Analysis of the distribution of HII regions in external galaxies

García-Gómez, C.; Athanassoula, E.; Barberà, C.

doi:10.1051/0004-6361:20020460

Cited by 24 publications

(25 citation statements)

References 99 publications

(66 reference statements)

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“…Both the figures and tables show that the PA values are better determined in a statistical sense than the IA values, in good agreement with what was already found by García-Gómez & Athanassoula (1991) and García-Gómez et al (2002). The mean correlation coefficient for the PA values is 0.86, while the mean correlation coefficient for the IA is 0.81.…”

Section: Comparison Of the Deprojection Methodssupporting

confidence: 90%

“…In this paper we introduce two methods, based on the Fourier transforms and which are closely linked to the two methods used by García-Gómez et al (2002) for HII region distributions. Let I(u, θ) be the image of the galaxy written in polar coordinates (r, θ), and u = ln(r).…”

Section: Deprojection Methodsmentioning

confidence: 99%

“…Iye et al (1982) used an image of NGC 4254 and selected the angles that maximized the axisymmetric component. Finally García-Gómez & Athanassoula (1991) and García-Gómez et al (2002) also used HII region distributions and maximized the axisymmetric components These authors also used a second method selecting the deprojection angles that made the HII region distribution most uniform.…”

Section: Introductionmentioning

confidence: 99%

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Deprojecting spiral galaxies using Fourier analysis. Application to the Frei sample

Barberà¹,

Athanassoula²,

García-Gómez³

2004

A&A

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Abstract. We present two methods that can be used to deproject spirals, based on Fourier analysis of their images, and discuss their potential and restrictions. Our methods perform particularly well for galaxies more inclined than 50• or for non-barred galaxies more inclined than 35• . They are fast and straightforward to use, and thus ideal for large samples of galaxies. Moreover, they are very robust for low resolutions and thus are appropriate for samples of cosmological interest. The relevant software is available from us upon request. We use these methods to determine the values of the position and inclination angles for a sample of 79 spiral galaxies contained in the Frei et al. (1996) sample. We compare our results with the values found in the literature, based on other methods. We find statistically very good agreement

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Section: Comparison Of the Deprojection Methodssupporting

confidence: 90%

Section: Deprojection Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Deprojecting spiral galaxies using Fourier analysis. Application to the Frei sample

Barberà¹,

Athanassoula²,

García-Gómez³

2004

A&A

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“…The surface density distributions of H ii regions in spiral galaxy disks can also be represented reasonably well by an exponential function (e.g., Hodge & Kennicutt 1983;Athanassoula et al 1993;García-Gómez et al 2002), the exceptions being mainly due to unsatisfactory fits of the maxima near the center. Athanassoula et al found that the H ii regions are marginally more concentrated to the centers of spiral galaxies than are the disk stars, with a ratio of scale lengths of h H ii /h is 0.8 ± 0.4.…”

Section: Isophotal Radius Normalizationmentioning

confidence: 99%

The radial distribution of core-collapse supernovae in spiral host galaxies

Hakobyan¹,

Mamon

Петросян³

et al. 2009

A&A

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Aims. With the goal of providing constraints on the nature of the progenitors of core-collapse (CC) supernovae (SNe), we compare their radial distribution within their spiral host galaxies with the distributions of stars and ionized gas in spiral disks. Methods. SNe positions are taken from the Asiago catalog for a well-defined sample of 224 SNe within 204 host galaxies. The SN radial distances are estimated from the deprojected separations from the host galaxy nuclei, and normalized both to the 25th mag arcsec −2 blue-band isophotal radius and (for the first time) to the statistically-estimated disk scale length. Results. The normalized radial distribution of all CCSNe is consistent with an exponential law, as previously found, with a possible depletion of CCSNe within one-fifth of the isophotal radius (less significant with scale-length normalization). There are no signs of truncation of the exponential distribution of CCSNe out to 7 disk scale lengths. The scale length of the distribution of type II SNe appears to be significantly larger than that of the stellar disks of their host galaxies, but consistent with the scale lengths of Freeman disks. SNe Ib/c have a significantly smaller scale length than SNe II, with little difference between types Ib and Ic. The radial distribution of type Ib/c SNe is more centrally concentrated than that of the stars in a Freeman disk, but is similar to the stellar disk distribution that we infer for the host galaxies. All CCSN subsamples are consistent with the still uncertain distribution of H ii regions. The scale length of the CCSN radial distribution shows no significant correlation with the host galaxy morphological type, or the presence of bars. However, low luminosity as well as inclined hosts have a less concentrated distribution (with the scale-length normalized radial distances) of CCSNe, which are probably a consequence of metallicity and selection effects, respectively. Conclusions. The exponential distribution of CCSNe shows a scale length consistent with that of the ionized gas confirming the generally accepted hypothesis that the progenitors of these SNe are young massive stars. Given the lack of correlation of the normalized radial distances of CCSNe with the morphological type of the host galaxy, we conclude that the more concentrated distribution of SNe Ib/c relative to SNe II must arise from the higher metallicity of their progenitors or possibly from a shallower initial mass function in the inner regions of spirals.

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“…Throughout this work, we measure the pitch angle P of the m = 2 component. Pitch angles are determined from peaks in the Fourier spectra, as this is the most powerful method to find periodicity in a distribution [24,25].…”

Section: Measurement Of Spiral Arm Pitchmentioning

confidence: 99%

The Dark Matter Halo Density Profile, Spiral Arm Morphology, and Supermassive Black Hole Mass of M33

Seigar

2011

ISRN Astronomy and Astrophysics

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We investigate the dark matter halo density profile of M33. We find that the HÁ rotation curve of M33 is best described by an NFW dark matter halo density profile model, with a halo concentration of c vir = 4.0±1.0 and a virial mass of M vir = (2.2±0.1)×10 11 M . We go on to use the NFW concentration (c vir ) of M33, along with the values derived for other galaxies (as found in the literature), to show that c vir correlates with both spiral arm pitch angle and supermassive black hole mass.

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Analysis of the distribution of HII regions in external galaxies

Cited by 24 publications

References 99 publications

Deprojecting spiral galaxies using Fourier analysis. Application to the Frei sample

Deprojecting spiral galaxies using Fourier analysis. Application to the Frei sample

The radial distribution of core-collapse supernovae in spiral host galaxies

The Dark Matter Halo Density Profile, Spiral Arm Morphology, and Supermassive Black Hole Mass of M33

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