scholarly journals Magnetar birth: rotation rates and gravitational-wave emission

2020 ◽  
Vol 494 (4) ◽  
pp. 4838-4847 ◽  
Author(s):  
S K Lander ◽  
D I Jones
Keyword(s):  
Viscous Dissipation ◽  
Radio Burst ◽  
Stellar Rotation ◽  
Radio Pulsars ◽  
Rotation Rates ◽  
Buoyancy Forces ◽  
Wave Emission ◽  
Fast Radio Burst ◽  
Electromagnetic Signals ◽  
First Time

ABSTRACT Understanding the evolution of the angle χ between a magnetar’s rotation and magnetic axes sheds light on the star’s birth properties. This evolution is coupled with that of the stellar rotation Ω, and depends on the competing effects of internal viscous dissipation and external torques. We study this coupled evolution for a model magnetar with a strong internal toroidal field, extending previous work by modelling – for the first time in this context – the strong protomagnetar wind acting shortly after birth. We also account for the effect of buoyancy forces on viscous dissipation at late times. Typically, we find that χ → 90° shortly after birth, then decreases towards 0° over hundreds of years. From observational indications that magnetars typically have small χ, we infer that these stars are subject to a stronger average exterior torque than radio pulsars, and that they were born spinning faster than ∼100–300 Hz. Our results allow us to make quantitative predictions for the gravitational and electromagnetic signals from a newborn rotating magnetar. We also comment briefly on the possible connection with periodic fast radio burst sources.

scholarly journals Butterfly diagram of a Sun-like star observed using asteroseismology

2018 ◽  
Vol 619 ◽  
pp. L9 ◽  
Author(s):  
M. Bazot ◽  
M. B. Nielsen ◽  
D. Mary ◽  
J. Christensen-Dalsgaard ◽  
O. Benomar ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Stellar Evolution ◽  
Theoretical Models ◽  
Observational Constraint ◽  
Stellar Rotation ◽  
Magnetic Field Generation ◽  
Rotation Rates ◽  
Butterfly Diagram ◽  
Stellar Magnetic Fields ◽  
First Time

Stellar magnetic fields are poorly understood, but are known to be important for stellar evolution and exoplanet habitability. They drive stellar activity, which is the main observational constraint on theoretical models for magnetic field generation and evolution. Starspots are the main manifestation of the magnetic fields at the stellar surface. In this study we measured the variation in their latitude with time, called a butterfly diagram in the solar case, for the solar analogue HD 173701 (KIC 8006161). To this end, we used Kepler data to combine starspot rotation rates at different epochs and the asteroseismically determined latitudinal variation in the stellar rotation rates. We observe a clear variation in the latitude of the starspots. It is the first time such a diagram has been constructed using asteroseismic data.

scholarly journals Fast Radio Burst Morphology in the First CHIME/FRB Catalog

2021 ◽  
Vol 923 (1) ◽  
pp. 1 ◽  
Author(s):  
Ziggy Pleunis ◽  
Deborah C. Good ◽  
Victoria M. Kaspi ◽  
Ryan Mckinven ◽  
Scott M. Ransom ◽  
...  
Keyword(s):  
Radio Burst ◽  
Intensity Mapping ◽  
Mapping Experiment ◽  
Propagation Effects ◽  
Fast Radio Burst ◽  
Morphological Differences ◽  
First Time

Abstract We present a synthesis of fast radio burst (FRB) morphology (the change in flux as a function of time and frequency) as detected in the 400–800 MHz octave by the FRB project on the Canadian Hydrogen Intensity Mapping Experiment (CHIME/FRB), using events from the first CHIME/FRB catalog. The catalog consists of 62 bursts from 18 repeating sources, plus 474 one-off FRBs, detected between 2018 July 25 and 2019 July 2. We identify four observed archetypes of burst morphology (“simple broadband,” “simple narrowband,” “temporally complex,” and “downward drifting”) and describe relevant instrumental biases that are essential for interpreting the observed morphologies. Using the catalog properties of the FRBs, we confirm that bursts from repeating sources, on average, have larger widths, and we show, for the first time, that bursts from repeating sources, on average, are narrower in bandwidth. This difference could be due to beaming or propagation effects, or it could be intrinsic to the populations. We discuss potential implications of these morphological differences for using FRBs as astrophysical tools.

A fast radio burst in our own Galaxy

Nature ◽  
2020 ◽  
Vol 587 (7832) ◽  
pp. 43-44
Author(s):  
Amanda Weltman ◽  
Anthony Walters
Keyword(s):  
Radio Burst ◽  
Fast Radio Burst

Astronomers spot first fast radio burst in the Milky Way

Nature ◽  
2020 ◽  
Vol 582 (7812) ◽  
pp. 322-323 ◽  
Author(s):  
Alexandra Witze
Keyword(s):  
Radio Burst ◽  
Milky Way ◽  
Fast Radio Burst

Distributed Fast Radio Burst Detection: Algorithm and Application

2018 ◽  
Vol 2018 (16) ◽  
pp. 224-1-224-5
Author(s):  
Stephen Itschner ◽  
Kevin Bandura ◽  
Xin Li
Keyword(s):  
Radio Burst ◽  
Detection Algorithm ◽  
Burst Detection ◽  
Fast Radio Burst

scholarly journals Fast radio burst detection in the presence of coloured noise

2021 ◽  
Vol 503 (4) ◽  
pp. 5223-5231
Author(s):  
C F Zhang ◽  
J W Xu ◽  
Y P Men ◽  
X H Deng ◽  
Heng Xu ◽  
...  
Keyword(s):  
False Alarm ◽  
Radio Burst ◽  
Pulse Width ◽  
False Alarm Probability ◽  
False Positives ◽  
Parameter Distribution ◽  
Correlated Noise ◽  
Width Distribution ◽  
Fast Radio Burst ◽  
The Impact

ABSTRACT In this paper, we investigate the impact of correlated noise on fast radio burst (FRB) searching. We found that (1) the correlated noise significantly increases the false alarm probability; (2) the signal-to-noise ratios (S/N) of the false positives become higher; (3) the correlated noise also affects the pulse width distribution of false positives, and there will be more false positives with wider pulse width. We use 55-h observation for M82 galaxy carried out at Nanshan 26m radio telescope to demonstrate the application of the correlated noise modelling. The number of candidates and parameter distribution of the false positives can be reproduced with the modelling of correlated noise. We will also discuss a low S/N candidate detected in the observation, for which we demonstrate the method to evaluate the false alarm probability in the presence of correlated noise. Possible origins of the candidate are discussed, where two possible pictures, an M82-harboured giant pulse and a cosmological FRB, are both compatible with the observation.

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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