The Supersonic Project: SIGOs, A Proposed Progenitor to Globular Clusters, and Their Connections to Gravitational-wave Anisotropies
Abstract
Supersonically induced gas objects (SIGOs), are structures with little to no dark-matter component predicted to exist in regions of the universe with large relative velocities between baryons and dark matter at the time of recombination. They have been suggested to be the progenitors of present-day globular clusters. Using simulations, SIGOs have been studied on small scales (around 2 Mpc) where these relative velocities are coherent. However, it is challenging to study SIGOs using simulations on large scales due to the varying relative velocities at scales larger than a few Mpc. Here, we study SIGO abundances semi-analytically: using perturbation theory, we predict the number density of SIGOs analytically, and compare these results to small-box numerical simulations. We use the agreement between the numerical and analytic calculations to extrapolate the large-scale variation of SIGO abundances over different stream velocities. As a result, we predict similar large-scale variations of objects with high gas densities before reionization that could possibly be observed by JWST. If indeed SIGOs are progenitors of globular clusters, then we expect a similar variation of globular cluster abundances over large scales. Significantly, we find that the expected number density of SIGOs is consistent with observed globular cluster number densities. As a proof-of-concept, and because globular clusters were proposed to be natural formation sites for gravitational wave sources from binary black-hole mergers, we show that SIGOs should imprint an anisotropy on the gravitational wave signal on the sky, consistent with their distribution.
Additional Information
© 2021. The American Astronomical Society. Received 2021 May 3; revised 2021 August 19; accepted 2021 August 23; published 2021 November 23. We thank the anonymous referee for useful comments. We also thank Naoki Yoshida and Carl Rodriguez for useful discussions. W.L., S.N., Y.S.C, B.B., F.M., and M.V. are grateful for the support of NASA grant No. 80NSSC20K0500 and the XSEDE AST180056 allocation, as well as the Simons Foundation Center for Computational Astrophysics and the UCLA cluster Hoffman2 for computational resources. F.M. acknowledges support from the Program "Rita Levi Montalcini" of the Italian MUR. W.L. thanks Ryan Carlson for helpful conversations. S.N thanks Howard and Astrid Preston for their generous support. Y.S.C is thankful for partial support from a UCLA dissertation year fellowship. B.B. also thanks the Alfred P. Sloan Foundation and the Packard Foundation for support. M.V. acknowledges support through NASA ATP grants 16-ATP16-0167, 19-ATP19-0019, 19-ATP19-0020, 19-ATP19-0167, and NSF grants AST-1814053, AST-1814259, AST-1909831 and AST-2007355. K.K. is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-2001751.Attached Files
Published - Lake_2021_ApJ_922_86.pdf
Accepted Version - 2104.11226.pdf
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Additional details
- Eprint ID
- 112209
- Resolver ID
- CaltechAUTHORS:20211203-204702298
- 80NSSC20K0500
- NASA
- AST-180056
- NSF
- Ministero dell'Istruzione, dell'Università e della Ricerca (MIUR)
- UCLA
- Alfred P. Sloan Foundation
- David and Lucile Packard Foundation
- 16-ATP16-0167
- NASA
- 19-ATP19-0019
- NASA
- 19-ATP19-0020
- NASA
- 19-ATP19-0167
- NASA
- AST-1814053
- NSF
- AST-1814259
- NSF
- AST-1909831
- NSF
- AST-2007355
- NSF
- AST-2001751
- NSF Astronomy and Astrophysics Fellowship
- Created
-
2021-12-03Created from EPrint's datestamp field
- Updated
-
2021-12-03Created from EPrint's last_modified field
- Caltech groups
- TAPIR