The YMW16 Electron Density Model for Estimating Pulsar and FRB Distances

• Developed by Jumei Yao, RNM and Nina Wang – paper to be submitted today

• Electron density models for the Galaxy, Magellanic Clouds and intergalactic medium

• Galactic model based on independent distances for 189 pulsars – 31 fitted parameters, 57 fixed parameters • Magellanic Cloud model based on spectral-line and radio

continuum data – 3 fitted parameters, 16 fixed parameters

•  IGM model based on Katz (2016) relations, 1 fixed parameter

Components of Galactic Model • Thick disk, DMperp=19 cm-3 pc,

plane parallel, n1=0.0116 cm-3, H1=1640 pc

•  n2(4 kpc)= 0.40 cm-3, half-width=1200 pc, scale height ~ 50pc, fn(RG), n2 ~sech2(z)

• Spiral arms, based on Hou & Han fitting of HII-region distances, Ha=fn(RG)

• Local features: Local Bubble, LB shell (2 clumps), Gum Nebula., Loop I, Carina over-density, Sagittarius under-density • Galactic Centre disk

DM – D Build-up

Distance Estimations

Red circle: Derr<20% Blue square: Under-estimated D Green triangle: Over-estimated D

Ne in Local Region

Relative Derr = (Dm-Di)/Di for YMY16, NE2001 and TC93

Relative Distance Errors

Thick Disk: DMperp vs |z|

Cumulative Histograms of Distance Ratios

R = Dm/Di for Dm/Di> 1; R = Di/Dm for Dm/Di < 1

189 distances Predicted distances

Galactic Scattering Timescales

• Predicted scattering times based on Krishnakumar et al. (2015) fit: τsc = 4.10 x 10-11 DM2.2 (1.0 + 0.00194 DM2)

• NE2001 predictions low by about a factor of four (except for PSR J1745-2900!)

Magellanic Cloud and FRB Scattering MC Scattering:

τGal = 0.5 τsc(DMGal) τMC = 0.5 τsc(DMMC)

FRB Scattering: “Survival analysis” fit to observed scattering times: tIGM ~ DMIGM

1.3

τMC = max(τGal, τMC)

τFRB = max(τGal, τMC, τIGM, τHost)

Appendix Table Extract

Appendix FRB Table