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Observation of a Rapidly Pulsating Radio Source

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Abstract

Unusual signals from pulsating radio sources have been recorded at the Mullard Radio Astronomy Observatory. The radiation seems to come from local objects within the galaxy, and may be associated with oscillations of white dwarf or neutron stars.
... About 55 years has passed since the first pulsar was discovered in 1967 [1], identified as the beacon phenomena of rotating neutron stars (NSs) [2,3]. From then on, more than 3500 radio pulsars have been observed [4], including over 600 ones recently detected by five-hundred-meter aperture spherical radio telescope (FAST) [5][6][7][8], but the puzzle of how the rotation and magnetic field of pulsar evolves remains [9,10]. ...
... As one of the simplest theories to describe pulsar emission, the MDR model was developed by Gunn and Ostriker [19,96] based on pioneer NS proposals [2,3] soon after the discovery of the first pulsar [1], which was taken as a "standard version" for the evolution and emission mechanism in the pulsar and NS text books [15,16,20,[97][98][99][100][101]. It has been a successful model in pulsar astronomy for over 50 years, and is usually applied on the pulsars powered by their rotational energy loss. ...
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Article
The evolutions of a neutron star’s rotation and magnetic field (B-field) have remained unsolved puzzles for over half a century. We ascribe the rotational braking torques of pulsar to both components, the standard magnetic dipole radiation (MDR) and particle wind flow (MDR + Wind, hereafter named MDRW), which we apply to the Crab pulsar (B0531 + 21), the only source with a known age and long-term continuous monitoring by radio telescope. Based on the above presumed simple spin-down torques, we obtain the exact analytic solution on the rotation evolution of the Crab pulsar, together with the related outcomes as described below: (1) unlike the constant characteristic B-field suggested by the MDR model, this value for the Crab pulsar increases by a hundred times in 50 kyr while its real B-field has no change; (2) the rotational braking index evolves from ∼3 to 1 in the long-term, however, it drops from 2.51 to 2.50 in ∼45 years at the present stage, while the particle flow contributes approximately 25% of the total rotational energy loss rate; (3) strikingly, the characteristic age has the maximum limit of ∼10 kyr, meaning that it is not always a good indicator of a real age. Furthermore, we discussed the evolutionary path of the Crab pulsar from the MDR to the wind domination by comparing with the possible wind braking candidate pulsar PSR J1734-3333.
... The turning point was the discovery of pulsating radio sources (pulsars) by Jocelyn Bell and Antony Hewish [12]. The link with neutron stars was then quickly established because only an extremely compact object such as a neutron star could explain the high rotation frequency of millisecond pulsars [10]. ...
... The first pulsar observed [12] was a rotation powered pulsar. ...
Thesis
If the main features of the core-collapse supernova mechanism are now understood, some important details about the microphysics are still subject to a lot of uncertainties. In particular, neutrinos are playing a key role in the core-collapse mechanism but interactions rates between neutrinos and dense matter are still poorly understood. In this thesis we present a new code for proto-neutron star evolution, and we use it together with the CoCoNuT core-collapse code to study the influence of the uncertainties on neutrino reaction rates. Convective effects, which plays a crucial role in proto-neutron stars evolution, have been taken into account with the mixing length theory.
... The discovery of FRBs became possible due to development of high time resolution radio instrumentation and software tools, mainly used for pulsar surveys. Radio pulsars are rapidly-rotating highly-magnetised neutron stars that emit beams of emission that appear to pulse as they rotate (2)(3)(4)(5), like a light house. By 2007 over half of known pulsars had been discovered using the Parkes 64-m telescope (Figure 2A), due to its relatively radio interference-free environment, and access to the Southern hemisphere sky (where the majority of pulsars reside) (6)(7)(8)(9). ...
... The study of radio pulsars has been advanced by discoveries of unusual objects, usually in largescale surveys (2,10,11). A new class of pulsar-like objects, the rotating radio transients (RRATs) were discovered in 2006 using the Parkes Multibeam Receiver (12), a 13-pixel radio camera which was used in multiple pulsar surveys (6,7,13,14). ...
Preprint
Fast radio bursts (FRBs) are millisecond-timescale bursts of coherent radio emission that are luminous enough to be detectable at cosmological distances. In this review I describe the discovery of FRBs, subsequent advances in our understanding of them, and future prospects. Thousands of potentially observable FRBs reach Earth every day; they probably originate from highly magnetic and/or rapidly rotating neutron stars in the distant Universe. Some FRBs repeat, with this sub-class often occurring in highly magnetic environments. Two repeaters exhibit cyclic activity windows, consistent with an orbital period. One nearby FRB was from a Galactic magnetar during an X-ray outburst. The host galaxies of some FRBs have been located, providing information about the host environments and the total baryonic content of the Universe.
... Nearly 55 yr after their discovery (Hewish et al. 1968), radio pulsars continue to be versatile probes of fundamental physics, plasma processes under extreme conditions, and the distribution of ionized gas in the Galaxy. Since early pioneering studies (Scheuer 1968;Rickett 1969Rickett , 1970, the unique wideband, pulsed character of the signal has been employed to explore the ionized component of gas along the line of sight (LoS) to these sources. ...
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Article
Context. By providing information about the location of scattering material along the line of sight (LoS) to pulsars, scintillation arcs are a powerful tool for exploring the distribution of ionized material in the interstellar medium (ISM). Here, we present observations that probe the ionized ISM on scales of ∼0.001–30 au. Aims. We have surveyed pulsars for scintillation arcs in a relatively unbiased sample with DM < 100 pc cm ⁻³ . We present multifrequency observations of 22 low to moderate DM pulsars. Many of the 54 observations were also observed at another frequency within a few days. Methods. For all observations, we present dynamic spectra, autocorrelation functions, and secondary spectra. We analyze these data products to obtain scintillation bandwidths, pulse broadening times, and arc curvatures. Results. We detect definite or probable scintillation arcs in 19 of the 22 pulsars and 34 of the 54 observations, showing that scintillation arcs are a prevalent phenomenon. The arcs are better defined in low DM pulsars. We show that well-defined arcs do not directly imply anisotropy of scattering. Only the presence of reverse arclets and a deep valley along the delay axis, which occurs in about 20% of the pulsars in the sample, indicates substantial anisotropy of scattering. Conclusions. The survey demonstrates substantial patchiness of the ionized ISM on both astronomical-unit-size scales transverse to the LoS and on ∼100 pc scales along it. We see little evidence for distributed scattering along most lines of sight in the survey.
... If this rotating beam crosses the Earth, it will be appear to observers as a lighthouse-like pulsing radio signal, leading to the name pulsar. The first such pulsating radio signal, nicknamed LGM-1 after the "Little Green Man" that could perhaps have sent the signal, was discovered by Jocelyn Bell Burnell in 1967 [73]. Many more pulsars have subsequently been discovered across the sky, disfavouring any alien origin for these radio signals. ...
Thesis
Das IceCube Neutrino Observatory, das größte Neutrino-Observatorium der Welt, entdeckte 2013 erstmals einen Fluss hochenergetischer Neutrinos. Diese Neutrinos müssen von astrophysikalischen Beschleunigern erzeugt werden, aber ihr genauer Ursprung ist bisher unbekannt. Vorgeschlagene Neutrinoquellen sind Gezeitenkatastrophen (Tidal Disruption Events, TDEs), Ereignisse bei denen Sterne zerfallen, wenn sie supermassiven Schwarzen Löchern zu nahe kommen. In dieser Doktorarbeit wurde erstmals nach Korrelationen zwischen Neutrinos und TDEs gesucht, wobei eine Zusammenstellung veröffentlichter TDEs und ein IceCube-Datensatz von einer Million Myon-Neutrinos mit GeV-PeV-Energien von verwendet wurde. Es wurde keine signifikante Korrelation gefunden, sodass der Beitrag von TDEs ohne relativistische Jets auf 0-38,0% des gesamten astrophysikalischen Neutrinoflusses begrenzt werden kann. Der Beitrag von TDEs mit relativistischen Jets wurde auf 0-3,0% des Gesamtflusses begrenzt. IceCube veröffentlicht auch hochenergetische (>100 TeV) Myon-Neutrino-Ereignisse in Form von automatischen, öffentlichen Echtzeit-‘Neutrinoalerts’. Im Rahmen dieser Arbeit wurde die Lokalisierung von 22 solcher Neutrinoalerts mit dem optischen Zwicky Transient Facility (ZTF) Teleskop beobachtet, um nach möglichen elektromagnetischen Gegenstücken zu Neutrinos zu suchen. Mit diesem Neutrino-Nachfolgebeobachtungsprogramm wurde die helle TDE AT2019dsg als mutmaßliche Neutrinoquelle identifiziert. Die Wahrscheinlichkeit, solch eine helle TDE zufällig zu finden, beträgt 0,2%. Die Assoziation bedeutet, dass TDEs 3-100% der astrophysikalischen Neutrino-Alerts von IceCube ausmachen. Zusammengenommen deuten diese beiden Ergebnisse darauf hin, dass TDEs einen subdominanten Anteil des astrophysikalischen Neutrinoflusses bei hohen Energien emittieren. Die Assoziation des Neutrinoalerts IC191001A mit AT2019dsg ist erst das zweite Mal, dass ein hochenergetisches Neutrino mit einer mutmaßlichen astrophysikalischen Quelle in Verbindung gebracht werden konnte.
... The first pulsar has been observed in 1967 [17], but the first binary system containing such object, the PSR 1913+1916, named as the Hulse-Taylor pulsar, became a smooking gun for the confirmation of gravitational waves according to the GR predictions [18]. The latter is related to the decay of the orbital period, presumed to occur as the system was losing energy in the form of gravitational waves. ...
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Preprint
We revisit the decay of the orbital period in binary systems that occurs due to the emission of gravitational waves in the context of modified gravity models where the coupling $G_{gw}$ between matter and on-shell gravitons is allowed to differ from the Newton constant $G_N$. Using the most precise orbital parameters of binary pulsars, those of the Double Pulsar, we constrain the ratio $G_{gw}/G_N$ to the level of $10^{-4}$, improving by two orders of magnitude the present bound on this quantity.
... From the first observation of a pulsar in 1967 by Jocelyn Bell (Hewish et al., 1968) until now, computational and instrumental developments, especially in the current century, helped to increase the available sample of objects and improved precision on measurements with new generations of highquality telescopes. In particular, the masses of the NSs has been targeted to connect them with the birth events and the properties of superdense matter. ...
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The number of millisecond pulsars (MSPs) observed in Milky Way globular clusters has increased explosively in recent years, but the underlying population is still uncertain due to observational biases. We use state-of-the-art N -body simulations to study the evolution of MSP populations in dense star clusters. These cluster models span a wide range in initial conditions, including different initial masses, metallicities, and virial radii, which nearly cover the full range of properties exhibited by the population of globular clusters in the Milky Way. We demonstrate how different initial cluster properties affect the number of MSPs, for which we provide scaling relations as a function of cluster age and mass. As an application, we use our formulae to estimate the number of MSPs delivered to the Galactic center from inspiralling globular clusters to probe the origin of the Galactic-center gamma-ray excess detected by Fermi. We predict about 400 MSPs in the Galactic center from disrupted globular clusters, which can potentially explain most of the observed gamma-ray excess.
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In this study, we revisit the magnetic field ( B -field) distribution of normal pulsars, motivated by the fact that the number of known pulsars has exceeded 3300. Here, we divided the normal pulsar samples into three subgroups by constant lines of characteristic age τ ch , i.e., young, middle-aged, and old pulsars. We note that τ ch is not used as the time indicator in this study; instead, it just served as cutting lines to divide the pulsar samples. Then, we applied several statistical tests, i.e., the Anderson–Darling, Shapiro–Wilk, Kolmogorov–Smirnov, and Mann–Whitney–Wilcoxon tests, to the selected normal pulsar samples ( N = 1970) and to a data set of 32 neutron stars (NSs) in high-mass X-ray binaries (HMXBs) for comparison purposes. We obtained that (i) the conclusion on the characteristic B field ( B ch ) log-normal distribution for the normal pulsars by the previous studies is no longer appropriate, while only young pulsars ( N = 24, τ ch < 15 kyr) follow a log-normal distribution, indicating that only the B ch of young pulsars is close to real B fields. (ii) In the directly measured B -field range of NS-HMXBs (∼10 ¹² –10 ¹³ G), the B ch of young pulsars ( N = 15) and the real B fields of NS-HMXBs ( N = 32) are inferred to be log-normal, and they are further verified to come from the same distribution, implying that there is no significant decay for real B fields, at least within the timescale of ∼10 Myr for normal pulsars. (iii) Statistically, young pulsars ( N = 24) are inferred to be self-contained, suggesting that the initial spin period of pulsars is less than 515 ms. (iv) The B ch distributions of three normal pulsar subsamples are different, hinting at the existence of multiple origins for NSs.
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