scholarly journals Fast radio bursts: Superpulsars, magnetars, or something else?

2018 ◽  
Vol 27 (10) ◽  
pp. 1844016 ◽  
Author(s):  
Sergei Popov ◽  
Konstantin Postnov ◽  
Maxim Pshirkov
Keyword(s):  
Rotational Energy ◽  
Energy Losses ◽  
Radio Bursts ◽  
Radio Pulsars ◽  
The Moment ◽  
Near Future ◽  
Millisecond Radio

We briefly review main observational properties of fast radio bursts (FRBs) and discuss two most popular hypothesis for the explanation of these enigmatic intense millisecond radio flashes. FRBs most probably originate on extragalactic distances, and their rate on the sky is about a few thousand per day with fluences above [Formula: see text]1[Formula: see text]Jy[Formula: see text]ms (or with fluxes larger than few tenths of Jy). Two leading scenarios describing these events include strong flares of magnetars and supergiant pulses of young radio pulsars with large rotational energy losses, correspondingly. At the moment, it is impossible to choose between these models. However, new telescopes can help to solve the puzzle of FRBs in near future.

Modeling Pulsars in dense star clusters

2019 ◽  
Vol 14 (S351) ◽  
pp. 549-552
Author(s):  
Claire S. Ye ◽  
Kyle Kremer ◽  
Sourav Chatterjee ◽  
Carl L. Rodriguez ◽  
Frederic A. Rasio
Keyword(s):  
Globular Clusters ◽  
Stellar Dynamics ◽  
Monte Carlo Code ◽  
Intrinsic Properties ◽  
Radio Pulsars ◽  
Dynamical Interaction ◽  
Interaction Processes ◽  
Formation And Evolution ◽  
Cluster Monte Carlo ◽  
Millisecond Radio

AbstractOver a hundred millisecond radio pulsars (MSPs) have been observed in globular clusters (GCs), motivating theoretical studies of the formation and evolution of these sources through stellar evolution coupled to stellar dynamics. Here we study MSPs in GCs using realistic N-body simulations with our Cluster Monte Carlo code. We show that neutron stars (NSs) formed in electron-capture supernovae can be spun up through mass transfer to form MSPs. Both NS formation and spin-up through accretion are greatly enhanced through dynamical interaction processes. We find that our models for average GCs at the present day with masses ≍ 2 × 105M⊙ can produce up to 10 – 20 MSPs, while a very massive GC model with mass ≍ 106M⊙ can produce close to 100. We show that the number of MSPs is anti-correlated with the total number of stellar-mass black holes (BHs) retained in the host cluster. As a result, the number of MSPs in a GC could be used to place constraints on its BH population. Some intrinsic properties of MSP systems in our models (such as the magnetic fields and spin periods) are in good overall agreement with observations.

The Structure and Presentation of Contemporary Psychiatric Classifications with Special Reference to ICD-9 and 10

1988 ◽  
Vol 152 (S1) ◽  
pp. 21-28 ◽  
Author(s):  
J. E. Cooper
Keyword(s):  
Special Reference ◽  
Focus Of Attention ◽  
The Other ◽  
The Moment ◽  
The One ◽  
Near Future

The discussion here is largely concerned with the purposes and structure of classifications of clinical concepts, variously called diseases, illnesses, disorders and syndromes, which are the main reasons why patients go to see doctors. Multiaspect (or multiaxial) classification has deservedly come to the fore in recent years, and seems likely to increase in importance for purposes of education, communication and research in the near future, but it is mentioned only briefly in the following discussion. The main focus of attention for the moment is the clinical descriptions of disorders; this is, of course, usually the first aspect in a multiaspect system, and the one around which the other aspects tend to be organised.

scholarly journals Common envelope episodes that lead to double neutron star formation

2020 ◽  
Vol 37 ◽  
Author(s):  
Alejandro Vigna-Gómez ◽  
Morgan MacLeod ◽  
Coenraad J. Neijssel ◽  
Floor S. Broekgaarden ◽  
Stephen Justham ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Initial Conditions ◽  
Large Fraction ◽  
Computational Modelling ◽  
Evolutionary Stage ◽  
Population Synthesis ◽  
Radio Pulsars ◽  
Common Envelope ◽  
The Common ◽  
The Moment

Abstract Close double neutron stars (DNSs) have been observed as Galactic radio pulsars, while their mergers have been detected as gamma-ray bursts and gravitational wave sources. They are believed to have experienced at least one common envelope episode (CEE) during their evolution prior to DNS formation. In the last decades, there have been numerous efforts to understand the details of the common envelope (CE) phase, but its computational modelling remains challenging. We present and discuss the properties of the donor and the binary at the onset of the Roche lobe overflow (RLOF) leading to these CEEs as predicted by rapid binary population synthesis models. These properties can be used as initial conditions for detailed simulations of the CE phase. There are three distinctive populations, classified by the evolutionary stage of the donor at the moment of the onset of the RLOF: giant donors with fully convective envelopes, cool donors with partially convective envelopes, and hot donors with radiative envelopes. We also estimate that, for standard assumptions, tides would not circularise a large fraction of these systems by the onset of RLOF. This makes the study and understanding of eccentric mass-transferring systems relevant for DNS populations.

Formation and evolution of binary and millisecond radio pulsars

1991 ◽  
Vol 203 (1-2) ◽  
pp. 1-124 ◽  
Author(s):  
D Bhattacharya
Keyword(s):  
Radio Pulsars ◽  
Formation And Evolution ◽  
Millisecond Radio

scholarly journals Millisecond radio pulsars in globular clusters

1989 ◽  
Vol 241 (1) ◽  
pp. 51-57 ◽  
Author(s):  
F. Verbunt ◽  
W. H. G. Lewin ◽  
J. van Paradijs
Keyword(s):  
Globular Clusters ◽  
Radio Pulsars ◽  
Millisecond Radio

scholarly journals Constraining the dense matter equation-of-state with radio pulsars

2020 ◽  
Vol 497 (3) ◽  
pp. 3118-3130 ◽  
Author(s):  
Huanchen Hu ◽  
Michael Kramer ◽  
Norbert Wex ◽  
David J Champion ◽  
Marcel S Kehl
Keyword(s):  
Equations Of State ◽  
Dense Matter ◽  
Leading Order ◽  
Radio Pulsars ◽  
Mass Measurements ◽  
Pulsar Timing ◽  
Orbital Periods ◽  
To Come ◽  
The Moment ◽  
First Time

ABSTRACT Radio pulsars provide some of the most important constraints for our understanding of matter at supranuclear densities. So far, these constraints are mostly given by precision mass measurements of neutron stars (NS). By combining single measurements of the two most massive pulsars, J0348+0432 and J0740+6620, the resulting lower limit of 1.98 M⊙ (99 per cent confidence) of the maximum NS mass, excludes a large number of equations of state (EOSs). Further EOS constraints, complementary to other methods, are likely to come from the measurement of the moment of inertia (MOI) of binary pulsars in relativistic orbits. The Double Pulsar, PSR J0737−3039A/B, is the most promising system for the first measurement of the MOI via pulsar timing. Reviewing this method, based in particular on the first MeerKAT observations of the Double Pulsar, we provide well-founded projections into the future by simulating timing observations with MeerKAT and the SKA. For the first time, we account for the spin-down mass-loss in the analysis. Our results suggest that an MOI measurement with 11 per cent accuracy (68 per cent confidence) is possible by 2030. If by 2030 the EOS is sufficiently well known, however, we find that the Double Pulsar will allow for a 7 per cent test of Lense–Thirring precession, or alternatively provide a ∼3σ-measurement of the next-to-leading order gravitational wave damping in GR. Finally, we demonstrate that potential new discoveries of double NS systems with orbital periods shorter than that of the Double Pulsar promise significant improvements in these measurements and the constraints on NS matter.

scholarly journals Theoretical Implications of the 47 Tuc Pulsars

2000 ◽  
Vol 177 ◽  
pp. 589-594
Author(s):  
Frederic A. Rasio
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Radio Pulsars ◽  
Formation And Evolution ◽  
Millisecond Radio

AbstractTwenty millisecond radio pulsars have now been observed in the globular cluster 47 Tuc. This is by far the largest sample of radio pulsars known in any globular cluster. These recent observations provide a unique opportunity to re-examine theoretically the formation and evolution of recycled pulsars in globular clusters.

Non-invasive prenatal testing (NIPT): limitations on the way to become diagnosis

Diagnosis ◽  
2015 ◽  
Vol 2 (3) ◽  
pp. 141-158 ◽  
Author(s):  
Ioanna Kotsopoulou ◽  
Panagiota Tsoplou ◽  
Konstantinos Mavrommatis ◽  
Christos Kroupis
Keyword(s):  
Prenatal Testing ◽  
Maternal Plasma ◽  
Screening Tests ◽  
Positive Finding ◽  
Non Invasive ◽  
Cell Free Fetal Dna ◽  
The Future ◽  
The Moment ◽  
Next Generation Sequencing Ngs ◽  
Near Future

AbstractWith the discovery of existing circulating cell-free fetal DNA (ccffDNA) in maternal plasma and the advent of next-generation sequencing (NGS) technology, there is substantial hope that prenatal diagnosis will become a predominately non-invasive process in the future. At the moment, non-invasive prenatal testing (NIPT) is available for high-risk pregnancies with significant better sensitivity and specificity than the other existing non-invasive methods (biochemical and ultrasonographical). Mainly it is performed by NGS methods in a few commercial labs worldwide. However, it is expected that many other labs will offer analogous services in the future in this fast-growing field with a multiplicity of in-house methods (e.g., epigenetic, etc.). Due to various limitations of the available methods and technologies that are explained in detail in this manuscript, NIPT has not become diagnostic yet and women may still need to undergo risky invasive procedures to verify a positive finding or to secure (or even expand) a negative one. Efforts have already started to make the NIPT technologies more accurate (even at the level of a complete fetal genome) and cheaper and thus more affordable, in order to become diagnostic screening tests for all pregnancies in the near future.

scholarly journals The First Month Spread of COVID-19 in Madagascar

2020 ◽  
Author(s):  
Stephan Narison
Keyword(s):  
Linear Increase ◽  
Published Data ◽  
The Real ◽  
The Moment ◽  
Near Future ◽  
Insufficient Number

AbstractUsing the officially published data and aware of the unclear source and inaccurate number of samples, we present a first and (for the moment) unique attempt to study the spread of the pandemic COVID-19 in Madagascar. The approach has been tested by predicting the number of contaminated persons until 20 days after fitting the inputs data collected within 15 days using standard least χ2-fit method. Encouraged by this first test, we add the new data collected within 30 days and give prevision until 33 days. The present data show an approximate linear increase of about (4-5) infected persons per day while the analysis signals an eventual near future stronger growth. These results may also be interpreted as the lowest values of the real cases due to the insufficient number of samples (about 2200 for 20 millions of population). A comparison with some other approaches is done. Some social, economical and political impacts of COVID-19 and confinement for Madagascar and Worldwide are shortly discussed.

scholarly journals Periodically repeating fast radio bursts: Lense–Thirring precession of a debris disk?

2020 ◽  
Vol 72 (4) ◽  
Author(s):  
Wen-Cong Chen
Keyword(s):  
Magnetic Field ◽  
Rotational Energy ◽  
Radio Bursts ◽  
Spin Period ◽  
Disk Mass ◽  
Debris Disk ◽  
The Magnetic Field ◽  
Normal Magnetic Field ◽  
Current Stage ◽  
Tilted Disk

Abstract Recently, repeating fast radio bursts (FRBs) with a period of PFRB = 16.35 ± 0.18 d from FRB 180916.J0158+65 were reported. It still remains controversial how such a periodicity might arise for this FRB. In this Letter, based on an assumption of a young pulsar surrounding by a debris disk, we attempt to diagnose whether Lense–Thirring precession of the disk on the emitter can produce the observed periodicity. Our calculations indicate that the Lense–Thirring effect of a tilted disk can result in a precession period of 16 d for a mass inflow rate of 0.5–1.5 × 1018 g s−1, a pulsar spin period of 1–20 ms, and an extremely low viscous parameter α = 10−8 in the disk. The disk mass and the magnetic field of the pulsar are also constrained to be ∼10−3 M⊙ and <2.5 × 1013 G. In our model, a new-born pulsar with normal magnetic field and millisecond period would successively experience the accretion and propeller phases, and is visible as a strong radio source in the current stage. The rotational energy of such a young neutron star can provide the observed radio bursting luminosity for 400 yr.

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