Astronomy and Astrophysics – Astrophysics – Cosmology and Extragalactic Astrophysics
Scientific paper
2011-04-20
Astronomy and Astrophysics
Astrophysics
Cosmology and Extragalactic Astrophysics
21 pages, 9 figures, 4 tables, accepted for publication in ApJ
Scientific paper
We have conducted interferometric observations with CARMA and an OTF mapping with the 45-m telescope at NRO in the CO (J=1-0) emission line of NGC 3521. Combining these new data, together with CARMA+NRO45 data for M51a and archival SINGS H$\alpha$, 24$\mu$m, THINGS H I and GALEX FUV data for both galaxies, we investigate the empirical scaling law that connects the surface density of SFR and cold gas (the Schmidt-Kennicutt law) on a spatially-resolved basis. We argue that plausibly deriving SFR maps of nearby galaxies requires the diffuse stellar/dust background emission to be carefully subtracted. An approach to complete this task is presented and applied in our pixel-by-pixel analysis on both galaxies, showing that the controversial results whether the molecular S-K law is super-linear or basically linear is a result of removing or preserving the local background. In both galaxies, the power index of the molecular S-K law is 1.5-1.9 at the highest available resolution (230 pc), and decreases monotonically for decreasing resolution; while the scatter (mainly intrinsic) increases as the resolution becomes higher, indicating a trend for which the S-K law breaks down below some scale. Both quantities are systematically larger in M51a than in NGC 3521, but when plotted against the de-projected scale (\delta_{dp}), they become highly consistent between the two galaxies, tentatively suggesting that the sub-kpc molecular S-K law in spiral galaxies depends only on the considered scale, without varying amongst spiral galaxies. A logarithmic function \gamma_{H_2}=-1.1 log[\delta_{dp}/kpc]+1.4 and a linear relation \sigma_{H_2}=-0.2 [\delta_{dp}/kpc]+0.7 are obtained through fitting to the M51a data, which describes both galaxies impressively well on sub-kpc scales. A larger sample of galaxies with better quality data are required to test the general applicability of these relations.
Calzetti Daniela
Fukuhara Masayuki
Koda Jin
Liu Guilin
Momose Rieko
No associations
LandOfFree
The Super-linear Slope of the Spatially-Resolved Star Formation Law in NGC 3521 and NGC 5194 (M51a) 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 Super-linear Slope of the Spatially-Resolved Star Formation Law in NGC 3521 and NGC 5194 (M51a), we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Super-linear Slope of the Spatially-Resolved Star Formation Law in NGC 3521 and NGC 5194 (M51a) will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-177561