We test the efficacy of the energy-balance spectral energy distribution (SED) fitting code Magphys for recovering the spatially-resolved properties of a simulated isolated disc galaxy, for which it was not designed. We perform 226,950 Magphys SED fits to regions between 0.2kpc and 25kpc in size across the galaxy's disc, viewed from three different sight-lines, to probe how well Magphys can recover key galaxy properties based on 21 bands of UV--far-infrared model photometry. Magphys yields statistically acceptable fits to $> 99$ per cent of the pixels within the $r$-band effective radius and between 59 and 77 per cent of pixels within 20kpc of the nucleus. Magphys is able to recover the distribution of stellar mass, star formation rate (SFR), specific SFR, dust luminosity, dust mass, and $V$-band attenuation reasonably well, especially when the pixel size is $> \sim1$ kpc, whereas non-standard outputs (stellar metallicity and mass-weighted age) are recovered less well. Accurate recovery is more challenging in the smallest sub-regions of the disc (pixel scale $< \sim 1$ kpc), where the energy balance criterion becomes increasingly incorrect. Estimating integrated galaxy properties by summing the recovered pixel values, the true integrated values of all parameters considered except metallicity and age are well recovered at all spatial resolutions, ranging from 0.2kpc to integrating across the disc, albeit with some evidence for resolution-dependent biases. These results must be considered when attempting to analyse the structure of real galaxies with actual observational data, for which the `ground truth' is unknown.
Modelling and interpreting the SEDs of galaxies has become one of the key tools at the disposal of extragalactic astronomers. Ideally, we could hope that, through a detailed study of its SED, we can infer the correct physical properties and the evolutionary history of a galaxy. In the past decade, panchromatic SED fitting, i.e. modelling the SED over the entire UV-submm wavelength regime, has seen an enormous advance. Several advanced new codes have been developed, nearly all based on Bayesian inference modelling. In this review, we briefly touch upon the different ingredients necessary for pa…
Sparks II: Panchromatic SED modeling and galaxy physical properties across the starburst to post-starburst sequence
Kavli Institute for Particle Astrophysics & Cosmology, Stanford University（斯坦福大学卡弗里粒子天体物理与宇宙学研究所）；Center for Decoding the Universe, Stanford University（斯坦福大学解码宇宙中心）；Department of Astrophysical Sciences, Princeton University（普林斯顿大学天体物理科学系）；Department of Astronomy and Astrophysics, University of California Santa Cruz（加州大学圣克鲁兹分校天文与天体物理系）；Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU)（宇宙物理与数学卡弗里研究所）；Division of Science, National Astronomical Observatory of Japan（日本国立天文台科学部）；Max-Planck-Institut für extraterrestrische Physik（马克斯·普朗克地外物理学研究所）
Forward modeling of the full galaxy SED is a powerful technique, providing self-consistent constraints on stellar ages, dust properties, and metallicities. However, the accuracy of these results is contingent on the accuracy of the model. One significant source of uncertainty is the contribution of obscured AGN, as they are relatively common and can produce substantial mid-IR (MIR) emission. Here we include emission from dusty AGN torii in the Prospector SED-fitting framework, and fit the UV-IR broadband photometry of 129 nearby galaxies. We find that 10% of the fitted galaxies host an AGN con…
Fitting the multi-wavelength spectral energy distributions (SEDs) of galaxies is a widely used technique to extract information about the physical properties of galaxies. However, a major difficulty lies in the numerous uncertainties regarding almost all ingredients of the SED modeling of galaxies. The Bayesian methods provide a consistent conceptual basis for dealing with the problem of inference with many uncertainties. While the Bayesian parameter estimation method have become quite popular in the field of SED fitting of galaxies, the Bayesian model comparison method, which is based on the …
We study spatially resolved properties (on spatial scales of $\sim 1-2$ kpc out to at least $3$ effective radii) of the stars, dust, and gas in ten nearby spiral galaxies. The properties of the stellar population and dust are derived by fitting the spatially resolved spectral energy distribution (SED) with more than 20 photometric bands ranging from far-ultraviolet to far-infrared. Our newly developed software piXedfit performs point spread function matching of images, pixel binning, and models the stellar light, dust attenuation, dust emission, and emission from a dusty torus heated by an act…
Galaxy observations are influenced by many physical parameters: stellar masses, star formation rates (SFRs), star formation histories (SFHs), metallicities, dust, black hole activity, and more. As a result, inferring accurate physical parameters requires high-dimensional models which capture or marginalize over this complexity. Here we re-assess inferences of galaxy stellar masses and SFRs using the 14-parameter physical model Prospector-$α$ built in the Prospector Bayesian inference framework. We fit the photometry of 58,461 galaxies from the 3D-HST catalogs at $0.5 < z < 2.5$. The resulting …
We present predictions of Spectral Energy Distributions (SEDs), from the UV to the FIR, of simulated galaxies at $z=0$. These were obtained by post-processing the results of an N-body+hydro simulation of a small cosmological volume, that uses the Multi-Phase Particle Integrator (MUPPI) for star formation and stellar feedback, with the GRASIL-3D radiative transfer code, that includes reprocessing of UV light by dust. Physical properties of galaxies resemble observed ones, though with some tension at small and large stellar masses. Comparing predicted SEDs of simulated galaxies with different sa…
We have developed a pipeline called \mentari to generate the far-ultraviolet to far-infrared spectral energy distribution (SED) of galaxies from the \dustysage semi-analytic galaxy formation model (SAM). \dustysage incorporates dust-related processes directly on top of the basic ingredients of galaxy formation like gas infall, cooling, star formation, feedback, and mergers. We derive a physically motivated attenuation model from the computed dust properties in \dustysage, so each galaxy has a self-consistent set of attenuation parameters based on the complicated dust physics that occurred acro…
The Milky Way as a distant galaxy: an IFU and panchromatic view
Leibniz-Institut für Astrophysik Potsdam (AIP)（波茨坦莱布尼茨天体物理研究所）；Department of Astrophysics, University of Vienna（维也纳大学天体物理系）；LIRA, Observatoire de Paris, Université PSL, Sorbonne Université, Université Paris Cité, CY Cergy Paris Université, CNRS（拉伊拉、巴黎天文台、PSL大学、索邦大学、巴黎西岱大学、CY塞尔吉巴黎大学、法国国家科学研究中心）
We present a detailed spectral modelling of NGC4993 -- the host galaxy of GW170817 -- and other SGRB host galaxies. In order to determine their physical conditions and the element abundances, we have gathered spectroscopic and photometric data from the literature. The observation data are sometimes missing preventing us from fully constraining the model. However, for most of the SGRB hosts the [OIII]5007/Hb and [NII]6548/Ha line ratios are reported. The analysis of NGC4993 by a composite model (photoionization+shock) confirms that an AGN, most probably a LINER or a LLAGN, is the gas photoioniz…
We have studied in detail a sample of 967 SPIRE sources with 5-sigma detections at 350 and 500 micron and associations with Spitzer-SWIRE 24 micron galaxies in the HerMES-Lockman survey area, fitting their mid- and far-infrared, and submillimetre, SEDs in an automatic search with a set of six infrared templates. For almost 300 galaxies we have modelled their SEDs individually to ensure the physicality of the fits. We confirm the need for the new cool and cold cirrus templates, and also of the young starburst template, introduced in earlier work. We also identify 109 lensing candidates via thei…
Galaxy spectral energy distribution (SED) modelling is a powerful tool, but constraining how well it is able to infer the true values for galaxy properties (e.g. the star formation rate, SFR) is difficult because independent determinations are often not available. However, galaxy simulations can provide a means of testing SED modelling techniques. Here, we present a numerical experiment in which we apply the SED modelling code MAGPHYS to ultraviolet (UV)--millimetre (mm) synthetic photometry generated from hydrodynamical simulations of an isolated disc galaxy and a major galaxy merger by perfo…
By means of the updated PARSEC database of evolutionary tracks of massive stars, we compute the integrated stellar light, the ionizing photon budget and the supernova rates of young simple stellar populations (SSPs), for different metallicities and IMF upper mass limits. Using CLOUDY we compute and include in the SSP spectra the neb- ular emission contribution. We also revisit the thermal and non-thermal radio emission contribution from young stars. Using GRASIL we can thus predict the panchromatic spectrum and the main recombination lines of any type of star-forming galaxy, including the effe…
In this work, we characterise the contributions from both ongoing star formation and the ambient radiation field in Local Group galaxy M33, as well as estimate the scale of the local dust-energy balance (i.e. the scale at which the dust is re-emitting starlight generated in that same region) in this galaxy through high-resolution radiative transfer (RT) modelling, with defined stellar and dust geometries. We have characterised the spectral energy distribution (SED) of M33 from UV to sub-mm wavelengths, at a spatial scale of 100 pc. We constructed input maps of the various stellar and dust geom…
The Hubble Frontier Fields represent the opportunity to probe the high-redshift evolution of the main sequence of star-forming galaxies to lower masses than possible in blank fields thanks to foreground lensing of massive galaxy clusters. We use the BEAGLE SED-fitting code to derive stellar masses, $\mathrm{M_{\star}}=\log(M/\mathrm{M_{\odot}})$, SFRs, $Ψ=\log(ψ/\mathrm{M_{\odot}}\,\mathrm{yr}^{-1})$ and redshifts from galaxies within the ASTRODEEP catalogue. We fit a fully Bayesian hierarchical model of the main sequence over $1.25<z<6$ of the form $Ψ= α_\mathrm{9.7}(z) + β(\mathrm{M_{\star}}…
Continuum SED models of gamma-ray burst (GRB) and obscured GRB host galaxies at moderately high redshifts are presented and compared with those of superluminous supernovae (SLSN), starburst (SB) and active galactic nuclei (AGN). We consider that continuum radiation (bremsstrahlung) is emitted from the same clouds which emit the line spectrum in each object. Therefore, we have selected from the samples of the GRB host continuum observations those that were previously modelled on the basis of the line spectra, because modelling the continuum SED is less constraining. The bremsstrahlung is genera…
The HELP project focuses on the data from ESA's Herschel mission, which covered over 1300$deg^2$ and is preparing to publish a multi-wavelength catalogue of millions of objects. Our main goal is to find the best approach to simultaneously fitting SEDs of millions of galaxies across a wide redshift range to obtain homogeneous estimates of the main physical parameters of detected IR galaxies. We perform SED fitting on the UV/NIR to FIR emission of 42 047 galaxies from the pilot HELP field: ELAIS N1. We use the latest release of CIGALE, a galaxy SED fitting code relying on energy balance, to deli…
The dust in nearby galaxies absorbs a fraction of the UV-optical-near-infrared radiation produced by stars. This energy is consequently re-emitted in the infrared. We investigate the portion of the stellar radiation absorbed by spiral galaxies from the HRS by modelling their UV-to-submillimetre spectral energy distributions. Our models provide an attenuated and intrinsic SED from which we find that on average 32 % of all starlight is absorbed by dust. We define the UV heating fraction as the percentage of dust luminosity that comes from absorbed UV photons and find that this is 56 %, on averag…
We present the first direct comparison between Balmer line and panchromatic SED-based SFRs for z~2 galaxies. For this comparison we used 17 star-forming galaxies selected from the MOSFIRE Deep Evolution Field (MOSDEF) survey, with $3σ$ detections for H$α$ and at least two IR bands (Spitzer/MIPS 24$μ$m and Herschel/PACS 100 and 160$μ$m, and in some cases Herschel/SPIRE 250, 350, and 500$μ$m). The galaxies have total IR (8-1000$μ$m) luminosities of $\sim10^{11.4}-10^{12.4}\,\textrm{L}_\odot$ and star-formation rates (SFRs) of $\sim30-250\,\textrm{M}_\odot\,\mathrm{yr^{-1}}$. We fit the UV-to-far…
We present a new-generation tool to model and interpret spectral energy distributions (SEDs) of galaxies, which incorporates in a consistent way the production of radiation and its transfer through the interstellar and intergalactic media. This flexible tool, named BEAGLE (for BayEsian Analysis of GaLaxy sEds), allows one to build mock galaxy catalogues as well as to interpret any combination of photometric and spectroscopic galaxy observations in terms of physical parameters. The current version of the tool includes versatile modeling of the emission from stars and photoionized gas, attenuati…
The presence of spectroscopically confirmed Balmer breaks in galaxy spectral energy distributions (SEDs) at $z>9$ provides one of the best probes of the assembly history of the first generations of stars in our Universe. Recent observations of the gravitationally lensed source, MACS 1149_JD1 (JD1), indicate that significant amounts of star formation likely occurred at redshifts as high as $z\simeq15$. The inferred stellar mass, dust mass, and assembly history of JD1, or any other galaxy at these redshifts that exhibits a strong Balmer break, can provide a strong test of our best theoretical mo…
Prospects for Observing Galaxy Spectral Energy Distribution from the Radio to the far-Infrared in the Era of Next-Generation Radio Telescopes
National Radio Astronomy Observatory（美国国家射电天文台）；Department of Astronomy, University of Virginia（弗吉尼亚大学天文学系）；Department of Physics, Northeastern University（东北大学物理系）；Department of Physics, Cornell University（康奈尔大学物理系）；Eureka Scientific（尤里卡科学公司）；Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México（墨西哥国立自治大学无线电天文学与天体物理学研究所）；Space Telescope Science Institute（太空望远镜科学研究所）；Department of Physics, University of California, Santa Barbara（加州大学圣塔芭芭拉分校物理系）；Department of Astronomy, University of Massachusetts, Amherst（马萨诸塞大学阿默斯特分校天文学系）
X-ray disc reverberation modelling of the X-ray/UV/optical spectral/timing properties of Fairall 9
University of Crete（克里特大学）；Università Federico II（那不勒斯费德里科二世大学）；Institute of Astrophysics, FORTH（FORTH天体物理研究所）；Department of Physics and Institute of Theoretical and Computational Physics, University of Crete（克里特大学物理系与理论与计算物理研究所）；MIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology（麻省理工学院卡弗里天体物理学与空间研究研究所）；California Institute of Technology（加州理工学院）；Astronomical Institute of the Academy of Sciences（科学院天文研究所）
In this paper we propose a way to use optical polarisation observations to provide independent constraints and guide to the modelling of the spectral energy distribution (SED) of blazars, which is particularly useful when two-zone models are required to fit the observed SED. As an example, we apply the method to the 2008 multiwavelength campaign of PKS 2155-304, for which the required polarisation information was already available. We find this approach succesful in being able to simultaneously describe the SED and variability of the source, otherwise difficult to interpret. More generally, by…
We investigate the stellar and dust properties of massive (log$(M_*/M_\odot) \ge 10.5$) and dusty ($A_V \ge 1$) galaxies at $1 \le z \le 4$ by modeling their spectral energy distributions (SEDs) obtained from the combination of UltraVISTA DR3 photometry and \textit{Herschel} PACS-SPIRE data using MAGPHYS. Although the rest-frame U-V vs V-J (UVJ) diagram traces well the star-formation rates (SFR) and dust obscuration (A$_V$) out to $z \sim 3$, $\sim$15-20\% of the sample surprisingly resides in the quiescent region of the UVJ diagram, while $\sim50$\% at $3<z<4$ fall in the unobscured star-form…
Spectral population synthesis (PS) is a fundamental tool in extragalactic research that aims to decipher the assembly history of galaxies from their SED. However, until recently all PS codes were restricted to purely stellar fits, neglecting the essential contribution of nebular emission (NE). With the advent of FADO, the now possible self-consistent modelling of stellar and NE opens new routes to the exploration of galaxy SFHs. The main goal of this study is to quantitatively explore the accuracy to which FADO can recover physical and evolutionary properties of galaxies and compare its output…
Interstellar dust absorbs stellar light very efficiently and thus shapes the energetic output of galaxies. Studying the impact of different stellar populations on the dust heating remains hard because it requires decoupling the relative geometry of stars and dust, and involves complex processes as scattering and non-local dust heating. We aim to constrain the relative distribution of dust and stellar populations in the spiral galaxy M81 and create a realistic model of the radiation field that describes the observations. Investigating the dust-starlight interaction on local scales, we want to q…
We revised the treatment of interstellar dust in the KOSMA-τ PDR model code to achieve a consistent description of the dust-related physics in the code. The detailed knowledge of the dust properties is then used to compute the dust continuum emission together with the line emission of chemical species. We coupled the KOSMA-τ PDR code with the MCDRT (multi component dust radiative transfer) code to solve the frequency-dependent radiative transfer equations and the thermal balance equation in a dusty clump under the assumption of spherical symmetry, assuming thermal equilibrium in calculating th…
Panchromatic spectral energy distribution (SED) fitting is a critical tool for determining the physical properties of distant galaxies, such as their stellar mass and star formation rate. One widely used method is the publicly available MAGPHYS code. We build on our previous analysis (Hayward & Smith 2015) by presenting some modifications which enable MAGPHYS to automatically estimate galaxy star formation histories (SFHs), including uncertainties, based on ultra-violet to far-infrared photometry. We use state-of-the art synthetic photometry derived by performing three-dimensional dust radiati…
[abridged] The ALESS survey has followed-up a sample of 122 sub-millimeter sources in the Extended Chandra Deep Field South at 870um with ALMA, allowing to pinpoint the positions of sub-millimeter galaxies (SMGs) to 0.3'' and to find their precise counterparts at different wavelengths. This enabled the first compilation of the multi-wavelength spectral energy distributions (SEDs) of a statistically reliable survey of SMGs. In this paper, we present a new calibration of the MAGPHYS modelling code that is optimized to fit these UV-to-radio SEDs of z>1 star-forming galaxies using an energy balanc…
In order to investigate whether massive stars form similarly to their low-mass counterparts, we have used the standard envelope plus disc geometry successfully applied to low-mass protostars to model the near-IR to sub-millimetre SED and several mid-IR images of the embedded massive star IRAS20126+4104. We have used a Monte Carlo radiative transfer dust code to model the continuum absorption, emission and scattering through two azimuthally symmetric dust geometries, the first consisting of a rotationally flattened envelope with outflow cavities, and the second which also includes a flared accr…
We introduce a new model for the spectral energy distribution of galaxies, GRASIL-3D, which includes a careful modelling of the dust component of the interstellar medium. GRASIL-3D is an entirely new model based on the formalism of an existing and widely applied spectrophotometric model, GRASIL, but specifically designed to be interfaced with galaxies with any arbitrarily given geometry, such as galaxies calculated by theoretical hydrodynamical galaxy formation codes. GRASIL-3D is designed to separately treat radiative transfer in molecular clouds and in the diffuse cirrus component. The code …
CIGALE is a powerful multiwavelength spectral energy distribution (SED) fitting code for extragalactic studies. However, the current version of CIGALE is not able to fit X-ray data, which often provide unique insights into AGN intrinsic power. We develop a new X-ray module for CIGALE, allowing it to fit SEDs from the X-ray to infrared (IR). We also improve the AGN fitting of CIGALE from UV-to-IR wavelengths. We implement a modern clumpy two-phase torus model, SKIRTOR. To account for moderately extincted type 1 AGNs, we implement polar-dust extinction. We publicly release the source code (named…
