Evolutionary stellar population synthesis at high spectral resolution: optical wavelengths

Delgado, R. M. González; Cerviño, M.; Martins, Lucimara P.; Leitherer, Claus; Hauschildt, P. H.

doi:10.1111/j.1365-2966.2005.08692.x

Cited by 314 publications

(243 citation statements)

References 78 publications

(89 reference statements)

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“…We note that the value chosen for the EW abs (λ5876)/ EW abs (λ4471) ratio is consistent with the one given by González Delgado et al (2005). Since the output high-resolution spectra in Starburst99 are calculated only for wavelengths < 7000Å, we do not have a prediction for the EW abs (λ7065)/ EW abs (λ4471) ratio.…”

Section: Adjustment Of Nir To Optical Spectrasupporting

confidence: 79%

“…It is assumed that EW(abs) is the same for all hydrogen lines. This assumption is justified by the evolutionary stellar population synthesis models of González Delgado et al (2005). The physical conditions, and the ionic and total heavy element abundances in the H ii regions were derived following Izotov et al (2006).…”

Section: Physical Conditions and Heavy Element Abundancesmentioning

confidence: 99%

“…The equivalent width of the He i λ4471 absorption line is chosen to be EW abs (λ4471) = 0.4Å, following González Delgado et al (2005), Izotov & Thuan (2010), and Izotov et al (2013). The equivalent widths of the other absorption lines in the optical range were fixed according to the ratios EW abs (λ3889)/EW abs (λ4471) = 1.0, EW abs (λ5876)/EW abs (λ4471) = 0.8,…”

Section: Adjustment Of Nir To Optical Spectramentioning

confidence: 99%

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A new determination of the primordial He abundance using the He i λ10830 Å emission line: cosmological implications

Izotov¹,

Thuan²,

Гусева³

2014

Monthly Notices of the Royal Astronomical Society

255

355

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We present near-infrared spectroscopic observations of the high-intensity He i λ10830Å emission line in 45 low-metallicity H ii regions. We combined these NIR data with spectroscopic data in the optical range to derive the primordial He abundance. The use of the He i λ10830Å line, the intensity of which is very sensitive to the density of the H ii region, greatly improves the determination of the physical conditions in the He + zone. This results in a considerably tighter Y -O/H linear regression compared to all previous studies. We extracted a final sample of 28 H ii regions with Hβ equivalent width EW(Hβ) 150Å, excitation parameter O 2+ /O 0.8, and with helium mass fraction Y derived with an accuracy better than 3%. With this final sample we derived a primordial 4 He mass fraction Y p = 0.2551 ± 0.0022. The derived value of Y p is higher than the one predicted by the standard big bang nucleosynthesis (SBBN) model. Using our derived Y p together with D/H = (2.53±0.04)×10 −5 , and the χ 2 technique, we found that the best agreement between these light element abundances is achieved in a cosmological model with a baryon mass density Ω b h 2 = 0.0240±0.0017 (68% CL), ±0.0028 (95.4% CL), ±0.0034 (99% CL) and an effective number of neutrino species N eff = 3.58±0.25 (68% CL), ±0.40 (95.4% CL), ±0.50 (99% CL). A non-standard value of N eff is preferred at the 99% CL, implying the possible existence of additional types of neutrino species.

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Section: Adjustment Of Nir To Optical Spectrasupporting

confidence: 79%

Section: Physical Conditions and Heavy Element Abundancesmentioning

confidence: 99%

Section: Adjustment Of Nir To Optical Spectramentioning

confidence: 99%

See 1 more Smart Citation

A new determination of the primordial He abundance using the He i λ10830 Å emission line: cosmological implications

Izotov¹,

Thuan²,

Гусева³

2014

Monthly Notices of the Royal Astronomical Society

255

355

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“…Brodie & Huchra 1990) to those which perform the simultaneous χ 2 -minimisation of a large number of spectral indices (see, e.g., Proctor et al 2004). Nevertheless, both photometric and spectroscopic methods are dependent on the accurate modelling of simple stellar populations (SSPs, see, Table 4 is available in electronic form at http://www.aanda.org e.g., Bruzual & Charlot 2003;Le Borgne et al 2004;Delgado et al 2005;Maraston 2005;Coelho et al 2007;Percival et al 2009;Lee et al 2009;Conroy & Gunn 2010;Vazdekis et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Full spectral fitting of Milky Way and M 31 globular clusters: ages and metallicities

Cezario

Coelho

Alves-Brito

et al. 2012

A&A

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Context. The formation and evolution of disk galaxies are long standing questions in astronomy. Understanding the properties of globular cluster systems can lead to important insights on the evolution of its host galaxy. Aims. We aim to obtain the stellar population parameters -age and metallicity -of a sample of M 31 and Galactic globular clusters. Studying their globular cluster systems is an important step towards understanding their formation and evolution in a complete way. Methods. Our analysis employs a modern pixel-to-pixel spectral fitting technique to fit observed integrated spectra to updated stellar population models. By comparing observations to models we obtain the ages and metallicities of their stellar populations. We apply this technique to a sample of 38 globular clusters in M 31 and to 41 Galactic globular clusters, used as a control sample. Results. Our sample of M 31 globular clusters spans ages from 150 Myr to the age of the Universe. Metallicities [Fe/H] range from -2.2 dex to the solar value. The age-metallicity relation obtained can be described as having two components: an old population with a flat age-[Fe/H] relation, possibly associated with the halo and/or bulge, and a second one with a roughly linear relation between age and metallicity, higher metallicities corresponding to younger ages, possibly associated with the M 31 disk. While we recover the very well known Galactic GC metallicity bimodality, our own analysis of M 31's metallicity distribution function (MDF) suggests that both GC systems cover basically the same [Fe/H] range yet M 31's MDF is not clearly bimodal. These results suggest that both galaxies experienced different star formation and accretion histories.

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“…It is assumed that EW(abs) is the same for all hydrogen lines. This assumption is justified by the evolutionary stellar population synthesis models of González Delgado et al (2005). (Baldwin et al 1981) for narrow emission lines.…”

Section: Empirical Analysismentioning

confidence: 99%

Tol 2240–384 – a new low-metallicity AGN candidate

Izotov

Гусева²,

Fricke³

et al. 2010

A&A

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Context. Active galactic nuclei (AGNs) have typically been discovered in massive galaxies of high metallicity. Aims. We attempt to increase the number of AGN candidates in low metallicity galaxies. We present VLT/UVES and archival VLT/FORS1 spectroscopic and NTT/SUSI2 photometric observations of the low-metallicity emission-line galaxy Tol 2240-384 and perform a detailed study of its morphology, chemical composition, and emission-line profiles. Methods. The profiles of emission lines in the UVES and FORS1 spectra are decomposed into several components with different kinematical properties by performing multicomponent fitting with Gaussians. We determine abundances of nitrogen, oxygen, neon, sulfur, chlorine, argon, and iron by analyzing the fluxes of narrow components of the emission lines using empirical methods. We verify with a photoionisation model that the physics of the narrow-line component gas is similar to that in common metal-poor galaxies. Results. Image deconvolution reveals two high-surface brightness regions in Tol 2240-384 separated by 2.4 kpc. The brightest southwestern region is surrounded by intense ionised gas emission that strongly affects the observed B − R colour on a spatial scale of ∼5 kpc. The profiles of the strong emission lines in the UVES spectrum are asymmetric and all these lines apart from Hα and Hβ can be fitted by two Gaussians of FWHM ∼ 75-92 km s −1 separated by ∼80 km s −1 implying that there are two regions of ionised gas emitting narrow lines. The oxygen abundances in both regions are equal within the errors and in the range 12 + log O/H = 7.83-7.89. The shapes of the Hα and Hβ lines are more complex. In particular, the Hα emission line consists of two broad components of FWHM ∼ 700 km s −1 and 2300 km s −1 , in addition to narrow components of two regions revealed from profiles of other lines. This broad emission in Hα and Hβ associated with the high-excitation, brighter southwestern H ii region of the galaxy is also present in the archival low-and medium-resolution VLT/FORS1 spectra. The extraordinarily high luminosity of the broad Hα line of 3× 10 41 erg s −1 cannot be accounted for by massive stars at different stages of their evolution. The broad Hα emission persists over a period of 7 years, which excludes supernovae as a powering mechanism of this emission. This emission most likely arises from an accretion disc around a black hole of mass ∼10 7 M .

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Evolutionary stellar population synthesis at high spectral resolution: optical wavelengths

Cited by 314 publications

References 78 publications

A new determination of the primordial He abundance using the He i λ10830 Å emission line: cosmological implications

A new determination of the primordial He abundance using the He i λ10830 Å emission line: cosmological implications

Full spectral fitting of Milky Way and M 31 globular clusters: ages and metallicities

Tol 2240–384 – a new low-metallicity AGN candidate

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