Search

Start Over Subject pulsars
41. Geometry of radio pulsar magnetospheres
ID:
ivo://CDS.VizieR/J/AZh/88/954
Title:
Geometry of radio pulsar magnetospheres
Short Name:
J/AZh/88/954
Date:
21 Oct 2021
Publisher:
CDS
Description:
Data on the profiles and polarization of the 10- and 20-cm emission of radio pulsars are used to calculate the angle {beta} between the rotational axis of the neutron star and its magnetic moment. It is shown that, for these calculations, it is sufficient to use catalog values of the pulse width at the 10% level W10, since the broadening of the observed pulses due to the transition to the full width W0 and narrowing of the pulses associated with the emission of radiation along tangents to the field lines approximately cancel each other out. The angles {beta}1 are calculated for 283 pulsars at 20cm and 132 pulsars at 10cm, assuming that the line of sight passes through the center of the emission cone.
42. 4.8GHz observations of SGR 1806-20
ID:
ivo://CDS.VizieR/J/ApJ/634/L89
Title:
4.8GHz observations of SGR 1806-20
Short Name:
J/ApJ/634/L89
Date:
21 Oct 2021
Publisher:
CDS
Description:
The 2004 December 27 giant {gamma}-ray flare detected from the magnetar SGR 1806-20 created an expanding radio nebula that we have monitored with the Australia Telescope Compact Array and the Very Large Array. These data indicate that there was an increase in the observed flux 25 days after the initial flare that lasted for 8 days, which we believe is the result of ambient material swept up and shocked by this radio nebula.
43. 5GHz TMRT observations of 71 pulsars
ID:
ivo://CDS.VizieR/J/ApJ/874/64
Title:
5GHz TMRT observations of 71 pulsars
Short Name:
J/ApJ/874/64
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present integrated pulse profiles at 5GHz for 71 pulsars, including eight millisecond pulsars (MSPs), obtained using the Shanghai Tian Ma Radio Telescope. Mean flux densities and pulse widths are measured. For 19 normal pulsars and one MSP, these are the first detections at 5GHz --and for a further 19, including five MPSs, the profiles have a better signal-to-noise ratio than previous observations. Mean flux density spectra between 400MHz and 9GHz are presented for 27 pulsars and correlations of power-law spectral index are found with characteristic age, radio pseudo-luminosity, and spin-down luminosity. Mode changing was detected in five pulsars. The separation between the main pulse and interpulse is shown to be frequency independent for six pulsars, but a frequency dependence of the relative intensity of the main pulse and interpulse is found. The frequency dependence of component separations is investigated for 20 pulsars, and three groups are found: in seven cases, the separation between the outmost leading and trailing components decreases with frequency, roughly in agreement with radius-to-frequency mapping; in 11 cases, the separation is nearly constant; in the remaining two cases, the separation between the outmost components increases with frequency. We obtain the correlations of pulse widths with pulsar period and estimate the core widths of 23 multicomponent profiles and conal widths of 17 multicomponent profiles at 5GHz using Gaussian fitting, and we discuss the width-period relationship at 5GHz compared with the results at at 1.0 and 8.6GHz.
44. 315 glitches in the rotation of 102 pulsars
ID:
ivo://CDS.VizieR/J/MNRAS/414/1679
Title:
315 glitches in the rotation of 102 pulsars
Short Name:
J/MNRAS/414/1679
Date:
21 Oct 2021
Publisher:
CDS
Description:
The rotation of more than 700 pulsars has been monitored using the 76-m Lovell Telescope at Jodrell Bank. Here we report on a new search for glitches in the observations, revealing 128 new glitches in the rotation of 63 pulsars. Combining these new data with those already published, we present a data base containing 315 glitches in 102 pulsars.
45. Gravitational waves from known pulsars
ID:
ivo://CDS.VizieR/J/ApJ/785/119
Title:
Gravitational waves from known pulsars
Short Name:
J/ApJ/785/119
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of searches for gravitational waves from a large selection of pulsars using data from the most recent science runs (S6, VSR2 and VSR4) of the initial generation of interferometric gravitational wave detectors LIGO (Laser Interferometric Gravitational-wave Observatory) and Virgo. We do not see evidence for gravitational wave emission from any of the targeted sources but produce upper limits on the emission amplitude. We highlight the results from seven young pulsars with large spin-down luminosities. We reach within a factor of five of the canonical spin-down limit for all seven of these, whilst for the Crab and Vela pulsars we further surpass their spin-down limits. We present new or updated limits for 172 other pulsars (including both young and millisecond pulsars). Now that the detectors are undergoing major upgrades, and, for completeness, we bring together all of the most up-to-date results from all pulsars searched for during the operations of the first-generation LIGO, Virgo and GEO600 detectors. This gives a total of 195 pulsars including the most recent results described in this paper.
46. Gravitational waves from pulsars
ID:
ivo://CDS.VizieR/J/ApJ/713/671
Title:
Gravitational waves from pulsars
Short Name:
J/ApJ/713/671
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a search for gravitational waves from 116 known millisecond and young pulsars using data from the fifth science run of the LIGO detectors. For this search, ephemerides overlapping the run period were obtained for all pulsars using radio and X-ray observations. We demonstrate an updated search method that allows for small uncertainties in the pulsar phase parameters to be included in the search. We report no signal detection from any of the targets and therefore interpret our results as upper limits on the gravitational wave signal strength. The most interesting limits are those for young pulsars. We present updated limits on gravitational radiation from the Crab pulsar, where the measured limit is now a factor of 7 below the spin-down limit. This limits the power radiated via gravitational waves to be less than ~2% of the available spin-down power. For the X-ray pulsar J0537-6910 we reach the spin-down limit under the assumption that any gravitational wave signal from it stays phase locked to the X-ray pulses over timing glitches, and for pulsars J1913+1011 and J1952+3252 we are only a factor of a few above the spin-down limit. Of the recycled millisecond pulsars, several of the measured upper limits are only about an order of magnitude above their spin-down limits. For these our best (lowest) upper limit on gravitational wave amplitude is 2.3x10^-26^ for J1603-7202 and our best (lowest) limit on the inferred pulsar ellipticity is 7.0x10^-8^ for J2124-3358.
47. Gravitational waves search from known PSR with LIGO
ID:
ivo://CDS.VizieR/J/ApJ/839/12
Title:
Gravitational waves search from known PSR with LIGO
Short Name:
J/ApJ/839/12
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the result of searches for gravitational waves from 200 pulsars using data from the first observing run of the Advanced LIGO detectors. We find no significant evidence for a gravitational-wave signal from any of these pulsars, but we are able to set the most constraining upper limits yet on their gravitational-wave amplitudes and ellipticities. For eight of these pulsars, our upper limits give bounds that are improvements over the indirect spin-down limit values. For another 32, we are within a factor of 10 of the spin-down limit, and it is likely that some of these will be reachable in future runs of the advanced detector. Taken as a whole, these new results improve on previous limits by more than a factor of two.
48. Her X-1 pulse profiles
ID:
ivo://CDS.VizieR/J/A+A/550/A110
Title:
Her X-1 pulse profiles
Short Name:
J/A+A/550/A110
Date:
21 Oct 2021
Publisher:
CDS
Description:
The accreting X-ray pulsar Her X-1 shows two types of long-term variations, both with periods of ~35 days: 1) Turn-on cycles, a modulation of the flux, with a ten-day long Main-On and a five-day long Short-On, separated by two Off-states, and 2) a systematic variation in the shape of the 1.24s pulse profile. While there is general consensus that the flux modulation is due to variable shading of the X-ray emitting regions on the surface of the neutron star by the precessing accretion disk, the physical reason for the variation in the pulse profiles has remained controversial. Following the suggestion that free precession of the neutron star may be responsible for the variation in the pulse profiles, we developed a physical model of strong feedback interaction between the neutron star and the accretion disk in order to explain the seemingly identical values for the periods of the two types of variations, which were found to be in basic synchronization. In a deep analysis of pulse profiles observed by several different satellites over the last three decades we now find that the clock behind the pulse profile variations shows exactly the same erratic behavior as the turn-on clock, even on short time scales (a few 35d cycles), suggesting that there may in fact be only one 35d clock in the system. If this is true, it raises serious questions with respect to the idea of free precession of the neutron star, namely how the neutron star can change its precessional period every few years by up to 2.5% and how the feedback can be so strong, such that these changes can be transmitted to the accretion disk on rather short time scales.
49. HESS and Suzaku observations of Vela X
ID:
ivo://CDS.VizieR/J/A+A/627/A100
Title:
HESS and Suzaku observations of Vela X
Short Name:
J/A+A/627/A100
Date:
21 Oct 2021
Publisher:
CDS
Description:
Pulsar Wind Nebulae (PWNe) represent the most prominent population of Galactic very-high-energy gamma-ray sources and are thought to be an efficient source of leptonic cosmic rays. Vela X is a nearby middle-aged PWN, which shows bright X-ray and TeV gamma-ray emission toward an elongated structure called the cocoon. Since TeV emission is likely inverse-Compton emission of electrons, predominantly from interactions with the cosmic microwave background, while X-ray emission is synchrotron radiation of the same electrons, we aim to derive the properties of the relativistic particles and of magnetic fields with minimal modelling. We use data from the Suzaku XIS to derive the spectra from three compact regions in Vela X covering distances from 0.3pc to 4pc from the pulsar along the cocoon. We obtain gamma-ray spectra of the same regions from H.E.S.S. observations and fit a radiative model to the multi-wavelength spectra. The TeV electron spectra and magnetic field strengths are consistent within the uncertainties for the three regions, with energy densities of the order 10^-12^erg/cm^-3^. The data indicate the presence of a cutoff in the electron spectrum at energies of 100TeV and a magnetic field strength of 6G. Constraints on the presence of turbulent magnetic fields are weak. The pressure of TeV electrons and magnetic fields in the cocoon is dynamically negligible, requiring the presence of another dominant pressure component to balance the pulsar wind at the termination shock. Sub-TeV electrons cannot account completely for the missing pressure, that may be provided either by relativistic ions or from mixing of the ejecta with the pulsar wind. The electron spectra are consistent with expectations from transport scenarios dominated either by advection via the reverse shock or by diffusion, but for the latter the role of radiative losses near the termination shock needs to be further investigated in the light of the measured cutoff energies. Constraints on turbulent magnetic fields and the shape of the electron cutoff can be improved by spectral measurements in the energy range >~10keV.
50. HESS J1825-137 particle transport
ID:
ivo://CDS.VizieR/J/A+A/621/A116
Title:
HESS J1825-137 particle transport
Short Name:
J/A+A/621/A116
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a detailed view of the pulsar wind nebula (PWN) HESS J1825--137. We aim to constrain the mechanisms dominating the particle transport within the nebula, accounting for its anomalously large size and spectral characteristics. The nebula is studied using a deep exposure from over 12 years of H.E.S.S. I operation, together with data from H.E.S.S. II improving the low energy sensitivity. Enhanced energy- dependent morphological and spatially-resolved spectral analyses probe the Very High Energy (VHE, E>0.1TeV) gamma-ray properties of the nebula. The nebula emission is revealed to extend out to 1.5 degrees from the pulsar, ~1.5 times further than previously seen, making HESS J1825-137, with an intrinsic diameter of ~100pc, potentially the largest gamma-ray PWN currently known. Characterisation of the nebula's strongly energy-dependent morphology enables the particle transport mechanisms to be constrained. A dependence of the nebula extent with energy of R{prop.to} E^alpha^ with alpha=-0.29+/-0.04(stat)+/-0.05(sys) disfavours a pure diffusion scenario for particle transport within the nebula. The total gamma-ray flux of the nebula above 1~TeV is found to be (1.12+/-0.03(stat)+/-0.25(sys))x10^-11^cm^-2^s^-1^, corresponding to ~64% of the flux of the Crab Nebula. HESS J1825-137 is a PWN with clear energy-dependent morphology at VHE gamma-ray energies. This source is used as a laboratory to investigate particle transport within middle-aged PWNe. Deep observations of this highly spatially-extended PWN enable a spectral map of the region to be produced, providing insights into the spectral variation within the nebula.