, additional, Cordes, James M., additional, Cornish, Neil J., additional, Crawford, Fronefield, additional, Cromartie, H. Thankful, additional, Crowter, Kathryn, additional, DeCesar, Megan E., additional, Demorest, Paul B., additional, Dolch, Timothy, additional, Drachler, Brendan, additional, Ferrara, Elizabeth C., additional, Fiore, William, additional, Fonseca, Emmanuel, additional, Freedman, Gabriel E., additional, Garver-Daniels, Nate, additional, Gentile, Peter A., additional, Glaser, Joseph, additional, Good, Deborah C., additional, Gültekin, Kayhan, additional, Hazboun, Jeffrey S., additional, Jennings, Ross J., additional, Jessup, Cody, additional, Johnson, Aaron D., additional, Jones, Megan L., additional, Kaiser, Andrew R., additional, Kaplan, David L., additional, Kelley, Luke Zoltan, additional, Kerr, Matthew, additional, Key, Joey S., additional, Kuske, Anastasia, additional, Laal, Nima, additional, Lam, Michael T., additional, Lamb, William G., additional, W. Lazio, T. Joseph, additional, Lewandowska, Natalia, additional, Lin, Ye, additional, Liu, Tingting, additional, Lorimer, Duncan R., additional, Luo, Jing, additional, Lynch, Ryan S., additional, Ma, Chung-Pei, additional, Madison, Dustin R., additional, Maraccini, Kaleb, additional, McEwen, Alexander, additional, McKee, James W., additional, McLaughlin, Maura A., additional, McMann, Natasha, additional, Meyers, Bradley W., additional, Mingarelli, Chiara M. F., additional, Mitridate, Andrea, additional, Ng, Cherry, additional, Nice, David J., additional, Ocker, Stella Koch, additional, Olum, Ken D., additional, Panciu, Elisa, additional, Pennucci, Timothy T., additional, Perera, Benetge B. P., additional, Pol, Nihan S., additional, Radovan, Henri A., additional, Ransom, Scott M., additional, Ray, Paul S., additional, Romano, Joseph D., additional, Salo, Laura, additional, Sardesai, Shashwat C., additional, Schmiedekamp, Carl, additional, Schmiedekamp, Ann, additional, Schmitz, Kai, additional, Shapiro-Albert, Brent J., additional, Siemens, Xavier, additional, Simon, Joseph, additional, Siwek, Magdalena S., additional, Stairs, Ingrid H., additional, Stinebring, Daniel R., additional, Stovall, Kevin, additional, Susobhanan, Abhimanyu, additional, Swiggum, Joseph K., additional, Taylor, Stephen R., additional, Turner, Jacob E., additional, Unal, Caner, additional, Vallisneri, Michele, additional, Vigeland, Sarah J., additional, Wahl, Haley M., additional, Wang, Qiaohong, additional, Witt, Caitlin A., additional, and Young, Olivia, additional
Published: 2023
Full Text: View/download PDF

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