- ID:
- ivo://CDS.VizieR/J/AZh/74/63
- Title:
- Cluster analysis of pulsar parameters
- Short Name:
- J/AZh/74/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalogue of pulsars with several calculated data is used by the cluster analysis for the division of pulsars into groups. Pulsars with periods P>1s and P<0.1s form two separate classes; the short-period objects, in turn, divide into two groups. One of these consist of young pulsars that form in the galactic plane or in globular clusters, while the other group consist of spun-up pulsars.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/565/L12
- Title:
- Crab pulsar 50-400GeV light curve
- Short Name:
- J/A+A/565/L12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Crab pulsar is the only astronomical pulsed source detected at very high energy (VHE, E>100GeV) gamma rays. The emission mechanism of VHE pulsation is not yet fully understood, although several theoretical models have been proposed. In order to test new models, we measured the light curve and the spectra of the Crab pulsar with high precision by means of deep observations. We analyzed 135h of selected MAGIC data taken between 2009 and 2013 in stereoscopic mode. In order to discuss the spectral shape in connection with lower energies, 5.5 years of Fermi-LAT data were also analyzed
- ID:
- ivo://CDS.VizieR/J/A+A/640/A77
- Title:
- Crystallization of a neutron star inner crust
- Short Name:
- J/A+A/640/A77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The possible presence of amorphous and heterogeneous phases in the inner crust of a neutron star is expected to reduce the electrical conductivity of the crust, with potentially important consequences on the magneto-thermal evolution of the star. In cooling simulations, the disorder is quantified by an impurity parameter which is often taken as a free parameter. We aim to give a quantitative prediction of the impurity parameter as a function of the density in the crust, performing microscopic calculations including up-to-date microphysics of the crust. A multi-component approach is developed at finite temperature using a compressible liquid drop description of the ions with an improved energy functional based on recent microscopic nuclear models and optimized on extended Thomas-Fermi calculations. Thermodynamic consistency is ensured by adding a rearrangement term and deviations from the linear mixing rule are included in the liquid phase. The impurity parameter is consistently calculated at the crystallization temperature as determined in the one-component plasma approximation for the different functionals. Our calculations show that at the crystallization temperature the composition of the inner crust is dominated by nuclei with charge number around Z~40, while the range of the Z distribution varies from about 20 near the neutron drip to about 40 closer to the crust-core transition. This reflects on the behavior of the impurity parameter that monotonically increases with density up to around 40 in the deeper regions of the inner crust. Our study shows that the contribution of impurities is non-negligible, thus potentially having an impact on the transport properties in the neutron-star crust. The obtained values of the impurity parameter represent a lower limit; larger values are expected in the presence of non-spherical geometries and/or fast cooling dynamics.
- ID:
- ivo://CDS.VizieR/J/A+A/633/A149
- Title:
- Crystallization of neutron star outer crust
- Short Name:
- J/A+A/633/A149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The interior of a neutron star is usually assumed to be made of cold catalyzed matter. However, the outer layers are unlikely to remain in full thermodynamic equilibrium during the formation of the star and its subsequent cooling, especially after crystallization occurs. We study the cooling and the equilibrium composition of the outer layers of a non-accreting neutron star down to crystallization. Here the impurity parameter, generally taken as a free parameter in cooling simulations, is calculated self-consistently using a microscopic nuclear model for which a unified equation of state has recently been determined. We follow the evolution of the nuclear distributions of the multi-component Coulomb liquid plasma fully self-consistently, adapting a general formalism originally developed for the description of supernova cores. We calculate the impurity parameter at the crystallization temperature as determined in the one-component plasma approximation. Our analysis shows that the sharp changes in composition obtained in the one-component plasma approximation are smoothed out when a full nuclear distribution is allowed. The Coulomb coupling parameter at melting is found to be reasonably close to the canonical value of 175, except for specific values of the pressure for which supercooling occurs in the one-component plasma approximation. Our multi-component treatment leads to non-monotonic variations of the impurity parameter with pressure. Its values can change by several orders of magnitude reaching about 50, suggesting that the crust may be composed of an alternation of pure (highly conductive) and impure (highly resistive) layers. The results presented here complement the recent unified equation of state obtained within the same nuclear model. Our self-consistent approach to hot dense multi-component plasma shows that the presence of impurities in the outer crust of a neutron star is non- negligible and may have a sizeable impact on transport properties. In turn, this may have important implications not only for the cooling of neutron stars, but also for their magneto-rotational evolution.
- ID:
- ivo://CDS.VizieR/J/PAZh/42/200
- Title:
- Dispersion measure of Milky Way and MC pulsars
- Short Name:
- J/PAZh/42/200
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A number of recent studies indicates a significant amount of ionized gas in a form of the hot gas halo around the Milky Way. The halo extends over the region of 100 kpc and may be acountable for the missing baryon mass. In this paper we calculate the contribution of the proposed halo to the dispersion measure (DM) of the pulsars. The Navarro, Frenk, and White (NFW), Maller and Bullock (MB), and Feldmann, Hooper, and Gnedin (FHG) density distributions are considered for the gas halo. The data set includes pulsars with the distance known independently from the DM, e.g., pulsars in globular clusters, LMC, SMC and pulsars with known parallax. The results exclude the NFW distribution for the hot gas, while the more realisticMB and FHG models are compatible with the observed dispersion measure.
- ID:
- ivo://CDS.VizieR/J/A+A/618/A186
- Title:
- Dynamic spectra of 10 pulsars
- Short Name:
- J/A+A/618/A186
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Pulsars scintillate. Dynamic spectra show brightness variation of pulsars in the time and frequency domain. Secondary spectra demonstrate the distribution of fluctuation power in the dynamic spectra. Dynamic spectra strongly depend on observational frequencies, but were often observed at frequencies lower than 1.5GHz. Scintillation observations at higher frequencies help to constrain the turbulence feature of the interstellar medium over a wide frequency range and can detect the scintillations of more distant pulsars. Ten pulsars were observed at 2250MHz (S-band) with the Jiamusi 66m telescope to study their scintillations. Their dynamic spectra were first obtained, from which the decorrelation bandwidths and time scales of diffractive scintillation were then derived by autocorrelation. Secondary spectra were calculated by forming the Fourier power spectra of the dynamic spectra. Most of the newly obtained dynamic spectra are at the highest frequency or have the longest time span of any published data for these pulsars. For PSRs B0540+23, B2324+60 and B2351+61, these were the first dynamic spectra ever reported. The frequency-dependence of scintillation parameters indicates that the intervening medium can rarely be ideally turbulent with a Kolmogorov spectrum. The thin screen model worked well at S-band for the scintillation of PSR B1933+16. Parabolic arcs were detected in the secondary spectra of three pulsars, PSRs B0355+54, B0540+23 and B2154+40, all of which were asymmetrically distributed. The inverted arclets of PSR B0355+54 were seen to evolve along the main parabola within a continuous observing session of 12 hours, from which the angular velocity of the pulsar was estimated that was consistent with the measurement by very long baseline interferometry (VLBI).
- ID:
- ivo://CDS.VizieR/J/ApJS/157/324
- Title:
- EGRET high-energy cosmic photons (E>10GeV)
- Short Name:
- J/ApJS/157/324
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- During its 9 year lifetime, the Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (CGRO) detected 1506 cosmic photons with measured energy E>10GeV. Of this number, 187 are found within a 1{deg} of sources that are listed in the Third EGRET Catalog (Cat. <J/ApJS/123/79>) and were included in determining the detection likelihood, flux, and spectra of those sources. In particular, five detected EGRET pulsars are found to have events above 10GeV, and together they account for 37 events. A pulsar not included in the Third EGRET Catalog has two events, both with the same phase and in one peak of the lower energy gamma-ray light curve.
- ID:
- ivo://CDS.VizieR/J/MNRAS/423/1351
- Title:
- Energy distribution in pulsars
- Short Name:
- J/MNRAS/423/1351
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the pulse-to-pulse energy distributions and phase-resolved modulation properties for catalogued pulsars in the southern High Time Resolution Universe intermediate-latitude survey. We selected the 315 pulsars detected in a single-pulse search of this survey, allowing a large sample unbiased regarding any rotational parameters of neutron stars.
- ID:
- ivo://CDS.VizieR/J/ApJS/183/46
- Title:
- Fermi/LAT bright gamma-ray source list (0FGL)
- Short Name:
- J/ApJS/183/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Following its launch in 2008 June, the Fermi Gamma-ray Space Telescope (Fermi) began a sky survey in August. The Large Area Telescope (LAT) on Fermi in three months produced a deeper and better resolved map of the {gamma}-ray sky than any previous space mission. We present here initial results for energies above 100MeV for the 205 most significant (statistical significance greater than ~10{sigma}) {gamma}-ray sources in these data. These are the best characterized and best localized point-like (i.e., spatially unresolved) {gamma}-ray sources in the early mission data.
- ID:
- ivo://CDS.VizieR/J/ApJS/188/405
- Title:
- Fermi-LAT first source catalog (1FGL)
- Short Name:
- J/ApJS/188/405
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of high-energy gamma-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), during the first 11 months of the science phase of the mission, which began on 2008 August 4. The First Fermi-LAT catalog (1FGL) contains 1451 sources detected and characterized in the 100MeV to 100GeV range. Source detection was based on the average flux over the 11 month period, and the threshold likelihood Test Statistic is 25, corresponding to a significance of just over 4{sigma}. The 1FGL catalog includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and power-law spectral fits as well as flux measurements in five energy bands for each source. In addition, monthly light curves are provided. Using a protocol defined before launch we have tested for several populations of gamma-ray sources among the sources in the catalog. For individual LAT-detected sources we provide firm identifications or plausible associations with sources in other astronomical catalogs. Identifications are based on correlated variability with counterparts at other wavelengths, or on spin or orbital periodicity. For the catalogs and association criteria that we have selected, 630 of the sources are unassociated. Care was taken to characterize the sensitivity of the results to the model of interstellar diffuse gamma-ray emission used to model the bright foreground, with the result that 161 sources at low Galactic latitudes and toward bright local interstellar clouds are flagged as having properties that are strongly dependent on the model or as potentially being due to incorrectly modeled structure in the Galactic diffuse emission.
