arXiv subjects

Jason W. T. Hessels

Publications and source records attributed to Jason W. T. Hessels.

At least 19 recordsLinked to original sources

arXiv2026

The CHIME/FRB Outriggers: Commissioning the Hat Creek Outrigger and an Updated Calibration Scheme for Mitigating RFI

This work presents commissioning of the Hat Creek Outrigger (HCO), a dual-polarization 256-element radio interferometer that is part of the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) Outrigger project. Driven by a complex radio-frequency interference (RFI) environment that consistently contaminates $\sim40\%$ of HCO's usable bandwidth, we implement an improved calibration scheme using Gaussian Process Regression to recover complex gain solutions over RFI contaminated channels. To validate our method, we test the performance of the array using known transients and continuum sources over relevant timescales used for fast-transient research ($\lesssim$ seconds). We find that our updated calibration scheme results in a $\sim1.69\times~\mathrm{to}~1.87\times$ improvement in the array's point-source sensitivity, while simultaneously maintaining noise properties consistent with thermal statistics. As a result, we find that the array performs consistently within theoretical expectations across $\gtrsim80\%$ of HCO's bandpass. We further observe an improvement in the interferometric performance after applying recently developed spatial filtering techniques for RFI mitigation, which rely on accurate calibration solutions for effective removal of unwanted interference. We conclude that our approach provides a valid framework for improving calibration solutions over RFI contaminated channels for large-$N$ interferometric arrays more broadly. Our work motivates future development of more sophisticated techniques to recover astrophysical information in RFI-contaminated channels, departing from the historical practice of discarding them outright.

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arXiv2026

Unveiling Radio Transients with SKAO Telescopes

Transient astrophysics provides a set of unique laboratories for studying fundamental physics. From the launching of powerful relativistic jets to merging neutron stars, highly-magnetised compact objects, or stellar explosions, transients probe the Universe at its most extreme. The SKAO will provide an unrivalled set of capabilities for transient observations on timescales from nanoseconds to decades, opening new discovery space. With its sensitivity, broad spectral coverage, wide field of view, and high survey speed, SKAO will allow us to discover and understand rare events that provide powerful new insights into regimes of high energy density, strong gravity, and intense magnetic fields. Complemented by a suite of multi-wavelength and multi-messenger facilities, and supported by a network of smaller existing radio telescopes and new computational capabilities, SKAO will unveil the most powerful and exotic events in our Universe, addressing some of the key questions in modern astrophysics and cosmology.

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arXiv2026

Debiasing the Observed Fast Radio Burst Population with the CHIME/FRB Selection Function

The recent release of CHIME/FRB Catalog~2 provides the largest sample to date with which to investigate the intrinsic distributions of fast radio bursts (FRBs). Leveraging an expanded campaign of 587,367 synethetic bursts injected into the live CHIME/FRB search pipeline, we perform a population analysis of the fluence, scattering timescale, pulse width, and dispersion measure distributions of Catalog~2 FRBs. We first infer the intrinsic population using a resampling-based framework that accounts for instrumental selection effects following previous CHIME/FRB population studies. A central goal of this work is to constrain the intrinsic distribution of scattering timescales, that remained weakly constrained in Catalog~1 owing to limited statistics at moderate and large scattering times ($τ\gtrsim 10\,\mathrm{ms}$ at 600~MHz) and sparse injection coverage in this regime. Second, we construct an explicit multidimensional selection function by training a logistic regression model on the injected events. This model estimates the detection probability as a function of FRB observable properties, including higher-order interaction terms. We incorporate this selection function into a simulation-based inference framework to refine the inferred intrinsic scattering-timescale distribution. We find evidence for a slight downturn in the intrinsic FRB scattering timescale distribution, though a flat or slightly rising distribution cannot be ruled out, that is further supported through a comparison with the higher-frequency scattering timescale distribution observed by Commensal Real-time ASKAP Fast Transients (CRAFT) survey.

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arXiv2026

Discovery of 30 Repeating Fast Radio Burst Sources and Uniform Population Statistics of 80 Repeating Sources from CHIME/FRB

We present 30 newly discovered repeating fast radio burst (FRB) sources from the second catalog of bursts detected by the FRB backend on the Canadian Hydrogen Intensity Mapping Experiment (CHIME/FRB). These repeaters have extragalactic dispersion measures (DMs) spanning $99.4-1446.0\ \text{pc cm}^{-3}$ and burst rates between $10^{-5.7}$ and $10^{-0.5}$ hr$^{-1}$ scaled to a fluence threshold of 5 Jy ms. We report evidence of monotonic, linear DM variations in four repeaters on years-long timescales. The newly discovered sources bring CHIME/FRB's total number of observed repeating FRBs to 80, 79 of which were discovered by CHIME/FRB, between 2018 July 25 and 2023 September 15. In the full CHIME/FRB sample, only 2.4$\pm 0.4\%$ of sources have been observed to repeat, and we do not find evidence for significant evolution of this value over the duration of the experiment. We find no substantial evidence for bimodal populations of one-off and repeating FRBs in their burst rate distributions; the distribution of upper limits on repeat rates implied from observations of as-yet one-offs is entirely contained within the observed range of repeater burst rates and the distributions do not appear inconsistent. Similarly, using the population analysis framework of C. W. James (2023), we find that our observations of repeating and yet-one-off FRBs are equally well fit assuming a power-law distribution of repeat rates with 50$-$100% of the population repeating.

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arXiv2026

On the polarization position angle jumps in FRB 20240114A

Fast radio bursts (FRBs), thought to originate from magnetars, exhibit diverse polarization properties that constrain their emission physics and local magneto-ionic environments. The polarization position angle (PPA) is particularly sensitive to magnetic-field geometry in the emitting region and propagation effects in the magnetosphere and beyond. In hyper-active repeaters, PPAs are typically stable within bursts and over timescales of hours to days. Here, we present observations of the repeating source FRB~20240114A, which show significant burst-to-burst PPA variations. Using full-Stokes, high-time-resolution observations from the Nançay Radio Telescope (1.1--1.8\,GHz) and the Effelsberg 100-m telescope (1.3--1.5\,GHz) over $\sim1$~year, we measure rotation measures (RMs), polarization fractions, and time-resolved PPAs across 12 epochs. The RMs remain stable, and the emission is predominantly highly linearly polarized, with $\sim81\%$ of bursts showing $L/I > 0.8$, while circular polarization is weaker ($\sim16\%$ with $|V/I| > 0.1$). We find no evidence for Faraday conversion. The PPA exhibits rapid, stochastic variations from milliseconds to hours, spanning $\pm90^\circ$ during two active periods and $\pm50^\circ$ in a third. The distribution of PPA jumps shows that (1) there is no difference in the distribution of jumps on timescales shorter or longer than 1\,s; (2) positive and negative jumps are equally likely; and (3) a jump of $\pm90^\circ$, as expected from, e.g., orthogonal mode jumps, is not more common than any other value. This combination of stable RM, high linear polarization, and extreme PPA variability is not seen in other hyper-active repeaters. These results disfavor emission from a single fixed region and instead suggest multiple emission regions and/or strong magnetospheric and foreground propagation effects, such as plasma lensing.

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arXiv2026

VLBI Observations of SN 2012au Reveal a Compact Radio Source a Decade Post Explosion

Three leading models have been put forth to justify the observed radio re-brightening associated with stripped-envelope supernovae (SESNe) years post-explosion: radiation from an emerging pulsar wind nebula (PWN), shock interaction with a dense circumstellar medium (CSM), or emission from off-axis, relativistic jets. SN 2012au is a particularly intriguing SESN in this regard as observations obtained $\gtrsim$ 6 years post-explosion have shown both (i) optical emission features consistent with a young PWN and (ii) a radio re-brightening. We present the results of our Very-Long-Baseline-Interferometric (VLBI) observations of SN 2012au performed between 8 to 13 years post core-collapse. Our VLBI observations reveal a luminous, steadily fading radio source that remains compact ($\leq1.4\times10^{17}~\mathrm{cm}$) and stationary ($\leq0.36c$) over the course of our campaign. Overall, we find that our VLBI measurements can be readily explained by a $\sim$decade-old PWN, potentially explained by shock interaction with specific CSM geometries, and are unlikely to be explained by emission from an off-axis, relativistic jet. Assuming a PWN origin, our observations require that the initial spin-down luminosity of the central pulsar be between $10^{36}~\mathrm{erg~s^{-1}}\leq\dot{E}_0\leq {4\times10^{42}}~\mathrm{erg~s^{-1}}$ and radio efficiency factor be $η_\mathrm{R}\geq {3\times10^{-7}}$ (both quoted at the $ {99.7\%}$ confidence interval). These results are consistent with independent inferences obtained using optical spectroscopy of SN 2012au, alongside inferences of known Galactic systems. If a PWN origin is confirmed, SN 2012au would represent the first extragalactic PWN emerging from a modern day SN, providing a novel opportunity to study the formation properties of a decade-old pulsar.

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arXiv2026

Probing the maximum energy of fast radio bursts using thousands of sources from the Second CHIME/FRB Catalog

Quantifying the maximum energy of fast radio bursts (FRBs) can provide stringent constraints on their emission mechanisms and progenitor models. However, the most energetic bursts are rare, requiring a large sample of FRBs to detect them. In this work, we use the largest available such sample, 2,998 one-off FRBs from the Second CHIME/FRB Catalog, to obtain a lower limit on the maximum energy ($E^{\mathrm{max}}_{\mathrm{iso}}$) of FRBs, assuming isotropic energy distribution from FRB sources. In the absence of known redshifts ($z$) for most sources, we present a framework that uses the dispersion measures (DMs) and fluences of these FRBs, together with the probability distribution of $z$ given DM, to derive the lower limit on $E^{\mathrm{max}}_{\mathrm{iso}}$. We generate simulated FRB samples assuming different parameter values for a log-normal $\mathrm{DM}_{\mathrm{host}}$ distribution and a Schechter function form of the FRB energy function to estimate how many outliers -- FRBs with large DM contributions from the host galaxy or intervening galaxy halos -- could artificially inflate this limit. After accounting for outliers, the lower limit on $E^{\mathrm{max}}_{\mathrm{iso}}$ from Catalog 2 FRBs ranges between $1.2\times10^{41}$ and $1.9\times10^{42}$ erg, with best estimate $1.2\times10^{42}$ erg. This limit is consistent with those derived from much smaller FRB samples. Moreover, inferred energies of hundreds of FRBs appear collectively limited around $\sim10^{42}$ erg, suggesting a physical limit on the energy reservoir of FRB sources. The corresponding isotropic-equivalent FRB source energy is consistent with the total energy available in a magnetar's external dipole magnetic field, supporting magnetars as FRB progenitors.

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arXiv2026

The Second CHIME/FRB Catalog of Fast Radio Bursts

We present a catalog of 4539 fast radio bursts (FRBs) observed with the Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope between 25 July 2018 and 15 September 2023. These bursts originate from 3641 unique sources, including 981 bursts from 83 known repeating sources. For each FRB, the catalog provides a $O(10')$ estimate of sky location along with corresponding measurements of cumulative exposure time and survey sensitivity over the observing period. It includes a total-intensity dynamic spectrum between 400 and 800 MHz at 0.983 ms resolution. From this spectrum, we constrain a model of the burst morphology and measure key parameters such as arrival time, intrinsic temporal width, dispersion measure, scattering time, and flux density. This second catalog includes all FRBs from the first catalog, with every event reprocessed using a uniform and improved analysis framework. We show that previously published inferences remain valid under the updated measurements. We assess consistency of the detection rate across observational parameters, present initial distributions of burst properties, and outline ongoing and future studies that will use this catalog to investigate the nature of FRBs and their utility as astrophysical and cosmological probes.

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arXiv2025

A Novel Technique for Long-term Timing of Redback Millisecond Pulsars

We present timing solutions spanning nearly two decades for five redback (RB) systems found in globular clusters (GC), created using a novel technique that effectively "isolates" the pulsar. By accurately measuring the time of passage through periastron ($T_0$) at points over the timing baseline, we use a piecewise-continuous, binary model to get local solutions of the orbital variations that we pair with long-term orbital information to remove the orbital timing delays. The isolated pulse times of arrival can then be fit to describe the spin behavior of the millisecond pulsar (MSP). The results of our timing analyses via this method are consistent with those of conventional timing methods for binaries in GCs as demonstrated by analyses of NGC 6440D. We also investigate the observed orbital phase variations for these systems. Quasi-periodic oscillations in Terzan 5P's orbit may be the result of changes to the gravitational-quadruple moment of the companion as prescribed by the Applegate model. We find a striking correlation between the standard deviation of the phase variations as a fraction of a system's orbit ($σ_{ΔT_0}$) and the MSP's spin frequency, as well as a potential correlation between $σ_{ΔT_0}$ and the binary's projected semi-major axis. While long-term RB timing is fraught with large systematics, our work provides a needed alternative for studying systems with significant orbital variations, especially when high-cadence monitoring observations are unavailable.

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arXiv2025

Pulsars in Globular Clusters With the SKAO

Because of their extreme stellar densities, globular clusters are highly efficient factories of X-ray binaries and radio pulsars: per unit of stellar mass, they contain about 1000 times more of these exotic objects. Thus far, 345 radio pulsars have been found in globular clusters. These can be used as precision probes of the structure, gas content, magnetic field, and dynamic history of their host clusters; some of them are also highly interesting in their own right because they probe exotic stellar evolution scenarios as well as the physics of dense matter, accretion, and gravity; one of them (PSR~J0514$-$4002E) might even be the first pulsar - black hole system known. Deep searches with SKA-MID and SKA-LOW will only require one to a few tied-array beams, and can be done during early commissioning of the telescope, before an all-sky pulsar survey using hundreds to thousands of tied-array beams is feasible. Even a conservative approach predicts new discoveries only with the core of SKA-MID AA*, and the full AA* and eventually AA4 is expected to increase the number of discoveries even more, leading to more than doubling the current known population. This offers a great opportunity for early SKAO pulsar science, even before all the collecting area is in place. On the other hand, a more optimistic prediction calls for a 4-5 times growth of the population, leading to a total of about 1700 pulsars to be detectable with SKA-MID AA4 configuration in all Galactic GCs visible by SKA telescopes. Thus, a dedicated search for pulsars in globular clusters will fully exploit the best possible natural laboratories to study many branches of physics and astrophysics, including properties of dense matter, stellar evolution, and the dynamical history of the Galactic globular cluster systems.

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arXiv2025

A milliarcsecond localization associates FRB 20190417A with a compact persistent radio source and an extreme magneto-ionic environment

We report the milliarcsecond localization of a high (1379 pc/cc) dispersion measure (DM) repeating fast radio burst, FRB 20190417A. Combining European VLBI Network detections of five repeat bursts, we confirm the FRB's host to be a low-metallicity, star-forming dwarf galaxy at z = 0.12817, similar to the hosts of FRBs 20121102A, 20190520B and 20240114A. We also confirm that it is associated with a previously reported persistent radio source (PRS), which is compact on milliarcsecond scales. Visibility-domain model fitting constrains the transverse physical size of the PRS to < 23 pc and yields an integrated flux density of 191(39) microJy at 1.4 GHz. Though we do not find significant evidence for DM evolution, FRB 20190417A exhibits a time-variable rotation measure (RM) ranging between +3958(11) and +5061(24) rad/m2 over three years. We find no evidence for intervening galaxy clusters in the FRB's line-of-sight and place a conservative lower limit on the rest-frame host DM contribution of 1228 pc/cc (90% confidence) -- the largest known for any FRB so far. This system strengthens the emerging picture of a rare subclass of repeating FRBs with large and variable RMs, above-average host DMs, and luminous PRS counterparts in metal-poor dwarf galaxies. Our results suggest that these systems are the result of environmental selection, or a distinct engine for FRB emission.

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arXiv2025

The double neutron star PSR J1946+2052 I. Masses and tests of general relativity

We conducted high-precision timing of PSR J1946+2052 to determine the masses of the two neutron stars in the system, test general relativity (GR) and assessed the system's potential for future measurement of the moment of inertia of the pulsar. We analysed seven years of timing data from the Arecibo 305-m radio telescope, the Green Bank Telescope (GBT), and the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The data processing accounted for dispersion measure variations and relativistic spin precession-induced profile evolution. We employed both DDFWHE and DDGR binary models to measure the spin parameters, kinematic parameters and orbital parameters. The timing campaign has resulted in the precise measurement of five post-Keplerian parameters, which yield very precise masses for the system and three tests of general relativity. One of these is the second most precise test of the radiative properties of gravity to date: the intrinsic orbital decay, $\dot{P}_{\rm b,int}=-1.8288(16)\times10^{-12}\rm\,s\,s^{-1}$, represents $1.00005(91)$ of the GR prediction, indicating that the theory has passed this stringent test. The other two tests, of the Shapiro delay parameters, have precisions of 6\% and 5\% respectively; this is caused by the moderate orbital inclination of the system, $\sim 74^{\circ}$; the measurements of the Shapiro delay parameters also agree with the GR predictions. Additionally, we analysed the higher-order contributions of $\dotω$, including the Lense-Thirring contribution. Both the second post-Newtonian and the Lense-Thirring contributions are larger than the current uncertainty of $\dotω$ ($δ\dotω=4\times10^{-4}\,\rm deg\,yr^{-1}$), leading to the higher-order correction for the total mass.

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arXiv2025

CHIME/FRB Discovery of an Unusual Circularly Polarized Long-Period Radio Transient with an Accelerating Spin Period

We report the discovery of CHIME J1634+44, a Long Period Radio Transient (LPT) unique for two aspects: it is the first known LPT to emit fully circularly polarized radio bursts, and it is the first LPT with a significant spin-up. Given that high circular polarization ($>90$\%) has been observed in FRB~20201124A and in some giant pulses of PSR~B1937+21, we discuss the implications of the high circular polarization of CHIME J1634+44 and conclude its emission mechanism is likely to be ``pulsar-like''. While CHIME J1634+44 has a pulse period of 841 s, its burst arrival patterns are indicative of a secondary 4206 s period, probably associated with binary activity. The timing properties suggest it has a significantly negative period derivative of $\dot{P}=-9.03(0.11)\times 10^{-12}$ s s$^{-1}$. Few systems have been known to spin-up, most notably transitional millisecond pulsars and cataclysmic binaries, both of which seem unlikely progenitors for CHIME J1634+44. If the period was only associated with the spin of the object, then the spin up is likely generated by accretion of material from a companion. If, however, the radio pulse period and the orbital period are locked, as appears to be the case for two other LPTs, the spin up of CHIME J1634+44 could be driven by gravitational wave radiation.

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arXiv2025

FRB 20250316A: A Brilliant and Nearby One-Off Fast Radio Burst Localized to 13 parsec Precision

Precise localizations of a small number of repeating fast radio bursts (FRBs) using very long baseline interferometry (VLBI) have enabled multiwavelength follow-up observations revealing diverse local environments. However, the 2--3\% of FRB sources that are observed to repeat may not be representative of the full population. Here we use the VLBI capabilities of the full CHIME Outriggers array for the first time to localize a nearby (40 Mpc), bright (kJy), and apparently one-off FRB source, FRB 20250316A, to its environment on 13-pc scales. We use optical and radio observations to place deep constraints on associated transient emission and the properties of its local environment. We place a $5σ$ upper limit of $L_{\mathrm{9.9~\mathrm{GHz}}} < 2.1\times10^{25}~\mathrm{erg~s^{-1}~Hz^{-1}}$ on spatially coincident radio emission, a factor of 100 lower than any known compact persistent radio source associated with an FRB. Our KCWI observations allow us to characterize the gas density, metallicity, nature of gas ionization, dust extinction and star-formation rate through emission line fluxes. We leverage the exceptional brightness and proximity of this source to place deep constraints on the repetition of FRB 20250316A, and find it is inconsistent with all well-studied repeaters given the non-detection of bursts at lower spectral energies. We explore the implications of a measured offset of 190$\pm20$ pc from the center of the nearest star-formation region, in the context of progenitor channels. FRB 20250316A marks the beginning of an era of routine localizations for one-off FRBs on tens of mas-scales, enabling large-scale studies of their local environments.

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arXiv2025

Discovery and Localization of the Swift-Observed FRB 20241228A in a Star-forming Host Galaxy

On 2024 December 28, CHIME/FRB detected the thus-far non-repeating FRB 20241228A with a real-time signal-to-noise ratio of $>50$. Approximately 112~s later, the X-ray Telescope onboard the Neil Gehrels Swift Observatory was on source, the fastest follow-up to-date of a non-repeating FRB (Tohuvavohu et al. in prep.). Using CHIME/FRB and two of the three CHIME/FRB Outriggers, we obtained a Very Long Baseline Interferometry localization for FRB 20241228A with a 1$σ$ confidence ellipse of 11$^{\prime\prime}$ by 0.2$^{\prime\prime}$. This represents the first published localization using both the CHIME-KKO and CHIME-GBO Outriggers. We associate FRB 20241228A with a star-forming galaxy at a redshift of $z = 0.1614\pm0.0002$. The persistent X-ray luminosity limit at this source's location and distance is $<1.2 \times 10^{43}$ erg s$^{-1}$ in the $0.3-10$ keV band, the most stringent limit of any non-repeating FRB to-date (Tohuvavohu et al. in prep.). The stellar mass ($\sim 2.6 \times 10^{10}\,M_{\odot}$) and star formation rate ($\sim 2.9\,M_{\odot}$~yr$^{-1}$) of the host galaxy of FRB 20241228A are consistent with the broader FRB host galaxy population. We measure significant scattering ($\sim$1ms) and scintillation ($\sim$20 kHz at 600 MHz) along the line of sight to this source, and suggest the scintillation screen is Galactic while the scattering screen is extragalactic. FRB 20241228A represents an exciting example of a new era in which we can harness VLBI-localizations and rapid high-energy follow-up to probe FRB progenitors.

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arXiv2025

A 34 Yr Timing Solution of the Redback Millisecond Pulsar Terzan 5A

We present a 34-year timing solution of the redback pulsar system Terzan 5A (Ter5A). Ter5A, also known as B1744$-$24A or J1748$-$2446A, has a 11.56 ms pulse period, a $\sim$0.1 solar mass dwarf companion star, and an orbital period of 1.82 hours. Ter5A displays highly variable eclipses and orbital perturbations. Using new timing techniques, we have determined a phase-connected timing solution for this system over 34 years. This is the longest ever published for a redback pulsar. We find that the pulsar's spin variability is much larger than most globular cluster pulsars. In fact, of the nine redback pulsars with published or in preparation long-term timing solutions, Ter5A is by far the noisiest. We see no evidence of strong correlations between orbital and spin variability of the pulsar. We also find that long-term astrometric timing measurements are likely too contaminated by this variability to be usable, and therefore require careful short-term timing to determine reasonable positions. Finally, we measure an orbital period contraction of $-2.5(3) \times 10^{-13}$, which is likely dominated by the general relativistic orbital decay of the system. The effects of the orbital variability due to the redback nature of the pulsar are not needed to explain the observed orbital period derivative, but they are constrained to less than $\sim$30% of the observed value.

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arXiv2025

A Catalog of Local Universe Fast Radio Bursts from CHIME/FRB and the KKO Outrigger

We present the first catalog of fast radio burst (FRB) host galaxies from CHIME/FRB Outriggers, selected uniformly in the radio and the optical by localizing 81 new bursts to 2'' x ~60'' accuracy using CHIME and the KKO Outrigger, located 66 km from CHIME. Of the 81 localized bursts, we use the Probabilistic Association of Transients to their Hosts (PATH) algorithm to securely identify 21 new FRB host galaxies, and compile spectroscopic redshifts for 19 systems, 15 of which are newly obtained via spectroscopic observations. The most nearby source is FRB 20231229A, at a distance of 90 Mpc. One burst in our sample is from a previously reported repeating source in a galaxy merger (FRB 20190303A). Three new FRB host galaxies (FRBs 20230203A, 20230703A, and 20231206A) are found towards X-ray and optically selected galaxy clusters, potentially doubling the sample of known galaxy cluster FRBs. A search for radio counterparts reveals that FRB 20231128A is associated with a luminous persistent radio source (PRS) candidate with high significance ($P_{cc} \sim 10^{-2}$). If its compactness is confirmed, it would be the nearest known compact PRS at $z = 0.1079$. Our catalog significantly increases the statistics of the Macquart relation at low redshifts ($z < 0.2$). In the near future, the completed CHIME/FRB Outriggers array will produce hundreds of FRBs localized with very long baseline interferometry (VLBI). This will significantly expand the known sample and pave the way for future telescopes relying on VLBI for FRB localization.

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arXiv2025

Representation learning for fast radio burst dynamic spectra

Fast radio bursts (FRBs) are millisecond-duration radio transients of extragalactic origin, with diverse time-frequency patterns and emission properties that require explanation. With one possible exception, FRBs are detected only in the radio, so analyzing their dynamic spectra is therefore crucial to disentangling the physical processes governing their generation and propagation. Furthermore, comparing FRB morphologies provides insights into possible differences among their progenitors and environments. This study applies unsupervised learning and deep learning techniques to investigate FRB dynamic spectra, focusing on two approaches: Principal Component Analysis (PCA) and a Convolutional Autoencoder (CAE) enhanced by an Information-Ordered Bottleneck (IOB) layer. PCA served as a computationally efficient baseline, capturing broad trends, identifying outliers, and providing valuable insights into large datasets. However, its linear nature limited its ability to reconstruct complex FRB structures. In contrast, the IOB-augmented CAE excelled at capturing intricate features, with high reconstruction accuracy and effective denoising at modest signal-to-noise ratios. The IOB layer's ability to prioritize relevant features enabled efficient data compression, preserving key morphological characteristics with minimal latent variables. When applied to real FRBs from CHIME, the IOB-CAE generalized effectively, revealing a latent space that highlighted the continuum of FRB morphologies and the potential for distinguishing intrinsic differences between burst types. This framework demonstrates that while FRBs may not naturally cluster into discrete groups, advanced representation learning techniques can uncover meaningful structures, offering new insights into the diversity and origins of these bursts.

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