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Abstract This paper presents the first public data release (DR1) of the FRB Line-of-sight Ionization Measurement From Lightcone AAOmega Mapping (FLIMFLAM) survey, a wide field spectroscopic survey targeted on the fields of 10 precisely localized fast radio bursts (FRBs). DR1 encompasses spectroscopic data for 10,468 galaxy redshifts across 10 FRB fields withz < 0.4, covering approximately 26 deg²of the sky in total. FLIMFLAM is composed of several layers, encompassing the “wide” (covering ∼degree or >10 Mpc scales), “narrow” (several arcminutes or ∼Mpc), and integral field unit (“IFU”; ∼arcminute or ∼100 kpc) components. The bulk of the data comprises spectroscopy from the Two Degree Field-AAOmega instrument on the 3.9 m Anglo-Australian Telescope, while most of the narrow and IFU data was achieved using an ensemble of 8–10 m class telescopes. We summarize the information on our selected FRB fields, the criteria for target selection, methodologies employed for data reduction, spectral analysis processes, and an overview of our data products. An evaluation of our data reveals an average spectroscopic completeness of 48.43%, with over 80% of the observed targets having secure redshifts. Additionally, we describe our approach to generating angular masks and calculating the target selection functions, setting the stage for the impending reconstruction of the matter density field. 

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. 

ABSTRACT There has been a rapid increase in the known fast radio burst (FRB) population, yet the progenitor(s) of these events have remained an enigma. A small number of FRBs have displayed some level of quasi-periodicity in their burst profile, which can be used to constrain their plausible progenitors. However, these studies suffer from the lack of polarization data which can greatly assist in constraining possible FRB progenitors and environments. Here, we report on the detection and characterisation of FRB 20230708A by the Australian Square Kilometre Array Pathfinder (ASKAP), a burst which displays a rich temporal and polarimetric morphology. We model the burst time series to test for the presence of periodicity, scattering and scintillation. We find a potential period of T = 7.267 ms within the burst, but with a low statistical significance of 1.77$$\sigma$$. Additionally, we model the burst’s time- and frequency-dependent polarization to search for the presence of (relativistic and non-relativistic) propagation effects. We find no evidence to suggest that the high circular polarization seen in FRB 20230708A is generated by Faraday conversion. The majority of the properties of FRB 20230708A are broadly consistent with a (non-millisecond) magnetar model in which the quasi-periodic morphology results from microstructure in the beamed emission, but other explanations are not excluded. 

Abstract We report the discovery of the repeating fast radio burst (FRB) source FRB 20240209A using the Canadian Hydrogen Intensity Mapping Experiment (CHIME)/FRB telescope. We detected 22 bursts from this repeater between 2024 February and July, 6 of which were also recorded at the Outrigger station k’niʔatn k’l_⌣stk’masqt (KKO). The multiple very long baseline interferometry localizations using the 66 km long CHIME–KKO baseline, each with a different baseline vector orientation due to the repeater’s high decl. of ∼86°, enabled the combined localization region to be constrained to 1″ × 2″. We present deep Gemini optical observations that, combined with the FRB localization, enabled a robust association of FRB 20240209A to the outskirts of a luminous galaxy (P(O∣x) = 0.99;L ≈ 5.3 × 10¹⁰L_⊙). FRB 20240209A has a projected physical offset of 40 ± 5 kpc from the center of its host galaxy, making it the FRB with the largest host galaxy offset to date. When normalized by the host galaxy size, the offset of FRB 20240209A (5.1R_eff) is comparable to that of FRB 20200120E (5.7R_eff), the only FRB source known to originate in a globular cluster. We consider several explanations for the large offset, including a progenitor that was kicked from the host galaxy or in situ formation in a low-luminosity satellite galaxy of the putative host, but find the most plausible scenario to be a globular cluster origin. This, coupled with the quiescent, elliptical nature of the host as demonstrated in our companion Letter, provides strong evidence for a delayed formation channel for the progenitor of the FRB source. 

Abstract We present observations from the Gemini Multi-Conjugate Adaptive Optics System/Gemini South Adaptive Optics Imager at Gemini South of five fast radio burst (FRB) host galaxies of FRBs with subarcsecond localizations. We examine and quantify the spatial distributions and locations of the FRBs with respect to their host galaxy light distributions, finding a median host-normalized offset of 2.09 half-light radii (r_e) and the trend that these FRBs occur in fainter regions of their host galaxies. When combined with the FRB host galaxy sample from Mannings et al., we find that FRBs are statistically distinct from Ca-rich transients in terms of light at the source location and from SGRBs and LGRBs in terms of host-normalized offset. We further find that most FRBs are in regions of elevated local stellar mass surface densities in comparison to the mean global values of their hosts. This, along with the finding that the FRB locations trace the distribution of stellar mass, points toward a possible similarity of the environments of CCSNe and FRBs. We also find that four out of five FRB hosts exhibit distinct spiral arm features, and the bursts originating from such hosts tend to appear on or close to their host’s spiral structure, with a median distance of 0.53 ± 0.27 kpc. With many well-localized FRB detections looming on the horizon, we will be able to better characterize the properties of FRB environments relative to their host galaxies and other transient classes. Such insights may only require us to double the number of FRBs with subarcsecond localizations. 

Abstract The discovery and localization of FRB 20240209A by the Canadian Hydrogen Intensity Mapping Fast Radio Burst (CHIME/FRB) experiment marks the first repeating FRB localized with the CHIME/FRB Outriggers and adds to the small sample of repeating FRBs with associated host galaxies. Here we present Keck and Gemini observations of the host that reveal a redshiftz = 0.1384 ± 0.0004. We perform stellar population modeling to jointly fit the optical through mid-IR data of the host and infer a median stellar mass log(M_*/M_⊙) = 11.35 ± 0.01 and a mass-weighted stellar population age  ~11 Gyr, corresponding to the most massive and oldest FRB host discovered to date. Coupled with a star formation rate  <0.31M_⊙yr⁻¹, the specific star formation rate  <10^−11.9yr⁻¹classifies the host as quiescent. Through surface brightness profile modeling, we determine an elliptical galaxy morphology, marking the host as the first confirmed elliptical FRB host. The discovery of a quiescent early-type host galaxy within a transient class predominantly characterized by late-type star-forming hosts is reminiscent of short-duration gamma-ray bursts, Type Ia supernovae, and ultraluminous X-ray sources. Based on these shared host demographics, coupled with a large offset as demonstrated in our companion Letter, we conclude that preferred sources for FRB 20240209A include magnetars formed through merging binary neutron stars/white dwarfs or the accretion-induced collapse of a white dwarf, or a luminous X-ray binary. Together with FRB 20200120E localized to a globular cluster in M81, our findings provide strong evidence that some fraction of FRBs may arise from a process distinct from the core collapse of massive stars. 

Abstract We present the host galaxies of four apparently nonrepeating fast radio bursts (FRBs), FRB 20181223C, FRB 20190418A, FRB 20191220A, and FRB 20190425A, reported in the first Canadian Hydrogen Intensity Mapping Experiment (CHIME/FRB) catalog. Our selection of these FRBs is based on a planned hypothesis testing framework where we search all CHIME/FRB Catalog-1 events that have low extragalactic dispersion measure (<100 pc cm⁻³), with high Galactic latitude (∣b∣ > 10°) and saved baseband data. We associate the selected FRBs with galaxies with moderate to high star formation rates located at redshifts between 0.027 and 0.071. We also search for possible multimessenger counterparts, including persistent compact radio and gravitational-wave sources, and find none. Utilizing the four FRB hosts from this study, along with the hosts of 14 published local Universe FRBs (z< 0.1) with robust host association, we conduct an FRB host demographics analysis. We find all 18 local Universe FRB hosts in our sample to be spirals (or late-type galaxies), including the host of FRB 20220509G, which was previously reported to be elliptical. Using this observation, we scrutinize proposed FRB source formation channels and argue that core-collapse supernovae are likely the dominant channel to form FRB sources. Moreover, we infer no significant difference in the host properties of repeating and apparently nonrepeating FRBs in our local Universe FRB host sample. Finally, we find the burst rates of these four apparently nonrepeating FRBs to be consistent with those of the sample of localized repeating FRBs observed by CHIME/FRB. Therefore, we encourage further monitoring of these FRBs with more sensitive radio telescopes. 

ABSTRACT Localization of fast radio bursts (FRBs) to arcsecond and subarcsecond precision maximizes their potential as cosmological probes. To that end, FRB detection instruments are deploying triggered complex-voltage capture systems to localize FRBs, identify their host galaxy, and measure a redshift. Here, we report the discovery and localization of two FRBs (20220717A and 20220905A) that were captured by the transient buffer system deployed by the MeerTRAP instrument at the MeerKAT telescope in South Africa. We were able to localize the FRBs to precision of $$\sim$$1 arcsecond that allowed us to unambiguously identify the host galaxy for FRB 20220717A (posterior probability $$\sim$$0.97). FRB 20220905A lies in a crowded region of the sky with a tentative identification of a host galaxy but the faintness and the difficulty in obtaining an optical spectrum preclude a conclusive association. The bursts show low linear polarization fractions (10–17 per cent) that conform to the large diversity in the polarization fraction observed in apparently non-repeating FRBs akin to single pulses from neutron stars. We also show that the host galaxy of FRB 20220717A contributes roughly 15 per cent of the total dispersion measure (DM), indicating that it is located in a plasma-rich part of the host galaxy which can explain the large rotation measure. The scattering in FRB 20220717A can be mostly attributed to the host galaxy and the intervening medium and is consistent with what is seen in the wider FRB population. 

Abstract We report on contemporaneous optical observations at ≈10 ms timescales from the fast radio burst (FRB) 20180916B of two repeat bursts (FRB 20201023 and FRB 20220908) taken with the ‘Alopeke camera on the Gemini-North telescope. These repeats have radio fluences of 2.8 and 3.5 Jy ms, respectively, approximately in the lower 50th percentile for fluence from this repeating burst. The ‘Alopeke data reveal no significant optical detections at the FRB position and we place 3σupper limits to the optical fluences of <8.3 × 10⁻³and <7.7 × 10⁻³Jy ms after correcting for line-of-sight extinction. Together, these yield the most sensitive limits to the optical-to-radio fluence ratio of an FRB on these timescales withη_ν< 3 × 10⁻³by roughly an order of magnitude. These measurements rule out progenitor models where FRB 20180916B has a similar fluence ratio to optical pulsars, such as the Crab pulsar, or where optical emission is produced as inverse-Compton radiation in a pulsar magnetosphere or young supernova remnant. Our ongoing program with ‘Alopeke on Gemini-North will continue to monitor repeating FRBs, including FRB 20180916B, to search for optical counterparts on millisecond timescales. 

Abstract Identification and follow-up observations of the host galaxies of fast radio bursts (FRBs) not only help us understand the environments in which the FRB progenitors reside, but also provide a unique way of probing the cosmological parameters using the dispersion measures (DMs) of FRBs and distances to their origin. A fundamental requirement is an accurate distance measurement to the FRB host galaxy, but for some sources viewed through the Galactic plane, optical/near-infrared spectroscopic redshifts are extremely difficult to obtain due to dust extinction. Here we report the first radio-based spectroscopic redshift measurement for an FRB host galaxy, through detection of its neutral hydrogen (Hi) 21 cm emission using MeerKAT observations. We obtain an Hi–based redshift ofz= 0.0357 ± 0.0001 for the host galaxy of FRB 20230718A, an apparently nonrepeating FRB detected in the Commensal Real-time ASKAP Fast Transients survey and localized at a Galactic latitude of –0.°367. Our observations also reveal that the FRB host galaxy is interacting with a nearby companion, which is evident from the detection of an Hibridge connecting the two galaxies. A subsequent optical spectroscopic observation confirmed an FRB host galaxy redshift of 0.0359 ± 0.0004. This result demonstrates the value of Hito obtain redshifts of FRBs at low Galactic latitudes and redshifts. Such nearby FRBs whose DMs are dominated by the Milky Way can be used to characterize these components and thus better calibrate the remaining cosmological contribution to dispersion for more distant FRBs that provide a strong lever arm to examine the Macquart relation between cosmological DM and redshift.