- ID:
- ivo://CDS.VizieR/J/AJ/128/1646
- Title:
- The Galactic Center region at 330MHz
- Short Name:
- J/AJ/128/1646
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a wide-field, subarcminute-resolution VLA image of the Galactic center region at 330MHz. With a resolution of ~7"x12" and an rms noise of 1.6mJy/beam, this image represents a significant increase in resolution and sensitivity over the previously published VLA image at this frequency. The improved sensitivity has more than tripled the census of small-diameter sources in the region, has resulted in the detection of two new nonthermal filaments (NTFs), 18 NTF candidates, and 30 pulsar candidates, reveals previously known extended sources in greater detail, and has resulted in the first detection of Sagittarius A* in this frequency range.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/892/76
- Title:
- The GBNCC pulsar survey. V. Pulsar census
- Short Name:
- J/ApJ/892/76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Green Bank North Celestial Cap (GBNCC) pulsar survey will cover the entire northern sky ({delta}>-40{deg}) at 350MHz, and is one of the most uniform and sensitive all-sky pulsar surveys to date. We have created a pipeline to reanalyze GBNCC survey data to take a 350MHz census of all pulsars detected by the survey, regardless of their discovery survey. Of the 1413 pulsars in the survey region, we were able to recover 670. For these we present measured signal-to-noise ratios (S/N), flux densities, pulse widths, profiles, and where appropriate, refined measurements of dispersion measures (DMs) (656 out of 670) and new or improved spectral indices (339 out of 670 total, 47 new, 292 improved). We also measure the period-pulse width relation at 350MHz to scale as W{propto}P^-0.27^. Detection scans for several hundred sources were reanalyzed in order to inspect pulsars' single pulse behavior and 223 were found to exhibit evidence of nulling. With a detailed analysis of measured and expected S/N values and the evolving radio frequency interference environment at 350MHz, we assess the GBNCC survey's sensitivity as a function of spin period, DM, and sky position. We find the sky-averaged limiting flux density of the survey to be 0.74mJy. Combining this analysis with PsrPopPy pulsar population simulations, we predict 60/5 nonrecycled/MSP discoveries in the survey's remaining 21000 pointings, and we begin to place constraints on population model parameters.
- ID:
- ivo://CDS.VizieR/J/ApJS/212/6
- Title:
- The McGill magnetar catalog
- Short Name:
- J/ApJS/212/6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of the 26 currently known magnetars and magnetar candidates. We tabulate astrometric and timing data for all catalog sources, as well as their observed radiative properties, particularly the spectral parameters of the quiescent X-ray emission. We show histograms of the spatial and timing properties of the magnetars, comparing them with the known pulsar population, and we investigate and plot possible correlations between their timing, X-ray, and multiwavelength properties. We find the scale height of magnetars to be in the range of 20-31pc, assuming they are exponentially distributed. This range is smaller than that measured for OB stars, providing evidence that magnetars are born from the most massive O stars. From the same fits, we find that the Sun lies ~13-22pc above the Galactic plane, consistent with previous measurements. We confirm previously identified correlations between quiescent X-ray luminosity, L_X_, and magnetic field, B, as well as X-ray spectral power-law indexes, {Gamma} and B, and show evidence for an excluded region in a plot of L_X_ versus {Gamma}. We also present an updated kT versus characteristic age plot, showing that magnetars and high-B radio pulsars are hotter than lower-B neutron stars of similar age. Finally, we observe a striking difference between magnetars detected in the hard X-ray and radio bands; there is a clear correlation between the hard and soft X-ray fluxes, whereas the radio-detected magnetars all have low, soft X-ray flux, suggesting, if anything, that the two bands are anticorrelated.
- ID:
- ivo://CDS.VizieR/J/ApJ/814/128
- Title:
- Timing noise & astrometry of Fermi-LAT pulsars
- Short Name:
- J/ApJ/814/128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have constructed timing solutions for 81 {gamma}-ray pulsars covering more than five years of Fermi data. The sample includes 37 radio-quiet or radio-faint pulsars which cannot be timed with other telescopes. These timing solutions and the corresponding pulse times of arrival are prerequisites for further study, e.g., phase-resolved spectroscopy or searches for mode switches. Many {gamma}-ray pulsars are strongly affected by timing noise (TN), and we present a new method for characterizing the noise process and mitigating its effects on other facets of the timing model. We present an analysis of TN over the population using a new metric for characterizing its strength and spectral shape, namely, its time-domain correlation. The dependence of the strength on {nu} and {dot}{nu} is in good agreement with previous studies. We find that noise process power spectra S(f) for unrecycled pulsars are steep, with strong correlations over our entire data set and spectral indices s(f){propto}f^-{alpha}^ of {alpha}~5-9. One possible explanation for these results is the occurrence of unmodeled, episodic "microglitches". Finally, we show that our treatment of TN results in robust parameter estimation, and in particular we measure a precise timing position for each pulsar. We extensively validate our results with multi-wavelength astrometry, and using our updated position, we firmly identify the X-ray counterpart of PSR J1418-6058.
- ID:
- ivo://CDS.VizieR/J/A+A/584/A103
- Title:
- Unified EoS for neutron stars
- Short Name:
- J/A+A/584/A103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive a new equation of state (EoS) for neutron stars (NS) from the outer crust to the core based on modern microscopic calculations using the Argonne v18 potential plus three-body forces computed with the Urbana model. To deal with the inhomogeneous structures of matter in the NS crust, we use a recent nuclear energy density functional that is directly based on the same microscopic calculations, and which is able to reproduce the ground-state properties of nuclei along the periodic table. The EoS of the outer crust requires the masses of neutron-rich nuclei, which are obtained through Hartree-Fock-Bogoliubov calculations with the new functional when they are unknown experimentally. To compute the inner crust, Thomas-Fermi calculations in Wigner-Seitz cells are performed with the same functional. Existence of nuclear pasta is predicted in a range of average baryon densities between 0.067fm^-3^ and 0.0825fm^-3^, where the transition to the core takes place. The NS core is computed from the new nuclear EoS assuming non-exotic constituents (core of n-p-e-mu matter). In each region of the star, we discuss the comparison of the new EoS with previous EoSs for the complete NS structure, widely used in astrophysical calculations. The new microscopically derived EoS fulfills at the same time a NS maximum mass of 2 solar masses with a radius of 10km, and a 1.5 solar mass NS with a radius of 11.6km.
- ID:
- ivo://CDS.VizieR/J/MNRAS/484/3691
- Title:
- UTMOST pulsar timing programme. I.
- Short Name:
- J/MNRAS/484/3691
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an overview and the first results from a large-scale pulsar timing programme that is part of the UTMOST project at the refurbished Molonglo Observatory Synthesis Radio Telescope (MOST) near Canberra, Australia. We currently observe more than 400 mainly bright southern radio pulsars with up to daily cadences. For 205 (8 in binaries, 4 millisecond pulsars), we publish updated timing models, together with their flux densities, flux density variability, and pulse widths at 843 MHz, derived from observations spanning between 1.4 and 3 yr. In comparison with the ATNF pulsar catalogue, we improve the precision of the rotational and astrometric parameters for 123 pulsars, for 47 by at least an order of magnitude. The time spans between our measurements and those in the literature are up to 48 yr, which allow us to investigate their long-term spin-down history and to estimate proper motions for 60 pulsars, of which 24 are newly determined and most are major improvements. The results are consistent with interferometric measurements from the literature. A model with two Gaussian components centred at 139 and 463km/s fits the transverse velocity distribution best. The pulse duty cycle distributions at 50 and 10 per cent maximum are best described by lognormal distributions with medians of 2.3 and 4.4 per cent, respectively. We discuss two pulsars that exhibit spin-down rate changes and drifting subpulses. Finally, we describe the autonomous observing system and the dynamic scheduler that has increased the observing efficiency by a factor of 2-3 in comparison with static scheduling.
- ID:
- ivo://CDS.VizieR/J/A+A/543/A67
- Title:
- WDA and WDB apsidal-motion constants
- Short Name:
- J/A+A/543/A67
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The internal structure constants k_j_ and the radius of gyration are useful tools for investigating the apsidal motion and tidal evolution of close binaries and planetary systems. These parameters are available for various evolutionary phases but they are scarce for the late stages of stellar evolution. To cover this gap, we present here the calculations of the apsidal-motion constants, the fractional radius of gyration, and the gravitational potential energy for two grids of cooling evolutionary sequences of white dwarfs and for neutron star models. The cooling sequences of white dwarfs were computed with LPCODE. An additional alternative to the white dwarf models was also adopted with the MESA code which allows non-stop calculations from the pre main-sequence (PMS) to the white dwarf cooling sequences. Neutron star models were acquired from the NSCool/TOV subroutines. The apsidal-motion constants, the moment of inertia and the gravitational potential energy were computed with a fourth-order Runge-Kutta method. The parameters are made available for four cooling sequences of white dwarfs (DA and DB types): 0.52, 0.57, 0.837 and 1.0M_{sun}_ and for neutron star models covering a mass range from 1.0 up to 2.183M_{sun}_, in 0.1 mass step. We show that, contrary to previously established opinion, the product of the form-factors {beta} and {alpha}, which are related to the moment of inertia, and gravitational potential energy, is not constant during some evolutionary phases. Regardless of the final products of stellar evolution (white dwarfs, neutron stars and perhaps black holes), we found that they recover the initial value of product {alpha}{beta} at the pre main-sequence phase (~0.4). These results may have important consequences for the investigation of the Jacobi virial equation.
- ID:
- ivo://CDS.VizieR/J/ApJ/819/40
- Title:
- XMM-Newton brightest serendipitous sources
- Short Name:
- J/ApJ/819/40
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyzed a deep XMM-Newton observation of the radio-quiet {gamma}-ray PSR J2055+2539. The spectrum of the X-ray counterpart is nonthermal, with a photon index of {Gamma}=2.36+/-0.14 (1{sigma} confidence). We detected X-ray pulsations with a pulsed fraction of 25%+/-3% and a sinusoidal shape. Taking into account considerations on the {gamma}-ray efficiency of the pulsar and on its X-ray spectrum, we can infer a pulsar distance ranging from 450 to 750 pc. We found two different nebular features associated with PSR J2055+2539 and protruding from it. The angle between the two nebular main axes is ~162.8{deg}+/-0.7{deg}. The main, brighter feature is 12' long and <20" thick, characterized by an asymmetry with respect to the main axis that evolves with the distance from the pulsar, possibly forming a helical pattern. The secondary feature is 250"x30". Both nebulae present an almost flat brightness profile with a sudden decrease at the end. The nebulae can be fitted by either a power-law model or a thermal bremsstrahlung model. A plausible interpretation of the brighter nebula is in terms of a collimated ballistic jet. The secondary nebula is most likely a classical synchrotron-emitting tail.
- ID:
- ivo://CDS.VizieR/J/BaltA/24/395
- Title:
- X-ray and radio sources in binaries
- Short Name:
- J/BaltA/24/395
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The goal of the present study was to compile complete list of binaries discovered at non-optical bands: X-ray binaries (XRB) and radio pulsars in binaries. Due to the lack of a unified identification system for XRB we had to select them from five principal catalogues of X-ray sources. After cross-identification and positional cross-matching, a general catalogue of 373 XRB was constructed for the first time. It contains coordinates, indication of photometric and spectroscopic binarity and extensive cross-identification. In the preparation of the catalogue, a number of XRB classification collisions were resolved, some catalogued identifiers and coordinates were corrected, and duplicated entries in the original catalogues were found.
- ID:
- ivo://CDS.VizieR/J/PAZh/29/571
- Title:
- X-ray fluxes of radio pulsars
- Short Name:
- J/PAZh/29/571
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss the correlations between the luminosities of radio pulsars in various frequency ranges and the magnetic fields of the light cylinder.
