Star formation rates in resolved galaxies: Calibrations with near- and far-infrared data for NGC 5055 and NGC 6946

Yiming Li; Alison F. Crocker; Daniela Calzetti; Christine D. Wilson; Robert C. Kennicutt; Eric J. Murphy; Bernhard R. Brandl; B. T. Draine; M. Galametz; B. D. Johnson; L. Armus; K. D. Gordon; K. Croxall; D. A. Dale; C. W. Engelbracht; B. Groves; C. N. Hao; G. Helou; J. Hinz; L. K. Hunt; O. Krause; H. Roussel; M. Sauvage; J. D.T. Smith

doi:10.1088/0004-637X/768/2/180

Star formation rates in resolved galaxies: Calibrations with near- and far-infrared data for NGC 5055 and NGC 6946

Yiming Li, Alison F. Crocker, Daniela Calzetti, Christine D. Wilson, Robert C. Kennicutt, Eric J. Murphy, Bernhard R. Brandl, B. T. Draine, M. Galametz, B. D. Johnson, L. Armus, K. D. Gordon, K. Croxall, D. A. Dale, C. W. Engelbracht, B. Groves, C. N. Hao, G. Helou, J. Hinz, L. K. HuntO. Krause, H. Roussel, M. Sauvage, J. D.T. Smith

Astrophysical Sciences

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Abstract

We use the near-infrared Brγ hydrogen recombination line as a reference star formation rate (SFR) indicator to test the validity and establish the calibration of the Herschel/PACS 70 μm emission as a SFR tracer for sub-galactic regions in external galaxies. Brγ offers the double advantage of directly tracing ionizing photons and of being relatively insensitive to the effects of dust attenuation. For our first experiment, we use archival Canada-France-Hawaii Telescope Brγ and Ks images of two nearby galaxies: NGC 5055 and NGC 6946, which are also part of the Herschel program KINGFISH (Key Insights on Nearby Galaxies: a Far-Infrared Survey with Herschel). We use the extinction corrected Brγ emission to derive the SFR(70) calibration for H II regions in these two galaxies. A comparison of the SFR(70) calibrations at different spatial scales, from 200 pc to the size of the whole galaxy, reveals that about 50% of the total 70 μm emission is due to dust heated by stellar populations that are unrelated to the current star formation. We use a simple model to qualitatively relate the increase of the SFR(70) calibration coefficient with decreasing region size to the star formation timescale. We provide a calibration for an unbiased SFR indicator that combines the observed Hα with the 70 μm emission, also for use in H II regions. We briefly analyze the PACS 100 and 160 μm maps and find that longer wavelengths are not as good SFR indicators as 70 μm, in agreement with previous results. We find that the calibrations show about 50% difference between the two galaxies, possibly due to effects of inclination.

Original language	English (US)
Article number	180
Journal	Astrophysical Journal
Volume	768
Issue number	2
DOIs	https://doi.org/10.1088/0004-637X/768/2/180
State	Published - May 10 2013

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

Keywords

Hii regions
ISM: structure
galaxies: ISM
infrared: ISM
infrared: galaxies

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10.1088/0004-637X/768/2/180

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Li, Y., Crocker, A. F., Calzetti, D., Wilson, C. D., Kennicutt, R. C., Murphy, E. J., Brandl, B. R., Draine, B. T., Galametz, M., Johnson, B. D., Armus, L., Gordon, K. D., Croxall, K., Dale, D. A., Engelbracht, C. W., Groves, B., Hao, C. N., Helou, G., Hinz, J., ... Smith, J. D. T. (2013). Star formation rates in resolved galaxies: Calibrations with near- and far-infrared data for NGC 5055 and NGC 6946. Astrophysical Journal, 768(2), Article 180. https://doi.org/10.1088/0004-637X/768/2/180

@article{831f5802c9db47a4865ef8c694c4b414,

title = "Star formation rates in resolved galaxies: Calibrations with near- and far-infrared data for NGC 5055 and NGC 6946",

abstract = "We use the near-infrared Brγ hydrogen recombination line as a reference star formation rate (SFR) indicator to test the validity and establish the calibration of the Herschel/PACS 70 μm emission as a SFR tracer for sub-galactic regions in external galaxies. Brγ offers the double advantage of directly tracing ionizing photons and of being relatively insensitive to the effects of dust attenuation. For our first experiment, we use archival Canada-France-Hawaii Telescope Brγ and Ks images of two nearby galaxies: NGC 5055 and NGC 6946, which are also part of the Herschel program KINGFISH (Key Insights on Nearby Galaxies: a Far-Infrared Survey with Herschel). We use the extinction corrected Brγ emission to derive the SFR(70) calibration for H II regions in these two galaxies. A comparison of the SFR(70) calibrations at different spatial scales, from 200 pc to the size of the whole galaxy, reveals that about 50% of the total 70 μm emission is due to dust heated by stellar populations that are unrelated to the current star formation. We use a simple model to qualitatively relate the increase of the SFR(70) calibration coefficient with decreasing region size to the star formation timescale. We provide a calibration for an unbiased SFR indicator that combines the observed Hα with the 70 μm emission, also for use in H II regions. We briefly analyze the PACS 100 and 160 μm maps and find that longer wavelengths are not as good SFR indicators as 70 μm, in agreement with previous results. We find that the calibrations show about 50% difference between the two galaxies, possibly due to effects of inclination.",

keywords = "Hii regions, ISM: structure, galaxies: ISM, infrared: ISM, infrared: galaxies",

author = "Yiming Li and Crocker, {Alison F.} and Daniela Calzetti and Wilson, {Christine D.} and Kennicutt, {Robert C.} and Murphy, {Eric J.} and Brandl, {Bernhard R.} and Draine, {B. T.} and M. Galametz and Johnson, {B. D.} and L. Armus and Gordon, {K. D.} and K. Croxall and Dale, {D. A.} and Engelbracht, {C. W.} and B. Groves and Hao, {C. N.} and G. Helou and J. Hinz and Hunt, {L. K.} and O. Krause and H. Roussel and M. Sauvage and Smith, {J. D.T.}",

year = "2013",

month = may,

day = "10",

doi = "10.1088/0004-637X/768/2/180",

language = "English (US)",

volume = "768",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "IOP Publishing Ltd.",

number = "2",

}

Li, Y, Crocker, AF, Calzetti, D, Wilson, CD, Kennicutt, RC, Murphy, EJ, Brandl, BR, Draine, BT, Galametz, M, Johnson, BD, Armus, L, Gordon, KD, Croxall, K, Dale, DA, Engelbracht, CW, Groves, B, Hao, CN, Helou, G, Hinz, J, Hunt, LK, Krause, O, Roussel, H, Sauvage, M & Smith, JDT 2013, 'Star formation rates in resolved galaxies: Calibrations with near- and far-infrared data for NGC 5055 and NGC 6946', Astrophysical Journal, vol. 768, no. 2, 180. https://doi.org/10.1088/0004-637X/768/2/180

TY - JOUR

T1 - Star formation rates in resolved galaxies

T2 - Calibrations with near- and far-infrared data for NGC 5055 and NGC 6946

AU - Li, Yiming

AU - Crocker, Alison F.

AU - Calzetti, Daniela

AU - Wilson, Christine D.

AU - Kennicutt, Robert C.

AU - Murphy, Eric J.

AU - Brandl, Bernhard R.

AU - Draine, B. T.

AU - Galametz, M.

AU - Johnson, B. D.

AU - Armus, L.

AU - Gordon, K. D.

AU - Croxall, K.

AU - Dale, D. A.

AU - Engelbracht, C. W.

AU - Groves, B.

AU - Hao, C. N.

AU - Helou, G.

AU - Hinz, J.

AU - Hunt, L. K.

AU - Krause, O.

AU - Roussel, H.

AU - Sauvage, M.

AU - Smith, J. D.T.

PY - 2013/5/10

Y1 - 2013/5/10

N2 - We use the near-infrared Brγ hydrogen recombination line as a reference star formation rate (SFR) indicator to test the validity and establish the calibration of the Herschel/PACS 70 μm emission as a SFR tracer for sub-galactic regions in external galaxies. Brγ offers the double advantage of directly tracing ionizing photons and of being relatively insensitive to the effects of dust attenuation. For our first experiment, we use archival Canada-France-Hawaii Telescope Brγ and Ks images of two nearby galaxies: NGC 5055 and NGC 6946, which are also part of the Herschel program KINGFISH (Key Insights on Nearby Galaxies: a Far-Infrared Survey with Herschel). We use the extinction corrected Brγ emission to derive the SFR(70) calibration for H II regions in these two galaxies. A comparison of the SFR(70) calibrations at different spatial scales, from 200 pc to the size of the whole galaxy, reveals that about 50% of the total 70 μm emission is due to dust heated by stellar populations that are unrelated to the current star formation. We use a simple model to qualitatively relate the increase of the SFR(70) calibration coefficient with decreasing region size to the star formation timescale. We provide a calibration for an unbiased SFR indicator that combines the observed Hα with the 70 μm emission, also for use in H II regions. We briefly analyze the PACS 100 and 160 μm maps and find that longer wavelengths are not as good SFR indicators as 70 μm, in agreement with previous results. We find that the calibrations show about 50% difference between the two galaxies, possibly due to effects of inclination.

AB - We use the near-infrared Brγ hydrogen recombination line as a reference star formation rate (SFR) indicator to test the validity and establish the calibration of the Herschel/PACS 70 μm emission as a SFR tracer for sub-galactic regions in external galaxies. Brγ offers the double advantage of directly tracing ionizing photons and of being relatively insensitive to the effects of dust attenuation. For our first experiment, we use archival Canada-France-Hawaii Telescope Brγ and Ks images of two nearby galaxies: NGC 5055 and NGC 6946, which are also part of the Herschel program KINGFISH (Key Insights on Nearby Galaxies: a Far-Infrared Survey with Herschel). We use the extinction corrected Brγ emission to derive the SFR(70) calibration for H II regions in these two galaxies. A comparison of the SFR(70) calibrations at different spatial scales, from 200 pc to the size of the whole galaxy, reveals that about 50% of the total 70 μm emission is due to dust heated by stellar populations that are unrelated to the current star formation. We use a simple model to qualitatively relate the increase of the SFR(70) calibration coefficient with decreasing region size to the star formation timescale. We provide a calibration for an unbiased SFR indicator that combines the observed Hα with the 70 μm emission, also for use in H II regions. We briefly analyze the PACS 100 and 160 μm maps and find that longer wavelengths are not as good SFR indicators as 70 μm, in agreement with previous results. We find that the calibrations show about 50% difference between the two galaxies, possibly due to effects of inclination.

KW - Hii regions

KW - ISM: structure

KW - galaxies: ISM

KW - infrared: ISM

KW - infrared: galaxies

UR - http://www.scopus.com/inward/record.url?scp=84877045056&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84877045056&partnerID=8YFLogxK

U2 - 10.1088/0004-637X/768/2/180

DO - 10.1088/0004-637X/768/2/180

M3 - Article

AN - SCOPUS:84877045056

SN - 0004-637X

VL - 768

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2

M1 - 180

ER -

Star formation rates in resolved galaxies: Calibrations with near- and far-infrared data for NGC 5055 and NGC 6946

Abstract

All Science Journal Classification (ASJC) codes

Keywords

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