scholarly journals Redshift estimates for fast radio bursts and implications on intergalactic magnetic fields

2020 ◽  
Vol 498 (4) ◽  
pp. 4811-4829
Author(s):  
S Hackstein ◽  
M Brüggen ◽  
F Vazza ◽  
L F S Rodrigues
Keyword(s):  
Magnetic Fields ◽  
Dispersion Measure ◽  
Radio Bursts ◽  
Probability Estimates ◽  
Rotation Measure ◽  
Upper Limits ◽  
Fast Radio Burst ◽  
Stellar Sources ◽  
Lower Limits ◽  
Temporal Broadening

ABSTRACT Fast radio bursts are transient radio pulses from presumably compact stellar sources of extragalactic origin. With new telescopes detecting multiple events per day, statistical methods are required in order to interpret observations and make inferences regarding astrophysical and cosmological questions. We present a method that uses probability estimates of fast radio burst observables to obtain likelihood estimates for the underlying models. Considering models for all regions along the line of sight, including intervening galaxies, we perform Monte Carlo simulations to estimate the distribution of the dispersion measure (DM), rotation measure (RM), and temporal broadening. Using Bayesian statistics, we compare these predictions to observations of fast radio bursts. By applying Bayes theorem, we obtain lower limits on the redshift of fast radio bursts with extragalactic DM ≳ 400 pc cm−3. We find that intervening galaxies cannot account for all highly scattered fast radio bursts in FRBcat, thus requiring a denser and more turbulent environment than an SGR 1935+2154-like magnetar. We show that a sample of ≳103 unlocalized fast radio bursts with associated extragalactic RM ≥ 1 rad m−2 can improve current upper limits on the strength of intergalactic magnetic fields.

scholarly journals On the magnetoionic environments of fast radio bursts

2020 ◽  
Vol 499 (1) ◽  
pp. 355-361 ◽  
Author(s):  
Wei-Yang Wang ◽  
Bing Zhang ◽  
Xuelei Chen ◽  
Renxin Xu
Keyword(s):  
Magnetic Field ◽  
Mean Value ◽  
Line Of Sight ◽  
Galactic Centre ◽  
Dispersion Measure ◽  
Radio Bursts ◽  
Host Galaxies ◽  
Surface Magnetic Field ◽  
Rotation Measure ◽  
The Mean

ABSTRACT Observations of the Faraday rotation measure, combined with the dispersion measure, can be used to infer the magnetoionic environment of a radio source. We investigate the magnetoionic environments of fast radio bursts (FRBs) by deriving their estimated average magnetic field strengths along the line of sight 〈B∥〉 in their host galaxies and comparing them with those of Galactic pulsars and magnetars. We find that for those FRBs with RM measurements, the mean 〈B∥〉 are $1.77^{+9.01}_{-1.48}\, \rm \mu G$ and $1.74^{+14.82}_{-1.55}\, \rm \mu G$ using two different methods, which is slightly larger but not inconsistent with the distribution of Galactic pulsars, $1.00^{+1.51}_{-0.60}\, \rm \mu G$. Only six Galactic magnetars have estimated 〈B∥〉. Excluding PSR J1745–2900 that has an anomalously high value due to its proximity with the Galactic Centre, the other five sources have a mean value of $1.70\, \rm \mu G$, which is statistically consistent with the 〈B∥〉 distributions of both Galactic pulsars and FRBs. There is no apparent trend of evolution of magnetar 〈B∥〉 as a function of age or surface magnetic field strength. Galactic pulsars and magnetars close to the Galactic Centre have relatively larger 〈B∥〉 values than other pulsars/magnetars. We discuss the implications of these results for the magnetoionic environments of FRB 121102 within the context of magnetar model and the model invoking a supermassive black hole, and for the origin of FRBs in general.

scholarly journals A fast radio burst source at a complex magnetised site in a barred galaxy

2021 ◽  
Author(s):  
K.J. Lee ◽  
Heng Xu ◽  
J.R. Niu ◽  
P. Chen ◽  
Weiwei Zhu ◽  
...  
Keyword(s):  
Optical Observations ◽  
Host Galaxy ◽  
Radio Bursts ◽  
Radio Waves ◽  
Galactocentric Distance ◽  
Burst Source ◽  
Radiation Mechanism ◽  
Circular Polarisation ◽  
Rotation Measure ◽  
Fast Radio Burst

Abstract Fast radio bursts (FRBs) are highly dispersed radio bursts prevailing in the universe. The recent detection of FRB~200428 from a Galactic magnetar suggested that at least some FRBs originate from magnetars, but it is unclear whether the majority of cosmological FRBs, especially the actively repeating ones, are produced from the magnetar channel. Here we report the detection of 1863 polarised bursts from the repeating source FRB~20201124A during a dedicated radio observational campaign of Five-hundred-meter Aperture Spherical radio Telescope (FAST). The large sample of radio bursts detected in 88 hr over 54 days indicate a significant, irregular, short-time variation of the Faraday rotation measure (RM) of the source during the first 36 days, followed by a constant RM during the later 18 days. Significant circular polarisation up to 75\% was observed in a good fraction of bursts. Evidence suggests that some low-level circular polarisation originates from the conversion from linear polarisation during the propagation of the radio waves, but an intrinsic radiation mechanism is required to produce the higher degree of circular polarisation. All of these features provide evidence for a more complicated, dynamically evolving, magnetised immediate environment around this FRB source. Its host galaxy was previously known. Our optical observations reveal that it is a Milky-Way-sized, metal-rich, barred-spiral galaxy at redshift z=0.09795+-0.00003, with the FRB residing in a low stellar density, interarm region at an intermediate galactocentric distance, an environment not directly expected for a young magnetar formed during an extreme explosion of a massive star.

scholarly journals The Northern Cross fast radio burst project – I. Overview and pilot observations at 408 MHz

2020 ◽  
Vol 494 (1) ◽  
pp. 1229-1236 ◽  
Author(s):  
Nicola T Locatelli ◽  
Gianni Bernardi ◽  
Germano Bianchi ◽  
Riccardo Chiello ◽  
Alessio Magro ◽  
...  
Keyword(s):  
Radio Burst ◽  
System Performance ◽  
Field Of View ◽  
High Dispersion ◽  
Dispersion Measure ◽  
Radio Bursts ◽  
Radio Telescopes ◽  
Present Test ◽  
New Radio ◽  
Fast Radio Burst

ABSTRACT Fast radio bursts (FRBs) remain one of the most enigmatic astrophysical sources. Observations have significantly progressed over the last few years, due to the capabilities of new radio telescopes and the refurbishment of existing ones. Here, we describe the upgrade of the Northern Cross radio telescope, operating in the 400–416 MHz frequency band, with the ultimate goal of turning the array into a dedicated instrument to survey the sky for FRBs. We present test observations of the pulsar B0329+54 to characterize the system performance and forecast detectability. Observations with the system currently in place are still limited by modest sky coverage (∼9.4 deg2) and biased by smearing of high dispersion measure events within each frequency channels. In its final, upgraded configuration, however, the telescope will be able to carry out unbiased FRB surveys over a ∼350 deg2 instantaneous field of view up to z ∼ 5, with a (nearly constant) $\sim 760 \, (\tau /{\rm ms})^{-0.5}$ mJy rms sensitivity.

scholarly journals The impact of the environment of white dwarf mergers on fast radio bursts

2019 ◽  
Vol 492 (3) ◽  
pp. 3753-3762 ◽  
Author(s):  
Esha Kundu ◽  
Lilia Ferrario
Keyword(s):  
Radio Pulse ◽  
Outer Part ◽  
Dispersion Measure ◽  
Constant Density ◽  
Radio Bursts ◽  
Free Expansion ◽  
Expansion Phase ◽  
Rotation Measure ◽  
Power Law Index ◽  
The Impact

ABSTRACT Fast radio bursts (FRBs) are transient intense radio pulses with duration of milliseconds. Although, the first FRB was detected more than a decade ago, the progenitors of these energetic events are not yet known. The currently preferred formation channel involves the formation of a neutron star (NS)/magnetar. While these objects are often the end product of the core-collapse (CC) explosion of massive stars, they could also be the outcome of the merging of two massive white dwarfs. In the merger scenario the ejected material interacts with a constant-density circumbinary medium and creates supersonic shocks. We found that when a radio pulse passes through these shocks the dispersion measure (DM) increases with time during the free expansion phase. The rotation measure (RM) displays a similar trend if the power-law index, n, of the outer part of the ejecta is >6. For n = 6, the RM remains constant during this phase. Later, when the ejecta move into the Sedov–Taylor phase while the DM still increases, however, with a different rate, the RM reduces. This behaviour is somewhat similar to that of FRB 121102 for which a marginal increase of DM and a 10 per cent decrease of RM have been observed over time. These features are in contrast to the CC scenario, where the DM and RM contributions to the radio signal always diminish with time.

scholarly journals Joint inference on the redshift distribution of fast radio burst and on the intergalactic baryon content

2020 ◽  
Author(s):  
S Hackstein ◽  
M Brüggen ◽  
F Vazza
Keyword(s):  
Radio Burst ◽  
Intergalactic Medium ◽  
Local Environment ◽  
Dispersion Measure ◽  
Selection Effects ◽  
Radio Bursts ◽  
Host Galaxies ◽  
Redshift Distribution ◽  
Joint Inference ◽  
Fast Radio Burst

Abstract Context: Fast radio bursts are transient radio pulses of extragalactic origin. Their dispersion measure is indicative of the baryon content in the ionized intergalactic medium between the source and the observer. However, inference using unlocalized fast radio bursts is degenerate to the distribution of redshifts of host galaxies. Method: We perform a joint inference of the intergalactic baryon content and the fast radio burst redshift distribution with the use of Bayesian statistics by comparing the likelihood of different models to reproduce the observed statistics in order to infer the most likely models. In addition to two models of the intergalactic medium, we consider contributions from the local environment of the source, assumed to be a magnetar, as well as a representative ensemble of host and intervening galaxies. Results: Assuming that the missing baryons reside in the ionized intergalactic medium, our results suggest that the redshift distribution of observed fast radio bursts peaks at z ≲ 0.6. However, conclusions from different instruments regarding the intergalactic baryon content diverge and thus require additional changes to the observed distribution of host redshifts, beyond those caused by telescope selection effects.

scholarly journals Fast radio burst dispersion measures and rotation measures and the origin of intergalactic magnetic fields

2019 ◽  
Vol 488 (3) ◽  
pp. 4220-4238 ◽  
Author(s):  
S Hackstein ◽  
M Brüggen ◽  
F Vazza ◽  
B M Gaensler ◽  
V Heesen
Keyword(s):  
Magnetic Fields ◽  
Radio Burst ◽  
Milky Way ◽  
Intergalactic Medium ◽  
Local Environment ◽  
Distribution Functions ◽  
Host Galaxy ◽  
Radio Bursts ◽  
Dispersion Measures ◽  
Fast Radio Burst

ABSTRACT We investigate the possibility of measuring intergalactic magnetic fields using the dispersion measures and rotation measures of fast radio bursts. With Bayesian methods, we produce probability density functions for values of these measures. We distinguish between contributions from the intergalactic medium, the host galaxy, and the local environment of the progenitor. To this end, we use constrained, magnetohydrodynamic simulations of the local Universe to compute lines-of-sight integrals from the position of the Milky Way. In particular, we differentiate between predominantly astrophysical and primordial origins of magnetic fields in the intergalactic medium. We test different possible types of host galaxies and probe different distribution functions of fast radio burst progenitor locations inside the host galaxy. Under the assumption that fast radio bursts are produced by magnetars, we use analytic predictions to account for the contribution of the local environment. We find that less than 100 fast radio bursts from magnetars in stellar-wind environments hosted by starburst dwarf galaxies at redshift z ≳ 0.5 suffice to discriminate between predominantly primordial and astrophysical origins of intergalactic magnetic fields. However, this requires the contribution of the Milky Way to be removed with a precision of ≈1 rad m−2. We show the potential existence of a subset of fast radio bursts whose rotation measures carry information on the strength of the intergalactic magnetic field and its origins.

scholarly journals A bright, high rotation-measure FRB that skewers the M33 halo

2020 ◽  
Vol 499 (4) ◽  
pp. 4716-4724
Author(s):  
L Connor ◽  
J van Leeuwen ◽  
L C Oostrum ◽  
E Petroff ◽  
Y Maan ◽  
...  
Keyword(s):  
Local Group ◽  
Magnetized Plasma ◽  
Host Galaxy ◽  
Dispersion Measure ◽  
Spectral Structure ◽  
Rotation Measure ◽  
Andromeda Galaxy ◽  
Fast Radio Burst ◽  
Group Galaxy ◽  
Local Group Galaxy

ABSTRACT We report the detection of a bright fast radio burst, FRB 191108, with Apertif on the Westerbork Synthesis Radio Telescope. The interferometer allows us to localize the FRB to a narrow 5 arcsec × 7 arcmin ellipse by employing both multibeam information within the Apertif phased-array feed beam pattern, and across different tied-array beams. The resulting sightline passes close to Local Group galaxy M33, with an impact parameter of only 18 kpc with respect to the core. It also traverses the much larger circumgalactic medium (CGM) of M31, the Andromeda Galaxy. We find that the shared plasma of the Local Group galaxies could contribute ∼10 per cent of its dispersion measure of 588 pc cm−3. FRB 191108 has a Faraday rotation measure (RM) of +474 $\pm \, 3$ rad m−2, which is too large to be explained by either the Milky Way or the intergalactic medium. Based on the more moderate RMs of other extragalactic sources that traverse the halo of M33, we conclude that the dense magnetized plasma resides in the host galaxy. The FRB exhibits frequency structure on two scales, one that is consistent with quenched Galactic scintillation and broader spectral structure with Δν ≈ 40 MHz. If the latter is due to scattering in the shared M33/M31 CGM, our results constrain the Local Group plasma environment. We found no accompanying persistent radio sources in the Apertif imaging survey data.

scholarly journals A search for fast-radio-burst-like emission from Fermi gamma-ray bursts

2020 ◽  
Vol 497 (1) ◽  
pp. 125-129 ◽  
Author(s):  
Mieke Bouwhuis ◽  
Keith W Bannister ◽  
Jean-Pierre Macquart ◽  
R M Shannon ◽  
David L Kaplan ◽  
...  
Keyword(s):  
Radio Emission ◽  
Radio Burst ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Dispersion Measure ◽  
Radio Bursts ◽  
Square Kilometre Array ◽  
Fast Radio Burst ◽  
Short Grbs

ABSTRACT We report the results of the rapid follow-up observations of gamma-ray bursts (GRBs) detected by the Fermi satellite to search for associated fast radio bursts. The observations were conducted with the Australian Square Kilometre Array Pathfinder at frequencies from 1.2 to 1.4 GHz. A set of 20 bursts, of which four were short GRBs, were followed up with a typical latency of about 1 min, for a duration of up to 11 h after the burst. The data were searched using 4096 dispersion measure trials up to a maximum dispersion measure of 3763 pc cm−3, and for pulse widths w over a range of duration from 1.256 to 40.48 ms. No associated pulsed radio emission was observed above $26 \, {\rm Jy\, ms}\, (w/1\, {\rm ms})^{-1/2}$ for any of the 20 GRBs.

scholarly journals FRB 190520B Embedded in a Magnetar Wind Nebula and Supernova Remnant: A Luminous Persistent Radio Source, Decreasing Dispersion Measure, and Large Rotation Measure

2021 ◽  
Vol 923 (1) ◽  
pp. L17
Author(s):  
Z. Y. Zhao ◽  
F. Y. Wang
Keyword(s):  
Radio Source ◽  
Supernova Remnant ◽  
Massive Stars ◽  
Large Fraction ◽  
Dispersion Measure ◽  
Core Collapse ◽  
Host Galaxies ◽  
Large Rotation ◽  
Rotation Measure ◽  
Fast Radio Burst

Abstract Recently, FRB 190520B, which has the largest extragalactic dispersion measure (DM), was discovered by the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The DM excess over the intergalactic medium and Galactic contributions is estimated as ∼900 pc cm−3, which is nearly ten times higher than that of other fast-radio-burst (FRB) host galaxies. The DM decreases with the rate ∼0.1 pc cm−3 per day. It is the second FRB associated with a compact persistent radio source (PRS). The rotation measure (RM) is found to be larger than 1.8 × 105rad m−2. In this Letter, we argue that FRB 190520B is powered by a young magentar formed by core collapse of massive stars, embedded in a composite of a magnetar wind nebula (MWN) and supernova remnant (SNR). The energy injection of the magnetar drives the MWN and SN ejecta to evolve together and the PRS is generated by the synchrotron radiation of the MWN. The magnetar has an interior magnetic field B int ∼ (2–4) × 1016 G and an age t age ∼ 14–22 yr. The dense SN ejecta and the shocked shell contribute a large fraction of the observed DM and RM. Our model can naturally and simultaneously explain the luminous PRS, decreasing DM, and extreme RM of FRB 190520B.

scholarly journals Multiwavelength Observations of Fast Radio Bursts

Universe ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 76
Author(s):  
Luciano Nicastro ◽  
Cristiano Guidorzi ◽  
Eliana Palazzi ◽  
Luca Zampieri ◽  
Massimo Turatto ◽  
...  
Keyword(s):  
Radio Burst ◽  
High Energy ◽  
Medium Size ◽  
Radio Bursts ◽  
Starting Point ◽  
Key Points ◽  
Fast Radio Burst ◽  
Theoretical Results ◽  
Observational Strategy ◽  
Shed Light

The origin and phenomenology of the Fast Radio Burst (FRB) remains unknown despite more than a decade of efforts. Though several models have been proposed to explain the observed data, none is able to explain alone the variety of events so far recorded. The leading models consider magnetars as potential FRB sources. The recent detection of FRBs from the galactic magnetar SGR J1935+2154 seems to support them. Still, emission duration and energetic budget challenge all these models. Like for other classes of objects initially detected in a single band, it appeared clear that any solution to the FRB enigma could only come from a coordinated observational and theoretical effort in an as wide as possible energy band. In particular, the detection and localisation of optical/NIR or/and high-energy counterparts seemed an unavoidable starting point that could shed light on the FRB physics. Multiwavelength (MWL) search campaigns were conducted for several FRBs, in particular for repeaters. Here we summarize the observational and theoretical results and the perspectives in view of the several new sources accurately localised that will likely be identified by various radio facilities worldwide. We conclude that more dedicated MWL campaigns sensitive to the millisecond–minute timescale transients are needed to address the various aspects involved in the identification of FRB counterparts. Dedicated instrumentation could be one of the key points in this respect. In the optical/NIR band, fast photometry looks to be the only viable strategy. Additionally, small/medium size radiotelescopes co-pointing higher energies telescopes look a very interesting and cheap complementary observational strategy.

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