STECMAP: STEllar Content from high-resolution galactic spectra via Maximum A Posteriori

By P. Ocvirk, C. Pichon, Ariane Lançon, E. Strasbourg, I. D. Paris, Observatoire de Lyon. 2005

195 citations recorded by the source corpus.

In this paper we describe STECMAP (STEllar Content via Maximum A Posteriori), a flexible, non-parametric inversion method for the interpretation of the integrated light spectra of galaxies, based on synthetic spectra of single stellar populations (SSPs). We focus on the recovery of a galaxy's star formation history and stellar age–metallicity relation. We use the high-resolution SSPs produced by pegase-hr to quantify the informational content of the wavelength range λλ= 4000–6800. Regularization of the inversion is achieved by requiring that the solutions are relatively smooth functions of age. The smoothness parameter is set automatically via generalized cross validation. A detailed investigation of the properties of the corresponding simplified linear problem is performed using singular value decomposition. It turns out to be a powerful tool for explaining and predicting the behaviour of the inversion, and may help designing SSP models in the future. We provide means of quantifying the fundamental limitations of the problem considering the intrinsic properties of the SSPs in the spectral range of interest, as well as the noise in these models and in the data. We demonstrate that the information relative to the stellar content is relatively evenly distributed within the optical spectrum. We show that one should not attempt to recover more than about eight characteristic episodes in the star formation history from the wavelength domain we consider. STECMAP preserves optimal (in the cross validation sense) freedom in the characterization of these episodes for each spectrum. We performed a systematic simulation campaign and found that, when the time elapsed between two bursts of star formation is larger than 0.8 dex, the properties of each episode can be constrained with a precision of 0.02 dex in age and 0.04 dex in metallicity from high-quality data [R= 10 000, signal-to-noise ratio (SNR) = 100 per pixel], not taking model errors into account. We also found that the spectral resolution has little effect on population separation provided low- and high-resolution experiments are performed with the same SNR per A. However, higher spectral resolution does improve the accuracy of metallicity and age estimates in double-burst separation experiments. When the fluxes of the data are properly calibrated, extinction can be estimated; otherwise the continuum can be discarded or used to estimate flux correction factors. The described methods and error estimates will be useful in the design and in the analysis of extragalactic spectroscopic surveys.

Subfields: Atomic and Molecular Physics, and Optics, Electrical and Electronic Engineering, Signal Processing

View Paper: https://www.semanticscholar.org/paper/878468f19de5c752d63f4a407d2dedd83ae32e35

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In Atomic and Molecular Physics, and Optics

1. C. Conroy
2. G. Stasińska
3. M. Cappellari
4. J. Leja
5. Benjamin D. Johnson
6. M. Pettini
7. M. Koleva
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In Electrical and Electronic Engineering

1. C. Conroy
2. P. V. van Dokkum
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7. J. Leja
8. Benjamin D. Johnson

In Signal Processing

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2. M. Cappellari
3. Benjamin D. Johnson
4. J. Leja

Citations in the corpus

• Evolutionary stellar population synthesis with MILES – II. Scaled-solar and α-enhanced models (2015, methodology): “…use these model SEDs with newly developed algorithms that aim at constraining and recovering the SFH by means of full spectrum-fitting approach (e.g. Panter, Heavens & Jimenez 2003; Cid Fernandes et al. 2005; Ocvirk et al. 2006a,b; Chilingarian et al. 2007; Koleva et al. 2009; Tojeiro et al. 2011).”
• Age-dating luminous red galaxies observed with the Southern African Large Telescope (2016, methodology): “…two approaches are used for fitting models to data: (i) full–spectrum fitting (e.g. Heavens, Jimenez, & Lahav 2000; Cid Fernandes et al. 2005; Ocvirk et al. 2006a,b; Chilingarian et al. 2007; Tojeiro et al. 2007; Koleva et al. 2009a) and (ii) techniques that fit features in the spectra such…”
• How to Measure Galaxy Star Formation Histories. II. Nonparametric Models (2018, methodology): “…< t < 3.6 Gyr 3.6 < t < 11.7 Gyr 11.7 < t < 13.7 Gyr (2) Aside from the last bin, these are spaced equally in logarithmic time, following the finding of Ocvirk et al. (2006) that the distinguishability of simple stellar populations is roughly proportional to their separation in logarithmic time.”
• Erratum: Recovering galaxy stellar population properties from broad-band spectral energy distribution fitting (2012, methodology): “…approach in which population parameters are extracted by fitting the full available spectrum (Heavens et al. 2000; Cid Fernandes et al. 2004; Ocvirk et al. 2006; Panter et al. 2007; Tojeiro et al. 2007, 2009; Chen et al. 2012) and which also requires high quality and high S/N spectra in…”
• Evolutionary stellar population synthesis with MILES – I. The base models and a new line index system (2010, methodology): “In fact, there is a growing body of full spectrum fitting algorithms that are being developed for constraining and recovering in part the Star Formation History (e.g., Panter et al. 2003; Cid Fernandes et al. 2005; Ocvirk et al. 2006ab; Koleva et al. 2008).”
• THE RADIAL VELOCITY EXPERIMENT (RAVE): SECOND DATA RELEASE (2008, methodology): “Nevertheless, as stressed by Ocvirk et al. (2006a), solving the non linear case has also advantages.”
• Spectroscopic ages and metallicities of stellar populations : validation of full spectrum fitting (2008, methodology): “The method has been presented in several places (Prugniel et al. 2003; Ocvirk et al. 2006a,b) and its reliability assessed on the basis of various simulations.”
• Recovering galaxy star formation and metallicity histories from spectra using VESPA (2007, methodology): “We follow an analysis given in Ocvirk et al. (2006) in order to understand how much this affects our results, and to choose a suitable age parametrization for each galaxy.”
• Modeling the Panchromatic Spectral Energy Distributions of Galaxies (2013, methodology): “This is precisely the approach taken by several groups, including MOPED (Heavens, Jimenez & Lahav 2000), STARLIGHT (Cid Fernandes et al. 2005), STECMAP (Ocvirk et al. 2006), VESPA (Tojeiro et al. 2007), ULySS (Koleva et al. 2009), and MacArthur, González & Courteau (2009).”
• The star formation histories of galaxies in the sloan digital sky survey (2006, methodology): “…raulj@physics.upenn.edu †Scottish Universities Physics Alliance. et al.2004; Tremonti et al. 2004) or using the full spectrum (Panter, Heavens & Jimenez 2003; Heavens et al. 2004; Panter, Heavens & Jimenez 2004; Cid Fernandes 2005; Mathis, Charlot & Brinchmann 2006; Ocvirk et al. 2006).”
• EARLY-TYPE GALAXY ARCHEOLOGY: AGES, ABUNDANCE RATIOS, AND EFFECTIVE TEMPERATURES FROM FULL-SPECTRUM FITTING (2013, methodology): “This approach has great potential, and is now frequently used to measure star formation histories and metallicities non-parametrically (Heavens et al. 2000; Cid Fernandes et al. 2005; Ocvirk et al. 2006; Tojeiro et al. 2009).”
• Spatially resolved spectroscopy of early-type galaxies over a range in mass (2007, methodology): “The only way to deal with this is to use a deconstruction method to analyse the whole star formation history of the galaxy (e.g., Panter, Heavens & Jimenez 2003; Ocvirk et al. 2006a,b).”
• Bursty stellar populations and obscured active galactic nuclei in galaxy bulges (2007, background): “…star formation history (SFH) of galaxies from their present-day integrated optical spectra (Kauffmann et al. 2003b; Panter, Heavens & Jimenez 2003; Ocvirk et al. 2006; Cid Fernandes et al. 2007), the potential for recovering detailed recent SFHs from spectra in these large data sets has remained…”
• Improving the full spectrum fitting method: accurate convolution with Gauss-Hermite functions (2016, methodology): “A conceptually similar regularization approach was used in the stecmap full-spectrum fitting code (Ocvirk et al. 2006).”
• Stellar population gradients in galaxy discs from the CALIFA survey - The influence of bars (2014, methodology): “To derive star formation histories we used the code STECKMAP (STEllar Content and Kinematics via Maximum A Posteriori likelihood, Ocvirk et al. 2006a,b) on the emission linecleaned spectra (see previous section).”
• OPTICAL SPECTROSCOPY AND NEBULAR OXYGEN ABUNDANCES OF THE SPITZER/SINGS GALAXIES (2010, background): “…ill suited for solving this kind of problem, although more general methods for inferring these quantities from integrated optical spectra have been developed (e.g., Panter et al. 2003; Gallazzi et al. 2005; Ocvirk et al. 2006; Cid Fernandes et al. 2007; Tojeiro et al. 2007; Blanton & Roweis 2007).”
• Bimodal gas accretion in the Horizon–MareNostrum galaxy formation simulation (2008, methodology): “This observation is further supported by the analysis of spectroscopic data, using star formation history reconstruction methods (Reichardt et al. 2001; Panter et al. 2003; Cid Fernandes et al. 2004; Ocvirk et al. 2006b,a).”
• New insights into the stellar content and physical conditions of star-forming galaxies at z = 2-3 from spectral modelling (2008, methodology): “…in the size of galaxy surveys which we have witnessed in recent years has been accompanied by the development of increasingly sophisticated models for the analysis and interpretation of their spectra (e.g. Kewley et al. 2001a; Bruzual & Charlot 2003; Heavens et al. 2004; Ocvirk et al. 2006).”
• The history of star-forming galaxies in the Sloan Digital Sky Survey (2007, methodology): “STECMAP (Ocvirk et al. 2006) performs a compression by requiring the resulting SFH to be relatively smooth.”