Star formation in NGC 5194 (M51a). II. The spatially resolved star formation law

Robert C. Kennicutt; Daniela Calzeti; Fabian Walter; George Helou; David J. Hollenbach; Lee Armus; George Bendo; Daniel A. Dale; Bruce T. Draine; Charles W. Engelbracht; Karl D. Gordon; Moire K.M. Prescott; Michael W. Regan; Michele D. Thornley; Caroline Bot; Elias Brinks; Erwin De Blok; Dulia De Mello; Martin Meyer; John Moustakas; Eric J. Murphy; Kartik Sheth; J. D.T. Smith

doi:10.1086/522300

Star formation in NGC 5194 (M51a). II. The spatially resolved star formation law

Robert C. Kennicutt^*, Daniela Calzeti, Fabian Walter, George Helou, David J. Hollenbach, Lee Armus, George Bendo, Daniel A. Dale, Bruce T. Draine, Charles W. Engelbracht, Karl D. Gordon, Moire K.M. Prescott, Michael W. Regan, Michele D. Thornley, Caroline Bot, Elias Brinks, Erwin De Blok, Dulia De Mello, Martin Meyer, John MoustakasEric J. Murphy, Kartik Sheth, J. D.T. Smith

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

400 Citations (Scopus)

Abstract

We have studied the relationship between the star formation rate (SFR), surface density, and gas surface density in the spiral galaxy M51a (NGC 5194), using multiwavelength data obtained as part of the Spitzer Infrared Nearby Galaxies Survey (SINGS ). We introduce a new SFR index based on a linear combination of Hα emission-line and 24 μm continuum luminosities, which provides reliable extinction-corrected ionizing fluxes and SFR densities over a wide range of dust attenuations. The combination of these extinction-corrected SFR densities with aperture synthesis H I and CO maps has allowed us to probe the form of the spatially resolved star formation law on scales of 0.5-2 kpc. We find that the resolved SFR versus gas surface density relation is well represented by a Schmidt power law, which is similar in form and dispersion to the disk-averaged Schmidt law. We observe a comparably strong correlation of the SFR surface density with the molecular gas surface density, but no significant correlation with the surface density of atomic gas. The best-fitting slope of the Schmidt law varies from N = 1.37 to 1.56, with zero point and slope that change systematically with the spatial sampling scale. We tentatively attribute these variations to the effects of areal sampling and averaging of a nonlinear intrinsic star formation law. Our data can also be fitted by an alternative parameterization of the SFR surface density in terms of the ratio of gas surface density to local dynamical time, but with a considerable dispersion.

Original language	English
Pages (from-to)	333-348
Number of pages	16
Journal	Astrophysical Journal
Volume	671
Issue number	1
DOIs	https://doi.org/10.1086/522300
Publication status	Published - 10 Dec 2007

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Kennicutt, R. C., Calzeti, D., Walter, F., Helou, G., Hollenbach, D. J., Armus, L., Bendo, G., Dale, D. A., Draine, B. T., Engelbracht, C. W., Gordon, K. D., Prescott, M. K. M., Regan, M. W., Thornley, M. D., Bot, C., Brinks, E., De Blok, E., De Mello, D., Meyer, M., ... Smith, J. D. T. (2007). Star formation in NGC 5194 (M51a). II. The spatially resolved star formation law. Astrophysical Journal, 671(1), 333-348. https://doi.org/10.1086/522300

@article{c4bd730d68f54c799d5b5296a46b9b88,

title = "Star formation in NGC 5194 (M51a). II. The spatially resolved star formation law",

abstract = "We have studied the relationship between the star formation rate (SFR), surface density, and gas surface density in the spiral galaxy M51a (NGC 5194), using multiwavelength data obtained as part of the Spitzer Infrared Nearby Galaxies Survey (SINGS ). We introduce a new SFR index based on a linear combination of Hα emission-line and 24 μm continuum luminosities, which provides reliable extinction-corrected ionizing fluxes and SFR densities over a wide range of dust attenuations. The combination of these extinction-corrected SFR densities with aperture synthesis H I and CO maps has allowed us to probe the form of the spatially resolved star formation law on scales of 0.5-2 kpc. We find that the resolved SFR versus gas surface density relation is well represented by a Schmidt power law, which is similar in form and dispersion to the disk-averaged Schmidt law. We observe a comparably strong correlation of the SFR surface density with the molecular gas surface density, but no significant correlation with the surface density of atomic gas. The best-fitting slope of the Schmidt law varies from N = 1.37 to 1.56, with zero point and slope that change systematically with the spatial sampling scale. We tentatively attribute these variations to the effects of areal sampling and averaging of a nonlinear intrinsic star formation law. Our data can also be fitted by an alternative parameterization of the SFR surface density in terms of the ratio of gas surface density to local dynamical time, but with a considerable dispersion.",

keywords = "Galaxies: ISM, Galaxies: evolution, Galaxies: individual (M51a, NGC 5194), H II regions, Infrared: galaxies, Stars: formation",

author = "Kennicutt, {Robert C.} and Daniela Calzeti and Fabian Walter and George Helou and Hollenbach, {David J.} and Lee Armus and George Bendo and Dale, {Daniel A.} and Draine, {Bruce T.} and Engelbracht, {Charles W.} and Gordon, {Karl D.} and Prescott, {Moire K.M.} and Regan, {Michael W.} and Thornley, {Michele D.} and Caroline Bot and Elias Brinks and {De Blok}, Erwin and {De Mello}, Dulia and Martin Meyer and John Moustakas and Murphy, {Eric J.} and Kartik Sheth and Smith, {J. D.T.}",

year = "2007",

month = dec,

day = "10",

doi = "10.1086/522300",

language = "English",

volume = "671",

pages = "333--348",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

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Kennicutt, RC, Calzeti, D, Walter, F, Helou, G, Hollenbach, DJ, Armus, L, Bendo, G, Dale, DA, Draine, BT, Engelbracht, CW, Gordon, KD, Prescott, MKM, Regan, MW, Thornley, MD, Bot, C, Brinks, E, De Blok, E, De Mello, D, Meyer, M, Moustakas, J, Murphy, EJ, Sheth, K & Smith, JDT 2007, 'Star formation in NGC 5194 (M51a). II. The spatially resolved star formation law', Astrophysical Journal, vol. 671, no. 1, pp. 333-348. https://doi.org/10.1086/522300

TY - JOUR

T1 - Star formation in NGC 5194 (M51a). II. The spatially resolved star formation law

AU - Kennicutt, Robert C.

AU - Calzeti, Daniela

AU - Walter, Fabian

AU - Helou, George

AU - Hollenbach, David J.

AU - Armus, Lee

AU - Bendo, George

AU - Dale, Daniel A.

AU - Draine, Bruce T.

AU - Engelbracht, Charles W.

AU - Gordon, Karl D.

AU - Prescott, Moire K.M.

AU - Regan, Michael W.

AU - Thornley, Michele D.

AU - Bot, Caroline

AU - Brinks, Elias

AU - De Blok, Erwin

AU - De Mello, Dulia

AU - Meyer, Martin

AU - Moustakas, John

AU - Murphy, Eric J.

AU - Sheth, Kartik

AU - Smith, J. D.T.

PY - 2007/12/10

Y1 - 2007/12/10

N2 - We have studied the relationship between the star formation rate (SFR), surface density, and gas surface density in the spiral galaxy M51a (NGC 5194), using multiwavelength data obtained as part of the Spitzer Infrared Nearby Galaxies Survey (SINGS ). We introduce a new SFR index based on a linear combination of Hα emission-line and 24 μm continuum luminosities, which provides reliable extinction-corrected ionizing fluxes and SFR densities over a wide range of dust attenuations. The combination of these extinction-corrected SFR densities with aperture synthesis H I and CO maps has allowed us to probe the form of the spatially resolved star formation law on scales of 0.5-2 kpc. We find that the resolved SFR versus gas surface density relation is well represented by a Schmidt power law, which is similar in form and dispersion to the disk-averaged Schmidt law. We observe a comparably strong correlation of the SFR surface density with the molecular gas surface density, but no significant correlation with the surface density of atomic gas. The best-fitting slope of the Schmidt law varies from N = 1.37 to 1.56, with zero point and slope that change systematically with the spatial sampling scale. We tentatively attribute these variations to the effects of areal sampling and averaging of a nonlinear intrinsic star formation law. Our data can also be fitted by an alternative parameterization of the SFR surface density in terms of the ratio of gas surface density to local dynamical time, but with a considerable dispersion.

AB - We have studied the relationship between the star formation rate (SFR), surface density, and gas surface density in the spiral galaxy M51a (NGC 5194), using multiwavelength data obtained as part of the Spitzer Infrared Nearby Galaxies Survey (SINGS ). We introduce a new SFR index based on a linear combination of Hα emission-line and 24 μm continuum luminosities, which provides reliable extinction-corrected ionizing fluxes and SFR densities over a wide range of dust attenuations. The combination of these extinction-corrected SFR densities with aperture synthesis H I and CO maps has allowed us to probe the form of the spatially resolved star formation law on scales of 0.5-2 kpc. We find that the resolved SFR versus gas surface density relation is well represented by a Schmidt power law, which is similar in form and dispersion to the disk-averaged Schmidt law. We observe a comparably strong correlation of the SFR surface density with the molecular gas surface density, but no significant correlation with the surface density of atomic gas. The best-fitting slope of the Schmidt law varies from N = 1.37 to 1.56, with zero point and slope that change systematically with the spatial sampling scale. We tentatively attribute these variations to the effects of areal sampling and averaging of a nonlinear intrinsic star formation law. Our data can also be fitted by an alternative parameterization of the SFR surface density in terms of the ratio of gas surface density to local dynamical time, but with a considerable dispersion.

KW - Galaxies: ISM

KW - Galaxies: evolution

KW - Galaxies: individual (M51a, NGC 5194)

KW - H II regions

KW - Infrared: galaxies

KW - Stars: formation

UR - http://www.scopus.com/inward/record.url?scp=40249085653&partnerID=8YFLogxK

U2 - 10.1086/522300

DO - 10.1086/522300

M3 - Article

SN - 0004-637X

VL - 671

SP - 333

EP - 348

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

ER -

Star formation in NGC 5194 (M51a). II. The spatially resolved star formation law

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