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Abstract The FLIMFLAM survey is collecting spectroscopic data of field galaxies near fast radio burst (FRB) sight lines to constrain key parameters describing the distribution of matter in the Universe. In this work, we leverage the survey data to determine the source of the excess extragalactic dispersion measure (DM), compared to Macquart relation estimates of four FRBs: FRB20190714A, FRB20200906A, FRB20200430A, and FRB20210117A. By modeling the gas distribution around the foreground galaxy halos and galaxy groups of the sight lines, we estimate DMhalos, their contribution to the FRB DMs. The FRB20190714A sight line shows a clear excess of foreground halos which contribute roughly two-thirds of the observed excess DM, thus implying a sight line that is baryon dense. FRB20200906A shows a smaller but nonnegligible foreground halo contribution, and further analysis of the intergalactic medium is necessary to ascertain the true cosmic contribution to its DM. FRB20200430A and FRB20210117A show negligible foreground contributions, implying a large host galaxy excess and/or progenitor environment excess.
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This content will become publicly available on March 26, 2026
Modelling the cosmic dispersion measure in the D < 120 Mpc Local Universe
ABSTRACT The Local Universe ($D< 120$ Mpc) has been intensely studied for decades, with highly complete galaxy redshift surveys now publicly available. These data have driven density reconstructions of the underlying matter density field, as well as constrained simulations that aim to reproduce the observed structures. In this paper, we introduce a dispersion measure (DM) model that makes use of this detailed knowledge of our Local Universe within $D< 120$ Mpc. The model comprises three key components: (i) the DM from the Milky Way’s halo and the intragroup medium (up to 3.4 Mpc), derived from the H estia simulations, a series of constrained hydrodynamic simulations designed to reproduce our Local Group; (ii) the DM contribution from the large-scale intergalactic medium beyond the Local Group (3.4 Mpc $< D< 120$ Mpc), calculated using the Hamlet reconstructed matter density field; and (iii) the individual DM contributions from Local Universe galaxy haloes and clusters based on data from the Two Micron All Sky Survey Galaxy Group Catalogue and the NASA/IPAC Extragalactic Data base. This comprehensive model will be made available as a python package. As the most realistic model to date for DM in the local volume, it promises to improve the constraints of DM contributions from the intergalactic medium and circumgalactic medium of fast radio bursts (FRBs), thereby enhancing the accuracy of cosmic baryon distribution calculations based on DM analysis of FRBs.
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- PAR ID:
- 10618031
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Monthly Notices of the Royal Astronomical Society
- Volume:
- 538
- Issue:
- 4
- ISSN:
- 0035-8711
- Page Range / eLocation ID:
- 2785 to 2799
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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