The oxygen abundance gradient in M 101: The reliability of the<i>P</i>method

Cedrés, B.; Urbaneja, M. A.; Cepa, J.

doi:10.1051/0004-6361:20047055

Cited by 12 publications

(20 citation statements)

References 18 publications

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“…However, if we take into account the position of the regions from Castellanos et al (2002) in the figure, it is clear that they lie closer to the gradient drawn by the PT05 calibration than that of KK04. This agrees with the results of Cedrés et al (2004) and López- Sánchez & Esteban (2010).…”

Section: The Metallicity Of Ngc 628supporting

confidence: 93%

“…Even if the PT05 method produces a larger dispersion than that for the KK04 method, the gradient and the metallicity values for single regions are closer to the direct-method results, as previously suggested in the literature (e.g. Cedrés et al 2004;or López-Sánchez & Esteban 2010). Two-dimensional contour models for the metallicity (and associated parameters) for both galaxies were created using the Delaunay triangulation.…”

Section: Discussionsupporting

confidence: 66%

“…For almost all our regions, P < 0.4, so that they are located within a range of P that it is not well-sampled, because for PT05 the greater number of calibration points are in P > 0.6 for the upper branch of the metallicity. However, in Cedrés et al (2004), it is shown that even for M 101 regions with a low value of P, the calibration of Pilyugin (2001a,b), which is a previous version of the present PT05, ensures a more than reasonable agreement with the metallicity obtained by the direct method. This seems to indicate that for low values of P, abundances inferred using PT05 may have more scatter, but that the mean oxygen abundance value determined will behave as well as that for higher values of P, where more calibration points are present.…”

Section: The Problem With Empirical Calibrationsmentioning

confidence: 64%

“…The data set presented here allows us to obtain only the R 23 and P parameters. However, it has to be pointed out that the R 23 calibrations provide oxygen abundance determinations that are about 0.5 dex higher than those obtained by the direct method (López-Sánchez & Esteban 2010;Cedrés et al 2004). According to López-Sánchez & Esteban (2010), the Pilyugin & Thuan (2005, hereafter PT05) calibration is the most suitable for deriving oxygen abundances because it is in closer agreement with the metallicity obtained by the direct method.…”

Section: The Problem With Empirical Calibrationsmentioning

confidence: 90%

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Two-dimensional metallicity distribution of the ionized gas in NGC 628 and NGC 6946

Cedrés

Cepa

Bongiovanni

et al. 2012

A&A

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Aims. We present here two H II region catalogues with azimuthal resolution for the two grand design galaxies NGC 628 and NGC 6946. With the help of these catalogues, we study several properties of the star-forming processes occurring in spiral galaxies. Methods. We obtained direct imaging in the narrow-band filters centred at Hα, Hβ, [O II]λ3727, and [O III]λλ4959, 5007 and their respective continua. After the calibration and correction of the data, we obtained for each H II region the de-reddened fluxes in the aforementioned lines, the size, the Hα equivalent width, and, using two different empirical calibrations, the metallicity. Employing a method based on the Delaunay triangulation, a two-dimensional (2D) representation of the metallicity was obtained. Results. Data for 209 H II regions of NGC 628 and 226 H II regions of NGC 6946 are obtained. The radial behaviours of the Hα equivalent width, the excitation, and the oxygen abundance are derived. Two-dimensional representations of the metallicity and the excitation are calculated for the galaxies in the study. The two empirical calibrations of the metallicity are compared. Conclusions. The behaviours of the extinction and the Hα equivalent width are similar to those presented in the literature. The oxygen abundance gradients obtained in this study agree with previously published values. However, more regions were examined than in previous studies. We find a difference of about 0.6 dex between the two empirical calibrations employed. Finally, the 2D representations of the metallicity reveal high metallicity knots in NGC 628, and for NGC 6946 a high metallicity azimuthal structure is discovered. These high metallicity regions seem to be linked to the arms of the galaxies and are probably produced by an increase in the temperature of the ionizing clusters in the H II regions, which may be linked to variations in the initial mass functions of the galaxies between the arm and interarm regions.

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Section: The Metallicity Of Ngc 628supporting

confidence: 93%

Section: Discussionsupporting

confidence: 66%

Section: The Problem With Empirical Calibrationsmentioning

confidence: 64%

Section: The Problem With Empirical Calibrationsmentioning

confidence: 90%

See 2 more Smart Citations

Two-dimensional metallicity distribution of the ionized gas in NGC 628 and NGC 6946

Cedrés

Cepa

Bongiovanni

et al. 2012

A&A

Self Cite

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“…(1) Helfer et al (2003); (2) Sofue et al (1999); (3) Lu et al (1993); (4) Zimmer et al (2004); (5) Kamphuis & Briggs (1992); (6) Moustakas et al (2010); (7) Cedrés et al (2004). Foyle et al (2010), using a multiband analysis from H I to the far-UV for the grand design galaxies NGC 5194, NGC 682, and NGC 6946, found that there is no shock trigger, and that the spiral arms just reorganize the material from the disc, which will generate stars as a function of gas density, following a KennicuttSchmidt law, for example (Kennicutt 1998a).…”

Section: Introductionmentioning

confidence: 99%

Density waves and star formation in grand-design spirals

Cedrés

Cepa

Bongiovanni

et al. 2013

A&A

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Context. H II regions in the arms of spiral galaxies are indicators of recent star-forming processes. They may have been caused by the passage of the density wave or simply been created by other means near the arms. The study of these regions may give us clues to clarify the controversy about the existence of a triggering scenario, as proposed in the density-wave theory. Aims. If the passage of the density wave contributes significantly to the formation of H II regions in the arms of grand-design spirals, we can find a relationship in their position relative to the arms. Methods. Using Hα direct imaging, we characterize the H II regions from a sample of three grand-design galaxies: NGC 5457, NGC 628, and NGC 6946. Broad-band images in R and I were used to determine the position of the arms. The H II regions found to be associated with arms were selected for the study. The age and star formation rate of these H II regions was obtained using measurements on the Hα line. The distance between the current position of the selected H II regions and the position they would have if they had been created in the centre of the arm was calculated. A parameter, T , which measures whether a region was created in the arm or in the disc, was defined. Results. With the help of the T parameter we determine that the majority of regions were formed some time after the passage of the density wave, and the regions are located behind the zone they should have occupied (in the direction of the rotation of the galaxy) had they been formed in the centre of the arm. Moreover, the relative efficiency of the star formation rate between arm and interarm was calculated for all the galaxies. Conclusions. The large number of regions created after the passage of the arm may be explained by the effect of the density wave, which helps to create the star-forming regions after its passage. There is clear evidence of triggering for NGC 5457 and a co-rotation radius is proposed. A more modest triggering seems to exist for NGC 628, and insignificant evidence of triggering is found for NGC 6946.

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Metallicity dependence of high-mass X-ray binary populations

Douna

Pellizza

Mirabel

et al. 2015

A&A

133

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Context. High-mass X-ray binaries (HMXBs) might have contributed a non-negligible fraction of the energy feedback to the interstellar and intergalactic media at high redshift, becoming important sources for the heating and ionization history of the Universe. However, the importance of this contribution depends on the hypothesized increase in the number of HMXBs formed in lowmetallicity galaxies and in their luminosities. Aims. In this work we test the aforementioned hypothesis, and quantify the metallicity dependence of HMXB population properties. Methods. We compile from the literature a large set of data on the sizes and X-ray luminosities of HMXB populations in nearby galaxies with known metallicities and star formation rates. We use Bayesian inference to fit simple Monte Carlo models that describe the metallicity dependence of the size and luminosity of the HMXB populations. Results. We find that HMXBs are typically ten times more numerous per unit star formation rate in low-metallicity galaxies (12 + log(O/H) < 8, namely <20% solar) than in solar-metallicity galaxies. The metallicity dependence of the luminosity of HMXBs is small compared to that of the population size. Conclusions. Our results support the hypothesis that HMXBs are more numerous in low-metallicity galaxies, implying the need to investigate the feedback in the form of X-rays and energetic mass outflows of these high-energy sources during cosmic dawn.

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The oxygen abundance gradient in M 101: The reliability of thePmethod

Cited by 12 publications

References 18 publications

Two-dimensional metallicity distribution of the ionized gas in NGC 628 and NGC 6946

Two-dimensional metallicity distribution of the ionized gas in NGC 628 and NGC 6946

Density waves and star formation in grand-design spirals

Metallicity dependence of high-mass X-ray binary populations

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