Efficient multi-Gaussian expansion of galaxies

By M. Cappellari. 2002

349 citations recorded by the source corpus.

We describe a simple, efficient, robust and fully automatic a lgorithm for the determination of a Multi-Gaussian Expansion (MGE) fit to galaxy images, to be u sed as a parametrization for the galaxy stellar surface brightness. In most cases the lea st-squares solution found by this method essentially corresponds to the minimax, constant relative error, MGE approximation of the galaxy surface brightness, with the chosen number of Gaussians. The algorithm is well suited to be used with multiple resolution images (e.g., Hubble Space Telescope[HST] and ground-based). It works orders of magnitude faster and is more accurate than currently available methods. An alternative, more computing intensive, fully linear algorithm, that is guaranteed to converge to the smallest � 2 solution, is also discussed. Examples of MGE fits are presented for objects with HST or ground-based photo metry, including galaxies with significant isophote twist.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/1fc9fec937c01e420335ed6f292987b0e2c4c83f

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In Astronomy and Astrophysics

1. M. Cappellari
2. M. Sarzi
3. Eric Emsellem
4. Roger Davies
5. T. Naab
6. M. Bureau
7. P. de Zeeuw
8. D. Krajnovi'c

In Instrumentation

1. M. Cappellari
2. Eric Emsellem
3. M. Sarzi
4. M. Bureau
5. Roger Davies
6. P. de Zeeuw
7. D. Krajnovi'c
8. R. McDermid

Citations in the corpus

• THE M87 BLACK HOLE MASS FROM GAS-DYNAMICAL MODELS OF SPACE TELESCOPE IMAGING SPECTROGRAPH OBSERVATIONS (2013, methodology): “To carry out the deprojection, we used the Multi-Gaussian Expansion (MGE) software developed by Cappellari (2002a), which is based on the methods described in Emsellem et al. (1994).”
• The ATLAS3D project - II. Morphologies, kinemetric features and alignment between photometric and kinematic axes of early-type galaxies (2011, background): “On the other hand, going out to large scales to avoid bars 5 The IDL routine is called find_galaxy.pro and is a part of the MGE package (Cappellari 2002) that can be found at http://www.purl.org/cappellari/idl C© 2011 The Authors, MNRAS 414, 2923–2949 Monthly Notices of the Royal Astronomical…”
• H0LiCOW – IX. Cosmographic analysis of the doubly imaged quasar SDSS 1206+4332 and a new measurement of the Hubble constant (2018, methodology): “To perform the de-projections, we use a multi-Gaussian decomposition (Cappellari 2002) of the modelled projected light and lens model and perform the de-projection on the Gaussian functions.”
• The ATLAS3D project – XX. Mass–size and mass–σ distributions of early-type galaxies: bulge fraction drives kinematics, mass-to-light ratio, molecular gas fraction and stellar initial mass function (2012, methodology): “…adopted an axisymmetric modelling method which describes in detail both the individual galaxy images using the MGE technique (Emsellem et al. 1994; Cappellari 2002) and the richness of our two-dimensional kinematics (Cappellari 2008), thus avoiding the possible biases of previous more approximate…”
• EFFICIENT THREE-DIMENSIONAL NLTE DUST RADIATIVE TRANSFER WITH SKIRT (2011, methodology): “An MGE expansion basically expands any surface brightness distribution as a finite sum of two-dimensional gaussian components (Monnet et al. 1992; Emsellem et al. 1994a; Cappellari 2002).”
• Triaxial orbit based galaxy models with an application to the (apparent) decoupled core galaxy NGC 4365 (2007, methodology): “The largest deprojectable volume is obtained by maximizing min {q′j} and minimizing max{| ψ ′j |}, while still fitting the photometry within a certain accuracy (see also Cappellari 2002).”
• Structure and Kinematics of Early-Type Galaxies from Integral Field Spectroscopy (2016, methodology): “It uses the Multi-Gaussian Expansion (MGE; Emsellem et al. 1994; Cappellari 2002) to parametrize the observed galaxy surface brightness.”
• The Tully-Fisher relations of early-type spiral and S0 galaxies (2010, methodology): “The circular velocity of each flattened model is conveniently calculated numerically by flattening a multi-Gaussian fit to the mass distribution and using standard integrals to determine the circular velocity of the arbitrarily flattened distribution (Cappellari 2002).”
• The ATLAS3D project XV: benchmark for early-type galaxies scaling relations from 260 dynamical models: mass-to-light ratio, dark matter, fundamental plane and mass plane (2012, methodology): “…using the MGE Downloaded from https://academic.oup.com/mnras/article-abstract/432/3/1709/1747470 by guest on 25 July 2018 The ATLAS3D project – XV. Dynamical models 1713 parametrization (Emsellem et al. 1994), with the fitting method and MGE_FIT_SECTORS software package1 of Cappellari (2002).”
• The ATLAS3D project - XIV. The extent and kinematics of the molecular gas in early-type galaxies (2012, methodology): “The stellar surface brightness profiles was extracted from the MGE (Emsellem, Monnet & Bacon 1994) model of each ATLAS3D galaxy (Scott et al., in prep) with the software of Cappellari (2002).”
• Surface brightness profile of the Milky Way’s nuclear star cluster (2014, methodology): “To compute a surface brightness profile we use the MGE FIT S ECTORS package written by Cappellari (2002).”
• THE NGC 404 NUCLEUS: STAR CLUSTER AND POSSIBLE INTERMEDIATE-MASS BLACK HOLE (2010, methodology): “The MGE fit was performed with the method and software10 of Cappellari (2002).”
• A SAURON study of M32: measuring the intrinsic flattening and the central black hole mass (2002, methodology): “The parameters of these eleven Gaussians are listed in Table 1; this superposition reproduces the M32 surface brightness with an RMS error of ≈2.2 per cent (Cappellari 2002, Figure 6).”
• Masses and scaling relations for nuclear star clusters, and their co-existence with central black holes (2016, positive): “For those NSCs, we use the luminosities obtained by Neumayer & Walcher from a Multi-Gaussian Expansion fitting technique (MGE, Emsellem et al. 1994; Cappellari 2002).”
• The SAURON project – X. The orbital anisotropy of elliptical and lenticular galaxies: revisiting the (V/σ, ɛ) diagram with integral‐field stellar kinematics (2007, methodology): “We used this set of photometric data to parameterise the stellar density distribution in our models according to the multi-Gaussianexpansion (MGE) method (Emsellem et al. 1994; Cappellari 2002).”
• The SAURON project - IV. The mass-to-light ratio, the virial mass estimator and the Fundamental Plane of elliptical and lenticular galaxies (2005, methodology): “As discussed in Cappellari (2002) we ‘regularized’ our solutions by requiring the axial ratio of the flattest Gaussian tobe as big as possible, while still reproducing the observed photometry.”
• DISCOVERY OF AN ACTIVE GALACTIC NUCLEUS DRIVEN MOLECULAR OUTFLOW IN THE LOCAL EARLY-TYPE GALAXY NGC 1266 (2011, methodology): “For this we constructed a MGE model Emsellem et al. (1994) of the stellar mass distribution of NGC 1266 from our own R-band Isaac Newton Telescope (INT) photometry (Scott et al. 2011, in prep) and the software of Cappellari (2002).”
• Measuring the inclination and mass-to-light ratio of axisymmetric galaxies via anisotropic Jeans models of stellar kinematics (2008, methodology): “We adopt forboth the MGE parametrization of Emsellem et al. (1994) due to its flexibility in accurately reproducing the surfacebrightness of real galaxies and the availability of robust routines4 to fit the galaxy photometry (Cappellari 2002).”