Pulsar distances and the galactic distribution of free electrons

Taylor, J. H.; Cordes, J. M.

doi:10.1086/172870

Cited by 1,217 publications

(1,319 citation statements)

References 0 publications

Supporting

Mentioning

1,243

Contrasting

Unclassified

Order By: Relevance

“…COMPTEL all-sky image of 1.8 MeV emission (Oberlack et al 1997) that the large scale emission can be characterized by a Galactic scale height of 130 (iy™) pc, and a Galactocentric scale radius of 5 (1J;|) kpc, with features from spiral structure . We fit a set of plausible large scale models to COMPTEL data: geometrical disk models with exponential scale height and Galactocentric scale radius dependancies (Diehl et al 1995), spiral arm models derived from free electron measurements with exponential scale height as parameter (Taylor & Cordes 1993), molecular gas data as measured in CO (Dame et al 1987), and stellar light-through dust-dominated measurements of the whole Galaxy in the infrared (Sodroski et al 1994). Globally, we find terms of use, available at https://www.cambridge.org/core/terms.…”

Section: Gamma-ray Resultsmentioning

confidence: 99%

²⁶ Al Radioactivity in the Galaxy

Diehl¹,

Oberlack²,

Knödlseder³

et al. 1997

International Astronomical Union Colloquium

View full text Add to dashboard Cite

Abstract. 26 A1 radioactivity is believed to originate predominantly from massive stars, ejected into interstellar medium in wind phases and/or supernova events. With its million-year decay time, penetrating 7-rays from 26 A1 decay measure the massive-star history averaged over a time scale of ~million years, thus extending times cales accessible otherwise. The COMPTEL 1.809 MeV all-sky data from 5 years of observations show irregularities and features at intermediate latitudes, which may have a more local origin (~ 1 kpc). We find that the large scale emission can be characterized by a Galactic scale height of ~ 130 pc, and a Galactocentric scale radius of ~ 5 kpc, with features from spiral structure. Catalogues from massive-star related objects do not significantly improve the description of COMPTEL data above this. Emission associated with nearby structures such as the Gould Belt, Loop I, or stellar aggregates, is indicated, yet cannot be clearly detected. Combined with our imaging results, this suggests that 26 A1 yields from massive star ensembles depend on specifics of those stars and their history. Further 26 A17-ray studies are underway to help mapping of the massive star history in the solar vicinity.

show abstract

Section: Gamma-ray Resultsmentioning

confidence: 99%

²⁶ Al Radioactivity in the Galaxy

Diehl¹,

Oberlack²,

Knödlseder³

et al. 1997

International Astronomical Union Colloquium

View full text Add to dashboard Cite

show abstract

“…, where J FB is a constant scaling factor relating the electron density inside the 9 Both Taylor & Cordes (1993) and Cordes & Lazio (2002) used  = R 8500 pc. We ignore the small systematic offset introduced by this difference.…”

Section: Thick Diskmentioning

confidence: 99%

“…The next major step forward was by Taylor & Cordes (1993), building on the work of Cordes et al (1991), who included the effect of spiral structure in the model and also made use of the increased number of independent distances (74) and the overall dependence of pulsar DMs on Galactic longitude. For the first time, they also took into account observations of interstellar scattering.…”

Section: Introductionmentioning

confidence: 99%

A New Electron-Density Model for Estimation of Pulsar and FRB Distances

Yao¹,

Manchester²,

Wang³

2017

ApJ

1,010

997

View full text Add to dashboard Cite

We present a new model for the distribution of free electrons in the Galaxy, the Magellanic Clouds, and the intergalactic medium (IGM) that can be used to estimate distances to real or simulated pulsars and fast radio bursts (FRBs) based on their dispersion measure (DM). The Galactic model has an extended thick disk representing the so-called warm interstellar medium, a thin disk representing the Galactic molecular ring, spiral arms based on a recent fit to Galactic H II regions, a Galactic Center disk, and seven local features including the Gum Nebula, Galactic Loop I, and the Local Bubble. An offset of the Sun from the Galactic plane and a warp of the outer Galactic disk are included in the model. Parameters of the Galactic model are determined by fitting to 189 pulsars with independently determined distances and DMs. Simple models are used for the Magellanic Clouds and the IGM. Galactic model distances are within the uncertainty range for 86 of the 189 independently determined distances and within 20% of the nearest limit for a further 38 pulsars. We estimate that 95% of predicted Galactic pulsar distances will have a relative error of less than a factor of 0.9. The predictions of YMW16 are compared to those of the TC93 and NE2001 models showing that YMW16 performs significantly better on all measures. Timescales for pulse broadening due to interstellar scattering are estimated for (real or simulated) Galactic and Magellanic Cloud pulsars and FRBs.

show abstract

“…In galaxies, however, magnetic dynamos leave many unanswered questions (Parker 1979), the most immediate of them is the rather long characteristic time-scales over which they could operate. For instance, the interstellar medium in our Galaxy has an ordered field of ≈ 2 × 10 −10 T, superposed upon which there is a random 10 MARCELO CARVALHO, ALEXANDRE L. OLIVEIRA and CARLOS R. RABAÇA component of ≈ 1-2 times this value (Taylor and Cordes 1993). Considering that the period of rotation of the interstellar gas about the Galactic center is ≈ 2.5 × 10 8 years, there would have been at most 50 complete rotations of this gas about the center.…”

Section: Introductionmentioning

confidence: 91%