Exploring the star formation history of elliptical galaxies: beyond simple stellar populations with a new line strength estimator

Rogers, Bill; Ferreras, Ignacio; Peletier, Reynier F.; Silk, Joseph

doi:10.1111/j.1365-2966.2009.15892.x

Cited by 39 publications

(54 citation statements)

References 50 publications

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“…In fact, Rogers et al (2010) have shown that the mixture of two SSPs is the most reliable approach to describe the stellar population of early-type galaxies. Most recently, Lopez-Corredoira et al (2017) fit a set of 20 red galaxies with models of a single-burst SSP, combinations of two SSPs as well as an extended star formation history.…”

Section: Stellar Population Parametersmentioning

confidence: 99%

The ALHAMBRA survey: 2D analysis of the stellar populations in massive early-type galaxies atz< 0.3

Roman

Cenarro

Díaz-García

et al. 2017

A&A

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We present a technique that permits the analysis of stellar population gradients in a relatively low cost way compared to IFU surveys analyzing a vastly larger samples as well as out to larger radii. We developed a technique to analyze unresolved stellar populations of spatially resolved galaxies based on photometric multi-filter surveys. We derived spatially resolved stellar population properties and radial gradients by applying a Centroidal Voronoi Tesselation and performing a multi-color photometry SED fitting. This technique has been successfully applied to a sample of 29 massive (M > 10 10.5 M ), early-type galaxies at z < 0.3 from the ALHAMBRA survey. We produced detailed 2D maps of stellar population properties (age, metallicity and extinction) which allow us to identify galactic features. Radial structures have been studied and luminosity-weighted and mass-weighted gradients have been derived out to 2 -3.5 R eff . We find that the spatially resolved stellar population mass, age and metallicity are well represented by their integrated values. We find the gradients of early-type galaxies to be on average flat in age (∇log Age L = 0.02 ± 0.06 dex/R eff ) and negative in metallicity (∇[Fe/H] L = -0.09 ± 0.06 dex/R eff ). Overall, the extinction gradients are flat (∇A v = -0.03 ± 0.09 mag/R eff ) with a wide spread. These results are in agreement with previous studies that used standard long-slit spectroscopy as well as with the most recent integral field unit (IFU) studies. According to recent simulations, these results are consistent with a scenario where early-type galaxies were formed through major mergers and where their final gradients are driven by the older ages and higher metallicity of the accreted systems. We demonstrate the scientific potential of multi-filter photometry to explore the spatially resolved stellar populations of local galaxies and confirm previous spectroscopic trends from a complementary technique.

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Section: Stellar Population Parametersmentioning

confidence: 99%

The ALHAMBRA survey: 2D analysis of the stellar populations in massive early-type galaxies atz< 0.3

Roman

Cenarro

Díaz-García

et al. 2017

A&A

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“…It also has the advantage of reducing the uncertainty in the total flux of our measured spectral bands (Rogers et al 2010). The BMC method is sensitive to two parameters and a balancing act must be played with both.…”

Section: Effect Of Pseudo-continuum Placementmentioning

confidence: 99%

“…The BMC method is based on two parameters: (1) the width of the window around a given wavelength and (2) the percentile of the flux which defines the pseudo-continuum. We started by assuming the parameters used in Rogers et al (2010), a window of 100 Å with a percentile of 90 per cent. The effect of the choice of these parameters is analyzed in detail in Section 3.7.…”

Section: Processing Spectramentioning

confidence: 99%

“…All spectra were resampled to 0.5 Å pixels over a wavelength range of 4000 -7000 Å. We defined the local continuum via a boosted-median pseudocontinuum (BMC, Rogers et al 2010). This method is defined by taking a window around any particular wavelength and setting the continuum to be at a prescribed percentile of the fluxes within the window.…”

Section: Processing Spectramentioning

confidence: 99%

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On the relative ages of the α-rich and α-poor stellar populations in the Galactic halo

Hawkins

Jofré

Gilmore

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We study the ages of α-rich and α-poor stars in the halo using a sample of F and G dwarfs from the Sloan Digital Sky Survey (SDSS). To separate stars based on [α/Fe], we have developed a new semi-empirical spectral-index based method and applied it to the low-resolution, moderate signal-to-noise SDSS spectra. The method can be used to estimate the [α/Fe] directly providing a new and widely applicable way to estimate [α/Fe] from low-resolution spectra. We measured the main-sequence turnoff temperature and combined it with the metallicities and a set of isochrones to estimate the age of the α-rich and α-poor populations in our sample. We found all stars appear to be older than 8 Gyr confirming the idea that the Galactic halo was formed very early on. A bifurcation appears in the age-metallicity relation such that in the low metallicity regime the α-rich and α-poor populations are coeval while in the high metallicity regime the α-rich population is older than the α-poor population. Our results indicate the α-rich halo population, which has shallow age-metallicity relation, was formed in a rapid event with high star formation, while the α-poor stars were formed in an environment with a slower chemical evolution timescale.

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“…Also note there that in NGC 4278 obsIDs 7081 was taken prior to obsID 7080, and we therefore retain the chronological sequence with obsID 7081 labeled as pointing 5 in subsequent figures. Age estimates are from (a) Terlevich & Forbes (2002), (b) Kuntschner et al (2010), and (c) Rogers et al (2010). et al (2001).…”

Section: Notesmentioning

confidence: 99%

The Spectral and Temporal Properties of Transient Sources in Early-Type Galaxies

Brassington¹,

Fabbiano²,

Zezas³

et al. 2012

ApJ

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We report the spectral and temporal variability properties of 18 candidate transient (TC) and potential transient (PTC) sources detected in deep multi-epoch Chandra observation of the nearby elliptical galaxies, NGC 3379, NGC 4278, and NGC 4697. Only one source can be identified with a background counterpart, leaving 17 TCs + PTCs in the galaxies. Of these, 14 are in the galaxy field, supporting the theoretical picture that the majority of field X-ray binaries (XRBs) will exhibit transient accretion for >75% of their lifetime. Three sources are coincident with globular clusters, including two high-luminosity candidate black hole (BH) XRBs, with L X = 5.4 × 10 38 erg s −1 and L X = 2.8 × 10 39 erg s −1 , respectively. The spectra, luminosities, and temporal behavior of these 17 sources suggest that the transient population is heterogeneous, including neutron star (NS) and BH XRBs in both normal and high-rate accretion modes, and super soft sources containing white dwarf binaries. Our TC and PTC detections are noticeably fewer than the number expected from the population synthesis (PS) models of Fragos et al., tailored to our new Chandra pointings of NGC 4278. We attribute this discrepancy to the PS assumption that the transient population is composed of NS XRBs, as well as differences between the statistical analysis and error estimates used in the model and our observations.

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Exploring the star formation history of elliptical galaxies: beyond simple stellar populations with a new line strength estimator

Cited by 39 publications

References 50 publications

The ALHAMBRA survey: 2D analysis of the stellar populations in massive early-type galaxies atz< 0.3

The ALHAMBRA survey: 2D analysis of the stellar populations in massive early-type galaxies atz< 0.3

On the relative ages of the α-rich and α-poor stellar populations in the Galactic halo

The Spectral and Temporal Properties of Transient Sources in Early-Type Galaxies

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