J/A+A/693/A279 The Apertif fast radio burst sample (Pastor-Marazuela+, 2025)
Comprehensive analysis of the Apertif fast radio burst sample.
Similarities with young energetic neutron stars.
Pastor-Marazuela I., van Leeuwen J., Bilous A., Connor L., Maan Y.,
Oostrum L., Petroff E., Vohl D., Hess, K.-M., Orru E., Sclocco A., Wang Y.
<Astron. Astrophys. 693, A279 (2025)>
=2025A&A...693A.279P 2025A&A...693A.279P (SIMBAD/NED BibCode)
ADC_Keywords: Radio sources ; Stars, neutron ; Morphology ; Redshifts
Keywords: stars: neutron - intergalactic medium - galaxies: ISM
Abstract:
Understanding the origin of energetic fast radio bursts (FRBs) has
become the main science driver of recent dedicated FRB surveys powered
by real-time instrumentation. Between July 2019 and February 2022, we
carried out ALERT, an FRB survey at 1370MHz using the Apertif Radio
Transient System (ARTS) installed at the Westerbork Synthesis Radio
Telescope (WSRT). Here we report the detection of 18 new FRBs. We
studied the properties of the entire 24-burst sample that were
detected during the survey. For five bursts, we identified host galaxy
candidates within their error regions with >50% probability
association. We observed an average linear polarisation fraction of
∼43% and an average circular polarisation fraction consistent with 0%.
One-third of the FRBs display multiple components. These burst
structures and the polarisation fractions are strikingly similar to
those observed in young energetic pulsars and magnetars. The Apertif
FRBs next reveal a population of highly scattered bursts. Given the
observing frequency and time resolution, the scattering of most FRBs
is likely to have been produced in the immediate circumburst
environment. Furthermore, two FRBs show evidence of high rotation
measure values, which could reach |RM|>103rad/m2 in the source
reference frames. This corroborates that some source environments are
dominated by magneto-ionic effects. Together, the scattering and
rotation measures that ALERT has found prove that a large fraction of
FRBs are embedded in complex media such as star-forming regions or
supernova remnants. Through the discovery of FRB20200719A, the third
most dispersed FRB so far, we further show that one-off FRBs emit at
frequencies in excess of 6GHz, the highest known to date. We compare
this to the radio-bright high-frequency emission seen in magnetars.
Finally, we determine an FRB all-sky rate of
459+208-155sky-1day-1 above a fluence limit of 4.1Jy.ms, and a
fluence cumulative distribution with a power-law index
gamma=-1.23±0.06±0.2, which is roughly consistent with the
Euclidean Universe predictions. Through the high resolution in time,
frequency, polarisation, and localisation that ALERT featured, we were
able to determine the morphological complexity, polarisation, local
scattering and magnetic environment, and high-frequency luminosity of
FRBs. We find all of these parameters strongly resemble those seen in
young, energetic, highly magnetised neutron stars.
Description:
In this work we reported the discovery of 18 new, so-far one-off,
FRBs, and analysed the properties of the total of 24 bursts that were
detected during the ALERT Apertif FRB survey between July 2019 and
February 2022. For each FRB, we determined the localisation region and
expected redshift range and performed a flux calibration. We evaluated
their morphology, determining the number of components and the
spectral properties, and we studied the propagation effects by
verifying the presence of a resolved scattering tail in time and a
scintillation pattern in frequency.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
frbs.dat 271 24 Apertif fast radio burst properties
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Byte-by-byte Description of file: frbs.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- TNS Source id from transient name server
(FRBYYYYMMDDA)
14- 15 I2 h RAh Right Ascension J2000 (hours)
17- 18 I2 min RAm Right Ascension J2000 (minutes)
20- 23 F4.1 s RAs Right Ascension J2000 (seconds)
25 A1 --- DE- Declination J2000 (sign)
26- 27 I2 deg DEd Declination J2000 (degrees)
29- 30 I2 arcmin DEm Declination J2000 (minutes)
32- 35 F4.1 arcsec DEs Declination J2000 (seconds)
37- 50 F14.8 d MJD Barycentric modified Julian date of FRB
52- 58 F7.2 pc/cm3 DM Dispersion measure of FRB
60- 63 F4.2 pc/cm3 e_DM Dispersion measure error
66- 67 I2 --- S/N Signal-to-noise ratio
70 I1 --- N Number of burst subcomponents
72- 75 F4.2 Jy Flux Burst peak flux
79- 82 F4.2 Jy e_Flux Burst peak flux error
86- 90 F5.2 Jy.ms Fluence Burst fluence
96-100 F5.2 Jy.ms e_Fluence Burst fluence error
102-106 F5.2 ms Width Burst temporal width
111-114 F4.2 ms e_Width Burst temporal width error
116-120 F5.2 ms tausc ? Scattering timescale, τsc
123-126 F4.2 ms e_tausc ? Scattering timescale error
129-131 F3.1 MHz scbw ? Scintillation bandwidth, Δνsc
136-138 F3.1 MHz e_scbw ? Scintillation bandwidth error
142-145 I4 MHz Fpeak Burst peak frequency (1)
153-154 I2 MHz e_Fpeak ? Burst peak frequency error
156-159 A4 MHz BW Burst bandwidth (2)
163-164 I2 MHz e_BW ? Burst bandwidth error
166-169 I4 arcsec a Localisation ellipse semi-major axis (3)
171-174 F4.1 arcsec b Localisation ellipse semi-minor axis (3)
176-181 F6.2 deg theta Burst localisation ellipse angle (3)
183-187 F5.2 arcmin2 locarea Burst localisation area
189-190 I2 --- CB Burst detection compound beam
192-193 I2 --- SB Burst detection synthesised beam
201-203 I3 pc/cm3 DMNE2001 Galactic DM contribution from NE2001 model
210-211 I2 pc/cm3 DMhalo Galactic halo DM contribution from
Yamasaki & Totani (2020ApJ...888..105Y 2020ApJ...888..105Y)
model
214-217 F4.2 --- z Median redshift expected from the Macquart
relation for the FRB excess DM
221-224 F4.2 --- b_z Redshift 2.5% lower limit expected from the
Macquart relation for the FRB excess DM
229-232 F4.2 --- B_z Redshift 97.5% upper limit from the
Macquart relation for the FRB excess DM
234-237 F4.1 --- SI ? Spectral index Gamma of bursts with
power-law spectrum
240-242 F3.1 --- e_SI ? Spectral index error
245-248 F4.1 --- alpha ? Scattering index of scattered bursts
254-256 F3.1 --- e_alpha ? Scattering index error
261-263 F3.1 GHz Frest Expected rest frame frequency at Macquart
median redshift, nu0
265-271 E7.1 10-7J isoe Expected isotropic energy at Macquart
median redshift
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Note (1): Central frequency-peak for broadband bursts assumed to be the central
frequency, 1370MHz. For bursts with power law spectrum, 1520MHz and 1220MHz
if they peak at the top or the bottom of the band respectively.
Other values for narrowband bursts fitted to a Gaussian spectrum.
Note (2): Full width at tenth maximum for bursts with Gaussian spectrum or >300
for broadband bursts.
Note (3): Localisation ellipse given by 99% probability contour. Angle measured
from West (lowest RA) through the North, using the same convention as ds9.
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Acknowledgements:
Ines Pastor-Marazuela, ines.pastor.marazuela(at)gmail.com
(End) Ines Pastor-Marazuela [Manchester, UK], Patricia Vannier [CDS] 02-Dec-2024