Abstract Fast radio bursts (FRBs) are high-energy, short-duration phenomena in radio astronomy. Identifying their host galaxies can provide insights into their mysterious origins. In this paper, we introduce a novel approach to identifying potential host galaxies in three-dimensional space. We use FRB 20190425A and GW190425 as examples to illustrate our method. Recently, due to spatial and temporal proximity, the potential association of GW190425 with FRB 20190425A has drawn attention, leading to the identification of a likely host galaxy, UGC 10667, albeit without confirmed kilonova emissions. We search for the host galaxy of FRB 20190425A with a full CHIME localization map. Regardless of the validity of the association between GW190425 and FRB 20190425A, we identify an additional potential host galaxy (SDSS J171046.84+212732.9) from the updated GLADE galaxy catalog, supplementing the importance of exploring the new volume. We employed various methodologies to determine the most probable host galaxy of GW190424 and FRB 20190425A, including a comparison of galaxy properties and constraints on their reported observation limits using various kilonova models. Our analysis suggests that current observations do not definitively identify the true host galaxy. Additionally, the kilonova models characterized by a gradual approach to their peak are contradicted by the observational upper limits of both galaxies. Although the absence of optical emission detection raises doubts, it does not definitively disprove the connection between the gravitational wave (GW) and FRB.
Fast radio bursts (FRBs) are high-energy, short-duration phenomena in radio astronomy. Identifying their host galaxies can provide insights into their mysterious origins. In this paper, we introduce a novel approach to identifying potential host galaxies in three-dimensional space. We use FRB 20190425A and GW190425 as an example to illustrate our method. Recently, due to spatial and temporal proximity, the potential association of GW190425 with FRB 20190425A has drawn attention, leading to the identification of a likely host galaxy, UGC 10667, albeit without confirmed kilonova emissions. We search for the host galaxy of FRB 20190425A with a full CHIME localization map. Regardless of the validity of the association between GW190425 and FRB 20190425A, we identify an additional potential host galaxy (SDSS J171046.84+212732.9) from the updated GLADE galaxy catalog, supplementing the importance of exploring the new volume. We employed various methodologies to determine the most probable host galaxy of GW190424 and FRB 20190425A, including a comparison of galaxy properties and constraints on their reported observation limits using various Kilonova models. Our analysis suggests that current observations do not definitively identify the true host galaxy. Additionally, the Kilonova models characterized by a gradual approach to their peak are contradicted by the observational upper limits of both galaxies. Although the absence of optical emission detection raises doubts, it does not definitively disprove the connection between GW and FRB.
Fast radio bursts (FRBs) are a promising new probe for astronomy and cosmology. Thanks to their extragalactic and cosmological origin, FRBs could be used to study the intergalactic medium (IGM) and the cosmic expansion. It is expected that numerous FRBs with identified redshifts will be available in the near future through the identification of their host galaxies or counterparts. $\rm DM_{IGM}$, the contribution from IGM to the observed dispersion measure (DM) of FRB, carries the key information about IGM and the cosmic expansion history. We can thus study the evolution of the universe by using FRBs with identified redshifts. In the present work, we are interested in the fraction of baryon mass in the IGM, $f_{\rm IGM}$, which is useful to study the cosmic expansion and the problem of the "missing baryons". We propose to reconstruct the evolution of $f_{\rm IGM}$ as a function of redshift $z$ with FRBs via a completely model-independent method, namely Gaussian processes. Since there is not a large sample of FRBs with identified redshifts, we use simulated FRBs instead. Through various simulations, we show that this methodology works well.
Nowadays, fast radio bursts (FRBs) have been a promising probe for astronomy and cosmology. However, it is not easy to identify the redshifts of FRBs to date. Thus, no sufficient actual FRBs with identified redshifts can be used to study cosmology currently. In the past years, one has to use the simulated FRBs with "known" redshifts instead. To simulate an FRB, one should randomly assign a redshift to it from a given redshift distribution. But the actual redshift distribution of FRBs is still unknown so far. Therefore, many redshift distributions have been assumed in the literature. In the present work, we study the effect of various redshift distributions on cosmological constraints, while they are treated equally. We find that different redshift distributions lead to different cosmological constraining abilities from the simulated FRBs. This result emphasizes the importance to find the actual redshift distribution of FRBs, and reminds us of the possible bias in the FRB simulations due to the redshift distributions.
In the recent years, the field of fast radio bursts (FRBs) is thriving and growing rapidly. It is of interest to study cosmology by using FRBs with known redshifts. In the present work, we try to test the possible cosmic anisotropy with the simulated FRBs. In particular, we only consider the possible dipole in FRBs, rather than the cosmic anisotropy in general, while the analysis is only concerned with finding the rough number of necessary data points to distinguish a dipole from a monopole structure through simulations. Noting that there is no a large sample of actual data of FRBs with known redshifts by now, simulations are necessary to this end. We find that at least 2800, 190, 100 FRBs are competent to find the cosmic dipole with amplitude 0.01, 0.03, 0.05, respectively. Unfortunately, even 10000 FRBs are not competent to find the tiny cosmic dipole with amplitude of ${\cal O}(10^{-3})$. On the other hand, at least 20 FRBs with known redshifts are competent to find the cosmic dipole with amplitude 0.1. We expect that such a big cosmic dipole could be ruled out by using only a few tens of FRBs with known redshifts in the near future.
Abstract Currently, fast radio bursts (FRBs) have become a very active field in astronomy and cosmology. However, the origin of FRBs is still unknown to date. The studies on the intrinsic FRB distributions might help us to reveal the possible origins of FRBs, and improve the simulations for FRB cosmology. Recently, the first CHIME/FRB catalog of 536 events was released. Such a large uniform sample of FRBs detected by a single telescope is very valuable to test the FRB distributions. Later, it has been claimed that the FRB distribution model tracking the cosmic star formation history (SFH) was rejected by the first CHIME/FRB catalog. In the present work, we consider some empirical FRB distribution models, and find that many of them can be fully consistent with the CHIME/FRB observational data for some suitable model parameters. Notice that a suppressed evolution with respect to SFH is commonly found for FRBs. In particular, we independently confirm that the FRB distribution model tracking SFH can be rejected at very high confidence. On the other hand, all the "successful" models effectively require a certain degree of "delay" with respect to SFH. These results might shed light on the origin of FRBs and FRB cosmology.
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