Modeling the Pan-Spectral Energy Distribution of Starburst Galaxies. IV. The Controlling Parameters of the Starburst SED
01 Jun 2008-Astrophysical Journal Supplement Series (Institute of Physics Publishing)-Vol. 176, Iss: 2, pp 438-456
TL;DR: In this article, the stellar spectral synthesis code Starburst99, the nebular modeling code MAPPINGS III and a one-dimensional dynamical evolution model of H II regions around massive clusters of young stars were combined to generate improved models of the spectral energy distribution (SED) of starburst galaxies.
Abstract: We combine the stellar spectral synthesis code Starburst99, the nebular modeling code MAPPINGS III and a one-dimensional dynamical evolution model of H II regions around massive clusters of young stars to generate improved models of the spectral energy distribution (SED) of starburst galaxies. We introduce a compactness parameter, , which characterizes the specific intensity of the radiation field at ionization fronts in H II regions and which controls the shape of the far-infrared (IR) dust reemission, often referred to loosely as the dust temperature. We also investigate the effect of metallicity on the overall SED and in particular, on the strength of the polycyclic aromatic hydrocarbon (PAH) features. We provide templates for the mean emission produced by the young compact H II regions, the older (10-100 Myr) stars and for the wavelength-dependent attenuation produced by a foreground screen of the dust used in our model. We demonstrate that these components may be combined to produce a excellent fit to the observed SEDs of star formation-dominated galaxies which are often used as templates (Arp 220 and NGC 6240). This fit extends from the Lyman limit to wavelengths of about 1 mm. The methods presented in both this paper and in the previous papers of this series allow the extraction of the physical parameters of the starburst region (star formation rates, star formation rate history, mean cluster mass, metallicity, dust attenuation, and pressure) from the analysis of the pan-spectral SED.
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TL;DR: In this article, the spectral energy distribution of the power reradiated by dust in stellar birth clouds and in the ambient interstellar medium (ISM) in galaxies is computed using an angle-averaged prescription.
Abstract: We present a simple, largely empirical but physically motivated model to interpret the mid- and far-infrared spectral energy distributions of galaxies consistently with the emission at ultraviolet, optical and near-infrared wavelengths. Our model relies on an existing angle-averaged prescription to compute the absorption of starlight by dust in stellar birth clouds and in the ambient interstellar medium (ISM) in galaxies. We compute the spectral energy distribution of the power reradiated by dust in stellar birth clouds as the sum of three components: a component of polycyclic aromatic hydrocarbons (PAHs); a mid-infrared continuum characterising the emission from hot grains at temperatures in the range 130–250 K; and a component of grains in thermal equilibrium with adjustable temperature in the range 30–60 K. In the ambient ISM, we fix for simplicity the relative proportions of these three components to reproduce the spectral shape of diffuse cirrus emission in the Milky Way, and we include a component of cold grains in thermal equilibrium with adjustable temperature in the range 15–25 K. Our model is both simple and versatile enough that it can be used to derive statistical constraints on the star formation histories and dust contents of large samples of galaxies using a wide range of ultraviolet, optical and infrared observations. We illustrate this by deriving median-likelihood estimates of the star formation rates, stellar masses, effective dust optical depths, dust masses, and relative strengths of different dust components of 66 well-studied nearby star-forming galaxies from the Spitzer Infrared Nearby Galaxy Survey (SINGS). We explore how the constraints derived in this way depend on the available spectral information. From our analysis of the SINGS sample, we conclude that the mid- and far-infrared colours of galaxies correlate strongly with the specific star formation rate, as well as with other galaxywide quantities connected to this parameter, such as the ratio of infrared luminosity between stellar birth clouds and the ambient ISM, the contributions by PAHs and grains in thermal equilibrium to the total infrared emission, and the ratio of dust mass to stellar mass. Our model can be straightforwardly applied to interpret ultraviolet, optical and infrared spectral energy distributions from any galaxy sample.
1,156 citations
TL;DR: In this article, the effect of photo-ionization on the cooling rate of heavy ionizing background radiation has been investigated, and it has been shown that photoionization by the background radiation can reduce cooling rates by up to an order of magnitude.
Abstract: A B ST R A C T Radiativecooling iscentralto a widerangeofastrophysicalproblem s.Despiteits im portance,cooling ratesaregenerally com puted using very restrictiveassum ptions, such as collisionalionization equilibrium and solar relative abundances.W e sim ul- taneously relax both assum ptions and investigate the eects ofphoto-ionization of heavy elem entsby them eta-galacticUV/X-ray background and ofvariationsin rela- tiveabundanceson thecoolingratesofopticallythin gasin ionization equilibrium .W e �nd thatphoto-ionization by them eta-galacticbackground radiation reducesthenet cooling ratesby up to an orderofm agnitudeforgasdensitiesand tem peraturestyp- icalofthe shock-heated intergalactic m edium and proto-galaxies(10 4 K< T < 10 6 K, �=hi < 100).In addition,photo-ionization changesthe relative contributionsofdif- ferentelem entstothecoolingrates.W econcludethatphoto-ionization by theionizing background and heavy elem entsboth need to be taken into accountin orderforthe cooling ratesto be correctto orderofm agnitude.M oreover,ifthe ratesneed to be known to better than a factor ofa few,then departures ofthe relative abundances from solar need to be taken into account.W e propose a m ethod to com pute cool- ing rateson an elem ent-by-elem entbasisby interpolating pre-com puted tables that take photo-ionization into account.W e provide such tables for a popular m odelof the evolving UV/X-ray background radiation,com puted using the photo-ionization package cloudy. K ey w ords: atom icprocesses| plasm as| coolingows| galaxies:form ation | intergalacticm edium
848 citations
Cites result from "Modeling the Pan-Spectral Energy Di..."
...In Figure 1 we compare our CIE results (i.e., cloudy version 07.02) with those of Gnat & Sternberg (2007) (who used cloudy version 06.02), Sutherland & Dopita (1993) (who used mappings) and also with mappings iii (version r; Groves et al. 2008)....
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TL;DR: An overview of the stellar population synthesis (SPS) technique and what can be reliably measured from galaxy spectral energy distributions can be found in this paper, including stellar masses, star-formation rates and histories, metallicities and abundance patterns, dust properties, and the stellar initial mass function.
Abstract: The spectral energy distributions (SEDs) of galaxies are shaped by nearly every physical property of the system, including the star-formation history, metal content, abundance pattern, dust mass, grain size distribution, star-dust geometry, and interstellar radiation field. The principal goal of stellar population synthesis (SPS) is to extract these variables from observed SEDs. In this review I provide an overview of the SPS technique and discuss what can be reliably measured from galaxy SEDs. Topics include stellar masses, star-formation rates and histories, metallicities and abundance patterns, dust properties, and the stellar initial mass function.
687 citations
Cites background or methods from "Modeling the Pan-Spectral Energy Di..."
...…starlight (or simply the radiation field) to predict IR emission (Desert, Boulanger & Puget 1990; Silva et al. 1998; Devriendt, Guiderdoni & Sadat 1999; Popescu et al. 2000; Dale et al. 2001; Piovan, Tantalo & Chiosi 2006; Jonsson 2006; Draine & Li 2007; Groves et al. 2008; Popescu et al. 2011)....
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...…models for UV, optical, and NIR SEDs, and it is only recently that models have been developed to simultaneously and selfconsistently predict the FUV through FIR SEDs (e.g., Devriendt, Guiderdoni & Sadat 1999; Silva et al. 1998; da Cunha, Charlot & Elbaz 2008; Groves et al. 2008; Noll et al. 2009a)....
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...…varying degrees of complexity, and with some only including nebular continuum, others only line emission, and others including both (e.g., Leitherer et al. 1999, Charlot & Longhetti 2001, Panuzzo et al. 2003, Groves et al. 2008, Mollá, Garćıa-Vargas & Bressan 2009, Schaerer & de Barros 2010)....
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TL;DR: In this paper, the authors summarized the current status of star-forming galaxies (DSFGs) studies, focusing especially on the detailed characterization of the best-understood subset (submillimeter galaxies), and also the selection and characterization of more recently discovered DSFG populations.
583 citations
TL;DR: In this paper, the authors summarized the current status of star-forming galaxies (DSFGs), focusing especially on the detailed characterization of the best-understood subset (submillimeter galaxies), who were summarized in the last review of this field over a decade ago, Blain et al.
Abstract: Far-infrared and submillimeter wavelength surveys have now established the important role of dusty, star-forming galaxies (DSFGs) in the assembly of stellar mass and the evolution of massive galaxies in the Universe. The brightest of these galaxies have infrared luminosities in excess of 10$^{13}$ L$_{\odot}$ with implied star-formation rates of thousands of solar masses per year. They represent the most intense starbursts in the Universe, yet many are completely optically obscured. Their easy detection at submm wavelengths is due to dust heated by ultraviolet radiation of newly forming stars. When summed up, all of the dusty, star-forming galaxies in the Universe produce an infrared radiation field that has an equal energy density as the direct starlight emission from all galaxies visible at ultraviolet and optical wavelengths. The bulk of this infrared extragalactic background light emanates from galaxies as diverse as gas-rich disks to mergers of intense starbursting galaxies. Major advances in far-infrared instrumentation in recent years, both space-based and ground-based, has led to the detection of nearly a million DSFGs, yet our understanding of the underlying astrophysics that govern the start and end of the dusty starburst phase is still in nascent stage. This review is aimed at summarizing the current status of DSFG studies, focusing especially on the detailed characterization of the best-understood subset (submillimeter galaxies, who were summarized in the last review of this field over a decade ago, Blain et al., 2002), but also the selection and characterization of more recently discovered DSFG populations. We review DSFG population statistics, their physical properties including dust, gas and stellar contents, their environments, and current theoretical models related to the formation and evolution of these galaxies.
523 citations
Cites background from "Modeling the Pan-Spectral Energy Di..."
...The UV absorption and subsequent long-wavelength re-emission from the cold PDRs surrounding young stellar clusters formed in the galaxy merger is captured in sunrise via the inclusion of mappings photoionization calculations (Groves et al., 2008)....
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References
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TL;DR: In this article, a reprocessed composite of the COBE/DIRBE and IRAS/ISSA maps, with the zodiacal foreground and confirmed point sources removed, is presented.
Abstract: We present a full-sky 100 μm map that is a reprocessed composite of the COBE/DIRBE and IRAS/ISSA maps, with the zodiacal foreground and confirmed point sources removed. Before using the ISSA maps, we remove the remaining artifacts from the IRAS scan pattern. Using the DIRBE 100 and 240 μm data, we have constructed a map of the dust temperature so that the 100 μm map may be converted to a map proportional to dust column density. The dust temperature varies from 17 to 21 K, which is modest but does modify the estimate of the dust column by a factor of 5. The result of these manipulations is a map with DIRBE quality calibration and IRAS resolution. A wealth of filamentary detail is apparent on many different scales at all Galactic latitudes. In high-latitude regions, the dust map correlates well with maps of H I emission, but deviations are coherent in the sky and are especially conspicuous in regions of saturation of H I emission toward denser clouds and of formation of H2 in molecular clouds. In contrast, high-velocity H I clouds are deficient in dust emission, as expected. To generate the full-sky dust maps, we must first remove zodiacal light contamination, as well as a possible cosmic infrared background (CIB). This is done via a regression analysis of the 100 μm DIRBE map against the Leiden-Dwingeloo map of H I emission, with corrections for the zodiacal light via a suitable expansion of the DIRBE 25 μm flux. This procedure removes virtually all traces of the zodiacal foreground. For the 100 μm map no significant CIB is detected. At longer wavelengths, where the zodiacal contamination is weaker, we detect the CIB at surprisingly high flux levels of 32 ± 13 nW m-2 sr-1 at 140 μm and of 17 ± 4 nW m-2 sr-1 at 240 μm (95% confidence). This integrated flux ~2 times that extrapolated from optical galaxies in the Hubble Deep Field. The primary use of these maps is likely to be as a new estimator of Galactic extinction. To calibrate our maps, we assume a standard reddening law and use the colors of elliptical galaxies to measure the reddening per unit flux density of 100 μm emission. We find consistent calibration using the B-R color distribution of a sample of the 106 brightest cluster ellipticals, as well as a sample of 384 ellipticals with B-V and Mg line strength measurements. For the latter sample, we use the correlation of intrinsic B-V versus Mg2 index to tighten the power of the test greatly. We demonstrate that the new maps are twice as accurate as the older Burstein-Heiles reddening estimates in regions of low and moderate reddening. The maps are expected to be significantly more accurate in regions of high reddening. These dust maps will also be useful for estimating millimeter emission that contaminates cosmic microwave background radiation experiments and for estimating soft X-ray absorption. We describe how to access our maps readily for general use.
15,988 citations
"Modeling the Pan-Spectral Energy Di..." refers methods in this paper
...All UV to near-IR fluxes have been corrected for Galactic extinction using the E(B−V) values based upon IRAS 100µm cirrus emission maps (Schlegel et al. 1998) and extrapolating following Cardelli et al (89)....
[...]
TL;DR: In this paper, the authors presented a reprocessed composite of the COBE/DIRBE and IRAS/ISSA maps, with the zodiacal foreground and confirmed point sources removed.
Abstract: We present a full sky 100 micron map that is a reprocessed composite of the COBE/DIRBE and IRAS/ISSA maps, with the zodiacal foreground and confirmed point sources removed. Before using the ISSA maps, we remove the remaining artifacts from the IRAS scan pattern. Using the DIRBE 100 micron and 240 micron data, we have constructed a map of the dust temperature, so that the 100 micron map can be converted to a map proportional to dust column density. The result of these manipulations is a map with DIRBE-quality calibration and IRAS resolution.
To generate the full sky dust maps, we must first remove zodiacal light contamination as well as a possible cosmic infrared background (CIB). This is done via a regression analysis of the 100 micron DIRBE map against the Leiden- Dwingeloo map of H_I emission, with corrections for the zodiacal light via a suitable expansion of the DIRBE 25 micron flux. For the 100 micron map, no significant CIB is detected. In the 140 micron and 240 micron maps, where the zodiacal contamination is weaker, we detect the CIB at surprisingly high flux levels of 32 \pm 13 nW/m^2/sr at 140 micron, and 17 \pm 4 nW/m^2/sr at 240 micron (95% confidence). This integrated flux is ~2 times that extrapolated from optical galaxies in the Hubble Deep Field.
The primary use of these maps is likely to be as a new estimator of Galactic extinction. We demonstrate that the new maps are twice as accurate as the older Burstein-Heiles estimates in regions of low and moderate reddening. These dust maps will also be useful for estimating millimeter emission that contaminates CMBR experiments and for estimating soft X-ray absorption.
14,295 citations
TL;DR: In this article, the average extinction law over the 3.5 micron to 0.125 wavelength range was derived for both diffuse and dense regions of the interstellar medium. And the validity of the law over a large wavelength interval suggests that the processes which modify the sizes and compositions of grains are stochastic in nature.
Abstract: The parameterized extinction data of Fitzpatrick and Massa (1986, 1988) for the ultraviolet and various sources for the optical and near-infrared are used to derive a meaningful average extinction law over the 3.5 micron to 0.125 wavelength range which is applicable to both diffuse and dense regions of the interstellar medium. The law depends on only one parameter R(V) = A(V)/E(B-V). An analytic formula is given for the mean extinction law which can be used to calculate color excesses or to deredden observations. The validity of the law over a large wavelength interval suggests that the processes which modify the sizes and compositions of grains are stochastic in nature and very efficient.
11,704 citations
"Modeling the Pan-Spectral Energy Di..." refers methods in this paper
...All UV to near-IR fluxes have been corrected for Galactic extinction using the E(B−V) values based upon IRAS 100µm cirrus emission maps (Schlegel et al. 1998) and extrapolating following Cardelli et al (89)....
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TL;DR: In this article, the authors focus on the broad patterns in the star formation properties of galaxies along the Hubble sequence and their implications for understanding galaxy evolution and the physical processes that drive the evolution.
Abstract: Observations of star formation rates (SFRs) in galaxies provide vital clues to the physical nature of the Hubble sequence and are key probes of the evolutionary histories of galaxies. The focus of this review is on the broad patterns in the star formation properties of galaxies along the Hubble sequence and their implications for understanding galaxy evolution and the physical processes that drive the evolution. Star formation in the disks and nuclear regions of galaxies are reviewed separately, then discussed within a common interpretive framework. The diagnostic methods used to measure SFRs are also reviewed, and a self-consistent set of SFR calibrations is presented as an aid to workers in the field. One of the most recognizable features of galaxies along the Hubble sequence is the wide range in young stellar content and star formation activity. This variation in stellar content is part of the basis of the Hubble classification itself (Hubble 1926), and understanding its physical nature and origins is fundamental to understanding galaxy evolution in its broader context. This review deals with the global star formation properties of galaxies, the systematics of those properties along the Hubble sequence, and their implications for galactic evolution. I interpret “Hubble sequence” in this context very loosely, to encompass not only morphological type but other properties such as gas content, mass, bar structure, and dynamical environment, which can strongly influence the largescale star formation rate (SFR).
6,640 citations
01 Jan 1991
TL;DR: In this article, a reference catalogue of bright galaxies in three volumes reflects the explosive growth of extragalactic astronomy over the last 15 years and includes all galaxies with apparent diameters larger than one arc minute, magnitudes brighter than about magnitude 15.5, and redshifts not larger than 15,000 km/sec.
Abstract: This new, enlarged reference catalogue of bright galaxies in three volumes reflects the explosive growth of extragalactic astronomy over the last 15 years. With data on more than 23,000 galaxies, it includes all galaxies with apparent diameters larger than one arc minute, magnitudes brighter than about magnitude 15.5, and redshifts not larger than 15,000 km/sec, as well as many other objects of interest. Volume 1 contains the explanations and references; volumes 2 and 3 contain the catalogue proper. The catalogue gives for each galaxy, the position, names, type and luminosity class, optical diameters, optical and infrared magnitudes, various colour indices and radial velocities. The work also makes reference to papers on bright galaxies published between 1913 and 1988. This dictionary/encyclopaedia on stellar systems is intended for researchers in astronomy.
4,656 citations