The Lyon-Meudon Extragalactic database (LEDA) gives a free access to the main astrophysical parameters for more than 100,000 galaxies. The most common names are compiled allowing users to recover ...quickly any galaxy. All these measured astrophysical parameters are first reduced to a common system according to well defined reduction formulae leading to mean homogeneized parameters. Further, these parameters are also transformed into corrected parameters from widely accepted models. For instance, raw 21-cm line widths are transformed into mean standard widths after correction for instrumental effect and then into maximum velocity rotation properly corrected for inclination and non-circular velocity. This paper presents the reduction formulae for each parameter: coordinates, morphological type and luminosity class, diameter and axis ratio, apparent magnitude (UBV, IR, HI) and colors, maximum velocity rotation and central velocity dispersion, radial velocity, mean surface brightness, distance modulus and absolute magnitude, and group membership. For each of these parameters intermediate quantities are given: galactic extinction, inclination, K-correction etc.. All these parameters are available from direct connexion to LEDA (telnet lmc.univ-lyon1.fr, login: leda, no passwd OR http://www-obs.univ-lyon1.fr/leda ) and distributed on a standard CD-ROM (PGC-ROM 1996) by the Observatoire de Lyon via the CNRS (mail to petit@obs.univ-lyon1.fr).
We report on the results of a 4 year timing campaign of PSR J2222−0137, a 2.44 day binary pulsar with a massive white dwarf (WD) companion, with the Nançay, Effelsberg, and Lovell radio telescopes. ...Using the Shapiro delay for this system, we find a pulsar mass mp = 1.76 0.06 M and a WD mass mc = 1.293 0.025 M . We also measure the rate of advance of periastron for this system, which is marginally consistent with the general relativity prediction for these masses. The short lifetime of the massive WD progenitor star led to a rapid X-ray binary phase with little (< 10−2 M ) mass accretion onto the neutron star; hence, the current pulsar mass is, within uncertainties, its birth mass, which is the largest measured to date. We discuss the discrepancy with previous mass measurements for this system; we conclude that the measurements presented here are likely to be more accurate. Finally, we highlight the usefulness of this system for testing alternative theories of gravity by tightly constraining the presence of dipolar radiation. This is of particular importance for certain aspects of strong-field gravity, like spontaneous scalarization, since the mass of PSR J2222−0137 puts that system into a poorly tested parameter range.
Abstract
We report the detection of X-ray pulsations from the rotation-powered millisecond-period pulsars PSR J0740+6620 and PSR J1614−2230, two of the most massive neutron stars known, using ...observations with the Neutron Star Interior Composition Explorer (NICER). We also analyze X-ray Multi-Mirror Mission (XMM-Newton) data for both pulsars to obtain their time-averaged fluxes and study their respective X-ray fields. PSR J0740+6620 exhibits a broad double-peaked profile with a separation of ∼0.4 in phase. PSR J1614−2230, on the other hand, has a broad single-peak profile. We show the NICER detections of X-ray pulsations for both pulsars and also discuss the phase relationship to their radio pulsations. The XMM-Newton X-ray spectra of both pulsars shows they are thermally dominated but in the case of PSR J1614−2230 a weak nonthermal high energy tail appears to be present in the spectrum. The thermally dominated spectra along with broad modulations for both pulsars are indicative of thermal radiation from one or more small regions of the stellar surface. For PSR J0740+6620, this paper documents the data reduction performed to obtain the pulsation detection and prepare for pulse light curve modeling analysis.
Timing stability of three black widow pulsars Bak Nielsen, Ann-Sofie; Janssen, Gemma H; Shaifullah, Golam ...
Monthly Notices of the Royal Astronomical Society,
2020, Volume:
494, Issue:
2
Journal Article
Peer reviewed
Open access
ABSTRACT
We study the timing stability of three black widow pulsars (BWPs), both in terms of their long-term spin evolution and their shorter term orbital stability. The erratic timing behaviour and ...radio eclipses of the first two BWP systems discovered (PSRs B1957+20 and J2051−0827) were assumed to be representative for this class of pulsars. With several new black widow systems added to this population in the last decade, there are now several systems known that do not show these typical orbital variations or radio eclipses. We present timing solutions using 7–8 yr of observations from four of the European Pulsar Timing Array telescopes for PSRs J0023+0923, J2214+3000, and J2234+0944, and confirm that two of these systems do not show any significant orbital variability over our observing time span, both in terms of secular or orbital parameters. The third pulsar PSR J0023+0923 shows orbital variability and we discuss the implications for the timing solution. Our results from the long-term timing of these pulsars provide several new or improved parameters compared to earlier works. We discuss our results regarding the stability of these pulsars, and the stability of the class of BWPs in general, in the context of the binary parameters, and discuss the potential of the Roche lobe filling factor of the companion star being an indicator for stability of these systems.
We search for continuous gravitational waves (CGWs) produced by individual supermassive black hole binaries in circular orbits using high-cadence timing observations of PSR J1713+0747. We observe ...this millisecond pulsar using the telescopes in the European Pulsar Timing Array with an average cadence of approximately 1.6 d over the period between 2011 April and 2015 July, including an approximately daily average between 2013 February and 2014 April. The high-cadence observations are used to improve the pulsar timing sensitivity across the gravitational wave frequency range of 0.008−5$$\mu$$Hz. We use two algorithms in the analysis, including a spectral fitting method and a Bayesian approach. For an independent comparison, we also use a previously published Bayesian algorithm. We find that the Bayesian approaches provide optimal results and the timing observations of the pulsar place a 95 per cent upper limit on the sky-averaged strain amplitude of CGWs to be ≲3.5 × 10^−13 at a reference frequency of 1 $$\mu$$Hz. We also find a 95 per cent upper limit on the sky-averaged strain amplitude of low-frequency CGWs to be ≲1.4 × 10^−14 at a reference frequency of 20 nHz.
We report the discovery of the millisecond pulsar PSR J2043+1711 in a search of a Fermi Large Area Telescope (LAT) source with no known associations, with the Nanc¸ay Radio Telescope. The new pulsar, ...confirmed with the Green Bank Telescope, has a spin period of 2.38 ms, is relatively nearby (d 2 kpc) and is in a 1.48-d orbit around a low-mass companion, probably an He-type white dwarf. Using an ephemeris based on Arecibo, Nanc¸ay and Westerbork timing measurements, pulsed gamma-ray emission was detected in the data recorded by the Fermi LAT. The gamma-ray light curve and spectral properties are typical of other gamma-ray millisecond pulsars seen with Fermi. X-ray observations of the pulsar with Suzaku and the Swift X-ray Telescope yielded no detection. At 1.4 GHz, we observe strong flux density variations because of interstellar diffractive scintillation; however, a sharp peak can be observed at this frequency during bright scintillation states. At 327 MHz, the pulsar is detected with a much higher signal-to-noise ratio and its flux density is far more steady. However, at that frequency the Arecibo instrumentation cannot yet fully resolve the pulse profile. Despite that, our pulse time-of-arrival measurements have a post-fit residual rms of 2 μs. This and the expected stability of this system have made PSR J2043+1711 one of the first new Fermi-selected millisecond pulsars to be added to pulsar gravitational wave timing arrays. It has also allowed a significant measurement of relativistic delays in the times of arrival of the pulses due to the curvature of space-time near the companion, but not yet with enough precision to derive useful masses for the pulsar and the companion. Nevertheless, a mass for the pulsar between 1.7 and 2.0M can be derived if a standard millisecond pulsar formation model is assumed. In this paper, we also present a comprehensive summary of pulsar searches in Fermi LAT sources with the Nanc¸ay Radio Telescope to date.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
We study the timing stability of three black widow pulsars, both in terms of their long-term spin evolution and their shorter-term orbital stability. The erratic timing behaviour and radio eclipses ...of the first two black widow pulsar systems discovered (PSRs B1957+20 and J2051\(-\)0827) was assumed to be representative for this class of pulsars. With several new black widow systems added to this population in the last decade, there are now several systems known that do not show these typical orbital variations or radio eclipses. We present timing solutions using 7\(-\)8 yrs of observations from four of the European Pulsar Timing Array telescopes for PSRs\,J0023+0923, J2214+3000 and J2234+0944, and confirm that two of these systems do not show any significant orbital variability over our observing time span, both in terms of secular or orbital parameters. The third pulsar PSR J0023+0923 shows orbital variability and we discuss the implications for the timing solution. Our results from the long-term timing of these pulsars provide several new or improved parameters compared to earlier works. We discuss our results regarding the stability of these pulsars, and the stability of the class of black widow pulsars in general, in the context of the binary parameters, and discuss the potential of the Roche-lobe filling factor of the companion star being an indicator for stability of these systems.
We report on the results of a 4-year timing campaign of PSR~J2222\(-0137\), a 2.44-day binary pulsar with a massive white dwarf (WD) companion, with the Nançay, Effelsberg and Lovell radio ...telescopes. Using the Shapiro delay for this system, we find a pulsar mass \(m_{p}=1.76,\pm\,0.06,M_\odot\) and a WD mass \(m_{c}\,=\,1.293\,\pm\,0.025\, M_\odot\). We also measure the rate of advance of periastron for this system, which is marginally consistent with the GR prediction for these masses. The short lifetime of the massive WD progenitor star led to a rapid X-ray binary phase with little (\(< \, 10^{-2} \, M_\odot\)) mass accretion onto the neutron star (NS); hence, the current pulsar mass is, within uncertainties, its birth mass; the largest measured to date. We discuss the discrepancy with previous mass measurements for this system; we conclude that the measurements presented here are likely to be more accurate. Finally, we highlight the usefulness of this system for testing alternative theories of gravity by tightly constraining the presence of dipolar radiation. This is of particular importance for certain aspects of strong-field gravity, like spontaneous scalarization, since the mass of PSR~J2222\(-0137\) puts that system into a poorly tested parameter range.
The pulsar PSR J1756\(-\)2251 resides in a relativistic double neutron star (DNS) binary system with a 7.67-hr orbit. We have conducted long-term precision timing on more than 9 years of data ...acquired from five telescopes, measuring five post-Keplerian parameters. This has led to several independent tests of general relativity (GR), the most constraining of which shows agreement with the prediction of GR at the 4% level. Our measurement of the orbital decay rate disagrees with that predicted by GR, likely due to systematic observational biases. We have derived the pulsar distance from parallax and orbital decay measurements to be 0.73\(_{-0.24}^{+0.60}\) kpc (68%) and < 1.2 kpc (95% upper limit), respectively; these are significantly discrepant from the distance estimated using Galactic electron density models. We have found the pulsar mass to be 1.341\(\pm\)0.007 M\(_\odot\), and a low neutron star (NS) companion mass of 1.230\(\pm\)0.007 M\(_\odot\). We also determined an upper limit to the spin-orbit misalignment angle of 34{\deg} (95%) based on a system geometry fit to long-term profile width measurements. These and other observed properties have led us to hypothesize an evolution involving a low mass loss, symmetric supernova progenitor to the second-formed NS companion, as is thought to be the case for the double pulsar system PSR J0737\(-\)3039A/B. This would make PSR J1756\(-\)2251 the second compact binary system providing concrete evidence for this type of NS formation channel.
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