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Search for correlations between host properties and DMhost of fast radio bursts:constraints on the baryon mass fraction in IGM

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Chinese Physics C 2022年第7期46卷 201-211页

作者： Hai-Nan Lin Xin Li Li Tang Department of Physics Chongqing UniversityChongqing 401331China Department of Math and Physies Mianyang Normal University Mianyang 621000China

The application of fast radio bursts(FRBs)as probes for investigating astrophysics and cosmology requires proper modelling of the dispersion measures of the Milky Way(DM_(MW))and host galaxy(DM_(host)).DM_(MW)can be estimated using the Milky Way electron models,such as the NE2001 model and YMW16 ***,DM_(host)is hard to model due to limited information on the local environment of the *** this study,using 17 well-localized FRBs,we search for possible correlations betweenDM_(host)and the properties of the host galaxies,such as the redshift,stellar mass,star-formation rate,age of galaxy,offset of the FRB site from the galactic center,and half-light *** find no strong correlation betweenDM_(host)and any of the host *** thatDM_(host)is a constant for all host galaxies,we constrain the fraction of the baryon mass in the intergalactic medium today to bef_(IGM,0)=0.78_(-0.19)^(+0.15).If we modelDM_(host)as a log-normal distribution,however,we obtain a larger value,f_(IGM,0)=0.83_(-0.17)^(+0.12).Based on the limited number of FRBs,no strong evidence for a redshift evolution off_(IGM)is found.

关键词： fast radio bursts intergalactic medium cosmological parameters

Combined limit on the photon mass with nine localized fast radio bursts

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Research in Astronomy and Astrophysics 2020年第12期20卷 330-336页

作者： Jun-Jie Wei Xue-Feng Wu Purple Mountain Observatory Chinese Academy of SciencesNanjing 210023China School of Astronomy and Space Sciences University of Science and Technology of ChinaHefei 230026China

A nonzero-mass hypothesis for the photon can produce a frequency-dependent dispersion of light, which results in arrival-time differences of photons with different frequencies originating from a given transient source. Extragalactic fast radio bursts(FRBs), with their low frequency emissions, short time durations, and long propagation distances, are excellent astrophysical probes to constrain the rest mass of the photon mγ. However, the derivation of a limit on mγis complicated by the similar frequency dependences of dispersion expected from the plasma and nonzero photon mass effects. If a handful measurements of redshift for FRBs are available, then the different redshift dependences of the plasma and photon mass contributions to the dispersion measure(DM) might be able to break dispersion degeneracy in testing the photon mass. For now, nine FRBs with redshift measurements have been reported, which can turn this idea into reality. Taking into account the DM contributions from both the plasma and a possible photon mass,we use the data on the nine FRBs to derive a combined limit of mγ≤ 7.1 × 10^-51 kg, or equivalently mγ≤ 4.0 × 10^-15 e V/c2 at 68% confidence level, which is essentially as good as or represents a factor of 7 improvement over previous limits obtained by the single FRBs. Additionally, a reasonable estimation for the DM contribution from the host galaxy, DMhost, can be simultaneously achieved in our analysis. The rapid progress in localizing FRBs will further tighten the constraints on both mγ and DMhost.

关键词： radio continuum:general intergalactic medium astroparticle physics

Inferring redshift and energy distributions of fast radio bursts from the first CHIME/FRB catalog

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中国物理C:英文版 2023年第8期47卷 162-172页

作者：唐丽林海南李昕 Department of Math and Physics Mianyang Teachers’CollegeMianyang 621000China Department of Physics Chongqing UniversityChongqing 401331China Chongqing Key Laboratory for Strongly Coupled Physics Chongqing UniversityChongqing 401331China

We reconstruct the extragalactic dispersion measure-redshift(DM_(E)-z)relation from well-localized fast radio bursts(FRBs)using Bayesian ***,the DM_(E)-z relation is used to infer the redshift and energy of the first CHIME/FRB *** find that the distributions of the extragalactic dispersion measure and inferred redshift of the non-repeating CHIME/FRBs follow a cut-off power law but with a significant excess at the low-redshift *** apply a set of criteria to exclude events that are susceptible to the selection effect,but the excess at low redshifts still exists in the remaining FRBs(which we call the gold sample).The cumulative distributions of fluence and energy for both the full sample and the gold sample do not follow the simple power law,but they can be well fitted by the bent power *** underlying physical implications require further investigation.

关键词： fast radio bursts intergalactic medium cosmological parameters

Part III: Explaining the “Extra” Heat of intergalactic Hydrogen Clouds with Probabilistic Spacetime

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Journal of High Energy Physics, Gravitation and Cosmology 2023年第2期9卷 542-551页

作者： Dennis Doren James Harasymiw Independent Researcher Wisconsin USA

Recent observations have consistently shown a greater degree of heat in intergalactic hydrogen clouds when redshift z < 2 than what well-designed simulations have indicated. The reason for this “extra” energy has not been established, with the latest hypothesis being the effect of a certain type of dark matter. This paper presents a contrasting straightforward non-dark explanation for the extra energy based on the Probabilistic Spacetime Theory (PST). Both the dark matter and PST models are shown to involve the creation of new photons to explain the thermal enigma, but with very different underlying mechanisms. As this is the third paper in a three-part series of articles on the utility of that theory, a discussion is offered at the end of this paper concerning what the collective set of three articles has shown. Despite dark entities being hypothesized as a cause of all three reviewed research findings, dark entities are not needed to explicate the excess energy documented in each paper. Instead, the PST offers explanations for the reviewed research findings based solely on its five tenets and no dark entities. When viewed from an even larger context of other studies’ unexpected results, the PST was found to be a comprehensive yet parsimonious cosmological theory worthy of further testing.

关键词： intergalactic medium Absorption Lines Lyman-α Forest Probabilistic Spacetime Dark Photons Dark Matter