bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Non-Solar Abundance Ratios on Star Spectra: Observations versus Models
Authors: Sansom Anne E. , de Castro Milone André , Vazdekis Alexandre , Sánchez-Blázquez Patricia 
Published: August 2012

AbstractElement abundance ratios hold important clues to understanding the evolution of stellar populations, through the varying timescales of different nucleosynthetic contributors. Newly measured and compiled [Mg/Fe] ratios in the MILES stellar library are used to confront models of star spectra. Such models have been used in recent years to provide estimates of differential changes in spectral line strengths, due to enhancements in [α/Fe]. In this paper we test one widely used set of theoretical element response functions. Using magnesium as a proxy for all alpha elements we test the reliability of these theoretical response functions against empirical observations, and thus the reliability of current methods of measuring element abundance ratios in the stellar populations.
Spectral models of stellar populations resolved in chemical abundances
Authors: Prugniel Philippe , Koleva Mina 
Published: August 2012

AbstractWe present model spectra of stellar populations with variable chemical composition. We derived the [α/Fe] abundance ratio of the stars of the most important libraries (ELODIE, CFLIB and MILES) using full spectrum fitting and we generated PEGASE.HR models resolved in [α/Fe]. We used a semi-empirical approach that combines the observed spectra with synthetic stellar spectra. We tested the models using them to derive [α/Fe] in galaxies and star clusters using full spectrum fitting. The present models are available from http://ulyss.univ-lyon1.fr
The importance of nebular emission for SED modeling of distant star-forming galaxies
Authors: Schaerer Daniel , de Barros Stephane 
Published: August 2012

AbstractWe highlight and discuss the importance of accounting for nebular emission in the SEDs of high redshift galaxies, as lines and continuum emission can contribute significantly or subtly to broad-band photometry. Physical parameters such as the galaxy age, mass, star-formation rate, dust attenuation and others inferred from SED fits can be affected to different extent by the treatment of nebular emission.We analyse a large sample of Lyman break galaxies from z ~ 3–6, and show some main results illustrating e.g. the importance of nebular emission for determinations of the mass–SFR relation, attenuation and age. We suggest that a fairly large scatter in such relations could be intrinsic. We find that the majority of objects (~ 60–70%) is better fit with SEDs accounting for nebular emission; the remaining galaxies are found to show relatively weak or no emission lines. Our modeling, and supporting empirical evidence, suggests the existence of two categories of galaxies, “starbursts” and “post-starbursts” (lower SFR and older galaxies) among the LBG population, and relatively short star-formation timescales.
Stellar population models in the UV: I. Characterisation of the New Generation Stellar Library
Authors: Koleva Mina , Vazdekis Alexander 
Published: August 2012

AbstractWe have fully characterized the NGSL stellar spectral library, which allows us to open the UV stellar spectral range for stellar population studies. We have performed the necessary steps to prepare this library for its implementation in models synthesizing SEDs of stellar cluster and galaxy spectra. We have determined and homogenized the atmospheric parameters of the stars of this library with the aid of a full spectrum-fitting algorithm, using the MILES spectral library as a template. We also have characterized the resolution of this library and corrected systematic effects in the optical spectral range to achieve a precision of 10% of the dispersion.
A detailed dust energy balance study of the Sombrero galaxy
Authors: De Looze Ilse , Baes Maarten , Fritz Jacopo , Gentile Gianfranco , Verstappen Joris 
Published: August 2012

AbstractThe Sombrero galaxy (M104) is an interesting object for a dust energy balance study due to its very symmetric dust lane, its proximity and its (nearly edge-on) inclination of 84°. From a panchromatic radiative transfer analysis, including scattering, absorption and thermal dust re-emission, we construct a standard model for M104 accounting for observations in the optical wave bands (stellar SED, images and extinction profiles in the V and RC band). This standard model underestimates the observed dust emission at infrared wavelengths by a factor of ~ 3, similar to the discrepancy found in other energy balance studies of edge-on spirals. Supplementing this standard model with a young stellar component of low star formation activity in both the inner disk (SFR ~ 0.21 M⊙ yr−1) and dust ring (SFR ~ 0.05 M⊙ yr−1), we are capable of solving the discrepancy in the dust energy budget of the Sombrero galaxy at wavelengths shortwards of 100 μm. To account for the remaining discrepancy at longer wavelengths, we propose a secondary dust component distributed in quiescent clumps. This model with a clumpy dust structure predicts three-quarters of the total dust content to reside in compact dust clouds with no associated embedded sources.
The dust distribution in late-type low surface brightness disks
Authors: MacLachlan John , Matthews Lynn , Wood Kenny , Gallagher Jay 
Published: August 2012

AbstractLate-type low surface brightness (LSB) disk galaxies are common in the local universe and appear dynamically and chemically under evolved compared to their high surface brightness (HSB) counterparts. We have utilized multi-wavelength imaging and photometry of three edge-on, low-mass LSB disk galaxies to investigate the dust distribution in such systems. Through the use of Monte Carlo radiation transfer models to interpret the data, we find that the dust disk appears to have a vertical scale height similar to the stellar disk. This is in contrast to previous findings from HSB galaxies, where the dust is believed to be more concentrated in the galactic mid-plane. We believe the change in the relative scale heights of the dust and stellar disks is likely associated with the increased stability of the ISM against vertical collapse and the thin nature of the stellar disks.
The 3-dimensional structure of NGC 891 and M51
Authors: Schechtman-Rook Andrew , Bershady Matthew A. , Wood Kenneth , Robitaille Thomas P. 
Published: August 2012

AbstractWe investigate the three-dimensional structure of the nearby edge-on spiral galaxy NGC 891 using 3D Monte Carlo radiative transfer models, with realistic spiral structure and fractally clumped dust. Using the spiral and clumpiness parameters found from recently completed scattered light models we produce lower resolution SED models which reproduce the spatially-integrated UV-to-FIR SED of NGC 891. Our models contain a color gradient across the major axis of the galaxy - similar to what is seen in images of the NGC 891. With minor adjustment our SED models are able to match the SED of M51, a similar galaxy at a near face-on inclination.
Stellar and dust SED modelling of the Whirlpool interacting galaxy system
Authors: Mentuch Erin , Wilson Christine 
Published: August 2012

AbstractSome 300-500 Myr ago, the Whirlpool galaxy (NGC 5194/M51a) and its nearby post-starburst galaxy neighbour, NGC 5195/M51b closely interacted, resulting in significant changes to their star formation activity. Both galaxies display colors indicative of enhanced star formation during closest passage, but since then, star formation has ceased in NGC 5195 yet remained ongoing in the spiral NGC 5194. With a wealth of multi-wavelength (0.2–500 μm for this study) observations available, this nearby (10 Mpc) system, whose star formation history is well constrained through optical colors of individual stars and its dynamical history, provides the optimal laboratory to test the relation between dust emission and stellar emission within the fundamental framework of today's stellar population synthesis and dust emission models.
Hot & cold dust in M31: the resolved SED of Andromeda
Authors: Groves Brent , Krause Oliver ,   the MPIA Herschel Andromeda Team
Published: August 2012

AbstractDue to its proximity, the Andromeda galaxy (M31, NGC 224) offers a unique insight into how the spectra of stars, dust, and gas combine to form the integrated Spectral Energy Distribution (SED) of galaxies. We introduce here Herschel Space Observatory PACS and SPIRE photometric observations of M31 which cover the far-infrared to sub-mm wavelengths (70-500 μm). These new observations reveal that the total IR luminosity of M31 is relatively weak, with LIR=109.65L⊙, only 10% of the total luminosity of M31. However, as seen in the previous studies of M31, the IR luminosity is dominated by a 10 kpc ring in all Herschel bands. This is distinct from the optical, where the bulge in the central 2kpc, dominates the luminosity, clearly demonstrating how different components at distinct positions in a galaxy contribute to make the integrated SED.
Resolved optical-infrared SEDs of galaxies: universal relations and their break-down on local scales
Authors: Zibetti Stefano , Groves Brent 
Published: August 2012

AbstractA large body of evidence has demonstrated that the global rest-frame optical and IR colours of galaxies correlate well with each other, which can be readily interpreted as a sign of typically smooth star formation histories. However the processes that lead to the observed correlations are contrary: the stellar light that contributes to the optical is readily absorbed by dust which emits in the IR. Thus on small scales we expect these correlations to break down. In this contribution we present our recent results (Zibetti & Groves 2011) from a pixel-by-pixel multi-wavelength (u-band to 8μm) analysis of seven nearby galaxies ranging from early- to late-types. We show that such a break-down occurs already on scales on few 100 pc, as a result of the different physical conditions in spatially distinct regions inside the galaxy, as we demonstrate by means of a Principal Component Analysis. Despite the lack of internal correlation between optical and IR within individual galaxies, when the pixels of all galaxies are compared the well known optical-IR colour correlations return, demonstrating that the variance observed within galaxies is limited around a mean which follows the well-known trends. We also examine the extremely strong correlations between the mid IR (Spitzer-IRAC)-NIR colours which extend continuously across all galaxies. These correlations arise from the differing contribution of stellar light and dust to the IRAC bands, enabling us to determine pure stellar colours for these bands, but still demonstrating the need for dust (or stellar) corrections in these bands when being used as stellar (dust) tracers.
Detection of a large amount of diffuse extraplanar dust in NGC 891
Authors: Seon Kwang-Il , Witt Adolf N. 
Published: August 2012

AbstractSignificant discrepancies have been found between the dust masses derived from various tracers (optical/near-IR, far-IR/sub-millimeter observations, and the variation of dust attenuation with viewing angle). Here we report the first detection of the extended far-UV (FUV) and near-UV (NUV) haloes perpendicular to the galactic plane of NGC 891, which can be interpreted as scattered stellar light from the galactic plane. An additional “geometrically thick” dust disk, which contains about the same mass as the standard thin dust disk, is needed to reproduce the vertically extended UV profiles
On the nature of the peculiar superthin LSB galaxy UGC 12281
Authors: Günster Philip , Bomans Dominik J. 
Published: August 2012

AbstractUGC 12281 has been classified as having a pure disk and being a low surface brightness galaxy (LSBG), thus being an obvious member of the so-called superthin galaxies. At the same time it represents an extremely untypical type of LSBG due to its remarkable amount of current star formation and evidence for extraplanar ionized gas. This makes it become a perfect tool to investigate the triggering of star formation in LSB galaxies, located in an alleged isolated area. By means of deep photometry and long-slit spectroscopy we analyse the Hα halo and verify the existence of a potential dwarf companion which we found on processed SDSS images.
Low Metallicity ISM: excess submillimetre emission and CO-free H2 gas
Authors: Madden Suzanne C. , Rémy Aurélie , Galliano Frédéric , Galametz Maud , Bendo George , Cormier Diane , Lebouteiller Vianney , Hony Sacha ,   the Herschel SAG 2 consortium
Published: August 2012

AbstractThe low metallicity interstellar medium of dwarf galaxies gives a different picture in the far infrared(FIR)/submillimetre(submm)wavelengths than the more metal-rich galaxies. Excess emission is often found in the submm beginning at or beyond 500 μm. Even without taking this excess emission into account as a possible dust component, higher dust-to-gas mass ratios (DGR) are often observed compared to that expected from their metallicity for moderately metal-poor galaxies. The Spectral Energy Distributions (SEDs) of the lowest metallicity galaxies, however, give very low dust masses and excessively low values of DGR, inconsistent with the amount of metals expected to be captured into dust if we presume the usual linear relationship holding for all metallicities, including the more metal-rich galaxies. This transition seems to appear near metalllicities of 12 + log(O/H) 8.0 - 8.2. These results rely on accurately quantifying the total molecular gas reservoir, which is uncertain in low metallicity galaxies due to the difficulty in detecting CO(1-0) emission. Dwarf galaxies show an exceptionally high [CII] 158 μm/CO (1-0) ratio which may be indicative of a significant reservoir of ‘CO-free’ molecular gas residing in the photodissociated envelope, and not traced by the small CO cores.
Characterisation of the submillimeter excess in dwarf galaxies: Presentation of the Herschel Dwarf Galaxies Survey
Authors: Rémy Aurélie , Madden Suzanne C. , Galliano Frederic , Galametz Maud , Hony Sacha ,   the Herschel SAG2 Consortium
Published: August 2012

AbstractThe Herschel Space Observatory is revolutionizing our view of dust in galaxies with high sensitivity observations in the far infrared(FIR)/submillimeter (submm) regime from 70 to 500 μm. Herschel is confirming the submm excess that has been noted previously in low metallicity dwarfs. We present here the Dwarf Galaxies Survey sample through a Herschel colour-colour diagram. We will then focus on two galaxies, Haro11 and NGC4449 presenting different interesting behaviours in the FIR as revealed by Herschel.
A Multi-wavelength MOCASSIN model of the Magellanic-type galaxy NGC 4449
Authors: Karczewski O. Ł. , Barlow M. J. , Page M. J. , Madden S. C. 
Published: August 2012

AbstractWe use the photoionisation and dust radiative transfer code MOCASSIN to create a model of the dwarf irregular galaxy NGC 4449. The best-matching model reproduces the global optical emission line fluxes and the observed spectral energy distribution (SED) spanning wavelengths from the UV to sub-mm, and requires the bolometric luminosity of 6.25 × 109L⊙ for the underlying stellar component, Mdust/Mgas of 1/680 and Mdust of 2.2 × 106M⊙.
Identification of Spitzer-IRS staring mode targets in the Magellanic Clouds
Authors: Ruffle Paul M. E. , Woods Paul M. , Kemper Francisca 
Published: August 2012

AbstractThe SAGE-LMC, SAGE-SMC and HERITAGE surveys have mapped the Magellanic Clouds in the infrared using the Spitzer and Herschel Space Telescopes. Over 8.5 million point sources were detected and catalogued in the LMC alone. Staring mode observations using the InfraRed Spectrograph (IRS) on board Spitzer have been obtained for 1,000 positions in the LMC and ~250 in the SMC. From the infrared spectroscopy we have identified the nature of the sources for which spectroscopy is available. These IRS staring mode targets represent an important contribution to the SED of these dwarf galaxies. Here we report on our latest results.
The S4G view of stellar mass, mid-IR dust, and evolved, intermediate-age stars in nearby galaxies
Authors: Meidt Sharon E. ,   S4G team
Published: August 2012

AbstractWith deep imaging at 3.6 and 4.5 μm where the light in nearby galaxies is dominated by old stars, the Spitzer Survey of Stellar Structure in Nearby Galaxies (S4G) promises to be the ultimate inventory of stellar mass and structure in the local universe. We present results from a novel technique that makes it possible to fully exploit the information contained in these images, pertaining not only to the stellar light (and, ultimately, mass distribution), but also the nature and distribution of the mid-IR dust and the properties of evolved, intermediate age stars (e.g. in AGB-dominated star clusters). We apply Independent Component Analysis (ICA) to the 3.6 and 4.5 μm bands to separate the light from the old stars from the secondary non-stellar (i.e. PAH and hot dust) sources of emission, which are identified via comparison to the non-stellar emission imaged at 8 μm. Then, within the context of age and mass estimation at high z, we extract optical-to-mid-IR SEDs for a sample of ICA-identified AGB-dominated clusters to constrain the typically uncertain fractional contribution of AGB light to the total stellar emission in (rest-frame) NIR bands.
The peculiar dust properties of the LMC and their implications on modelling SEDs of galaxies
Authors: Galliano Frédéric 
Published: August 2012

AbstractIn a recent study based on the modelling of spatially resolved Spitzer and Herschel observations of the Large Magellanic Cloud (LMC), we have shown that the infrared (IR) to submillimetre (submm) grain opacities are systematically higher in the LMC than in our Galaxy. This discovery demonstrates an evolution of the dust properties with environment. Here, we discuss the consequences of this evolution on the modelling of SEDs of galaxies, emphasizing that the uncertainties on the grain properties can lead to erroneous interpretations of the structure of the interstellar medium (ISM) of galaxies, if no additional independent constraints are used.
Spikes in the SED and ripples in the outskirts of galaxies
Authors: Chakrabarti Sukanya 
Published: August 2012

AbstractWe describe a new method that allows us to quantitatively characterize galactic satellites from analysis of disturbances in outer gas disks, without requiring knowledge of their optical light. We have demonstrated the validity of this method, which we call Tidal Analysis, by applying it to local spirals with known optical companions, including M51 and NGC 1512. These galaxies span the range from having a low mass companion (~ one-hundredth the mass of the primary galaxy) to a fairly massive companion (~ one-third the mass of the primary galaxy). This approach has broad implications for many areas of astrophysics – for the indirect detection of dark matter (or dark matter-dominated dwarf galaxies), and for galaxy evolution in its use as a decipher of the dynamical impact of satellites on galactic disks. Here, we present some preliminary results on the emergent SEDs and images, calculated along the time sequence of these dynamical simulations using the 3-D self-consistent Monte Carlo radiative transfer code RADISHE. We explore star formation prescriptions and how they affect the emergent SEDs and images. Our goal is to identify SED colors that are primarily affected by the galaxy's interaction history, and are not significantly affected by the choice of star formation prescription. If successful, we may be able to utilize the emergent UV-IR SED of the primary galaxy to understand its recent interaction history.
TYPHOON observations of the Lindsay-Shapley Ring
Authors: Sturch Laura K. , Madore Barry F. 
Published: August 2012

AbstractWe present the first results of the TYPHOON program on the ring galaxy AM 0644-741. TYPHOON is a program for producing highly resolved spectrophotometric data cubes with wavelength coverage ranging from [OII] 3727A to 7000A. Using the first results of TYPHOON we will show its efficacy in producing images and from that we will create velocity maps, one of the many uses of TYPHOON results. From this program we will deduce the motion of gas in the ring structure of AM 0644-741 to better understand how the galaxy has evolved to its present state.
A new model for the infrared emission of IRAS F10214+4724
Authors: Efstathiou Andreas , Christopher Natalie , Verma Aprajita , Siebenmorgen Ralf 
Published: August 2012

AbstractWe present a new model for the infrared emission of the high redshift hyperluminous infrared galaxy IRAS F10214+4724 which takes into account recent photometric data from Spitzer and Herschel that sample the peak of its spectral energy distribution. We first demonstrate that the combination of the AGN tapered disc and starburst models of Efstathiou and coworkers, while able to give an excellent fit to the average spectrum of type 2 AGN measured by Spitzer, fails to match the spectral energy distribution of IRAS F10214+4724. This is mainly due to the fact that the ν Sν distribution of the galaxy falls very steeply with increasing frequency (a characteristic of heavy absorption by dust) but shows a silicate feature in emission. We propose a model that assumes two components of emission: clouds that are associated with the narrow-line region and a highly obscured starburst. The emission from the clouds must suffer significantly stronger gravitational lensing compared to the emission from the torus to explain the observed spectral energy distribution.
The SED of the nearby H i-massive LIRG HIZOA J0836–43: from the NIR to the radio domain
Authors: Kraan-Korteweg Renée C. , Cluver Michelle E. 
Published: August 2012

AbstractHIZOA J0836–43 is one of the most H i-massive galaxies in the local (z < 0.1) Universe. Not only are such galaxies extremely rare, but this “coelacanth” galaxy exhibits characteristics – in particular its active, inside-out stellar disk-building – that appear more typical of past (z ~ 1) star formation, when large gas fractions were more common. Unlike most local giant H i galaxies, it is actively star forming. Moreover, the strong infrared emission is not induced by a merger event or AGN, as is commonly found in other local LIRGs. The galaxy is suggestive of a scaled-up version of local spiral galaxies; its extended star formation activity likely being fueled by its large gas reservoir and, as such, can aid our understanding of star formation in systems expected to dominate at higher redshifts. The multi-wavelength imaging and spectroscopic observations that have led to these deductions will be presented. These include NIR (JHK) and MIR (Spitzer; 3 – 24μm) imaging and photometry, MIR spectroscopy, ATCA H i-interferometry and Mopra CO line emission observations. But no optical data, as the galaxy is heavily obscured due to its location in Vela behind the Milky Way.
Spectral energy distributions of quasars selected in the mid-infrared
Authors: Lacy M. , Sajina A. , Petric A. O. , Ridgway S. E. , Nielsen D. M. , Urrutia T. , Farrah D. , Gates E. L. 
Published: August 2012

AbstractWe present preliminary results on fitting of SEDs to 142 z < 1 quasars selected in the mid-infrared. Our quasar selection finds objects ranging in extinction from highly obscured, type-2 quasars, through more lightly reddened type-1 quasars and normal type-1s. We find a weak tendency for the objects with the highest far-infrared emission to be obscured quasars, but no bulk systematic offset between the far-infrared properties of dusty and normal quasars as might be expected in the most naive evolutionary schemes. The hosts of the type-2 quasars have stellar masses comparable to those of radio galaxies at similar redshifts. Many of the type-1s, and possibly a one of the type-2s require a very hot dust component in addition to the normal torus emission.