Integral field spectroscopy of a sample of nearby galaxies: II. Properties of the H ii regions

S. F. Sánchez, F. F. Rosales-Ortega, R. A. Marino, J. Iglesias-Páramo, J. M. Vílchez, R. C. Kennicutt, A. I. Díaz, D. Mast, A. Monreal-Ibero, R. García-Benito, J. Bland-Hawthorn, E. Pérez, R. González Delgado, B. Husemann, A. R. López-Sánchez, R. Cid Fernandes, C. Kehrig, C. J. Walcher, A. Gil De Paz, S. Ellis

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Abstract

We analyse the spectroscopic properties of thousands of H ii regions identified in 38 face-on spiral galaxies. All galaxies were observed out to 2.4 effective radii using integral field spectroscopy (IFS) over the wavelength range ~3700 to ~6900 Å. The near uniform sample has been assembled from the PPAK IFS Nearby Galaxy (PINGS) survey and a sample described in Paper I. We develop a new automatic procedure to detect H ii regions, based on the contrast of the Hα intensity maps extracted from the datacubes. Once detected, the algorithm provides us with the integrated spectra of each individual segmented region. In total, we derive good quality spectroscopic information for ~2600 independent H ii regions/complexes. This is by far the largest H ii region survey of its kind. Our selection criteria and the use of 3D spectroscopy guarantee that we cover the regions in an unbiased way. A well-tested automatic decoupling procedure has been applied to remove the underlying stellar population, deriving the main properties (intensity, dispersion and velocity) of the strongest emission lines in the considered wavelength range (covering from [O ii] λ3727 to [S ii] λ6731). A final catalogue of the spectroscopic properties of H ii regions has been created for each galaxy, which includes information on morphology, spiral structure, gaskinematics, and surface brightness of the underlying stellar population. In the current study, we focus on the understanding of the average properties of the H ii regions and their radial distributions. We find a significant change in the ionisation characteristics of H ii regions within r < 0.25 r e due to contamination from sources with different ionising characteristics, as we discuss. We find that the gas-phase oxygen abundance and the Hα equivalent width present a negative and positive gradient, respectively. The distribution of slopes is statistically compatible with a random Gaussian distribution around the mean value, if the radial distances are measured in units of the respective effective radius. No difference in the slope is found for galaxies of different morphologies, e.g. barred/non-barred, grand-design/flocculent. Therefore, the effective radius is a universal scale length for gradients in the evolution of galaxies. Some properties have a large variance across each object and between galaxies (e.g. electron density) without a clear characteristic value. But other properties are well described by an average value either galaxy by galaxy or among the different galaxies (e.g. dust attenuation).

LanguageEnglish
Article numberA2
Pages1-28
Number of pages28
JournalAstronomy and Astrophysics
Volume546
DOIs
Publication statusPublished - 2012

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spectroscopy
galaxies
radii
slopes
wavelength
gradients
spiral galaxies
normal density functions
radial distribution
wavelengths
decoupling
electron density
catalogs
brightness
contamination
ionization
coverings
dust
attenuation
vapor phases

Cite this

Sánchez, S. F., Rosales-Ortega, F. F., Marino, R. A., Iglesias-Páramo, J., Vílchez, J. M., Kennicutt, R. C., ... Ellis, S. (2012). Integral field spectroscopy of a sample of nearby galaxies: II. Properties of the H ii regions. Astronomy and Astrophysics, 546, 1-28. [A2]. https://doi.org/10.1051/0004-6361/201219578
Sánchez, S. F. ; Rosales-Ortega, F. F. ; Marino, R. A. ; Iglesias-Páramo, J. ; Vílchez, J. M. ; Kennicutt, R. C. ; Díaz, A. I. ; Mast, D. ; Monreal-Ibero, A. ; García-Benito, R. ; Bland-Hawthorn, J. ; Pérez, E. ; González Delgado, R. ; Husemann, B. ; López-Sánchez, A. R. ; Cid Fernandes, R. ; Kehrig, C. ; Walcher, C. J. ; Gil De Paz, A. ; Ellis, S. / Integral field spectroscopy of a sample of nearby galaxies : II. Properties of the H ii regions. In: Astronomy and Astrophysics. 2012 ; Vol. 546. pp. 1-28.
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title = "Integral field spectroscopy of a sample of nearby galaxies: II. Properties of the H ii regions",
abstract = "We analyse the spectroscopic properties of thousands of H ii regions identified in 38 face-on spiral galaxies. All galaxies were observed out to 2.4 effective radii using integral field spectroscopy (IFS) over the wavelength range ~3700 to ~6900 {\AA}. The near uniform sample has been assembled from the PPAK IFS Nearby Galaxy (PINGS) survey and a sample described in Paper I. We develop a new automatic procedure to detect H ii regions, based on the contrast of the Hα intensity maps extracted from the datacubes. Once detected, the algorithm provides us with the integrated spectra of each individual segmented region. In total, we derive good quality spectroscopic information for ~2600 independent H ii regions/complexes. This is by far the largest H ii region survey of its kind. Our selection criteria and the use of 3D spectroscopy guarantee that we cover the regions in an unbiased way. A well-tested automatic decoupling procedure has been applied to remove the underlying stellar population, deriving the main properties (intensity, dispersion and velocity) of the strongest emission lines in the considered wavelength range (covering from [O ii] λ3727 to [S ii] λ6731). A final catalogue of the spectroscopic properties of H ii regions has been created for each galaxy, which includes information on morphology, spiral structure, gaskinematics, and surface brightness of the underlying stellar population. In the current study, we focus on the understanding of the average properties of the H ii regions and their radial distributions. We find a significant change in the ionisation characteristics of H ii regions within r < 0.25 r e due to contamination from sources with different ionising characteristics, as we discuss. We find that the gas-phase oxygen abundance and the Hα equivalent width present a negative and positive gradient, respectively. The distribution of slopes is statistically compatible with a random Gaussian distribution around the mean value, if the radial distances are measured in units of the respective effective radius. No difference in the slope is found for galaxies of different morphologies, e.g. barred/non-barred, grand-design/flocculent. Therefore, the effective radius is a universal scale length for gradients in the evolution of galaxies. Some properties have a large variance across each object and between galaxies (e.g. electron density) without a clear characteristic value. But other properties are well described by an average value either galaxy by galaxy or among the different galaxies (e.g. dust attenuation).",
author = "S{\'a}nchez, {S. F.} and Rosales-Ortega, {F. F.} and Marino, {R. A.} and J. Iglesias-P{\'a}ramo and V{\'i}lchez, {J. M.} and Kennicutt, {R. C.} and D{\'i}az, {A. I.} and D. Mast and A. Monreal-Ibero and R. Garc{\'i}a-Benito and J. Bland-Hawthorn and E. P{\'e}rez and {Gonz{\'a}lez Delgado}, R. and B. Husemann and L{\'o}pez-S{\'a}nchez, {A. R.} and {Cid Fernandes}, R. and C. Kehrig and Walcher, {C. J.} and {Gil De Paz}, A. and S. Ellis",
year = "2012",
doi = "10.1051/0004-6361/201219578",
language = "English",
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pages = "1--28",
journal = "Astronomy and Astrophysics",
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Sánchez, SF, Rosales-Ortega, FF, Marino, RA, Iglesias-Páramo, J, Vílchez, JM, Kennicutt, RC, Díaz, AI, Mast, D, Monreal-Ibero, A, García-Benito, R, Bland-Hawthorn, J, Pérez, E, González Delgado, R, Husemann, B, López-Sánchez, AR, Cid Fernandes, R, Kehrig, C, Walcher, CJ, Gil De Paz, A & Ellis, S 2012, 'Integral field spectroscopy of a sample of nearby galaxies: II. Properties of the H ii regions' Astronomy and Astrophysics, vol. 546, A2, pp. 1-28. https://doi.org/10.1051/0004-6361/201219578

Integral field spectroscopy of a sample of nearby galaxies : II. Properties of the H ii regions. / Sánchez, S. F.; Rosales-Ortega, F. F.; Marino, R. A.; Iglesias-Páramo, J.; Vílchez, J. M.; Kennicutt, R. C.; Díaz, A. I.; Mast, D.; Monreal-Ibero, A.; García-Benito, R.; Bland-Hawthorn, J.; Pérez, E.; González Delgado, R.; Husemann, B.; López-Sánchez, A. R.; Cid Fernandes, R.; Kehrig, C.; Walcher, C. J.; Gil De Paz, A.; Ellis, S.

In: Astronomy and Astrophysics, Vol. 546, A2, 2012, p. 1-28.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Integral field spectroscopy of a sample of nearby galaxies

T2 - Astronomy and Astrophysics

AU - Sánchez,S. F.

AU - Rosales-Ortega,F. F.

AU - Marino,R. A.

AU - Iglesias-Páramo,J.

AU - Vílchez,J. M.

AU - Kennicutt,R. C.

AU - Díaz,A. I.

AU - Mast,D.

AU - Monreal-Ibero,A.

AU - García-Benito,R.

AU - Bland-Hawthorn,J.

AU - Pérez,E.

AU - González Delgado,R.

AU - Husemann,B.

AU - López-Sánchez,A. R.

AU - Cid Fernandes,R.

AU - Kehrig,C.

AU - Walcher,C. J.

AU - Gil De Paz,A.

AU - Ellis,S.

PY - 2012

Y1 - 2012

N2 - We analyse the spectroscopic properties of thousands of H ii regions identified in 38 face-on spiral galaxies. All galaxies were observed out to 2.4 effective radii using integral field spectroscopy (IFS) over the wavelength range ~3700 to ~6900 Å. The near uniform sample has been assembled from the PPAK IFS Nearby Galaxy (PINGS) survey and a sample described in Paper I. We develop a new automatic procedure to detect H ii regions, based on the contrast of the Hα intensity maps extracted from the datacubes. Once detected, the algorithm provides us with the integrated spectra of each individual segmented region. In total, we derive good quality spectroscopic information for ~2600 independent H ii regions/complexes. This is by far the largest H ii region survey of its kind. Our selection criteria and the use of 3D spectroscopy guarantee that we cover the regions in an unbiased way. A well-tested automatic decoupling procedure has been applied to remove the underlying stellar population, deriving the main properties (intensity, dispersion and velocity) of the strongest emission lines in the considered wavelength range (covering from [O ii] λ3727 to [S ii] λ6731). A final catalogue of the spectroscopic properties of H ii regions has been created for each galaxy, which includes information on morphology, spiral structure, gaskinematics, and surface brightness of the underlying stellar population. In the current study, we focus on the understanding of the average properties of the H ii regions and their radial distributions. We find a significant change in the ionisation characteristics of H ii regions within r < 0.25 r e due to contamination from sources with different ionising characteristics, as we discuss. We find that the gas-phase oxygen abundance and the Hα equivalent width present a negative and positive gradient, respectively. The distribution of slopes is statistically compatible with a random Gaussian distribution around the mean value, if the radial distances are measured in units of the respective effective radius. No difference in the slope is found for galaxies of different morphologies, e.g. barred/non-barred, grand-design/flocculent. Therefore, the effective radius is a universal scale length for gradients in the evolution of galaxies. Some properties have a large variance across each object and between galaxies (e.g. electron density) without a clear characteristic value. But other properties are well described by an average value either galaxy by galaxy or among the different galaxies (e.g. dust attenuation).

AB - We analyse the spectroscopic properties of thousands of H ii regions identified in 38 face-on spiral galaxies. All galaxies were observed out to 2.4 effective radii using integral field spectroscopy (IFS) over the wavelength range ~3700 to ~6900 Å. The near uniform sample has been assembled from the PPAK IFS Nearby Galaxy (PINGS) survey and a sample described in Paper I. We develop a new automatic procedure to detect H ii regions, based on the contrast of the Hα intensity maps extracted from the datacubes. Once detected, the algorithm provides us with the integrated spectra of each individual segmented region. In total, we derive good quality spectroscopic information for ~2600 independent H ii regions/complexes. This is by far the largest H ii region survey of its kind. Our selection criteria and the use of 3D spectroscopy guarantee that we cover the regions in an unbiased way. A well-tested automatic decoupling procedure has been applied to remove the underlying stellar population, deriving the main properties (intensity, dispersion and velocity) of the strongest emission lines in the considered wavelength range (covering from [O ii] λ3727 to [S ii] λ6731). A final catalogue of the spectroscopic properties of H ii regions has been created for each galaxy, which includes information on morphology, spiral structure, gaskinematics, and surface brightness of the underlying stellar population. In the current study, we focus on the understanding of the average properties of the H ii regions and their radial distributions. We find a significant change in the ionisation characteristics of H ii regions within r < 0.25 r e due to contamination from sources with different ionising characteristics, as we discuss. We find that the gas-phase oxygen abundance and the Hα equivalent width present a negative and positive gradient, respectively. The distribution of slopes is statistically compatible with a random Gaussian distribution around the mean value, if the radial distances are measured in units of the respective effective radius. No difference in the slope is found for galaxies of different morphologies, e.g. barred/non-barred, grand-design/flocculent. Therefore, the effective radius is a universal scale length for gradients in the evolution of galaxies. Some properties have a large variance across each object and between galaxies (e.g. electron density) without a clear characteristic value. But other properties are well described by an average value either galaxy by galaxy or among the different galaxies (e.g. dust attenuation).

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U2 - 10.1051/0004-6361/201219578

DO - 10.1051/0004-6361/201219578

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VL - 546

SP - 1

EP - 28

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

SN - 0004-6361

M1 - A2

ER -

Sánchez SF, Rosales-Ortega FF, Marino RA, Iglesias-Páramo J, Vílchez JM, Kennicutt RC et al. Integral field spectroscopy of a sample of nearby galaxies: II. Properties of the H ii regions. Astronomy and Astrophysics. 2012;546:1-28. A2. https://doi.org/10.1051/0004-6361/201219578