The radial distribution of the interstellar medium in disk galaxies

Evidence for secular evolution

Michael W. Regan, Michele D. Thornley, Stuart N. Vogel, Kartik Sheth, Bruce T. Draine, David J. Hollenbach, Martin Meyer, Daniel A. Dale, Charles W. Engelbracht, Robert C. Kennicutt, Armus Lee, Brent Buckalew, Daniela Calzetti, Karl D. Gordon, George Helou, Claus Leitherer, Sangeeta Malhotra, Eric Murphy, George H. Rieke, Marcia J Rieke & 1 others J. D. Smith

Research output: Contribution to journalArticle

49 Citations (Scopus)

Abstract

One possible way for spiral galaxies to internally evolve would be for gas to flow to the center and form stars in a central disk (pseudo-bulge). If the inflow rate is faster than the rate of star formation, a central concentration of gas will form. In this paper we present radial profiles of stellar and 8 μm emission from polycyclic aromatic hydrocarbons (PAHs) for 11 spiral galaxies to investigate whether the interstellar medium in these galaxies contains a central concentration above that expected from the exponential disk. In general, we find that the two-dimensional CO and PAH emission morphologies are similar, and that they exhibit similar radial profiles. We find that in 6 of the 11 galaxies there is a central excess in the 8 μm and CO emission above the inward extrapolation of an exponential disk. In particular, all four barred galaxies in the sample have strong central excesses in both 8 μm and CO emission. These correlations suggest that the excess seen in the CO profiles is, in general, not simply due to a radial increase in the CO emissivity. In the inner disk, the ratio of the stellar to the 8 μm radial surface brightness is similar for 9 of the 11 galaxies, suggesting a physical connection between the average stellar surface brightness and the average gas surface brightness at a given radius. We also find that the ratio of the CO to 8 μm PAH surface brightness is consistent over the sample, implying that the 8 μm PAH surface brightness can be used as an approximate tracer of the interstellar medium.

Original languageEnglish (US)
Pages (from-to)1112-1121
Number of pages10
JournalAstrophysical Journal
Volume652
Issue number2 I
DOIs
StatePublished - Dec 1 2006

Fingerprint

disk galaxies
radial distribution
polycyclic aromatic hydrocarbons
brightness
PAH
spiral galaxies
galaxies
profiles
gases
gas
barred galaxies
emissivity
tracers
star formation
extrapolation
inflow
tracer
distribution
stars
radii

Keywords

  • Dust, extinction
  • Galaxies: individual (NGC 628, NGC 3351, NGC 3521, NGC 3627, NGC 4321, NGC 4736, NGC 4826, NGC 5055, NGC 5194, NGC 6946, NGC 7331)
  • Galaxies: ISM
  • Galaxies: structure
  • Infrared: galaxies

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Regan, M. W., Thornley, M. D., Vogel, S. N., Sheth, K., Draine, B. T., Hollenbach, D. J., ... Smith, J. D. (2006). The radial distribution of the interstellar medium in disk galaxies: Evidence for secular evolution. Astrophysical Journal, 652(2 I), 1112-1121. https://doi.org/10.1086/505382

The radial distribution of the interstellar medium in disk galaxies : Evidence for secular evolution. / Regan, Michael W.; Thornley, Michele D.; Vogel, Stuart N.; Sheth, Kartik; Draine, Bruce T.; Hollenbach, David J.; Meyer, Martin; Dale, Daniel A.; Engelbracht, Charles W.; Kennicutt, Robert C.; Lee, Armus; Buckalew, Brent; Calzetti, Daniela; Gordon, Karl D.; Helou, George; Leitherer, Claus; Malhotra, Sangeeta; Murphy, Eric; Rieke, George H.; Rieke, Marcia J; Smith, J. D.

In: Astrophysical Journal, Vol. 652, No. 2 I, 01.12.2006, p. 1112-1121.

Research output: Contribution to journalArticle

Regan, MW, Thornley, MD, Vogel, SN, Sheth, K, Draine, BT, Hollenbach, DJ, Meyer, M, Dale, DA, Engelbracht, CW, Kennicutt, RC, Lee, A, Buckalew, B, Calzetti, D, Gordon, KD, Helou, G, Leitherer, C, Malhotra, S, Murphy, E, Rieke, GH, Rieke, MJ & Smith, JD 2006, 'The radial distribution of the interstellar medium in disk galaxies: Evidence for secular evolution', Astrophysical Journal, vol. 652, no. 2 I, pp. 1112-1121. https://doi.org/10.1086/505382
Regan MW, Thornley MD, Vogel SN, Sheth K, Draine BT, Hollenbach DJ et al. The radial distribution of the interstellar medium in disk galaxies: Evidence for secular evolution. Astrophysical Journal. 2006 Dec 1;652(2 I):1112-1121. https://doi.org/10.1086/505382
Regan, Michael W. ; Thornley, Michele D. ; Vogel, Stuart N. ; Sheth, Kartik ; Draine, Bruce T. ; Hollenbach, David J. ; Meyer, Martin ; Dale, Daniel A. ; Engelbracht, Charles W. ; Kennicutt, Robert C. ; Lee, Armus ; Buckalew, Brent ; Calzetti, Daniela ; Gordon, Karl D. ; Helou, George ; Leitherer, Claus ; Malhotra, Sangeeta ; Murphy, Eric ; Rieke, George H. ; Rieke, Marcia J ; Smith, J. D. / The radial distribution of the interstellar medium in disk galaxies : Evidence for secular evolution. In: Astrophysical Journal. 2006 ; Vol. 652, No. 2 I. pp. 1112-1121.
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abstract = "One possible way for spiral galaxies to internally evolve would be for gas to flow to the center and form stars in a central disk (pseudo-bulge). If the inflow rate is faster than the rate of star formation, a central concentration of gas will form. In this paper we present radial profiles of stellar and 8 μm emission from polycyclic aromatic hydrocarbons (PAHs) for 11 spiral galaxies to investigate whether the interstellar medium in these galaxies contains a central concentration above that expected from the exponential disk. In general, we find that the two-dimensional CO and PAH emission morphologies are similar, and that they exhibit similar radial profiles. We find that in 6 of the 11 galaxies there is a central excess in the 8 μm and CO emission above the inward extrapolation of an exponential disk. In particular, all four barred galaxies in the sample have strong central excesses in both 8 μm and CO emission. These correlations suggest that the excess seen in the CO profiles is, in general, not simply due to a radial increase in the CO emissivity. In the inner disk, the ratio of the stellar to the 8 μm radial surface brightness is similar for 9 of the 11 galaxies, suggesting a physical connection between the average stellar surface brightness and the average gas surface brightness at a given radius. We also find that the ratio of the CO to 8 μm PAH surface brightness is consistent over the sample, implying that the 8 μm PAH surface brightness can be used as an approximate tracer of the interstellar medium.",
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AU - Vogel, Stuart N.

AU - Sheth, Kartik

AU - Draine, Bruce T.

AU - Hollenbach, David J.

AU - Meyer, Martin

AU - Dale, Daniel A.

AU - Engelbracht, Charles W.

AU - Kennicutt, Robert C.

AU - Lee, Armus

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AU - Calzetti, Daniela

AU - Gordon, Karl D.

AU - Helou, George

AU - Leitherer, Claus

AU - Malhotra, Sangeeta

AU - Murphy, Eric

AU - Rieke, George H.

AU - Rieke, Marcia J

AU - Smith, J. D.

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N2 - One possible way for spiral galaxies to internally evolve would be for gas to flow to the center and form stars in a central disk (pseudo-bulge). If the inflow rate is faster than the rate of star formation, a central concentration of gas will form. In this paper we present radial profiles of stellar and 8 μm emission from polycyclic aromatic hydrocarbons (PAHs) for 11 spiral galaxies to investigate whether the interstellar medium in these galaxies contains a central concentration above that expected from the exponential disk. In general, we find that the two-dimensional CO and PAH emission morphologies are similar, and that they exhibit similar radial profiles. We find that in 6 of the 11 galaxies there is a central excess in the 8 μm and CO emission above the inward extrapolation of an exponential disk. In particular, all four barred galaxies in the sample have strong central excesses in both 8 μm and CO emission. These correlations suggest that the excess seen in the CO profiles is, in general, not simply due to a radial increase in the CO emissivity. In the inner disk, the ratio of the stellar to the 8 μm radial surface brightness is similar for 9 of the 11 galaxies, suggesting a physical connection between the average stellar surface brightness and the average gas surface brightness at a given radius. We also find that the ratio of the CO to 8 μm PAH surface brightness is consistent over the sample, implying that the 8 μm PAH surface brightness can be used as an approximate tracer of the interstellar medium.

AB - One possible way for spiral galaxies to internally evolve would be for gas to flow to the center and form stars in a central disk (pseudo-bulge). If the inflow rate is faster than the rate of star formation, a central concentration of gas will form. In this paper we present radial profiles of stellar and 8 μm emission from polycyclic aromatic hydrocarbons (PAHs) for 11 spiral galaxies to investigate whether the interstellar medium in these galaxies contains a central concentration above that expected from the exponential disk. In general, we find that the two-dimensional CO and PAH emission morphologies are similar, and that they exhibit similar radial profiles. We find that in 6 of the 11 galaxies there is a central excess in the 8 μm and CO emission above the inward extrapolation of an exponential disk. In particular, all four barred galaxies in the sample have strong central excesses in both 8 μm and CO emission. These correlations suggest that the excess seen in the CO profiles is, in general, not simply due to a radial increase in the CO emissivity. In the inner disk, the ratio of the stellar to the 8 μm radial surface brightness is similar for 9 of the 11 galaxies, suggesting a physical connection between the average stellar surface brightness and the average gas surface brightness at a given radius. We also find that the ratio of the CO to 8 μm PAH surface brightness is consistent over the sample, implying that the 8 μm PAH surface brightness can be used as an approximate tracer of the interstellar medium.

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KW - Galaxies: ISM

KW - Galaxies: structure

KW - Infrared: galaxies

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