bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemical and physical properties of interstellar dust
Authors: Tielens A. G. G. M. 
Published: August 2012

AbstractThe characteristics of interstellar dust reflect a complex interplay between stellar injection of stardust, destruction in the ISM, and regrowth in clouds. Astronomical observations and analysis of stardust isolated from meteorites have revealed a highly diverse interstellar and circumstellar grain inventory, including both amorphous materials and highly crystalline compounds (silicates and carbon). This review summarizes this dust budget and inventory. Interstellar dust is highly processed during its sojourn from its birthsite (stellar ejecta) to its incorporation into protoplanetary systems. Processing by strong shocks due to supernova explosions is particularly important. Sputtering by impacting gas ions in shocks in the intercloud medium of the ISM is counteracted by accretion in cloud phases and their balance sets the observed, interstellar, elemental depletion patterns. Astronomical and meteoritical-stardust evidence for these processes is reviewed and it is concluded that dust formation in the ISM is very rapid. Not surprisingly, the characteristics of interstellar dust are expected to vary widely reflecting local stellar sources, the effects of SNe processing, and the interstellar accretion process.
The processing of radiation by dust in galaxies
Authors: Siebenmorgen Ralf , Heymann Frank 
Published: August 2012

AbstractOptical/UV photons and even harder radiation components in galaxies are absorbed and scattered by dust and re-emitted at infrared wavelengths. For a better understanding of the obscured regions of the galaxies detailed models of the interaction of photons with dust grains and the propagation of light are required. A problem which can only be solved by means of numerical solution of the radiative transfer equation. As a prologue we present high angular mid IR observations of galactic nuclei in the spirit of future ELT instrumentation. Dust models are discussed, which are suited to fit the extinction curves and relevant to compute the emission of external galaxies. Self-consistent radiative transfer models have been presented in spherical symmetry for starburst nuclei, in two dimensions for disk galaxies (spirals) and, more recently, in three dimensional configuration of the dust density distribution. For the latter, a highlighting example is the clumpy dust tori around AGN. Modern advances in the field are reviewed which are either based on a more detailed physical picture or progress in computational sciences.
Investigations of dust heating in M81, M83 and NGC 2403 with Herschel and Spitzer
Authors: Bendo George J. ,   the Herschel-SPIRE Local Galaxies Guaranteed Time Programs
Published: August 2012

AbstractWe use Herschel Space Observatory and Spitzer Space Telescope 70-500 μm data along with ground-based optical and near-infrared data to understand how dust heating in the nearby face-on spiral galaxies M81, M83, and NGC 2403 is affected by the starlight from all stars and by the radiation from star-forming regions. We find that 70/160 μm flux density ratios tend to be more strongly influenced by star-forming regions. However, the 250/350 and 350/500 μm micron flux density ratios are more strongly affected by the light from the total stellar populations, suggesting that the dust emission at > 250 μm originates predominantly from a component that is colder than the dust seen at <160 μm and that is relatively unaffected by star formation activity. We conclude by discussing the implications of this for modelling the spectral energy distributions of both nearby and more distant galaxies and for using far-infrared dust emission to trace star formation.
Spectral Energy Distributions of a set of H ii regions in M33 (HerM33es)
Authors: Relaño Monica , Verley Simon , Pérez Isabel , Kramer Carsten , Xilouris Manolis , Boquien Médéric , Braine Jonathan , Calzetti Daniela , Henkel Christian ,   the HerM33es Team
Published: August 2012

AbstractWithin the framework of the HerM33es Key Project for Herschel and in combination with multi-wavelength data, we study the Spectral Energy Distribution (SED) of a set of H ii regions in the Local Group Galaxy M33. Using the Hα emission, we perform a classification of a selected H ii region sample in terms of morphology, separating the objects in filled, mixed, shell and clear shell objects. We obtain the SED for each H ii region as well as a representative SED for each class of objects. We also study the emission distribution of each band within the regions. We find different trends in the SEDs for each morphological type that are related to properties of the dust and their associated stellar cluster. The emission distribution of each band within the region is different for each morphological type of object.
Variation in the dust spectral index across M33
Authors: Tabatabaei Fatemeh S. , Braine Jonathan , Kramer Carsten , Xilouris Manolis , Boquien Mederic , Verley Simon , Schinnerer Eva , Calzetti Daniela , Combes Francoise , Israel Frank , Henkel Christian ,   The HerM33es Team
Published: August 2012

AbstractUsing the Herschel PACS and SPIRE FIR/submm data, we investigate variations in the dust spectral index β in the nearby spiral galaxy M33 at a linear resolution of 160 pc. We use an iteration method in two different approaches, single and two-component modified black body models. In both approaches, β is higher in the central disk than in the outer disk similar to the dust temperature. There is a positive correlation between β and Hα as well as with the molecular gas traced by CO(2-1). A Monte-Carlo simulation shows that the physical parameters are better constrained when using the two-component model.
Ionization of the diffuse gas in galaxies: hot low-mass evolved stars at work
Authors: Flores-Fajardo N. , Morisset C. , Stasińska G. , Binette L. 
Published: August 2012

AbstractWe revisit the question of the ionization of the diffuse medium in late type galaxies, by studying NGC 891. The most important challenge for the models considered so far was the observed increase of [O iii]/Hβ, [O iii]/Hβ, and [N ii]\Hα with increasing distance to the galactic plane. We propose a scenario based on the expected population of massive OB stars and hot low-mass evolved stars (HOLMES) in this galaxy to explain this observational fact. In the framework of this scenario we construct a finely meshed grid of photoionization models. For each value of the galactic latitude z we look for the models which simultaneously fit the observed values of the [O iii]/Hβ, [O ii]/Hβ, and [N ii]\Hα ratios. For each value of z we find a range of solutions which depends on the value of the oxygen abundance. The models which fit the observations indicate a systematic decrease of the electron density with increasing z. They become dominated by the HOLMES with increasing z only when restricting to solar oxygen abundance models, which argues that the metallicity above the galactic plane should be close to solar. They also indicate that N/O increases with increasing z.
Dust in dwarf galaxies: The case of NGC 4214
Authors: Lisenfeld U. , Hermelo I. , Relaño M. , Tuffs R. J. , Popescu C. C. , Fischera J. , Groves B. 
Published: August 2012

AbstractWe have carried out a detailed modelling of the dust heating and emission in the nearby, starbursting dwarf galaxy NGC 4214. Due to its proximity and the great wealth of data from the UV to the millimeter range (from GALEX, HST, Spitzer, Herschel, Planck and IRAM) it is possible to separately model the emission from HII regions and their associated photodissociation regions (PDRs) and the emission from diffuse dust. Furthermore, most model parameters can be directly determined from the data leaving very few free parameters. We can fit both the emission from HII+PDR regions and the diffuse emission in NGC 4214 with these models with “normal” dust properties and realistic parameters.
Modeling the dust Spectral Energy Distribution of NGC 4214
Authors: Hermelo Israel , Lisenfeld Ute , Relaño Mónica , Tuffs Richard J. , Popescu Cristina C. , Fischera Jörg , Groves Brent 
Published: August 2012

AbstractWe have carried out a detailed modeling of the dust Spectral Energy Distribution (SED) of the nearby, starbursting dwarf galaxy NGC 4214. A key point of our modeling is that we distinguish the emission from (i) HII regions and their associated photodissociation regions (PDRs) and (ii) diffuse dust. For both components we apply templates from the literature calculated with a realistic geometry and including radiation transfer. The large amount of existing data from the ultraviolet (UV) to the radio allows the direct measurement of most of the input parameters of the models. We achieve a good fit for the total dust SED of NGC 4214. In the present contribution we describe the available data, the data reduction and the determination of the model parameters, whereas a description of the general outline of our work is presented in the contribution of Lisenfeld et al. in this volume.
Optical SED models of galaxy mergers
Authors: Snyder Gregory F. , Cox T. J. , Hayward Christopher C. , Hernquist Lars , Jonsson Patrik 
Published: August 2012

AbstractI discuss recent work in which we construct models of poststarburst galaxies by combining fully three-dimensional hydrodynamic simulations of galaxy mergers with radiative transfer calculations of dust attenuation. The poststarburst signatures can occur shortly after a bright starburst phase in gas-rich mergers, and thus offer a unique opportunity to study the formation of bulges and the effects of feedback. Several additional applications of spatially-resolved spectroscopic models of interacting galaxies include multi-wavelength studies of AGN/starburst diagnostics, mock integral field unit data to interpret the evolution of ULIRGs, and the ‘Green Valley’.Optical spectra of simulated major gas-rich galaxy mergers can be found at http://www.cfa.harvard.edu/~gsnyder
The SEDs of interacting galaxies
Authors: Lanz Lauranne , Brassington Nicola , Zezas Andreas , Smith Howard A. , Ashby Matthew L. N. , da Cunha Elisabete , Klein Christopher , Jonsson Patrik , Hayward Christopher C. , Hernquist Lars , Fazio Giovanni 
Published: August 2012

AbstractThe evolution of galaxies is greatly influenced by their interactions. As part of a program to study interacting galaxies, we have measured and modeled the spectral energy distributions (SEDs) from the ultraviolet (UV) to the far-infrared (FIR). We describe the constraints imposed on star formation histories by these SEDs, and the variations therein seen across the interaction sequence, and we compare the results of different star formation rate prescriptions applied to the data. The sample itself is based on the Spitzer Interacting Galaxy Survey (SIGS) of 111 galaxies in 50 systems, a project designed to probe a range of galaxy interaction parameters in the infrared. Our SEDs combine the Spitzer results with multiwavelength data from other missions, in particular GALEX and Herschel. The subset presented here is the sample for which FIR Herschel observations are currently publicly available.
Properties of mid- to far-infrared dust emission in the nearby superwind galaxy M82
Authors: Arimatsu Ko , Onaka Takashi , Sakon Itsuki , Egusa Fumi , Kaneda Hidehiro 
Published: August 2012

AbstractUsing the reconstructed imaging data obtained with the Infrared Camera (IRC) on board AKARI, mid-infrared (MIR; 5-30 μm) emission characteristics of the superwind galaxy M82 are studied. The MIR images at four wavelengths (7, 11, 15, and 24 μm) show extended (out to distances of 4 kpc) emission mainly from polycyclic aromatic hydrocarbons (PAHs). The MIR SED of M82 halo is surprisingly constant. Using far-infrared imaging data obtained by Herschel/SPIRE, we reveal that the PAH abundance relative to the big (sub-micron sized) grains radially increases by about a factor of three. These results imply that PAHs may be formed in small and dense molecular clumps in the halo and efficiently supplied to the intergalactic space by the galactic superwind.
The Mid-Infrared luminosity function of galaxies using the AKARI mid-infrared All-Sky Survey Catalogue
Authors: Toba Y. , Oyabu S. , Matsuhara H. , Ishihara D. , Malkan M. , Wada T. , Kataza H. , Ohyama Y. , Takita S. 
Published: August 2012

AbstractWe present the first determination of the 18 μm luminosity function (LF) of galaxies at 0.006 < z < 0.7 (the average redshift is ~ 0.04) using the AKARI mid-infrared All-Sky Survey catalogue. We have selected a 18 μm flux-limited sample of 243 galaxies from the catalogue in the SDSS spectroscopic region. We then classified the sample into four types; Seyfert 1 galaxies (including QSOs), Seyfert 2 galaxies, LINERs and Star-Forming galaxies using mainly [OIII]/Hβ vs. [NII]/Hα line ratios obtained from the SDSS.As a result of constructing Seyfert 1 and Seyfert 2 LFs, we found the following results; (i) the number density ratio of Seyfert 2s to Seyfert 1s is 3.98 ± 0.41 obtained from Sy1 and Sy2 LFs; this value is larger than the results obtained from optical LFs. (ii) the fraction of Sy2s in the entire AGNs may be anti-correlated with 18 μm luminosity. These results suggest that the torus structure probably depends on the mid-infrared luminosity of AGNs and most of the AGNs in the local Universe are obscured by dust.
Optically faint radio sources: reborn AGN?
Authors: Filho Mercedes E. , Brinchmann Jarle , Lobo Catarina , Antón Sonia 
Published: August 2012

AbstractWe have discovered eight relatively strong radio sources that have no optical counterparts. A NIR follow-up has detected faint (17–20 mag) host galaxies in all targets. In general, the radio properties are similar to those observed in 3CRR sources but the optical-radio slopes are consistent with moderate to high redshift (z < 4) GHz-peaked spectrum sources. Our results suggest that these are galaxies whose black hole has been recently re-ignited into activity but that retain large-scale radio structures, signatures of previous AGN activity.
Stellar populations in the centers of nearby galaxies
Authors: Gomes Jean Michel , Filho Mercedes E. , Ho Luis C. 
Published: August 2012

AbstractThe great amount of data observed in recent years coupled with modelling using evolutionary synthesis codes (BPASS, COELHO, GALAXEV, GALEV, MILES, PÉGASE, etc. . .) to compute Single Stellar Populations (SSPs) and the availability of fast and ingenious spectral synthesis codes such asstarlight, ULySS and VESPA, have significantly shed light on our knowledge about the formation and evolution of galaxies. However, there are still open issues concerning the stellar populations in nearby galaxies, particularly those harbouring Active Galactic Nuclei (AGN): can stellar populations mimic nuclear activity, leading to a misclassification based on optical emission line ratios (Stasińskaet al. 2008)? We have applied thestarlightcode (Cid Fernandeset al. 2005) to a well studied sample of nearby galaxies' nuclear spectra (r < ~ 200 pc), observed with the Hale 5 m telescope at Palomar Observatory in two different regions: ~ 4230-5110 Å and ~ 6210-6860 Å (Hoet al. 1995), with spectral resolutions of approximately 4 Å, and 2.5 Å. The aim is to properly derive the star-formation history (SFH), mean stellar age and metallicity and total stellar mass. Our results show that the star-formation history of Seyfert galaxies are very heterogeneous, i.e. these are composed of young, intermediate and old stellar populations, while the SFH of Low-Ionization Nuclear Emission-Line Regions (LINERs) are basically composed of old stellar populations. The absence of young stars in LINERs indicates that these are not responsible for the observed low-ionization emission lines. Furthermore, although a significant fraction of AGN spectra require a featureless continuum in their Spectral Energy Distribution (SED) modelling, this is not an indicative of the presence of an AGN, instead the continuum may simulate the presence of young stellar populations. The main objective of this research is to complement the study of spectroscopic parameters from 486 galaxies analyzed by Hoet al. (1995) that are public available in the VizieR catalog (Hoet al. 1997, 2009) and provide information about their stellar population content by means of thestarlight. The base of Simple Stellar Populations used here was taken from Bruzual & Charlot (2003) and spans 25 ages (from 1 Myr to 18 Gyr) and 6 metallicities (Z = 0.005, 0.02, 0.2, 0.4, 1 & 2.5Z⊙).
The star-formation histories of early-type galaxies from ATLAS3D
Authors: McDermid Richard M. , Alatalo Katherine , Blitz Leo , Bois Maxime , Bournaud Frédéric , Bureau Martin , Cappellari Michele , Crocker Alison F. , Davies Roger L. , Davis Tim A. , de Zeeuw P.T. , Duc Pierre-Alain , Emsellem Eric , Khochfar Sadegh , Krajnović Davor , Kuntschner Harald , Lablanche Pierre-Yves , Morganti Rafaella , Naab Thorsten , Oosterloo Tom , Sarzi Marc , Scott Nic , Serra Paolo , Weijmans Anne-Marie , Young Lisa M. 
Published: August 2012

AbstractWe present an exploration of the integrated stellar populations of early-type galaxies (ETGs) from the ATLAS3D survey. We use two approaches: firstly the application of line-indices interpreted through single stellar population (SSP) models, which provide a single value of age, metallicity and abundance ratio. And secondly, by fitting a linear combination of SSP spectra to our data, smoothly weighted in the free parameters of age and metallicity, thereby inferring a star-formation history of these galaxies. Despite the significant differences in these approaches, we obtain generally consistent results, such that galaxies that are more massive appear older with enhanced abundance ratios using line indices, and have shorter star-formation histories weighted to early times. We highlight two limitations of the index-SSP approach. Firstly the SSP-equivalent ages belie the fact that ETGs are overwhelmingly composed of ancient stars. Secondly, the young stellar contributions implied in our star formation histories are required to obtain realistic UV-optical colours. We remark that, even fitting solar-abundance models, we can recover a star-formation duration that correlates with the measured alpha-enhancement, in agreement with other recent work.
Constrain the stellar population gradient of elliptical galaxies with SED
Authors: Shao Zhengyi 
Published: August 2012

AbstractWe use multiple wavelength photometric data, from Optical to NIR, to determine the radial gradient of stellar populations of nearby elliptical galaxies. Empirical model, such as the Sersic profile, is assumed to describe the radial stellar distribution, and the metallicity gradient is parameterlized in this model. The PSF effects of different wavebands are also involved to predict the photometric profiles which can be compared with observational surface brightness profile directly. For most of elliptical galaxies, they have negative gradients, which means their central parts is metal rich than outer parts. We also found the gradient is significantly correlated to the stellar mass of the whole galaxy. More massive elliptical galaxies have shallower gradients. But for our sample galaxies, their is no correlations between Sersic n and mass, and between Sersic n and gradient can be found.
Outer stellar disks of lenticular galaxies
Authors: Sil'chenko Olga K. 
Published: August 2012

AbstractBy studying the radial distribution of the properties of stellar populations in 15 nearby S0 galaxies, I have found that the outer stellar disks are mostly old, with SSP-equivalent ages of 8–15 Gyr, often being older than the bulges. This fact throws doubt on the currently accepted paradigm that S0 galaxies were formed at z=0.4 through the quenching of star formation in spiral galaxies.
Dust and PAHs in X-ray plasma of elliptical galaxies
Authors: Kaneda Hidehiro , Onaka Takashi , Suzuki Toyoaki , Mori Tatsuya , Yamagishi Mitsuyoshi , Kondo Toru , Yasuda Akiko 
Published: August 2012

AbstractMany elliptical galaxies possess an appreciable amount of X-ray-emitting hot plasma, providing a harsh interstellar environment for the survival of dust grains and polycyclic aromatic hydrocarbons (PAHs). Despite such a hostile environment, it has been found that a significant fraction of X-ray elliptical galaxies contain a considerable amount of dust, which cannot be explained solely from replenishment by old stars. Some of them even show the presence of PAHs. We present the results of AKARI and Spitzer observations of dust and PAHs in X-ray elliptical galaxies. We investigate their possible origins and discuss the implications of their presence for the evolution of elliptical galaxies.
Panchromatic properties of galaxies in wide-field optical spectroscopic and photometric surveys
Authors: Driver Simon P. 
Published: August 2012

AbstractThe past 15 years have seen an explosion in the number of redshifts recovered via wide area spectroscopic surveys. At the current time there are approximately 2 million spectroscopic galaxy redshifts known (and rising) which represents an extraordinary growth since the pioneering work of Marc Davis and John Huchra. Similarly there has been a parallel explosion in wavelength coverage with imaging surveys progressing from single band, to multi-band, to truly multiwavelength or pan-chromatic involving the coordination of multiple facilities. With these empirically motivated studies has come a wealth of new discoveries impacting almost all areas of astrophysics. Today individual surveys, as best demonstrated by the Sloan Digital Sky Survey, now rank shoulder-to-shoulder alongside major facilities. In the coming years this trend is set to continue as we begin the process of designing and conducting the next generation of spectroscopic surveys supported by multi-facility wavelength coverage.
Far-infrared and sub-millimeter properties of SDSS galaxies in the Herschel ATLAS SDP Field
Authors: Lam Man I. , Wu Hong , Zhu Yi-Nan 
Published: August 2012

AbstractUsing data from the new infrared facility the Herschel Space Observatory, we have analyzed correlations between morphological type, far-infrared (FIR) luminosity, and Hα luminosity for star-forming galaxies, composite galaxies, and AGNs. We found a trend in scatter from 100μm to 500μm, which indicates that the submillimeter bands are not a good star formation tracer in these galaxies, being contaminated either by the old stellar population or by the interstellar medium (ISM). AGNs have no significant effect on our fitting results since the far-infrared to submillimeter emission is from cold dust/large dust grains.
Dust effects on the derived Sérsic indexes of disks and bulges in spiral galaxies
Authors: Pastrav Bogdan A. , Popescu Cristina C. , Tuffs Richard J. , Sansom Anne E. 
Published: August 2012

AbstractWe present a theoretical study that quantifies the effect of dust on the derived Sérsic indexes of disks and bulges. The changes in the derived parameters from their intrinsic values (as seen in the absence of dust) were obtained by fitting Sérsic distributions on simulated images of disks and bulges produced using radiative transfer calculations and the model of Popescu et al. (2011). We found that dust has the effect of lowering the measured Sérsic index in most cases, with stronger effects for disks and bulges seen through more optically thick lines of sight.