2008A&A...490..179B


Query : 2008A&A...490..179B

2008A&A...490..179B - Astronomy and Astrophysics, volume 490, 179-187 (2008/10-4)

Densities and filling factors of the diffuse ionized gas in the Solar neighbourhood.

BERKHUIJSEN E.M. and MUELLER P.

Abstract (from CDS):

We analyse electron densities and filling factors of the diffuse ionized gas (DIG) in the Solar neighbourhood. We have combined dispersion measures and emission measures towards 38 pulsars at distances known to better than 50%, from which we derived the mean density in clouds, Nc, and their volume filling factor, Fv, averaged along the line of sight. The emission measures were corrected for absorption by dust and contributions from beyond the pulsar distance. The scale height of the electron layer for our sample is 0.93±0.13kpc and the midplane electron density is 0.023±0.004/cm3, in agreement with earlier results. The average density along the line of sight is <ne≥0.018±0.002cm–3 and is nearly constant. Since <ne≥FvNc, an inverse relationship between Fv and Nc is expected. We find Fv(Nc)=(0.011±0.003)Nc–1.20±0.13, which holds for the ranges Nc=0.05-1cm–3 and Fv=0.4-0.01. Near the Galactic plane the dependence of Fv on Nc is significantly stronger than away from the plane. Fv does not systematically change along or perpendicular to the Galactic plane, but the spread about the mean value of 0.08±0.02 is considerable. The total pathlength through the ionized regions increases linearly to about 80pc towards |z|=1kpc. Our study of Fv and Nc of the DIG is the first one based on a sample of pulsars with known distances. We confirm the existence of a tight, nearly inverse correlation between Fv and Nc in the DIG. The exact form of this relation depends on the regions in the Galaxy probed by the pulsar sample. The inverse Fv-Nc relation is consistent with a hierarchical, fractal density distribution in the DIG caused by turbulence. The observed near constancy of <ne> then is a signature of fractal structure in the ionized medium, which is most pronounced outside the thin disk.

Abstract Copyright:

Journal keyword(s): Galaxy: disk - HII regions - ISM: clouds - ISM: structure

CDS comments: Paragraph 2.3 PSR J1807+0943 is a probable misprint for PSR J1857+0943.

Simbad objects: 42

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Number of rows : 42
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 PSR J0024-7204C Psr 00 23 50.371 -72 04 31.44           ~ 61 1
2 PSR J0030+0451 Psr 00 30 27.4277 +04 51 39.710           ~ 422 1
3 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 12388 1
4 PSR B0138+59 Psr 01 41 39.938 +60 09 32.30     12.85     ~ 112 0
5 PSR J0437-47 Psr 04 37 15.7994581776 -47 15 08.544351636           DC 876 0
6 V* CM Tau Psr 05 34 31.9474694616 +22 00 52.153698024           ~ 5173 0
7 PSR B0613-02.0 Psr 06 13 43.9759 -02 00 47.228           ~ 248 1
8 PSR B0656+14 Psr 06 59 48.1960 +14 14 19.400   24.85 24.90     ~ 847 1
9 PSR B0809+74 Psr 08 14 59.500 +74 29 05.70           ~ 399 0
10 PSR B0823+26 Psr 08 26 51.4 +26 37 22           ~ 505 1
11 PSR B0919+06 Psr 09 22 14.1600 +06 38 28.800           ~ 285 0
12 PSR B0950+08 Psr 09 53 09.2970 +07 55 36.400           ~ 745 2
13 PSR J1022+10 Psr 10 22 58.011 +10 01 52.85           ~ 219 2
14 PSR J1024-0719 Psr 10 24 38.697 -07 19 19.07           ~ 225 0
15 PSR B1133+16 Psr 11 36 03.0720 +15 51 15.500           ~ 662 0
16 PSR B1237+25 Psr 12 39 40.386 +24 53 49.87           ~ 458 0
17 PSR B1451-68 Psr 14 56 00.0175876848 -68 43 40.034742348           ~ 186 0
18 PSR B1508+55 Psr 15 09 25.7 +55 31 33           ~ 294 1
19 NAME M 5 PSR A * 15 18 33.3176 +02 05 27.550           ~ 45 2
20 PSR B1534+11 Psr 15 37 09.9603 +11 55 55.554           ~ 418 1
21 PSR J1641+3627C Psr 16 41 41.0 +36 27 37           ~ 9 0
22 PSR J1701-30C Psr 17 01 12.9200 -30 06 59.085           ~ 14 0
23 PSR J1713+0447 Psr 17 13 49.53053 +07 47 37.5264           ~ 438 1
24 PSR B1718-19 Psr 17 21 01.48 -19 36 51.0           ~ 90 1
25 PSR J1740-5340 Psr 17 40 44.589 -53 40 40.90   17.43   16.25   ~ 145 2
26 PSR J1744-1134 Psr 17 44 29.4172 -11 34 54.710           ~ 252 1
27 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 13907 0
28 PSR J1748-2021C Psr 17 48 51.17320 -20 21 53.8100           ~ 5 0
29 PSR J1802-07 Psr 18 04 49.8954 -07 35 24.690     12.33     ~ 97 2
30 PSR J1823-3021C Psr 18 23 41.1516 -30 21 38.450           ~ 12 0
31 PSR J1824-2452C Psr 18 24 32.8 -24 52 11           ~ 22 1
32 PSR B1855+09 Psr 18 57 36.39161 +09 43 17.2322           DA 513 1
33 PSR J1909-3744 Psr 19 09 47.42820 -37 44 14.7740           ~ 267 2
34 PSR B1907-60C Psr 19 11 05.5561 -60 00 59.680           ~ 31 0
35 PSR B1908+00A Psr 19 11 11.02 +01 02 10.9           ~ 44 0
36 PSR B1929+10 Psr 19 32 14.0570 +10 59 33.380           ~ 741 0
37 PSR B2016+28 Psr 20 18 03.8999255016 +28 39 54.940329468           ~ 349 0
38 PSR B2020+28 Psr 20 22 37.0671 +28 54 23.104           ~ 303 1
39 PSR B2021+51 Psr 20 22 49.8730 +51 54 50.233           ~ 263 1
40 PSR J2124-3358 Psr 21 24 43.8464 -33 58 44.961           ~ 283 1
41 PSR J2129+1209C Psr 21 30 01.2030 +12 10 38.159           ~ 187 2
42 PSR B2145-07.8 Psr 21 45 50.45590 -07 50 18.5900           ~ 274 0

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2023.10.03-06:41:27

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