The Volume Densities of Giant Molecular Clouds in M81

Heiner, J. S.; Allen, R. J.; Emonts, Bjorn; Kruit, P.

doi:10.1086/524131

Cited by 22 publications

(46 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(1). By adopting the observed mean ICM density of 3 × 10 −2 cm −3 (Perseus cluster center; Churazov et al 2003) and a typical cold cloud density of 10 cm −3 (e.g., Heiner et al 2008), the required interaction volume was obtained and plotted in Fig. 1d as a function of temperature and velocity.…”

Section: Comparison With the Ulf Observationsmentioning

confidence: 99%

A novel scenario for the possible X-ray line feature at ~3.5 keV

Kaastra

Raassen

et al. 2015

A&A

View full text Add to dashboard Cite

Motivated by recent claims of a compelling ∼3.5 keV emission line from nearby galaxies and galaxy clusters, we investigate a novel plasma model incorporating a charge exchange component obtained from theoretical scattering calculations. Fitting this kind of component with a standard thermal model yields positive residuals around 3.5 keV, produced mostly by S xvi transitions from principal quantum numbers n ≥ 9 to the ground. Such high-n states can only be populated by the charge exchange process. In this scenario, the observed 3.5 keV line flux in clusters can be naturally explained by an interaction in an effective volume of ∼1 kpc 3 between a ∼3 keV temperature plasma and cold dense clouds moving at a few hundred keV −1 . The S xvi lines at ∼3.5 keV also provide a unique diagnostic of the charge exchange phenomenon in hot cosmic plasmas.

show abstract

Section: Comparison With the Ulf Observationsmentioning

confidence: 99%

A novel scenario for the possible X-ray line feature at ~3.5 keV

Kaastra

Raassen

et al. 2015

A&A

View full text Add to dashboard Cite

show abstract

“…Using the approach outlined in Heiner et al (2008a), we investigate the presence of candidate PDRs near the detected CO J = 3−2 emission. While Heiner et al selected the brightest FUV regions in the galaxy, we used our CO detections as reference points to locate the nearby peaks of UV emission and H i patches.…”

Section: Analysis Of Candidate Pdrsmentioning

confidence: 99%

“…The method applied was explained in depth in Heiner et al (2008a). However, for the sake of clarity, we include here a short explanation of the main steps.…”

Section: Analysis Of Candidate Pdrsmentioning

confidence: 99%

“…At the core of the GMC, we can then expect that n = 2n H 2 . The parameters used here are the same as in Heiner et al (2008a), except for the extinction (A FUV = 7.9×E(B−V) = 0.63, Gil de Paz et al 2007; with E(B − V) = 0.080 Schlegel et al 1998) and the calibration of the δ/δ 0 relation (log(δ/δ 0 ) = −0.045 × R gal + 0.31, now using an updated value of solar metallicity, Allende Prieto et al 2001). We used the distance referred to in Table 1.…”

Section: Analysis Of Candidate Pdrsmentioning

confidence: 99%

“…A description of the main results obtained, including a detailed comparison of the selected regions through different wavelengths, is given in Sect. 3 and a comparison with the photo-dissociation regions (PDRs) method of Heiner et al (2008a) in Sect. 4.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The JCMT Nearby Galaxies Legacy Survey

Sánchez-Gallego¹,

Knapen²,

Heiner³

et al. 2011

A&A

View full text Add to dashboard Cite

We present the first complete 12 CO J = 3−2 map of M 81, observed as part of the Nearby Galaxies Legacy Survey being carried out at the James Clerk Maxwell Telescope. We detect nine regions of significant CO emission located at different positions within the spiral arms, and confirm that the global CO emission in the galaxy is low. We combine these data with a new Hα map obtained using the Isaac Newton Telescope and archival H i, 24 μm, and FUV images to uncover a correlation between the molecular gas and star forming regions in M 81. For the nine regions detected in CO J = 3−2, we combine our CO J = 3−2 data with existing CO J = 1−0 data to calculate line ratios. We find that the ratio J = (3−2)/(1−0) is in agreement with the range of typical values found in the literature (0.2−0.8). Making reasonable assumptions, this allows us to constrain the hydrogen density to the range (10 3 −10 4 ) cm −3 . We also estimated the amount of hydrogen produced in photo-dissociation regions near the locations where CO J = 3−2 was detected.

show abstract

The opacity of spiral galaxy disks: IX. Dust and gas surface densities

Holwerda¹,

Allen²,

Blok³

et al. 2013

Astron Nachr

View full text Add to dashboard Cite

Our aim is to explore the relation between gas, atomic and molecular, and dust in spiral galaxies. Gas surface densities are from atomic hydrogen and CO line emission maps. To estimate the dust content, we use the disk opacity as inferred from the number of distant galaxies identified in twelve HST/WFPC2 fields of ten nearby spiral galaxies. The observed number of distant galaxies is calibrated for source confusion and crowding with artificial galaxy counts and here we verify our results with sub-mm surface brightnesses from archival Herschel-SPIRE data. We find that the opacity of the spiral disk does not correlate well with the surface density of atomic (H I) or molecular hydrogen (H2) alone implying that dust is not only associated with the molecular clouds but also the diffuse atomic disk in these galaxies. Our result is a typical dust-to-gas ratio of 0.04, with some evidence that this ratio declines with galactocentric radius, consistent with recent Herschel results. We discuss the possible causes of this high dust-to-gas ratio; an over-estimate of the dust surface-density, an under-estimate of the molecular hydrogen density from CO maps or a combination of both. We note that while our value of the mean dust-to-gas ratio is high, it is consistent with the metallicity at the measured radii if one assumes the Pilyugin & Thuan (2005) calibration of gas metallicity.

show abstract

The Volume Densities of Giant Molecular Clouds in M81

Cited by 22 publications

References 46 publications

A novel scenario for the possible X-ray line feature at ~3.5 keV

A novel scenario for the possible X-ray line feature at ~3.5 keV

The JCMT Nearby Galaxies Legacy Survey

The opacity of spiral galaxy disks: IX. Dust and gas surface densities

Contact Info

Product

Resources

About