The Astrophysics of Nanohertz Gravitational Waves

Abstract

Pulsar timing array (PTA) collaborations in North America, Australia, and Europe, have been exploiting the exquisite timing precision of millisecond pulsars over decades of observations to search for correlated timing deviations induced by gravitational waves (GWs). PTAs are sensitive to the frequency band ranging just below 1 nanohertz to a few tens of microhertz. The discovery space of this band is potentially rich with populations of inspiraling supermassive black-holes binaries, decaying cosmic string networks, relic post-inflation GWs, and even non-GW imprints of axionic dark matter. This article aims to provide an understanding of the exciting open science questions in cosmology, galaxy evolution, and fundamental physics that will be addressed by the detection and study of GWs through PTAs. The focus of the article is on providing an understanding of the mechanisms by which PTAs can address specific questions in these fields, and to outline some of the subtleties and difficulties in each case. The material included is weighted most heavily towards the questions which we expect will be answered in the near-term with PTAs; however, we have made efforts to include most currently anticipated applications of nanohertz GWs.

Accepted to The Astronomy and Astrophysics Review (A&ARv)

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• A dynamical approach in exploring the unknown mass in the Solar system using pulsar timing arrays
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Cited by in corpus (193)

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• On possible proxies of AGN light curves cadence selection in future time domain surveys
• Bayesian search for gravitational wave bursts in pulsar timing array data
• Charting the Nanohertz Gravitational Wave Sky with Pulsar Timing Arrays
• Noise analysis of the Indian Pulsar Timing Array data release I
• Pulsar Timing Array Experiments
• Discovering new forces with gravitational waves from supermassive black holes
• Measuring kinematic anisotropies with pulsar timing arrays
• Using Gravitational Wave Parallax to Measure the Hubble Parameter with Pulsar Timing Arrays
• Review of Pulsar Timing Array for Gravitational Wave Research
• Splitting the lentils: Clues to galaxy/black hole coevolution from the discovery of offset relations for non-dusty versus dusty (wet-merger-built) lenticular galaxies in the $M_{\mathrm{bh}}$-$M_{\ast ,\mathrm{spheroid}}$ diagram
• Probing Parity Violation in the Stochastic Gravitational Wave Background with Astrometry
• Searching for gravitational waves via Doppler tracking by future missions to Uranus and Neptune
• Differential Interferometric Signatures of Close Binaries of Supermassive Black Holes in Active Galactic Nuclei
• Efficient Gravitational Wave Searches with Pulsar Timing Arrays using Hamiltonian Monte Carlo
• Merging timescale for supermassive black hole binary in interacting galaxy NGC 6240
• The Impact of Black Hole Scaling Relation Assumptions on the Mass Density of Black Holes
• Signatures of Massive Black Hole Merger Host Galaxies from Cosmological Simulations I: Unique Galaxy Morphologies in Imaging
• Post-Newtonian-accurate pulsar timing array signals induced by inspiralling eccentric binaries: accuracy, computational cost, and single-pulsar search
• Third post-Newtonian gravitational radiation from two-body scattering II. Hereditary Energy radiation
• Distinctive GWBs from eccentric inspiraling SMBH binaries with a DM spike
• Sub-GeV dark matter and nano-Hertz gravitational waves from a classically conformal dark sector
• RABBITS -- II. The impact of AGN feedback on coalescing supermassive black holes in disc and elliptical galaxy mergers
• The ASTRID Simulation at z=0: From Massive Black Holes to Large-scale Structure
• The Intriguing Parsec-Scale Radio Structure in the "Offset AGN" KISSR 102
• Deep VLBI Observations Challenge Previous Evidence of a Binary Supermassive Black Hole Residing in the Seyfert Galaxy NGC 7674
• Parameter-Estimation Biases for Eccentric Supermassive Binary Black Holes in Pulsar Timing Arrays: Biases Caused by Ignored Pulsar Terms
• Toward a test of Gaussianity of a gravitational wave background
• Radio Millisecond pulsars
• X-ray Flux and Spectral Variability of the Blazar OJ 287 with Suzaku
• The Science of Fundamental Catalogs
• Angular correlation and deformed Hellings-Downs curve from spin-2 ultralight dark matter
• Reducing instrumental errors in Parkes Pulsar Timing Array data
• The Indian Pulsar Timing Array Data Release 2: I. Dataset and Timing Analysis
• Astrometry meets Pulsar Timing Arrays: Synergies for Gravitational Wave Detection
• Reading signatures of supermassive binary black holes in pulsar timing array observations
• Dark Matter Spike surrounding Supermassive Black Holes Binary and the Nanohertz Stochastic Gravitational Wave Background
• The primordial black holes solution to the cosmological monopole problem
• Astrophysics with the Laser Interferometer Space Antenna
• Toward Astrometric Constraints on a Supermassive Black Hole Binary in the Early-Type Galaxy NGC\,4472
• Damping of long wavelength gravitational waves by the intergalactic medium
• Probing Self-Interacting Dark Matter via Gravitational-Wave Background from Eccentric Supermassive Black Hole Mergers
• Improving pulsar-timing solutions through dynamic pulse fitting
• Unravelling the formation of the first supermassive black holes with the SKA pulsar timing array
• Optical Spectroscopy of Dual Quasar Candidates from the Subaru HSC-SSP program
• Probing intermediate scale Froggatt-Nielsen models at future gravitational wave observatories
• Implications for Pulsar Timing Arrays of Sub-solar Black Hole Detections: From LVK to Einstein Telescope and Cosmic Explorer
• Wide-band timing of GMRT discovered millisecond pulsars
• Milliarcsecond X-ray astrometry to resolve inner regions of AGN at $z>1$ using gravitational lensing
• The Timing Residual Patterns Due to Pulsar Acceleration
• The Impact of Dark Matter on Gravitational Wave Detection by Space-based Interferometers
• Detection of eccentric close-binary supermassive black holes with incomplete interferometric data
• Inferring Mbh-Mbulge Evolution from the Gravitational Wave Background
• On Variation of Light Curves and Broad Emission Lines for Periodic QSOs from co-rotating Supermassive binary black holes in elliptical orbits
• Pulsar timing and polarimetry: results and perspectives
• Improving pulsar timing precision through superior Time-of-Arrival creation
• Systematics of planetary ephemeris reference frames inferred from pulsar timing astrometry
• A nontrivial footprint of standard cosmology in the future observations of low-frequency gravitational waves
• Gravitational wave induced baryon acoustic oscillations
• Reconstructing inflationary potential from NANOGrav 15-year Data: A robust study using Non-Bunch Davies initial condition
• The Host Galaxies of PTA Sources: Converting Supermassive BH Binary Parameters into EM Observables
• Interpreting gravitational-wave burst detections: constraining source properties without astrophysical models
• Controlling Outlier Contamination In Multimessenger Time-domain Searches For Supermasssive Binary Black Holes
• An updated constraint for the Gravitational Wave Background from the Gamma-ray Pulsar Timing Array
• Improving DM estimates using low-frequency scattering-broadening estimates
• The Indian Pulsar Timing Array Data Release 2: II. Customised Single-Pulsar Noise Analysis and Noise Budget
• Non-Gaussianity of Tensor Induced Density Perturbations
• Probing supermassive black hole scalarization with Pulsar Timing Arrays
• Implications of pulsar timing arrays for Gauss-Bonnet Inflation
• Efficient prescription to search for linear gravitational wave memory from hyperbolic black hole encounters and its application to the NANOGrav 12.5-year dataset
• Finite Populations & Finite Time: The Non-Gaussianity of a Gravitational Wave Background
• From $U(1)\times U(1)$ Symmetry Breaking to Majoron Cosmology: Insights from NANOGrav 15-year Data
• First Light And Reionization Epoch Simulations (FLARES) -- XIX: Supermassive black hole mergers in the early Universe and their environmental dependence
• Testing No slip model with pulsar timing arrays: NANOGrav and IPTA
• Accretion of self-interacting dark matter onto supermassive black holes
• Investigating the Accretion Nature of Binary Supermassive Black Hole Candidate SDSS J025214.67-002813.7
• Spatial Correlation between Pulsars from Interfering Gravitational-Wave Sources in Massive Gravity
• Trails of clouds in binary black holes
• Upper limits on microhertz gravitational waves from supermassive black-hole binaries using PSR J1909-3744 data from the second IPTA data release
• A Parallelized Bayesian Approach To Accelerated Gravitational-Wave Background Characterization
• Investigating the Bulge Morphology of Dual AGN Host Galaxies from the GOTHIC survey
• Gravitational-wave standard sirens and application in cosmology
• Full analytic expressions of overlap reduction functions for anisotropies of the stochastic gravitational-wave background with pulsar timing arrays
• Gravitational waves from parabolic encounters: A study of linear and nonlinear memory
• Searching Stochastic Gravitational Wave Background Landscape Across Frequency Bands
• Cosmic Overture Echoed in a Stellar Final Act: Implications of Nanohertz Gravitational Waves for Core Collapse Supernova Neutrinos
• Assessing the performance of future space-based detectors: Astrophysical foregrounds and individual sources
• Stochastic gravitational wave background from the collisions of dark matter halos
• Observation of polarized stochastic gravitational-wave background in pulsar-timing-array experiments
• Exploring realistic nanohertz gravitational-wave backgrounds