| Title: |
Inferring M_(BH)–M_(bulge) Evolution from the Gravitational-wave Background |
| Authors: |
Matt, Cayenne; Gültekin, Kayhan; Kelley, Luke Zoltan; Blecha, Laura; Simon, Joseph; Agazie, Gabriella; Anumarlapudi, Akash; Archibald, Anne M.; Arzoumanian, Zaven; Baier, Jeremy G.; Baker, Paul T.; Bécsy, Bence; 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.; 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.; Harris, C. J.; Hazboun, Jeffrey S.; Jennings, Ross J.; Johnson, Aaron D.; Jones, Megan L.; Kaplan, David L.; 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.; 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.; Schmiedekamp, Ann; Schmiedekamp, Carl; Schmitz, Kai; Shapiro-Albert, Brent J.; Siemens, Xavier; Fiscella, Sophia V. Sosa; Stairs, Ingrid H.; Stinebring, Daniel R.; Stovall, Kevin; Susobhanan, Abhimanyu; Swiggum, Joseph K.; Taylor, Jacob; Taylor, Stephen R.; Thompson, Mercedes S.; Turner, Jacob E.; Vallisneri, Michele; van Haasteren, Rutger; Vigeland, Sarah J.; Wahl, Haley M.; Wilson, Kevin P.; Witt, Caitlin A.; Wright, David; Young, Olivia |
| Source: |
Astrophysical Journal, 997(2), 188, (2026-02-01) |
| Publisher Information: |
American Astronomical Society |
| Publication Year: |
2026 |
| Collection: |
Caltech Authors (California Institute of Technology) |
| Subject Terms: |
Black holes; Supermassive black holes; Gravitational waves; Gravitational wave sources; Galaxies; Scaling relations |
| Description: |
We test the impact of an evolving supermassive black hole mass scaling relation ( M BH – M bulge ) on the predictions for the gravitational-wave background (GWB). The observed GWB amplitude is 2–3 times higher than predicted by astrophysically informed models, which suggests the need to revise the assumptions in those models. We compare a semi-analytic model's ability to reproduce the observed GWB spectrum with a static versus evolving-amplitude M BH – M bulge relation. We additionally consider the influence of the choice of galaxy stellar mass function (GSMF) on the modeled GWB spectra. Our models are able to reproduce the GWB amplitude with either a large number density of massive galaxies or a positively evolving M BH – M bulge amplitude (i.e., the M BH / M bulge ratio was higher in the past). If we assume that the M BH – M bulge amplitude does not evolve, our models require a GSMF that implies an undetected population of massive galaxies ( M ⋆ ≥ 10 ¹ ¹ M ⊙ at z > 1). When the M BH – M bulge amplitude is allowed to evolve, we can model the GWB spectrum with all fiducial values and an M BH – M bulge amplitude that evolves as α ( z ) = α ₀ (1 + z ) 1.04±0.5 . ; © 2026. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence . Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. ; The authors would like to thank Joel Leja and CJ Harris for insightful discussions, which aided and improved the interpretation of this work. The authors additionally thank the anonymous referee for their thoughtful comments, which led to an increase in the clarity of communication and analysis of our results. L.B. acknowledges support from the National Science Foundation under award AST-2307171 and from the National Aeronautics and Space Administration under award 80NSSC22K0808. P.R.B. is supported by the Science and ... |
| Document Type: |
article in journal/newspaper |
| Language: |
English |
| Relation: |
https://arxiv.org/abs/arXiv:2508.18126; https://authors.library.caltech.edu/communities/caltechauthors/ |
| DOI: |
10.3847/1538-4357/ae2480 |
| Availability: |
https://doi.org/10.3847/1538-4357/ae2480 |
| Rights: |
info:eu-repo/semantics/openAccess ; Creative Commons Attribution 4.0 International ; https://creativecommons.org/licenses/by/4.0/legalcode |
| Accession Number: |
edsbas.B1190176 |
| Database: |
BASE |