11 research outputs found
Non-detection of CHIME/FRB sources with the Arecibo Observatory
In this work, we present follow-up observations of two known repeating fast
radio bursts (FRBs) and seven non-repeating FRBs with complex morphology
discovered with CHIME/FRB. These observations were conducted with the Arecibo
Observatory 327 MHz receiver. We detected no additional bursts from these
sources, nor did CHIME/FRB detect any additional bursts from these sources
during our follow-up program. Based on these non-detections, we provide
constraints on the repetition rate, for all nine sources. We calculate
repetition rates using both a Poisson distribution of repetition and the
Weibull distribution of repetition presented by Oppermann et al. (2018). For
both distributions, we find repetition upper limits of the order for all sources. These rates are much lower
than those recently published for notable repeating FRBs like FRB 20121102A and
FRB 20201124A, suggesting the possibility of a low-repetition sub-population.Comment: 12 pages, 4 figures, 5 tables; submitted to Ap
Proposed host galaxies of repeating fast radio burst sources detected by CHIME/FRB
We present a search for host galaxy associations for the third set of
repeating fast radio burst (FRB) sources discovered by the CHIME/FRB
Collaboration. Using the ~1 arcmin CHIME/FRB baseband localizations and
probabilistic methods. We identify potential host galaxies of two FRBs,
20200223B and 20190110C at redshifts of 0.06024(2) and 0.12244(6),
respectively. We also discuss the properties of a third marginal candidate host
galaxy association for FRB 20191106C with a host redshift of 0.10775(1). The
three putative host galaxies are all relatively massive, fall on the standard
mass-metallicity relationship for nearby galaxies, and show evidence of ongoing
star formation. They also all show signatures of being in a transitional
regime, falling in the "green valley" which is between the bulk of star-forming
and quiescent galaxies. The plausible host galaxies identified by our analysis
are consistent with the overall population of repeating and non-repeating FRB
hosts while increasing the fraction of massive and bright galaxies. Coupled
with these previous host associations, we identify a possible excess of FRB
repeaters whose host galaxies have M_u - M_r colors redder than the bulk of
star-forming galaxies. Additional precise localizations are required to confirm
this trend.Comment: 11 pages, submitted to AAS journal
An Injection System for the CHIME/FRB Experiment
Dedicated surveys searching for Fast Radio Bursts (FRBs) are subject to
selection effects which bias the observed population of events. Software
injection systems are one method of correcting for these biases by injecting a
mock population of synthetic FRBs directly into the realtime search pipeline.
The injected population may then be used to map intrinsic burst properties onto
an expected signal-to-noise ratio (SNR), so long as telescope characteristics
such as the beam model and calibration factors are properly accounted for. This
paper presents an injection system developed for the Canadian Hydrogen
Intensity Mapping Experiment Fast Radio Burst project (CHIME/FRB). The system
was tested to ensure high detection efficiency, and the pulse calibration
method was verified. Using an injection population of ~85,000 synthetic FRBs,
we found that the correlation between fluence and SNR for injected FRBs was
consistent with that of CHIME/FRB detections in the first CHIME/FRB catalog. We
also noted that the sensitivity of the telescope varied strongly as a function
of the broadened burst width, but not as a function of the dispersion measure.
We conclude that some of the machine-learning based Radio Frequency
Interference (RFI) mitigation methods used by CHIME/FRB can be re-trained using
injection data to increase sensitivity to wide events, and that planned
upgrades to the presented injection system will allow for determining a more
accurate CHIME/FRB selection function in the near future.Comment: 13 pages, 8 figures. Submitted to A
Comprehensive Bayesian analysis of FRB-like bursts from SGR 1935+2154 observed by CHIME/FRB
The bright millisecond-duration radio burst from the Galactic magnetar SGR
1935+2154 in 2020 April was a landmark event, demonstrating that at least some
fast radio burst (FRB) sources could be magnetars. The two-component burst was
temporally coincident with peaks observed within a contemporaneous short X-ray
burst envelope, marking the first instance where FRB-like bursts were observed
to coincide with X-ray counterparts. In this study, we detail five new radio
burst detections from SGR 1935+2154, observed by the CHIME/FRB instrument
between October 2020 and December 2022. We develop a fast and efficient
Bayesian inference pipeline that incorporates state-of-the-art Markov chain
Monte Carlo techniques and use it to model the intensity data of these bursts
under a flexible burst model. We revisit the 2020 April burst and corroborate
that both the radio sub-components lead the corresponding peaks in their
high-energy counterparts. For a burst observed in 2022 October, we find that
our estimated radio pulse arrival time is contemporaneous with a short X-ray
burst detected by GECAM and HEBS, and Konus-Wind and is consistent with the
arrival time of a radio burst detected by GBT. We present flux and fluence
estimates for all five bursts, employing an improved estimator for bursts
detected in the side-lobes. We also present upper limits on radio emission for
X-ray emission sources which were within CHIME/FRB's field-of-view at trigger
time. Finally, we present our exposure and sensitivity analysis and estimate
the Poisson rate for FRB-like events from SGR 1935+2154 to be
events/day above a fluence of
during the interval from 28 August 2018 to 1 December 2022, although we note
this was measured during a time of great X-ray activity from the source.Comment: 22 pages, 6 figures, 4 tables. To be submitted to Ap
Multiwavelength Constraints on the Origin of a Nearby Repeating Fast Radio Burst Source in a Globular Cluster
Since fast radio bursts (FRBs) were discovered, their precise origins have
remained a mystery. Multiwavelength observations of nearby FRB sources provide
one of the best ways to make rapid progress in our understanding of the
enigmatic FRB phenomenon. We present results from a sensitive, broadband
multiwavelength X-ray and radio observational campaign of FRB 20200120E, the
closest known extragalactic repeating FRB source. At a distance of 3.63 Mpc,
FRB 20200120E resides in an exceptional location, within a ~10 Gyr-old globular
cluster in the M81 galactic system. We place deep limits on both the persistent
X-ray luminosity and prompt X-ray emission at the time of radio bursts from FRB
20200120E, which we use to constrain possible progenitors for the source. We
compare our results to various classes of X-ray sources and transients. In
particular, we find that FRB 20200120E is unlikely to be associated with:
ultraluminous X-ray bursts (ULXBs), similar to those observed from objects of
unknown origin in other extragalactic globular clusters; giant flares, like
those observed from Galactic and extragalactic magnetars; or most intermediate
flares and very bright short X-ray bursts, similar to those seen from magnetars
in the Milky Way. We show that FRB 20200120E is also unlikely to be powered by
a persistent or transient ultraluminous X-ray (ULX) source or a young,
extragalactic pulsar embedded in a Crab-like nebula. We also provide new
constraints on the compatibility of FRB 20200120E with accretion-based FRB
models involving X-ray binaries and models that require a synchrotron maser
process from relativistic shocks to generate FRB emission. These results
highlight the power that multiwavelength observations of nearby FRBs can
provide for discriminating between potential FRB progenitor models.Comment: 58 pages, 10 figures, 7 tables, submitte
A fast radio burst localized at detection to a galactic disk using very long baseline interferometry
Fast radio bursts (FRBs) are millisecond-duration, luminous radio transients
of extragalactic origin. These events have been used to trace the baryonic
structure of the Universe using their dispersion measure (DM) assuming that the
contribution from host galaxies can be reliably estimated. However,
contributions from the immediate environment of an FRB may dominate the
observed DM, thus making redshift estimates challenging without a robust host
galaxy association. Furthermore, while at least one Galactic burst has been
associated with a magnetar, other localized FRBs argue against magnetars as the
sole progenitor model. Precise localization within the host galaxy can
discriminate between progenitor models, a major goal of the field. Until now,
localizations on this spatial scale have only been carried out in follow-up
observations of repeating sources. Here we demonstrate the localization of FRB
20210603A with very long baseline interferometry (VLBI) on two baselines, using
data collected only at the time of detection. We localize the burst to SDSS
J004105.82+211331.9, an edge-on galaxy at , and detect recent
star formation in the kiloparsec-scale vicinity of the burst. The edge-on
inclination of the host galaxy allows for a unique comparison between the line
of sight towards the FRB and lines of sight towards known Galactic pulsars. The
DM, Faraday rotation measure (RM), and scattering suggest a progenitor
coincident with the host galactic plane, strengthening the link between the
environment of FRB 20210603A and the disk of its host galaxy. Single-pulse VLBI
localizations of FRBs to within their host galaxies, following the one
presented here, will further constrain the origins and host environments of
one-off FRBs.Comment: 40 pages, 13 figures, submitted. Fixed typo in abstrac
CHIME/FRB Discovery of 25 Repeating Fast Radio Burst Sources
We present the discovery of 25 new repeating fast radio burst (FRB) sources
found among CHIME/FRB events detected between 2019 September 30 and 2021 May 1.
The sources were found using a new clustering algorithm that looks for multiple
events co-located on the sky having similar dispersion measures (DMs). The new
repeaters have DMs ranging from 220 pc cm to 1700 pc
cm, and include sources having exhibited as few as two bursts to as many
as twelve. We report a statistically significant difference in both the DM and
extragalactic DM (eDM) distributions between repeating and apparently
nonrepeating sources, with repeaters having lower mean DM and eDM, and we
discuss the implications. We find no clear bimodality between the repetition
rates of repeaters and upper limits on repetition from apparently nonrepeating
sources after correcting for sensitivity and exposure effects, although some
active repeating sources stand out as anomalous. We measure the repeater
fraction and find that it tends to an equilibrium of % over
our exposure thus far. We also report on 14 more sources which are promising
repeating FRB candidates and which merit follow-up observations for
confirmation.Comment: Submitted to ApJ. Comments are welcome and follow-up observations are
encouraged
Proposed Host Galaxies of Repeating Fast Radio Burst Sources Detected by CHIME/FRB
We present a search for host galaxy associations for the third set of repeating fast radio burst (FRB) sources discovered by the CHIME/FRB Collaboration. Using the ∼1′ CHIME/FRB baseband localizations and probabilistic methods, we identify potential host galaxies of two FRBs, 20200223B and 20190110C at redshifts of 0.06024(2) and 0.12244(6), respectively. We also discuss the properties of a third marginal candidate host galaxy association for FRB 20191106C with a host redshift of 0.10775(1). The three putative host galaxies are all relatively massive, fall on the standard mass–metallicity relationship for nearby galaxies, and show evidence of ongoing star formation. They also all show signatures of being in a transitional regime, falling in the green valley , which is between the bulk of star-forming and quiescent galaxies. The plausible host galaxies identified by our analysis are consistent with the overall population of repeating and nonrepeating FRB hosts while increasing the fraction of massive and bright galaxies. Coupled with these previous host associations, we identify a possible excess of FRB repeaters whose host galaxies have M _u − M _r colors redder than the bulk of star-forming galaxies. Additional precise localizations are required to confirm this trend
Polarization properties of the 128 non-repeating fast radio bursts from the first CHIME/FRB baseband catalog
International audienceWe present a 400-800 MHz polarimetric analysis of 128 non-repeating fast radio bursts (FRBs) from the first CHIME/FRB baseband catalog, increasing the total number of FRB sources with polarization properties by a factor of ~3. Of the 128 sources, 89 FRBs have >6 linearly polarized detections, 29 FRBs fall below this significance threshold and are deemed linearly unpolarized, and for 10 FRBs the polarization data are contaminated by instrumental polarization. For the 89 polarized FRBs, we find Faraday rotation measure (RM) amplitudes, after subtracting approximate Milky Way contributions, in the range 0.5-1160 rad m with a median of 53.8 rad m. Most non-repeating FRBs in our sample have RMs consistent with Milky Way-like host galaxies and their linear polarization fractions range from 10% to 100% with a median of 63%. The non-repeater RMs and linear polarization fraction distributions are consistent with those of repeating FRBs. We see marginal evidence that non-repeating FRBs have more constraining lower limits than repeating FRBs for the host electron-density-weighted line-of-sight magnetic field strength. We classify the non-repeating FRB polarization position angle (PA) profiles into four archetypes: (i) single component with constant PA (57% of the sample), (ii) single component with variable PA (10%), (iii) multiple components with a single constant PA (22%), and (iv) multiple components with different or variable PAs (11%). We see no evidence for population-wide frequency-dependent depolarization and, therefore, the spread in the distribution of fractional linear polarization is likely intrinsic to the FRB emission mechanism
Polarization properties of the 128 non-repeating fast radio bursts from the first CHIME/FRB baseband catalog
International audienceWe present a 400-800 MHz polarimetric analysis of 128 non-repeating fast radio bursts (FRBs) from the first CHIME/FRB baseband catalog, increasing the total number of FRB sources with polarization properties by a factor of ~3. Of the 128 sources, 89 FRBs have >6 linearly polarized detections, 29 FRBs fall below this significance threshold and are deemed linearly unpolarized, and for 10 FRBs the polarization data are contaminated by instrumental polarization. For the 89 polarized FRBs, we find Faraday rotation measure (RM) amplitudes, after subtracting approximate Milky Way contributions, in the range 0.5-1160 rad m with a median of 53.8 rad m. Most non-repeating FRBs in our sample have RMs consistent with Milky Way-like host galaxies and their linear polarization fractions range from 10% to 100% with a median of 63%. The non-repeater RMs and linear polarization fraction distributions are consistent with those of repeating FRBs. We see marginal evidence that non-repeating FRBs have more constraining lower limits than repeating FRBs for the host electron-density-weighted line-of-sight magnetic field strength. We classify the non-repeating FRB polarization position angle (PA) profiles into four archetypes: (i) single component with constant PA (57% of the sample), (ii) single component with variable PA (10%), (iii) multiple components with a single constant PA (22%), and (iv) multiple components with different or variable PAs (11%). We see no evidence for population-wide frequency-dependent depolarization and, therefore, the spread in the distribution of fractional linear polarization is likely intrinsic to the FRB emission mechanism