Central Cluster Galaxies: A Hot Spot for Detectable Gravitational Waves from Black Hole Mergers
Since pulsar timing arrays (PTAs) announced the evidence for a low-frequency gravitational-wave (GW) background, continuous waves (CWs) have been the next anticipated GW signals. In this work, we model CW sources detectable by PTAs based on the massive black hole (MBH) merger population in the ASTRI...
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| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal Letters |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/2041-8213/adf101 |
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| Summary: | Since pulsar timing arrays (PTAs) announced the evidence for a low-frequency gravitational-wave (GW) background, continuous waves (CWs) have been the next anticipated GW signals. In this work, we model CW sources detectable by PTAs based on the massive black hole (MBH) merger population in the ASTRID cosmological simulation. We evolve MBH binaries, simulate their GW emissions, and calculate their detection probability (DP) for PTAs. The most detectable CW sources are produced by MBH mergers with masses M _BH > 10 ^10 M _⊙ in the lowest-frequency bins with f < 10 nHz. Remarkably, these mergers occur within massive galaxies with stellar mass M _* > 10 ^12 M _⊙ located at the center of galaxy clusters. Particularly striking in ASTRID is a triple merger event, wherein two consecutive mergers occur within 500 Myr interval in the same cluster core, generating high-DP CW signals at ∼2 and ∼10 nHz. We also investigate the electromagnetic signatures associated with these events: either single or dual active galactic nuclei in the massive host galaxies that are undergoing star formation. This research provides new insights into the low-frequency GW sky and informs future multimessenger searches for PTA CW sources. |
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| ISSN: | 2041-8205 |