Search

Transitional millisecond pulsars (tMSPs) are neutron-star systems that alternate between a rotation-powered radio millisecond pulsar state and an accretion-disk-dominated low-mass X-ray binary (LMXB)-like state on multi-year timescales. During the LMXB-like state, the X-ray emission from tMSPs switches between "low" and "high" X-ray brightness modes on a timescale of seconds to minutes (or longer), while the radio emission shows variability on timescales of roughly minutes. Coordinated VLA and Chandra observations of the nearby tMSP PSR J1023+0038 uncovered a clear anti-correlation between radio and X-ray luminosities such that the radio emission consistently peaks during the X-ray low modes. In addition, there are sometimes also radio/X-ray flares that show no obvious correlation. In this paper, we present simultaneous radio and X-ray observations of a promising tMSP candidate system, 3FGL J1544.6-1125, which shows optical, gamma-ray, and X-ray phenomena similar to PSR J1023+0038, but which is challenging to study because of its greater distance. Using simultaneous VLA and Chandra observations we find that the radio and X-ray emission are consistent with being anti-correlated in a manner similar to PSR J1023+0038. We discuss how our results help in understanding the origin of bright radio emission from tMSPs. The greater sensitivity of upcoming telescopes like the Square Kilometre Array will be crucial for studying the correlated radio/X-ray phenomena of tMSP systems., Comment: 21 pages, 14 figures, 2 tables. Submitted to MNRAS

We present the first results from a new backend on the Australian Square Kilometre Array Pathfinder, the Commensal Realtime ASKAP Fast Transient COherent (CRACO) upgrade. CRACO records millisecond time resolution visibility data, and searches for dispersed fast transient signals including fast radio bursts (FRB), pulsars, and ultra-long period objects (ULPO). With the visibility data, CRACO can localise the transient events to arcsecond-level precision after the detection. Here, we describe the CRACO system and report the result from a sky survey carried out by CRACO at 110ms resolution during its commissioning phase. During the survey, CRACO detected two FRBs (including one discovered solely with CRACO, FRB 20231027A), reported more precise localisations for four pulsars, discovered two new RRATs, and detected one known ULPO, GPM J1839-10, through its sub-pulse structure. We present a sensitivity calibration of CRACO, finding that it achieves the expected sensitivity of 11.6 Jy ms to bursts of 110 ms duration or less. CRACO is currently running at a 13.8 ms time resolution and aims at a 1.7 ms time resolution before the end of 2024. The planned CRACO has an expected sensitivity of 1.5 Jy ms to bursts of 1.7 ms duration or less, and can detect 10x more FRBs than the current CRAFT incoherent sum system (i.e., 0.5-2 localised FRBs per day), enabling us to better constrain he models for FRBs and use them as cosmological probes., Comment: 26 pages, 19 figures, 9 tables, Accepted for publication in PASA

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 FRBs fields with z<0.4, covering approximately 26 deg^2 of the sky in total. FLIMFLAM is composed of several layers, encompassing the `Wide' (covering ~ degree or >10 Mpc scales), `Narrow', (several-arcminute or ~ Mpc) and integral field unit (`IFU'; ~ arcminute or ~ 100 kpc ) components. The bulk of the data comprise spectroscopy from the 2dF-AAOmega on the 3.9-meter Anglo-Australian Telescope, while most of the Narrow and IFU data was achieved using an ensemble of 8-10-meter 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 on generating angular masks and calculating the target selection functions, setting the stage for the impending reconstruction of the matter density field., Comment: 23 pages, 8 figures, Submitted to ApJS

We examine the energy distribution of the fast radio burst (FRB) population using a well-defined sample of 63 FRBs from the ASKAP radio telescope, 28 of which are localised to a host galaxy. We apply the luminosity-volume ($V/V_{\mathrm{max}}$) test to examine the distribution of these transient sources, accounting for cosmological and instrumental effects, and determine the energy distribution for the sampled population over the redshift range $0.01 \lesssim z \lesssim 1.02$. We find the distribution between $10^{23}$ and $10^{26}$J Hz$^{-1}$ to be consistent with both a pure power-law with differential slope $\gamma=-1.96 \pm 0.15$, and a Schechter function with $\gamma = -1.82 \pm 0.12$ and downturn energy $E_{\rm max} \sim 6.3 \cdot 10^{25}$J Hz$^{-1}$. We identify systematic effects which currently limit our ability to probe the luminosity function outside this range and give a prescription for their treatment. Finally, we find that with the current dataset, we are unable to distinguish between the evolutionary and spectral models considered in this work., Comment: 23 pages, 10 figures, submitted to PASA

Fast radio bursts (FRBs) are transient radio signals of extragalactic origins that are subjected to propagation effects such as dispersion and scattering. It follows then that these signals hold information regarding the medium they have traversed and are hence useful as cosmological probes of the Universe. Recently, FRBs were used to make an independent measure of the Hubble Constant $H_0$, promising to resolve the Hubble tension given a sufficient number of detected FRBs. Such cosmological studies are dependent on FRB population statistics, cosmological parameters and detection biases, and thus it is important to accurately characterise each of these. In this work, we empirically characterise the sensitivity of the Fast Real-time Engine for Dedispersing Amplitudes (FREDDA) which is the current detection system for the Australian Square Kilometer Array Pathfinder (ASKAP). We coherently redisperse high-time resolution data of 13 ASKAP-detected FRBs and inject them into FREDDA to determine the recovered signal-to-noise ratios as a function of dispersion measure (DM). We find that for 11 of the 13 FRBs, these results are consistent with injecting idealised pulses. Approximating this sensitivity function with theoretical predictions results in a systematic error of 0.3$\,$km$\,$s$^{-1}\,$Mpc$^{-1}$ on $H_0$ when it is the only free parameter. Allowing additional parameters to vary could increase this systematic by up to $\sim1\,$km$\,$s$^{-1}\,$Mpc$^{-1}$. We estimate that this systematic will not be relevant until $\sim$400 localised FRBs have been detected, but will likely be significant in resolving the Hubble tension., Comment: 8 pages, 6 figures, Published in MNRAS

Fast radio burst (FRB) science primarily revolves around two facets: the origin of these bursts and their use in cosmological studies. This work follows from previous redshift-dispersion measure ($z$-DM) analyses in which we model instrumental biases and simultaneously fit population parameters and cosmological parameters to the observed population of FRBs. This sheds light on both the progenitors of FRBs and cosmological questions. Previously, we have completed similar analyses with data from the Australian Square Kilometer Array Pathfinder (ASKAP) and the Murriyang (Parkes) Multibeam system. With this manuscript, we additionally incorporate data from the Deep Synoptic Array (DSA) and the Five-hundred-meter Aperture Spherical Telescope (FAST), invoke a Markov chain Monte Carlo (MCMC) sampler and implement uncertainty in the Galactic DM contributions. The latter leads to larger uncertainties in derived model parameters than previous estimates despite the additional data. We provide refined constraints on FRB population parameters and derive a new constraint on the minimum FRB energy of log$\,E_{\mathrm{min}}$(erg)=39.49$^{+0.39}_{-1.48}$ which is significantly higher than bursts detected from strong repeaters. This result may indicate a low-energy turnover in the luminosity function or may suggest that strong repeaters have a different luminosity function to single bursts. We also predict that FAST will detect 25-41% of their FRBs at $z \gtrsim 2$ and DSA will detect 2-12% of their FRBs at $z \gtrsim 1$., Comment: 17 pages, 7 figures, submitted to PASA

With wide-field phased array feed technology, the Australian Square Kilometre Array Pathfinder (ASKAP) is ideally suited to search for seemingly rare radio transient sources. The Commensal Real-time ASKAP Fast Transient (CRAFT) Survey Science Project has developed instrumentation to continuously search for fast radio transients (duration $\lesssim$ 1 second) with ASKAP, with a particular focus on finding and localising Fast Radio Bursts (FRBs). Of particular interest are Fast Radio Bursts (FRBs). Since 2018, the CRAFT survey has been searching for FRBs and other fast transients by incoherently adding the intensities received by individual ASKAP antennas, and then correcting for the impact of frequency dispersion on these short-duration signals in the resultant incoherent sum (ICS) in real-time. This low-latency detection enables the triggering of voltage buffers, which facilitates the localisation of the transient source and the study spectro-polarimetric properties at high time resolution. Here we report the sample of 43 FRBs discovered in this CRAFT/ICS survey to date. This includes 22 FRBs that had not previously been reported: 16 FRBs localised by ASKAP to $\lesssim$ 1 arcsec and 6 FRBs localised to approximately 10 arcmin. Of the new arcsecond-localised FRBs, we have identified and characterised host galaxies (and measured redshifts) for 11. The median of all 30 measured host redshifts from the survey to date is z = 0.23. We summarise results from the searches, in particular those contributing to our understanding of the burst progenitors and emission mechanisms, and on the use of bursts as probes of intervening media. We conclude by foreshadowing future FRB surveys with ASKAP using a coherent detection system that is currently being commissioned., Comment: 37 pages, 23 Figures, 7 Tables. Submitted for publication in PASA

Precise millisecond pulsar (MSP) positions determined with very long baseline interferometry (VLBI) hold the key to building the connection between the kinematic and dynamic reference frames respectively used by VLBI and pulsar timing. The frame connection would provide an important pathway to examining the planetary ephemerides used in pulsar timing, and potentially enhancing the sensitivities of pulsar timing arrays used to detect stochastic gravitational-wave background at nano-Hz regime. We aim at significantly improving the VLBI-based MSP position from its current $\gtrsim1\,$mas precision level by reducing the two dominant components in the positional uncertainty -- the propagation-related uncertainty and the uncertainty resulting from the frequency-dependent core shifts of the reference sources. We introduce a new differential astrometry strategy of using multiple calibrators observed at several widely separated frequencies, which we call PINPT (Phase-screen Interpolation plus frequeNcy-dePendent core shifT correction; read as "pinpoint") for brevity. The strategy allows determination of the core-shift and mitigates the impact of residual delay in the atmosphere. We implemented the strategy on PSR J2222-0137, an MSP well constrained astrometrically with VLBI and pulsar timing. Using the PINPT strategy, we determined core shifts for 4 AGNs around PSR J2222-0137, and derived a VLBI-based pulsar position with uncertainty of 0.17 mas and 0.32 mas in right ascension and declination, respectively, approaching the uncertainty level of the best-determined timing-based MSP positions. The realization of the PINPT strategy promises a factor-of-5 positional precision enhancement (over conventional VLBI astrometry) for all kinds of compact radio sources observed at $\lesssim2$ GHz, including most fast radio bursts., Comment: 14 pages, 3 figures, 8 tables, accepted for publication in A&A

Localisation of fast radio bursts (FRBs) to arcsecond and sub-arcsecond 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 localisation 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 a precision of $\sim$1 arc-second that allowed us to unambiguously identify the host galaxy for FRB 20220717A (posterior probability$\sim$0.97). FRB 20220905A lies in a crowded region of the sky with a tentative identification of a host galaxy but the faintness and the difficulty in obtaining an optical spectrum preclude a conclusive association. The bursts show low linear polarization fractions (10--17$\%$) that conform to the large diversity in the polarization fraction observed in apparently non-repeating FRBs akin to single pulses from neutron stars. We also show that the host galaxy of FRB 20220717A contributes roughly 15$\%$ 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., Comment: 13 pages, 8 figures, 1 Appendix, revised version after addressing the reviewer's comments

Fast radio bursts (FRBs) are brilliant short-duration flashes of radio emission originating at cosmological distances. The vast diversity in the properties of currently known FRBs, and the fleeting nature of these events make it difficult to understand their progenitors and emission mechanism(s). Here we report high time resolution polarization properties of FRB 20210912A, a highly energetic event detected by the Australian Square Kilometre Array Pathfinder (ASKAP) in the Commensal Real-time ASKAP Fast Transients (CRAFT) survey, which show intra-burst PA variation similar to Galactic pulsars and unusual variation of Faraday Rotation Measure (RM) across its two sub-bursts. The observed intra-burst PA variation and apparent RM variation pattern in FRB 20210912A may be explained by a rapidly-spinning neutron star origin, with rest-frame spin periods of ~1.1 ms. This rotation timescale is comparable to the shortest known rotation period of a pulsar, and close to the shortest possible rotation period of a neutron star. Curiously, FRB 20210912A exhibits a remarkable resemblance with the previously reported FRB 20181112A, including similar rest-frame emission timescales and polarization profiles. These observations suggest that these two FRBs may have similar origins., Comment: Accepted for publication in ApJ Letters

Several sources of repeating coherent bursts of radio emission with periods of many minutes have now been reported in the literature. These "ultra-long period" (ULP) sources have no clear multi-wavelength counterparts and challenge canonical pulsar emission models, leading to debate regarding their nature. In this work we report the discovery of a bright, highly-polarised burst of radio emission at low Galactic latitude as part of a wide-field survey for transient and variable radio sources. ASKAP\,J175534.9$-$252749.1 does not appear to repeat, with only a single intense two-minute $\sim$200-mJy burst detected from 60~hours of observations. The burst morphology and polarisation properties are comparable to those of classical pulsars but the duration is more than one hundred times longer, analogous to ULPs. Combined with the existing ULP population, this suggests that these sources have a strong Galactic latitude dependence and hints at an unexplored population of transient and variable radio sources in the thin disk of the Milky Way. The resemblance of this burst with both ULPs and pulsars calls for a unified coherent emission model for objects with spin periods from milliseconds to tens of minutes. However, whether or not these are all neutron stars or have the same underlying power source remains open for debate.

In addition to being the most magnetic objects in the known universe, magnetars are the only objects observed to generate fast-radio-burst-like emissions. The formation mechanism of magnetars is still highly debated, and may potentially be probed with the magnetar velocity distribution. We carried out a 3-year-long astrometric campaign on Swift J1818.0-1607 -- the fastest-spinning magnetar, using the Very Long Baseline Array. After applying the phase-calibrating 1D interpolation strategy, we obtained a small proper motion of 8.5 $\mathrm{mas~yr^{-1}}$ magnitude, and a parallax of $0.12\pm0.02$ mas (uncertainties at $1\,\sigma$ confidence throughout the Letter) for Swift J1818.0-1607. The latter is the second magnetar parallax, and is among the smallest neutron star parallaxes ever determined. From the parallax, we derived the distance $9.4^{+2.0}_{-1.6}$ kpc, which locates Swift J1818.0-1607 at the far side of the Galactic central region. Combined with the distance, the small proper motion leads to a transverse peculiar velocity $v_\perp=48^{+50}_{-16}$ $\mathrm{km~s^{-1}}$ -- a new lower limit to magnetar $v_\perp$. Incorporating previous $v_\perp$ estimates of seven other magnetars, we acquired $v_\perp=149^{+132}_{-68}$ $\mathrm{km~s^{-1}}$ for the sample of astrometrically studied magnetars, corresponding to the three-dimensional space velocity $\sim190^{+168}_{-87}$ $\mathrm{km~s^{-1}}$, smaller than the average level of young pulsars. Additionally, we found that the magnetar velocity sample does not follow the unimodal young pulsar velocity distribution reported by Hobbs et al. at $>2\,\sigma$ confidence, while loosely agreeing with more recent bimodal young pulsar velocity distributions derived from relatively small samples of quality astrometric determinations., Comment: 13 pages, 4 figures, 4 tables, accepted for publication in ApJL

PSR J0837-2454 is a young 629 ms radio pulsar whose uncertain distance has important implications. A large distance would place the pulsar far out of the Galactic plane and suggest it is the result of a runaway star, while a short distance would mean the pulsar is extraordinarily cold. Here we present further radio observations and the first deep X-ray observation of PSR J0837-2454. Data from the Parkes Murriyang telescope show flux variations over short and long timescales and also yield an updated timing model, while the position and proper motion (and, less strongly, parallax) of the pulsar are constrained by a number of low-significance detections with the Very Long Baseline Array. XMM-Newton data enable detection of X-ray pulsations for the first time from this pulsar and yield a spectrum that is thermal and blackbody-like, with a cool blackbody temperature ~70 eV or atmosphere temperature ~50 eV, as well as a small hotspot. The spectrum also indicates the pulsar is at a small distance of <~1 kpc, which is compatible with the marginal VLBA parallax constraint that favours a distance of >~330 pc. The low implied luminosity (~7.6x10^31 erg s^-1 at 0.9 kpc) suggests PSR J0837-2454 has a mass high enough that fast neutrino emission from direct Urca reactions operates in this young star and points to a nuclear equation of state that allows for direct Urca reactions at the highest densities present in neutron star cores., Comment: 11 pages, 9 figures; published in PASA; style change to better match published version

Fast Radio Bursts (FRBs) are short-timescale transients of extragalactic origin. The number of detected FRBs has grown dramatically since their serendipitous discovery from archival data. Some FRBs have also been seen to repeat. The polarimetric properties of repeating FRBs show diverse behaviour and, at times, extreme polarimetric morphology, suggesting a complex magneto-ionic circumburst environment for this class of FRB. The polarimetric properties such as circular polarisation behaviour of FRBs are crucial for understanding their surrounding magnetic-ionic environment. The circular polarisation previously observed in some of the repeating FRB sources has been attributed to propagation effects such as generalised Faraday rotation (GFR), where conversion from linear to circular polarisation occurs due to the non-circular modes of transmission in relativistic plasma. The discovery burst from the repeating FRB$~$20180301A showed significant frequency-dependent circular polarisation behaviour, which was initially speculated to be instrumental due to a sidelobe detection. Here we revisit the properties given the subsequent interferometric localisation of the burst, which indicates that the burst was detected in the primary beam of the Parkes/Murriyang 20-cm multibeam receiver. We develop a Bayesian Stokes-Q, U, and V fit method to model the GFR effect, which is independent of the total polarised flux parameter. Using the GFR model we show that the rotation measure (RM) estimated is two orders of magnitude smaller and opposite sign ($\sim$28 rad$\,$m$^{-2}$) than the previously reported value. We interpret the implication of the circular polarisation on its local magnetic environment and reinterpret its long-term temporal evolution in RM., Comment: 13 pages, 9 figures, submitted to MNRAS

Fast Radio Bursts (FRBs) are short-duration radio transients that occur at random times in host galaxies distributed all over the sky. Large field of view instruments can play a critical role in the blind search for rare FRBs. We present a concept for an all-sky FRB monitor using a compact all-sky phased array (CASPA), which can efficiently achieve an extremely large field of view of $\sim10^4$ square degrees. Such a system would allow us to conduct a continuous, blind FRB search covering the entire southern sky. Using the measured FRB luminosity function, we investigate the detection rate for this all-sky phased array and compare the result to a number of other proposed large field-of-view instruments. We predict a rate of a few FRB detections per week and determine the dispersion measure and redshift distributions of these detectable FRBs. This instrument is optimal for detecting FRBs in the nearby Universe and for extending the high-end of the FRB luminosity function through finding ultraluminous events. Additionally, this instrument can be used to shadow the new gravitational-wave observing runs, detect high energy events triggered from Galactic magnetars and search for other bright, but currently unknown transient signals., Comment: 10 pages, 5 figures, accepted for publication in PASA

The mergers of double neutron stars (DNSs) systems are believed to drive the majority of short $\gamma$-ray bursts (SGRBs), while also serving as production sites of heavy r-process elements. Despite being key to i) confirming the nature of the extragalactic SGRBs, ii) addressing the poorly-understood r-process enrichment in the ultra-faint dwarf galaxies (UFDGs), and iii) probing the formation process of DNS systems, the space velocity distribution of DNSs is still poorly constrained due to the small number of DNSs with well-determined astrometry. In this work, we determine new proper motions and parallaxes of two Galactic DNSs -- PSR J0509+3801 and PSR J1930-1852, using the Very Long Baseline Array, and estimate the transverse velocities $v_\perp$ of all the 11 isolated Galactic DNSs having proper motion measurements in a consistent manner. Our correlation analysis reveals that the DNS $v_\perp$ is tentatively correlated with three parameters: spin period, orbital eccentricity, and companion mass. With the preliminary $v_\perp$ distribution, we obtain the following findings. Firstly, the refined $v_\perp$ distribution is confirmed to agree with the observed displacements of the localized SGRBs from their host galaxy birth sites. Secondly, we estimate that around 11% and 25% of DNSs remain gravitationally bound to UFDGs with escape velocities of 15$\mathrm{~km~s^{-1}}$ and 25$\mathrm{~km~s^{-1}}$, respectively. Hence, the retained DNSs might indeed be responsible for the r-process enrichment confirmed so far in a few UFDGs. Finally, we discuss how a future ensemble of astrometrically determined DNSs may probe the multimodality of the $v_\perp$ distribution., Comment: 17 pages, 3 figures, 4 tables, accepted for publication in ApJ

We investigate the information extractable from measurement distributions of two non-commuting spin observables in a multi-well spin-1 Bose-Einstein condensate. We provide a variety of analytic and numerical evidence that suitably chosen classical entropies and classical mutual informations thereof contain the typical feature of quantum entropies known in quantum field theories, that is, the area law, even in the non-Gaussian regime and for a non-zero temperature. Towards a feasible experimental implementation, we estimate entropic quantities from a finite number of samples without any additional assumptions on the underlying quantum state using k-nearest neighbor estimators., Comment: 25 pages; comments welcome!

The scaling of local quantum entropies is of utmost interest for characterizing quantum fields, many-body systems, and gravity. Despite their importance, theoretically and experimentally accessing quantum entropies is challenging as they are nonlinear functionals of the underlying quantum state. Here, we show that suitably chosen classical entropies capture the very same features as their quantum analogs for an experimentally relevant setting. We describe the post-quench dynamics of a multi-well spin-1 Bose-Einstein condensate from an initial product state via measurement distributions of spin observables and estimate the corresponding entropies using the asymptotically unbiased k-nearest neighbor method. We observe the dynamical build-up of quantum correlations signaled by an area law, as well as local thermalization revealed by a transition to a volume law, both in regimes characterized by non-Gaussian distributions. We emphasize that all relevant features can be observed at small sample numbers without assuming a specific functional form of the distributions, rendering our method directly applicable to a large variety of models and experimental platforms., Comment: 5+2 pages; comments welcome!

The dispersion measure of fast radio bursts (FRBs), arising from the interactions of the pulses with free electrons along the propagation path, constitutes a unique probe of the cosmic baryon distribution. Their constraining power is further enhanced in combination with observations of the foreground large-scale structure and intervening galaxies. In this work, we present the first constraints on the partition of the cosmic baryons between the intergalactic medium (IGM) and circumgalactic medium (CGM), inferred from the FLIMFLAM spectroscopic survey. In its first data release, the FLIMFLAM survey targeted galaxies in the foreground of 8 localized FRBs. Using Bayesian techniques, we reconstruct the underlying ~Mpc-scale matter density field that is traced by the IGM gas. Simultaneously, deeper spectroscopy of intervening foreground galaxies (at impact parameters $b_\perp \lesssim r_{200}$) and the FRB host galaxies constrains the contribution from the CGM. Applying Bayesian parameter inference to our data and assuming a fiducial set of priors, we infer the IGM cosmic baryon fraction to be $f_{\rm igm}=0.59^{+0.11}_{-0.10}$, and a CGM gas fraction of $f_{\rm gas} = 0.55^{+0.26}_{-0.29}$ for $10^{10}\,M_\odot \lesssim M_{\rm halo}\lesssim 10^{13}\,M_\odot$ halos. The mean FRB host dispersion measure (rest-frame) in our sample is $\langle \rm{DM_{host}}\rangle = 90^{+29}_{-19}\rm{pc~cm^{-3}}$, of which $\langle{\rm DM_{host}^{unk}}\rangle =69^{+28}_{-19}~\rm{pc~cm^{-3}}$ arises from the host galaxy ISM and/or the FRB progenitor environment. While our current $f_{\rm igm}$ and $f_{\rm gas}$ uncertainties are too broad to constrain most galactic feedback models, this result marks the first measurement of the IGM and CGM baryon fractions, as well as the first systematic separation of the FRB host dispersion measure into two components: arising from the halo and from the inner ISM/FRB engine., Comment: 21 pages, 9 figures, 5 tables; Submitted to ApJ

Ejection of large boulder-like debris is a vigorous form of cometary activity that is unlikely induced by water ice out-gassing alone but rather associated with the sublimation of super-volatile ices. Though perceived on several comets, actual pattern and mechanism of such activity are still unclear. Here we report on a specialized observation of ejections of decimeter- to meter-sized boulders on comet 67P/Churyumov-Gerasimenko outbound between 2.5 and 3.3 AU from the Sun. With a common source region, these events recurred in local morning. The boulders of elongated shapes were ejected in clusters at low inclinations comparable to the solar elevation below 40 degrees at the time. We show that these chunks could be propelled by the surrounding, asymmetric gas field that produced a distinct lateral acceleration. Possibly both water and carbon dioxide have contributed to their mobilization, while the season and local topography are among deciding factors. The mechanisms for sustaining regular activity of comets at large heliocentric distances are likely more diverse and intricate than previously thought.

We present GeMS/GSAOI observations of five fast radio burst (FRB) host galaxies with sub-arcsecond localizations. We examine and quantify their spatial distributions and locations with respect to their host galaxy light distributions, finding a median host-normalized offset of 2.09 r_e and in fainter regions of the host. When combined with the FRB sample from Mannings et al. (2021), we find that FRBs are statistically distinct from Ca-rich transients in terms of light 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, in combination with the combined FRB sample trace the distribution of stellar mass, points towards a possible similarity of the environments of CC-SNe and FRBs. We also find that 4/5 FRB hosts exhibit distinct spiral arm features, and the bursts originating from such hosts tend to appear on or close to the spiral structure of their hosts, with a median distance of 0.53 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., Comment: 14 pages, 6 figures

FRB 20220610A is a high-redshift Fast Radio Burst (FRB) that has not been observed to repeat. Here, we present rest-frame UV and optical $\textit{Hubble Space Telescope}$ observations of the field of FRB 20220610A. The imaging reveals seven extended sources, one of which we identify as the most likely host galaxy with a spectroscopic redshift of $z$=1.017. We spectroscopically confirm at least three additional sources to be at the same redshift, and identify the system as a compact galaxy group with possible signs of interaction among group members. We determine the host of FRB 20220610A to be a star-forming galaxy with stellar mass of $\approx10^{9.7}\,M_{\odot}$, mass-weighted age of $\approx2.6$~Gyr, and star formation rate (integrated over the last 100 Myr) of $\approx1.7$~M$_{\odot}$~yr$^{-1}$. These host properties are commensurate with the star-forming field galaxy population at z~1 and trace their properties analogously to the population of low-$z$ FRB hosts. Based on estimates of the total stellar mass of the galaxy group, we calculate a fiducial contribution to the observed Dispersion Measure (DM) from the intragroup medium of $\approx 110-220$ $\rm pc \, cm^{-3}$ (rest-frame). This leaves a significant excess of $500^{+272}_{-109}$ $\rm pc \, cm^{-3}$ (in the observer frame), with additional sources of DM possibly originating from the circumburst environment, host galaxy interstellar medium, and/or foreground structures along the line of sight. Given the low occurrence rates of galaxies in compact groups, the discovery of an FRB in such a group demonstrates a rare and novel environment in which FRBs can occur., Comment: 24 pages, 8 figures, 2 tables, submitted

We present radio observations of 24 confirmed and candidate strongly lensed quasars identified by the Gaia Gravitational Lenses (GraL) working group. We detect radio emission from 8 systems in 5.5 and 9 GHz observations with the Australia Telescope Compact Array (ATCA), and 12 systems in 6 GHz observations with the Karl G. Jansky Very Large Array (VLA). The resolution of our ATCA observations is insufficient to resolve the radio emission into multiple lensed images, but we do detect multiple images from 11 VLA targets. We have analysed these systems using our observations in conjunction with existing optical measurements, including measuring offsets between the radio and optical positions, for each image and building updated lens models. These observations significantly expand the existing sample of lensed radio quasars, suggest that most lensed systems are detectable at radio wavelengths with targeted observations, and demonstrate the feasibility of population studies with high resolution radio imaging.

High-performance graphical processing units (GPU) are used for the repeated parallelised propagation of non-linear partial differential equations on large spatio-temporal grids. The main challenge results as a combination of the requirement of large grids for exploring scaling over several orders of magnitude, both in space and time, and the need for high statistics in averaging over many runs, in computing correlation functions for highly fluctuating quantum many-body states. With our simulations, we explore the dynamics of complex quantum systems far from equilibrium, with the aim of classifying their universal characteristics such as scaling exponents near non-thermal fixed points. Our results are strongly relevant for the development of synthetic quantum systems when exploring the respective physics in the laboratory., Comment: 6 pages, 2 figures, Proceedings of the 8th bwHPC-Symposium, organized by the High-Performance Computing Center Stuttgart (HLRS) (2022)

We present an analysis of the detection fraction and the number counts of radio sources imaged with Very Long Baseline Interferometry (VLBI) at 1.4 GHz as part of the mJIVE-20 survey. From a sample of 24,903 radio sources identified by FIRST, 4,965 are detected on VLBI-scales, giving an overall detection fraction of $19.9\pm2.9~$per cent. However, we find that the detection fraction falls from around 50 per cent at a peak surface brightness of $80~mJy~beam^{-1}$ in FIRST to around 8 per cent at the detection limit, which is likely dominated by the surface brightness sensitivity of the VLBI observations, with some contribution from a change in the radio source population. We also find that compactness at arcsec-scales is the dominant factor in determining whether a radio source is detected with VLBI, and that the median size of the VLBI-detected radio sources is 7.7 mas. After correcting for the survey completeness and effective sky area, we determine the slope of the differential number counts of VLBI-detected radio sources with flux densities $S_{\rm 1.4~GHz} > 1~mJy$ to be $\eta_{\rm VLBI} = -1.74\pm 0.02$, which is shallower than in the cases of the FIRST parent population ($\eta_{\rm FIRST} = -1.77\pm 0.02$) and for compact radio sources selected at higher frequencies ($\eta_{\rm JBF} = -2.06\pm 0.02$). From this, we find that all-sky ($3\pi~sr$) surveys with the EVN and the VLBA have the potential to detect $(7.2\pm0.9)\times10^{5}$ radio sources at mas-resolution, and that the density of compact radio sources is sufficient (5.3~deg$^{-2}$) for in-beam phase referencing with multiple sources (3.9 per primary beam) in the case of a hypothetical SKA-VLBI array.

Fast Radio Bursts (FRBs) are extragalactic transients of (sub-)millisecond duration that show wide-ranging spectral, temporal, and polarimetric properties. The polarimetric analysis of FRBs can be used to probe intervening media, study the emission mechanism, and test possible progenitor models. In particular, low frequency depolarisation of FRBs can identify dense, turbulent, magnetised, ionised plasma thought to be near the FRB progenitor. An ensemble of repeating FRBs has shown low-frequency depolarisation. The depolarisation is quantified by the parameter $\sigma_{\rm RM}$, which correlates with proxies for both the turbulence and mean magnetic field strength of the putative plasma. However, while many non-repeating FRBs show comparable scattering (and hence inferred turbulence) to repeating FRBs, it is unclear whether their surrounding environments are comparable to those of repeating FRBs. To test this, we analyse the spectro-polarimetric properties of five one-off FRBs and one repeating FRB, detected and localised by the Australian Square Kilometer Array Pathfinder. We search for evidence of depolarisation due to $\sigma_{\rm RM}$ and consider models where the depolarisation is intrinsic to the source. We find no evidence (for or against) the sample showing spectral depolarisation. Under the assumption that FRBs have multipath propagation-induced depolarisation, the correlation between our constraint on $\sigma_{\rm RM}$ and RM is consistent with repeating FRBs only if the values of $\sigma_{\rm RM}$ are much smaller than our upper limits. The observations provide further evidence for differences in the environments and sources of one-off and repeating FRBs., Comment: 10 pages, 5 figures, submitted to MNRAS

FRB 20210912A is a fast radio burst (FRB), detected and localised to sub-arcsecond precision by the Australian Square Kilometre Array Pathfinder. No host galaxy has been identified for this burst despite the high precision of its localisation and deep optical and infrared follow-up, to 5-$\sigma$ limits of $R=26.7$ mag and $K_\mathrm{s}=24.9$ mag with the Very Large Telescope. The combination of precise radio localisation and deep optical imaging has almost always resulted in the secure identification of a host galaxy, and this is the first case in which the line-of-sight is not obscured by the Galactic disk. The dispersion measure of this burst, $\mathrm{DM_{FRB}}=1233.696\pm0.006~\mathrm{pc}\ \mathrm{cm}^{-3}$, allows for a large source redshift of $z>1$ according to the Macquart relation. It could thus be that the host galaxy is consistent with the known population of FRB hosts, but is too distant to detect in our observations ($z>0.7$ for a host like that of the first repeating FRB source, FRB 20121102A); that it is more nearby with a significant excess in $\mathrm{DM_{host}}$, and thus dimmer than any known FRB host; or, least likely, that the FRB is truly hostless. We consider each possibility, making use of the population of known FRB hosts to frame each scenario. The fact of the missing host has ramifications for the FRB field: even with high-precision localisation and deep follow-up, some FRB hosts may be difficult to detect, with more distant hosts being the less likely to be found. This has implications for FRB cosmology, in which high-redshift detections are valuable., Comment: 14 pages, 6 figures. Revised based on referee's comments and accepted to MNRAS

We present a comprehensive study of the rotational and emission properties of PSR J0738$-$4042 using a combination of observations taken by the Deep Space Network, Hartebeesthoek, Parkes (Murriyang) and Molonglo observatories between 1972 and 2023. Our timing of the pulsar is motivated by previously reported profile/spin-down events that occurred in September 2005 and December 2015, which result in an anomalously large braking index of $n = 23300 \pm 1800$. Using a Gaussian process regression framework, we develop continuous models for the evolution of the pulsar spin-down rate ($\dot{\nu}$) and profile shape. We find that the pulse profile variations are similar regardless of radio observing frequency and polarisation. Small-scale differences can be ascribed to changes in the interstellar medium along the line of sight and frequency-dependent changes in magnetospheric radio emission height. No new correlated spin-down or profile events were identified in our extended dataset. However, we found that the disappearance of a bright emission component in the leading edge of archival profiles between 1981-1988 was not associated with a substantial change in $\dot{\nu}$. This marks a notable departure from the previous profile/spin-down events in this pulsar. We discuss the challenges these observations pose for physical models and conclude that interactions between the pulsar and in-falling asteroids or a form of magnetospheric state-switching with a long periodicity are plausible explanations., Comment: 14 pages, 8 figures. Fixed typo on page 5. Accepted for publication in MNRAS

Quantum simulators offer powerful means to investigate strongly correlated quantum matter. However, interpreting measurement outcomes in such systems poses significant challenges. Here, we present a theoretical framework for information extraction in synthetic quantum matter, illustrated for the case of a quantum quench in a spinor Bose-Einstein condensate experiment. Employing non-parametric unsupervised learning tools that provide different measures of information content, we demonstrate a system-agnostic approach to identify dominant degrees of freedom. This enables us to rank operators according to their relevance, akin to effective field theory. To characterize the corresponding effective description, we then explore the intrinsic dimension of data sets as a measure of the complexity of the dynamics. This reveals a simplification of the data structure, which correlates with the emergence of time-dependent universal behavior in the studied system. Our assumption-free approach can be immediately applied in a variety of experimental platforms., Comment: Published version

We present high-resolution 1.5 $-$ 6 GHz Karl G. Jansky Very Large Array (VLA) and Hubble Space Telescope (HST) optical and infrared observations of the extremely active repeating fast radio burst (FRB) FRB 20201124A and its barred spiral host galaxy. We constrain the location and morphology of star formation in the host and search for a persistent radio source (PRS) coincident with FRB 20201124A. We resolve the morphology of the radio emission across all frequency bands and measure a star formation rate SFR $\approx 8.9\,M_{\odot}$ yr$^{-1}$, approximately $\approx 2.5-6$ times larger than optically-inferred SFRs, demonstrating dust-obscured star formation throughout the host. Compared to a sample of all known FRB hosts with radio emission, the host of FRB 20201124A has the most significantly obscured star formation. While HST observations show the FRB to be offset from the bar or spiral arms, the radio emission extends to the FRB location. We propose that the FRB progenitor could have formed in situ (e.g., a magnetar born from a massive star explosion). It is still plausible, although less likely, that the progenitor of FRB 20201124A migrated from the central bar of the host. We further place a limit on the luminosity of a putative PRS at the FRB position of $L_{\rm 6.0 \ GHz}$ $\lesssim$ 1.8 $\times 10^{27}$ erg s$^{-1}$ Hz$^{-1}$, among the deepest PRS luminosity limits to date. However, this limit is still broadly consistent with both magnetar nebulae and hypernebulae models assuming a constant energy injection rate of the magnetar and an age of $\gtrsim 10^{5}$ yr in each model, respectively., Comment: 21 pages, 6 figures, 3 tables, Accepted to ApJ; doi:10.3847/1538-4357/ad0cbd

We present the first X-ray census of fast radio burst (FRB) host galaxies to conduct the deepest search for AGN and X-ray counterparts to date. Our sample includes seven well-localized FRBs with unambiguous host associations and existing deep Chandra observations, including two events for which we present new observations. We find evidence for AGN in two FRB host galaxies based on the presence of X-ray emission coincident with their centers, including the detection of a luminous ($L_X \approx 5 \times 10^{42} \ \rm erg \ s^{-1}$) X-ray source at the nucleus of FRB20190608B's host, for which we infer an SMBH mass of $\rm M_{\rm BH} \sim 10^{8} \ M_{\odot}$ and an Eddington ratio $L_{\rm bol}/ L_{\rm Edd} \approx 0.02$, characteristic of geometrically thin disks in Seyfert galaxies. We also report nebular emission line fluxes for 24 highly secure FRB hosts (including 10 hosts for the first time), and assess their placement on a BPT diagram, finding that FRB hosts trace the underlying galaxy population. We further find that the hosts of repeating FRBs are not confined to the star-forming locus, contrary to previous findings. Finally, we place constraints on associated X-ray counterparts to FRBs in the context of ultraluminous X-ray sources (ULXs), and find that existing X-ray limits for FRBs rule out ULXs brighter than $L_X \gtrsim 10^{40} \ \rm erg \ s^{-1}$. Leveraging the CHIME/FRB catalog and existing ULX catalogs, we search for spatially coincident ULX-FRB pairs. We identify two ULX in the galaxy NGC 2633 that are spatially coincident with the repeating FRB20180908B and for which the DM-inferred redshift is comparable to the distance of the galaxy, assuming a $\rm DM_{host}$ contribution of $150 \ \rm pc \ cm^{-3}$., Comment: 15 pages, 5 figures; submitted to ApJ

Efforts are underway to magnetically confine electron--positron pair plasmas to study their unique behavior, which is characterized by significant changes in plasma time and length scales, supported waves, and unstable modes. However, use of conventional plasma diagnostics presents challenges with these low-density and annihilating matter-antimatter plasma. To address this problem, we propose to develop techniques based on the distinct emission provided by annihilation. This emission exhibits two spatial correlations: the distance attenuation of isotropic sources and the back-to-back propagation of momentum-preserving 2-$\gamma$ annihilation. We present the results of our analysis of the $\gamma$ emission rate and the spatial profile of the annihilation in a magnetized pair plasma from direct pair collisions, from the formation and decay of positronium, as well as from transport processes. In order to demonstrate the effectiveness of annihilation-based techniques, we tested them on annular $\gamma$ emission profiles produced by a $\beta^+$ radioisotope on a rotating turntable. Direct and positronium-mediated annihilation result in overlapping volumetric $\gamma$ sources, and the 2-$\gamma$ emission from these volumetric sources can be tomographically reconstructed from coincident counts in multiple detectors. Transport processes result in localized annihilation where field lines intersect walls, limiters, or internal magnets. These localized sources can be identified by the fractional $\gamma$ counts on spatially distributed detectors., Comment: 21 pages, 11 figures, 2 tables, contribution to the 13th International Workshop on Non-Neutral Plasmas

Close to equilibrium, the underlying symmetries of a system determine its possible universal behavior. Far from equilibrium, however, different universal phenomena associated with the existence of multiple non-thermal fixed points can be realized for given microscopic symmetries. Here, we study this phenomenon using a quasi-one-dimensional spinor Bose-Einstein condensate. We prepare two different initial conditions and observe two distinct universal scaling dynamics with different exponents. Measurements of the complex-valued order parameter with spatial resolution allow us to characterize the phase-amplitude excitations for the two scenarios. Our study provides new insights into the phenomenon of universal dynamics far from equilibrium and opens a path towards mapping out the associated basins of non-thermal fixed points.

We use four observations with the European VLBI network to measure the first precise radio parallax of the Crab Pulsar. We found two in-beam extragalactic sources just outside the Crab Nebula, with one bright enough to use as a background reference source in our data. We use the Crab Pulsar's giant pulses to determine fringe and bandpass calibration solutions, which greatly improved the sensitivity and reliability of our images and allowed us to determine precise positional offsets between the pulsar and the background source. From those offsets, we determine a parallax of $\pi=0.53\pm0.06\rm{\;mas}$ and proper motion of $(\mu_{\alpha},\mu_{\delta})=(-11.34\pm0.06,2.65\pm0.14)\rm{\;mas\;yr^{-1}}$, yielding a distance of $d=1.90^{+0.22}_{-0.18}\rm{\;kpc}$ and transverse velocity of $v_{\perp}=104^{+13}_{-11}\rm{\;km\;s^{-1}}$. These results are consistent with the Gaia 3 measurements, and open up the possibility of far more accurate astrometry with further VLBI observations., Comment: 16 pages, 8 figures, accepted for publication in ApJ

We report on the commensal ASKAP detection of a fast radio burst (FRB), FRB20211127I, and the detection of neutral hydrogen (HI) emission in the FRB host galaxy, WALLABYJ131913-185018 (hereafter W13-18). This collaboration between the CRAFT and WALLABY survey teams marks the fifth, and most distant, FRB host galaxy detected in HI, not including the Milky Way. We find that W13-18 has a HI mass of $M_{\rm HI}$ = 6.5 $\times$ 10$^{9}$ M$_{\odot}$, a HI-to-stellar mass ratio of 2.17, and coincides with a continuum radio source of flux density at 1.4 GHz of 1.3 mJy. The HI global spectrum of W13-18 appears to be asymmetric, albeit the HI observation has a low S/N, and the galaxy itself appears modestly undisturbed. These properties are compared to the early literature of HI emission detected in other FRB hosts to date, where either the HI global spectra were strongly asymmetric, or there were clearly disrupted HI intensity map distributions. W13-18 lacks sufficient S/N to determine whether it is significantly less asymmetric in its HI distribution than previous examples of FRB host galaxies. However, there are no strong signs of a major interaction in the HI or optical image of the host galaxy that would stimulate a burst of star formation and hence the production of putative FRB progenitors related to massive stars and their compact remnants., Comment: 13 pages, 5 figures. Published in ApJ

Temporal broadening is a commonly observed property of fast radio bursts (FRBs), associated with turbulent media which cause radiowave scattering. Similarly to dispersion, scattering is an important probe of the media along the line of sight to an FRB source, such as the circum-burst or circum-galactic mediums (CGM). Measurements of characteristic scattering times alone are insufficient to constrain the position of the dominant scattering media along the line of sight. However, where more than one scattering screen exists, Galactic scintillation can be leveraged to form strong constraints. We quantify the scattering and scintillation in 10 FRBs with 1) known host galaxies and redshifts and 2) captured voltage data enabling high-time resolution analysis. We find strong evidence for two screens in three cases. For FRBs 20190608B and 20210320C, we find evidence for scattering screens less than approximately 16.7 and 3000 kpc respectively, from their sources, consistent with the scattering occurring in the circum-burst environment, the host ISM (inter-stellar medium) or the CGM. For FRB 20201124A we find a low modulation index that evolves over the burst's scattering tail, indicating the presence of a scattering screen $\approx9$ kpc from the host, and excluding the circum-burst environment from potential scattering sites. By assuming that pulse broadening is contributed by the host galaxy ISM or circum-burst environment, the lack of observed scintillation in four FRBs in our sample suggests that existing models may be poor estimators of scattering times associated with the Milky Way's ISM, similar to the anomalously low scattering observed for FRB 20201124A., Comment: 13 pages, 9 figures, 1 table. Accepted in MNRAS

The Macquart relation describes the correlation between the dispersion measure (DM) of fast radio bursts (FRBs) and the redshift $z$ of their host galaxies. The scatter of the Macquart relation is sensitive to the distribution of baryons in the intergalactic medium (IGM) including those ejected from galactic halos through feedback processes. The width of the distribution in DMs from the cosmic web (${\rm DM}_{\rm cosmic}$) is parameterized by a fluctuation parameter $F$, which is related to the cosmic DM variance by $\sigma_{\rm DM}= F z^{-0.5}$. In this work, we present a new measurement of $F$ using 78 FRBs of which 21 have been localized to host galaxies. Our analysis simultaneously fits for the Hubble constant $H_0$ and the DM distribution due to the FRB host galaxy. We find that the fluctuation parameter is degenerate with these parameters, most notably $H_0$, and use a uniform prior on $H_0$ to measure $\log_{10} F > -0.89$ at the $3\sigma$ confidence interval and a new constraint on the Hubble constant $H_0 = 85.3_{-8.1}^{+9.4} \, {\rm km \, s^{-1} \, Mpc^{-1}}$. Using a synthetic sample of 100 localized FRBs, the constraint on the fluctuation parameter is improved by a factor of $\sim 2$. Comparing our $F$ measurement to simulated predictions from cosmological simulation (IllustrisTNG), we find agreement between $0.4 < z < 2$. However, at $z < 0.4$, the simulations underpredict $F$ which we attribute to the rapidly changing extragalactic DM excess distribution at low redshift., Comment: Submitted to ApJ. 11 pages, 9 figures, 4 tables

Universal scaling dynamics of a many-body system far from equilibrium signals the proximity of the time-evolution to a non-thermal fixed point. We find universal dynamics connected with rogue-wave like events in the mutually coupled magnetic components of a spinor gas which propagate in an effectively random potential. The frequency of these caustics is affected by the time varying spatial correlation length of the potential, giving rise to an additional exponent $\delta_\mathrm{c} \simeq 1/3$ for temporal scaling, which is different by a factor $\sim 4/3$ from the exponent $\beta_V \simeq 1/4$ characterizing the scaling of the correlation length $\ell_V \sim t^{\,\beta_V}$ with time. As a result of the caustics, real-time instanton defects appear in the Larmor phase of the spin-1 system as vortices in space and time. The temporal correlations determining the frequency of instanton events to occur scale in time as $t^{\, \delta_\mathrm{I}}$. This suggests that the universality class of a non-thermal fixed point could be characterized by different, mutually related exponents defining the coarsening evolution in time and space, respectively. Our results have a strong relevance for understanding pattern coarsening from first principles and potential implications for dynamics ranging from the early universe to geophysical dynamics and micro physics.

As the sample size of repeating fast radio bursts (FRBs) has grown, an increasing diversity of phenomenology has emerged. Through long-term multi-epoch studies of repeating FRBs, it is possible to assess which phenomena are common to the population and which are unique to individual sources. We present a multi-epoch monitoring campaign of the repeating FRB source 20180301A using the ultra-wideband low (UWL) receiver observations with Murriyang, the Parkes 64-m radio telescope. The observations covered a wide frequency band spanning approximately 0.7--4 GHz, and yielded the detection of 46 bursts. None of the repeat bursts displayed radio emission in the range of 1.8--4 GHz, while the burst emission peaked at 1.1 GHz. We discover evidence for secular trends in the burst dispersion measure, indicating a decline at a rate of $-2.7\pm0.2\,{\rm pc\,cm^{-3}\,yr^{-1}}$. We also found significant variation in the Faraday rotation measure of the bursts across the follow-up period, including evidence of a sign reversal. While a majority of bursts did not exhibit any polarization, those that did show a decrease in the linear polarization fraction as a function of frequency, consistent with spectral depolarization due to scattering, as observed in other repeating FRB sources. Surprisingly, no significant variation in the polarization position angles was found, which is in contrast with earlier measurements reported for the FRB source. We measure the burst rate and sub-pulse drift rate variation and compare them with the previous results. These novel observations, along with the extreme polarization properties observed in other repeating FRBs, suggest that a sub-sample of FRB progenitors possess highly dynamic magneto-ionic environments., Comment: 21 pages, 14 figures; accepted for publication in MNRAS

The FLIMFLAM survey is collecting spectroscopic data of field galaxies near fast radio burst (FRB) sightlines to constrain key parameters describing the distribution of matter in the Universe. In this work, we leverage the survey data to determine the source of the excess extragalactic dispersion measure (DM), compared to the Macquart relation estimate of four FRBs: FRB20190714A, FRB20200430A, FRB20200906A, and FRB20210117A. By modeling the gas distribution around the foreground galaxy halos and galaxy groups of the sightlines, we estimate $\rm DM_{halos}$, their contribution to the FRB dispersion measures. The FRB20190714A sightline shows a clear excess of foreground halos which contribute roughly 2/3$^{rd}$ of the observed excess DM, thus implying a baryon-dense sightline. FRB20200906A shows a smaller but non-negligible foreground halo contribution, and further analysis of the IGM is necessary to ascertain the true cosmic contribution to its DM. RB20200430A and FRB20210117A show negligible foreground contributions, implying a large host galaxy excess and/or progenitor environment excess., Comment: 14 pages, 6 figures, 3 tables. Data access available here: https://drive.google.com/drive/folders/1gVVwTAmiHJtFB_GD56hgmDylXHYbOTFS

Studies of the time-domain structure of fast radio bursts (FRBs) require an accurate estimate of the FRB dispersion measure in order to recover the intrinsic burst shape. Furthermore, the exact DM is itself of interest when studying the time-evolution of the medium through which multiple bursts from repeating FRBs propagate. A commonly used approach to obtain the dispersion measure is to take the value that maximizes the FRB structure in the time domain. However, various authors use differing methods to obtain this structure parameter, and do not document the smoothing method used. Furthermore, there are no quantitative estimates of the error in this procedure in the FRB literature. In this letter, we present a smoothing filter based on the discrete cosine transform, and show that computing the structure parameter by summing the squares of the derivatives and taking the square root immediately lends itself to calculation of uncertainty of the structure parameter. We illustrate this with FRB181112 and FRB210117 data, which were detected by the Australian Square Kilometre Array Pathfinder, and for which high-time-resolution data is available., Comment: 10 pages, 15 figures; submitted to ApJ

We present a comprehensive catalog of observations and stellar population properties for 23 highly secure host galaxies of fast radio bursts (FRBs). Our sample comprises six repeating FRBs and 17 apparent non-repeaters. We present 82 new photometric and eight new spectroscopic observations of these hosts. Using stellar population synthesis modeling and employing non-parametric star formation histories (SFHs), we find that FRB hosts have a median stellar mass of $\approx 10^{9.9}\,M_{\odot}$, mass-weighted age $\approx 5.1$ Gyr, and ongoing star formation rate $\approx 1.3\,M_{\odot}$ yr$^{-1}$ but span wide ranges in all properties. Classifying the hosts by degree of star formation, we find that 87% (20/23 hosts) are star-forming, two are transitioning, and one is quiescent. The majority trace the star-forming main sequence of galaxies, but at least three FRBs in our sample originate in less active environments (two non-repeaters and one repeater). Across all modeled properties, we find no statistically significant distinction between the hosts of repeaters and non-repeaters. However, the hosts of repeating FRBs generally extend to lower stellar masses, and the hosts of non-repeaters arise in more optically luminous galaxies. While four of the galaxies with the most clear and prolonged rises in their SFHs all host repeating FRBs, demonstrating heightened star formation activity in the last $\lesssim 100$ Myr, one non-repeating host shows this SFH as well. Our results support progenitor models with short delay channels (i.e., magnetars formed via core-collapse supernova) for most FRBs, but the presence of some FRBs in less active environments suggests a fraction form through more delayed channels., Comment: 52 pages, 32 figures, 6 tables, submitted

Fast radio bursts (FRBs) are being detected with increasing regularity. However, their spontaneous and often once-off nature makes high-precision burst position and frequency-time structure measurements difficult without specialised real-time detection techniques and instrumentation. The Australian Square Kilometre Array Pathfinder (ASKAP) has been enabled by the Commensal Real-time ASKAP Fast Transients Collaboration (CRAFT) to detect FRBs in real-time and save raw antenna voltages containing FRB detections. We present the CRAFT Effortless Localisation and Enhanced Burst Inspection pipeline (CELEBI), an automated software pipeline that extends CRAFT's existing software to process ASKAP voltages in order to produce sub-arcsecond precision localisations and polarimetric data at time resolutions as fine as 3 ns of FRB events. We use Nextflow to link together Bash and Python code that performs software correlation, interferometric imaging, and beamforming, making use of common astronomical software packages., Comment: 17 pages, 13 figures, minor revisions, accepted for publication in Astronomy & Computing

With unparalleled rotational stability, millisecond pulsars (MSPs) serve as ideal laboratories for numerous astrophysical studies, many of which require precise knowledge of the distance and/or velocity of the MSP. Here, we present the astrometric results for 18 MSPs of the "MSPSR$\pi$" project focusing exclusively on astrometry of MSPs, which includes the re-analysis of 3 previously published sources. On top of a standardized data reduction protocol, more complex strategies (i.e., normal and inverse-referenced 1D interpolation) were employed where possible to further improve astrometric precision. We derived astrometric parameters using sterne, a new Bayesian astrometry inference package that allows the incorporation of prior information based on pulsar timing where applicable. We measured significant ($>3\,\sigma$) parallax-based distances for 15 MSPs, including $0.81\pm0.02\,$kpc for PSR J1518+4904 -- the most significant model-independent distance ever measured for a double neutron star system. For each MSP with a well-constrained distance, we estimated its transverse space velocity and radial acceleration. Among the estimated radial accelerations, the updated ones of PSR J1012+5307 and PSR J1738+0333 impose new constraints on dipole gravitational radiation and the time derivative of Newton's gravitational constant. Additionally, significant angular broadening was detected for PSR J1643-1224, which offers an independent check of the postulated association between the HII region Sh 2-27 and the main scattering screen of PSR J1643-1224. Finally, the upper limit of the death line of $\gamma$-ray-emitting pulsars is refined with the new radial acceleration of the hitherto least energetic $\gamma$-ray pulsar PSR J1730-2304., Comment: 23 pages, 6 figures, 10 tables, published in MNRAS