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Carma survey toward infrared-bright nearby galaxies (STING): Molecular gas star formation law in NGC 4254

Rahman, N.; Bolatto, Alberto; Wong, T; Leroy, Adam K.; Walter, Fabian; Rosolowsky, Erik; West, Andrew A.; Bigiel, Frank; Ott, Juergen; Xue, Rui; Jameson, Katherine

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This study explores the effects of different assumptions and systematics on the determination of the local, spatially resolved star formation law. Using four star formation rate (SFR) tracers (Hα with azimuthally averaged extinction correction, mid-infrared 24 μm, combined Hα and mid-infrared 24 μm, and combined far-ultraviolet and mid-infrared 24 μm), several fitting procedures, and different sampling strategies, we probe the relation between SFR and molecular gas at various spatial...[Show more]

dc.contributor.authorRahman, N.
dc.contributor.authorBolatto, Alberto
dc.contributor.authorWong, T
dc.contributor.authorLeroy, Adam K.
dc.contributor.authorWalter, Fabian
dc.contributor.authorRosolowsky, Erik
dc.contributor.authorWest, Andrew A.
dc.contributor.authorBigiel, Frank
dc.contributor.authorOtt, Juergen
dc.contributor.authorXue, Rui
dc.contributor.authorJameson, Katherine
dc.date.accessioned2018-11-29T22:52:40Z
dc.date.available2018-11-29T22:52:40Z
dc.identifier.issn0004-637X
dc.identifier.urihttp://hdl.handle.net/1885/152241
dc.description.abstractThis study explores the effects of different assumptions and systematics on the determination of the local, spatially resolved star formation law. Using four star formation rate (SFR) tracers (Hα with azimuthally averaged extinction correction, mid-infrared 24 μm, combined Hα and mid-infrared 24 μm, and combined far-ultraviolet and mid-infrared 24 μm), several fitting procedures, and different sampling strategies, we probe the relation between SFR and molecular gas at various spatial resolutions (500 pc and larger) and surface densities ($\hbox{$\Sigma _{{\rm H}_2}$}\approx 10\hbox{--}245$ M ☉ pc–2) within the central ~6.5 kpc in the disk of NGC 4254. We explore the effect of diffuse emission using an unsharp masking technique with varying kernel size. The fraction of diffuse emission, f DE, thus determined is a strong inverse function of the size of the filtering kernel. We find that in the high surface brightness regions of NGC 4254 the form of the molecular gas star formation law is robustly determined and approximately linear (~0.8-1.1) and independent of the assumed fraction of diffuse emission and the SFR tracer employed. When the low surface brightness regions are included, the slope of the star formation law depends primarily on the assumed fraction of diffuse emission. In such a case, results range from linear when the fraction of diffuse emission in the SFR tracer is f DE lesssim 30% (or when diffuse emission is removed in both the star formation and the molecular gas tracer) to super-linear (~1.4) when f DE gsim 50%. We find that the tightness of the correlation between gas and star formation varies with the choice of star formation tracer. The 24 μm SFR tracer by itself shows the tightest correlation with the molecular gas surface density, whereas the Hα corrected for extinction using an azimuthally averaged correction shows the highest dispersion. We find that for R < 0.5R 25 the local star formation efficiency is constant and similar to that observed in other large spirals, with a molecular gas depletion time τdep ~ 2 Gyr.
dc.format.mimetypeapplication/pdf
dc.publisherIOP Publishing
dc.sourceThe Astrophysical Journal
dc.titleCarma survey toward infrared-bright nearby galaxies (STING): Molecular gas star formation law in NGC 4254
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume730
dc.date.issued2011
local.identifier.absfor020199 - Astronomical and Space Sciences not elsewhere classified
local.identifier.ariespublicationu4351680xPUB114
local.type.statusPublished Version
local.contributor.affiliationRahman, N., University of Maryland
local.contributor.affiliationBolatto, Alberto, University of Maryland
local.contributor.affiliationWong, T, University of Illinois
local.contributor.affiliationLeroy, Adam K., National Radio Astronomy Observatory
local.contributor.affiliationWalter, Fabian, Max Planck Institute for Astronomy
local.contributor.affiliationRosolowsky, Erik, University of British Columbia
local.contributor.affiliationWest, Andrew A., Boston University
local.contributor.affiliationBigiel, Frank, University of California
local.contributor.affiliationOtt, Juergen, National Radio Astronomy Observatory
local.contributor.affiliationXue, Rui, University of Illinois
local.contributor.affiliationJameson, Katherine, College of Science, ANU
local.bibliographicCitation.issue2
local.identifier.doi10.1088/0004-637X/730/2/72
dc.date.updated2018-11-29T07:47:36Z
local.identifier.scopusID2-s2.0-79953689951
local.identifier.thomsonID000288441900012
dcterms.accessRightsOpen Access
CollectionsANU Research Publications

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