LOCATING THE ''MISSING'' BARYONS WITH EXTRAGALACTIC DISPERSION MEASURE ESTIMATES
- Department of Astronomy, University of California, Berkeley, CA 94720 (United States)
Recently, Thornton and coworkers confirmed a class of millisecond radio bursts likely of extragalactic origin that is well-suited for estimating dispersion measures (DMs). We calculate the probability distribution of DM(z) in different models for how the cosmic baryons are distributed (both analytically and with cosmological simulations). We show that the distribution of DM is quite sensitive to whether the ''missing'' baryons lie around the virial radius of 10{sup 11}-10{sup 13} M{sub ☉} halos or further out, which is not easily constrained with other observational techniques. The intrinsic contribution to DM from each source could complicate studies of the extragalactic contribution. This difficulty is avoided by stacking based on the impact parameter to foreground galaxies. We show that a stacking analysis using a sample of ∼100 DM measurements from arcminute-localized, z ≳ 0.5 sources would place interesting constraints at 0.2-2 halo virial radii on the baryonic mass profile surrounding different galaxy types. Conveniently for intergalactic studies, sightlines that intersect intervening galactic disks should be easily identified owing to scattering. A detectable level of scattering may also result from turbulence in the circumgalactic medium.
- OSTI ID:
- 22364046
- Journal Information:
- Astrophysical Journal Letters, Vol. 780, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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