The Herschel Virgo Cluster Survey. IX. Dust-to-gas mass ratio and metallicity gradients in four Virgo spiral galaxies

Details The Herschel Virgo Cluster Survey. IX. Dust-to-gas mass ratio and metallicity gradients in four Virgo spiral galaxies The Herschel Virgo Cluster Survey. IX. Dust-to-gas mass ratio and metallicity gradients in four Virgo spiral galaxies

2011-06-03

arxiv.org/abs/1106.0618v2

Astronomy and Astrophysics

Astrophysics

Cosmology and Extragalactic Astrophysics

13 pages, 8 figures, A&A accepted

Scientific paper

Using Herschel data from the Open Time Key Project the Herschel Virgo Cluster Survey (HeViCS), we investigated the relationship between the metallicity gradients expressed by metal abundances in the gas phase as traced by the chemical composition of HII regions, and in the solid phase, as traced by the dust-to-gas mass ratio. We derived the radial gradient of the dust-to-gas mass ratio for all galaxies observed by HeViCS whose metallicity gradients are available in the literature. They are all late type Sbc galaxies, namely NGC4254, NGC4303, NGC4321, and NGC4501. We examined different dependencies on metallicity of the CO-to-H$_2$ conversion factor (\xco), used to transform the $^{12}$CO observations into the amount of molecular hydrogen. We found that in these galaxies the dust-to-gas mass ratio radial profile is extremely sensitive to choice of the \xco\ value, since the molecular gas is the dominant component in the inner parts. We found that for three galaxies of our sample, namely NGC4254, NGC4321, and NGC4501, the slopes of the oxygen and of the dust-to-gas radial gradients agree up to $\sim$0.6-0.7R$_{25}$ using \xco\ values in the range 1/3-1/2 Galactic \xco. For NGC4303 a lower value of \xco$\sim0.1\times$ 10$^{20}$ is necessary. We suggest that such low \xco\ values might be due to a metallicity dependence of \xco (from close to linear for NGC4254, NGC4321, and NGC4501 to superlinear for NGC4303), especially in the radial regions R$_G<$0.6-0.7R$_{25}$ where the molecular gas dominates. On the other hand, the outer regions, where the atomic gas component is dominant, are less affected by the choice of \xco, and thus we cannot put constraints on its value.

Affiliated with

Also associated with

No associations

Rating

The Herschel Virgo Cluster Survey. IX. Dust-to-gas mass ratio and metallicity gradients in four Virgo spiral galaxies does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with The Herschel Virgo Cluster Survey. IX. Dust-to-gas mass ratio and metallicity gradients in four Virgo spiral galaxies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Herschel Virgo Cluster Survey. IX. Dust-to-gas mass ratio and metallicity gradients in four Virgo spiral galaxies will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-223762