No Need to Know: Toward Astrophysics-free Gravitational-wave Cosmology
Gravitational waves (GWs) from merging compact objects encode direct information about the luminosity distance to the binary. When paired with a redshift measurement, this enables standard-siren cosmology: a Hubble diagram can be constructed to directly probe the Universe’s expansion. This can be do...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/ad9253 |
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| author | Amanda M. Farah Thomas A. Callister Jose María Ezquiaga Michael Zevin Daniel E. Holz |
| author_facet | Amanda M. Farah Thomas A. Callister Jose María Ezquiaga Michael Zevin Daniel E. Holz |
| author_sort | Amanda M. Farah |
| collection | DOAJ |
| description | Gravitational waves (GWs) from merging compact objects encode direct information about the luminosity distance to the binary. When paired with a redshift measurement, this enables standard-siren cosmology: a Hubble diagram can be constructed to directly probe the Universe’s expansion. This can be done in the absence of electromagnetic measurements, as features in the mass distribution of GW sources provide self-calibrating redshift measurements without the need for a definite or probabilistic host galaxy association. This “spectral siren” technique has thus far only been applied with simple parametric representations of the mass distribution, and theoretical predictions for features in the mass distribution are commonly presumed to be fundamental to the measurement. However, the use of an inaccurate representation leads to biases in the cosmological inference, an acute problem given the current uncertainties in true source population. Furthermore, it is commonly presumed that the form of the mass distribution must be known a priori to obtain unbiased measurements of cosmological parameters in this fashion. Here, we demonstrate that spectral sirens can accurately infer cosmological parameters without such prior assumptions. We apply a flexible, nonparametric model for the mass distribution of compact binaries to a simulated catalog of 1000 GW signals, consistent with expectations for the next LIGO–Virgo–KAGRA observing run. We find that, despite our model’s flexibility, both the source mass model and cosmological parameters are correctly reconstructed. We predict a 11.2% https://github.com/afarah18/spectral-sirens-with-GPs/blob/3f2ac5181dde5fe7086e8b5bd206cec96fa0cc32/Snakefile#L25 measurement of H _0 , keeping all other cosmological parameters fixed, and a 6.4% https://github.com/afarah18/spectral-sirens-with-GPs/blob/3f2ac5181dde5fe7086e8b5bd206cec96fa0cc32/Snakefile#L47 measurement of H ( z = 0.9) https://github.com/afarah18/spectral-sirens-with-GPs/blob/3f2ac5181dde5fe7086e8b5bd206cec96fa0cc32/Snakefile#L47 when fitting for multiple cosmological parameters (1 σ uncertainties). This astrophysically agnostic spectral siren technique will be essential to arrive at precise and unbiased cosmological constraints from GW source populations. |
| format | Article |
| id | doaj-art-9f2cc993f75849898f86254975e97357 |
| institution | Kabale University |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj-art-9f2cc993f75849898f86254975e973572025-01-08T07:17:49ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01978215310.3847/1538-4357/ad9253No Need to Know: Toward Astrophysics-free Gravitational-wave CosmologyAmanda M. Farah0https://orcid.org/0000-0002-6121-0285Thomas A. Callister1https://orcid.org/0000-0001-9892-177XJose María Ezquiaga2https://orcid.org/0000-0002-7213-3211Michael Zevin3https://orcid.org/0000-0002-0147-0835Daniel E. Holz4https://orcid.org/0000-0002-0175-5064Department of Physics, The University of Chicago , Chicago, IL 60637, USA ; afarah@uchicago.eduKavli Institute for Cosmological Physics, The University of Chicago , Chicago, IL 60637, USANiels Bohr International Academy, Niels Bohr Institute , Blegdamsvej 17, DK-2100 Copenhagen, DenmarkThe Adler Planetarium , 1300 South DuSable Lake Shore Drive, Chicago, IL 60605, USADepartment of Physics, The University of Chicago , Chicago, IL 60637, USA ; afarah@uchicago.edu; Kavli Institute for Cosmological Physics, The University of Chicago , Chicago, IL 60637, USA; Department of Astronomy & Astrophysics, The University of Chicago , Chicago, IL 60637, USA; Enrico Fermi Institute, The University of Chicago , Chicago, IL 60637, USAGravitational waves (GWs) from merging compact objects encode direct information about the luminosity distance to the binary. When paired with a redshift measurement, this enables standard-siren cosmology: a Hubble diagram can be constructed to directly probe the Universe’s expansion. This can be done in the absence of electromagnetic measurements, as features in the mass distribution of GW sources provide self-calibrating redshift measurements without the need for a definite or probabilistic host galaxy association. This “spectral siren” technique has thus far only been applied with simple parametric representations of the mass distribution, and theoretical predictions for features in the mass distribution are commonly presumed to be fundamental to the measurement. However, the use of an inaccurate representation leads to biases in the cosmological inference, an acute problem given the current uncertainties in true source population. Furthermore, it is commonly presumed that the form of the mass distribution must be known a priori to obtain unbiased measurements of cosmological parameters in this fashion. Here, we demonstrate that spectral sirens can accurately infer cosmological parameters without such prior assumptions. We apply a flexible, nonparametric model for the mass distribution of compact binaries to a simulated catalog of 1000 GW signals, consistent with expectations for the next LIGO–Virgo–KAGRA observing run. We find that, despite our model’s flexibility, both the source mass model and cosmological parameters are correctly reconstructed. We predict a 11.2% https://github.com/afarah18/spectral-sirens-with-GPs/blob/3f2ac5181dde5fe7086e8b5bd206cec96fa0cc32/Snakefile#L25 measurement of H _0 , keeping all other cosmological parameters fixed, and a 6.4% https://github.com/afarah18/spectral-sirens-with-GPs/blob/3f2ac5181dde5fe7086e8b5bd206cec96fa0cc32/Snakefile#L47 measurement of H ( z = 0.9) https://github.com/afarah18/spectral-sirens-with-GPs/blob/3f2ac5181dde5fe7086e8b5bd206cec96fa0cc32/Snakefile#L47 when fitting for multiple cosmological parameters (1 σ uncertainties). This astrophysically agnostic spectral siren technique will be essential to arrive at precise and unbiased cosmological constraints from GW source populations.https://doi.org/10.3847/1538-4357/ad9253Gravitational wave astronomyBayesian statisticsHubble constantCompact binary stars |
| spellingShingle | Amanda M. Farah Thomas A. Callister Jose María Ezquiaga Michael Zevin Daniel E. Holz No Need to Know: Toward Astrophysics-free Gravitational-wave Cosmology The Astrophysical Journal Gravitational wave astronomy Bayesian statistics Hubble constant Compact binary stars |
| title | No Need to Know: Toward Astrophysics-free Gravitational-wave Cosmology |
| title_full | No Need to Know: Toward Astrophysics-free Gravitational-wave Cosmology |
| title_fullStr | No Need to Know: Toward Astrophysics-free Gravitational-wave Cosmology |
| title_full_unstemmed | No Need to Know: Toward Astrophysics-free Gravitational-wave Cosmology |
| title_short | No Need to Know: Toward Astrophysics-free Gravitational-wave Cosmology |
| title_sort | no need to know toward astrophysics free gravitational wave cosmology |
| topic | Gravitational wave astronomy Bayesian statistics Hubble constant Compact binary stars |
| url | https://doi.org/10.3847/1538-4357/ad9253 |
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