The distribution of interstellar dust in the solar neighborhood

Gaustad, John E.; Buren, D. van

doi:10.1086/133291

Cited by 37 publications

(68 citation statements)

References 17 publications

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“…So these clump properties also seem to follow the F v -N c relations derived for the DIG. Furthermore, Gaustad & Van Buren (1993) obtained a similar relationship for clouds of diffuse dust within 400 pc from the Sun, with mean densities of 1−10 cm −3 . Figure 9 shows that these clouds have about 3 times higher filling factors than ionized clouds of the same mean density.…”

Section: Comparison With Other Datamentioning

confidence: 61%

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

Berkhuijsen¹,

Müller

2008

A&A

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Aims. We analyse electron densities and filling factors of the diffuse ionized gas (DIG) in the Solar neighbourhood. Methods. 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, N c , and their volume filling factor, F v , averaged along the line of sight. The emission measures were corrected for absorption by dust and contributions from beyond the pulsar distance.Results. The scale height of the electron layer for our sample is 0.93±0.13 kpc and the midplane electron density is 0.023±0.004 cm −3 , in agreement with earlier results. The average density along the line of sight is n e = 0.018 ± 0.002 cm −3 and is nearly constant. Since n e = F v N c , an inverse relationship between F v and N c is expected. We find Conclusions. Our study of F v and N c 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 F v and N c in the DIG. The exact form of this relation depends on the regions in the Galaxy probed by the pulsar sample. The inverse F v -N c relation is consistent with a hierarchical, fractal density distribution in the DIG caused by turbulence. The observed near constancy of n e then is a signature of fractal structure in the ionized medium, which is most pronounced outside the thin disk.

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Section: Comparison With Other Datamentioning

confidence: 61%

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

Berkhuijsen¹,

Müller

2008

A&A

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“…The emission measures of the extinctioncorrected Hα emission from the galaxy M33 (Tabatabaei et al 2007) and the volume density of the dust-bearing gas near stars within 400 pc from the Sun (Gaustad & Van Buren 1993) have lognormal distributions. Furthermore, Seon (2011Seon ( , 2013 obtained lognormal PDFs for the FUV background emission from the ISRF, and Bowen et al (2008) plotted the volume density distribution of the O VI-line emitting gas in the MW, which is approximately lognormal.…”

Section: Introductionmentioning

confidence: 99%

Probability distribution functions of gas in M31 and M51

Berkhuijsen

Fletcher

2015

Monthly Notices of the Royal Astronomical Society

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We present probability distribution functions (PDFs) of the surface densities of ionized and neutral gas in the nearby spiral galaxies M31 and M51, as well as of dust emission and extinction A V in M31. The PDFs are close to lognormal and those for H I and A V in M31 are nearly identical. However, the PDFs for H 2 are wider than the H I PDFs and the M51 PDFs have larger dispersions than those for M31. We use a simple model to determine how the PDFs are changed by variations in the line-ofsight (LOS) pathlength L through the gas, telescope resolution and the volume filling factor of the gas, f v . In each of these cases the dispersion σ of the lognormal PDF depends on the variable with a negative power law. We also derive PDFs of mean LOS volume densities of gas components in M31 and M51. Combining these with the volume density PDFs for different components of the ISM in the Milky Way (MW), we find that σ decreases with increasing length L with an exponent of −0.76 ± 0.06, which is steeper than expected. We show that the difference is due to variations in f v . As f v is similar in M31, M51 and the MW, the density structure in the gas in these galaxies must be similar. Finally, we demonstrate that an increase in f v with increasing distance to the Galactic plane explains the decrease in σ with latitude of the PDFs of emission measure and FUV emission observed for the MW.

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“…An inverse correlation between f and the average density of a density structure in the diffuse ionized ISM has been indicated in earlier theoretical (Fleck 1996;Elmegreen 1999) and numerical (Elmegreen 1997; studies, as well as in observations (Gaustad & van Buren 1993;Berkhuijsen et al 2006;Berkhuijsen & Müller 2008). Moreover, observations also suggest that the correlation becomes considerably steeper at low latitudes than in the diffuse ionized gas away from the Galactic plane (Berkhuijsen & Müller 2008).…”

Section: Introductionmentioning

confidence: 55%

Scatter Broadening of Pulsars and Implications on the Interstellar Medium Turbulence

Zhang

2017

ApJ

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Observations reveal a uniform Kolmogorov turbulence throughout the diffuse ionized interstellar medium (ISM) and supersonic turbulence preferentially located in the Galactic plane. Correspondingly, we consider the Galactic distribution of electron density fluctuations consisting of not only a Kolmogorov density spectrum but also a short-wave-dominated density spectrum with the density structure formed at small scales due to shocks. The resulting dependence of the scatter broadening time on the dispersion measure (DM) naturally interprets the existing observational data for both low and high-DM pulsars. According to the criteria that we derive for a quantitative determination of scattering regimes over wide ranges of DMs and frequencies ν, we find that the pulsars with low DMs are primarily scattered by the Kolmogorov turbulence, while those at low Galactic latitudes with high DMs undergo more enhanced scattering dominated by the supersonic turbulence, where the corresponding density spectrum has a spectral index ≈ 2.6. Besides, by considering a volume filling factor of the density structures with the dependence on ν as ∝ ν 1.4 in the supersonic turbulence, our model can also explain the observed shallower ν scaling of the scattering time than the Kolmogorov scaling for the pulsars with relatively large DMs. The comparison between our analytical results and the scattering measurements of pulsars in turn makes a useful probe of the properties of the large-scale ISM turbulence, e.g., an injection scale of ∼ 100 pc, and also characteristics of small-scale density structures.

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The distribution of interstellar dust in the solar neighborhood

Cited by 37 publications

References 17 publications

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

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

Probability distribution functions of gas in M31 and M51

Scatter Broadening of Pulsars and Implications on the Interstellar Medium Turbulence

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