bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dissecting the 3D structure of elliptical galaxies with gravitational lensing and stellar kinematics
Authors: Barnabè Matteo , Spiniello Chiara , Koopmans Léon V. E. 
Published: February 2015

AbstractThe combination of strong gravitational lensing and stellar kinematics provides a powerful and robust method to investigate the mass and dynamical structure of early-type galaxies. We demonstrate this approach by analysing two massive ellipticals from the XLENS Survey for which both high-resolution HST imaging and X-Shooter spectroscopic observations are available. We adopt a flexible axisymmetric two-component mass model for the lens galaxies, consisting of a generalised NFW dark halo and a realistic self-gravitating stellar mass distribution. For both systems, we put constraints on the dark halo inner structure and flattening, and we find that they are dominated by the luminous component within one effective radius. By comparing the tight inferences on the stellar mass from the combined lensing and dynamics analysis with the values obtained from stellar population studies, we conclude that both galaxies are characterised by a Salpeter-like stellar initial mass function.
The star formation history of galaxies in 3D: CALIFA perspective
Authors: Delgado R. M. González , Fernandes R. Cid , García-Benito R. , Pérez E. , de Amorim A. L. , Cortijo-Ferrero C. , Lacerda E. A. D. , Fernández R. López , Sánchez S. F. , Asari N. Vale ,   CALIFA collaboration
Published: February 2015

AbstractWe resolve spatially the star formation history of 300 nearby galaxies from the CALIFA integral field survey to investigate: a) the radial structure and gradients of the present stellar populations properties as a function of the Hubble type; and b) the role that plays the galaxy stellar mass and stellar mass surface density in governing the star formation history and metallicity enrichment of spheroids and the disks of galaxies. We apply the fossil record method based on spectral synthesis techniques to recover spatially and temporally resolved maps of stellar population properties of spheroids and spirals with galaxy mass from 109 to 7×1011 M⊙. The individual radial profiles of the stellar mass surface density (μ⋆), stellar extinction (AV), luminosity weighted ages (〈logage〉L), and mass weighted metallicity (〈log Z/Z⊙〉M) are stacked in seven bins of galaxy morphology (E, S0, Sa, Sb, Sbc, Sc and Sd). All these properties show negative gradients as a sight of the inside-out growth of massive galaxies. However, the gradients depend on the Hubble type in different ways. For the same galaxy mass, E and S0 galaxies show the largest inner gradients in μ⋆; and Andromeda-like galaxies (Sb with log M⋆ (M⊙) ∼ 11) show the largest inner age and metallicity gradients. In average, spiral galaxies have a stellar metallicity gradient ∼ −0.1 dex per half-light radius, in agreement with the value estimated for the ionized gas oxygen abundance gradient by CALIFA. A global (M⋆-driven) and local (μ⋆-driven) stellar metallicity relation are derived. We find that in disks, the stellar mass surface density regulates the stellar metallicity; in spheroids, the galaxy stellar mass dominates the physics of star formation and chemical enrichment.
The Kinematic Morphology-Density Relation from the SAMI Pilot Survey
Authors: Fogarty L. M. R. ,   the SAMI Galaxy Survey Team
Published: February 2015

AbstractWe present the kinematic morphology-density relation in three galaxy clusters, Abell 85, 168 and 2399, using data from the SAMI Pilot Survey. We classify the early-type galaxies in our sample as fast or slow rotators (FRs/SRs) according to a measured proxy for their projected specific stellar angular momentum. We find each cluster contains both fast and slow rotators with and average fraction of SRs in the sample of fSR=0.15 ± 0.04. We investigate this fraction within each cluster as a function of local projected galaxy density. For Abell 85 we find that fSR increases at high local density but for Abell 168 and 2399 this trend is not seen. We find SRs not just at the centres of our clusters but also on the outskirts and hypothesise that these SRs may have formed in group environments eventually accreted to the larger cluster.
Counter-rotating disks in galaxies: dissecting kinematics and stellar populations with 3D spectroscopy
Authors: Coccato Lodovico , Morelli Lorenzo , Pizzella Alessandro , Corsini Enrico Maria , Bontà Elena Dalla , Fabricius Maximilian 
Published: February 2015

AbstractWe present a spectral decomposition technique that separates the contribution of different kinematic components in galaxies from the observed spectrum. This allows to study the kinematics and properties of the stellar populations of the individual components (e.g., bulge, disk, counter-rotating cores, orthogonal structures). Here, we discuss the results of this technique for galaxies that host counter-rotating stellar disks of comparable size. In all the studied cases, the counter-rotating stellar disk is the less massive, the youngest and has different chemical content (metallicity and α-elements abundance ratio) than the main galaxy disk. Further applications of the spectral decomposition technique are also discussed.
LOFAR and Radio-Loud AGN
Authors: Williams Wendy L. , Röttgering Huub J. A. ,   on behalf of the LOFAR collaboration
Published: February 2015

AbstractAt very low frequencies, the new pan-European radio telescope, LOFAR, is opening the last unexplored window of the electromagnetic spectrum for astrophysical studies. Operating at frequencies from 15 to 240 MHz, its superb sensitivity, high angular resolution, large field of view and flexible spectroscopic capabilities represent a dramatic improvement over previous facilities at these wavelengths. LOFAR will carry out a broad range of fundamental astrophysical studies in a number of key science topics including the formation and evolution of clusters, galaxies and black holes. In this contribution we describe some of the capabilities of LOFAR and present some recent results from the ongoing imaging efforts. We also discuss the impact of LOFAR on our studies of radio-loud AGN. Our recent study of the evolution of radio-loud AGN as a function of host stellar mass shows a clear increase in the fraction of lower mass galaxies which host radio-loud AGN at 1 < z < 2 while the fraction for higher mass galaxies remains the same. This shows that the upturn in the radio luminosity function is driven by increasing AGN activity among low mass galaxies at higher redshifts. New LOFAR observations will allow us to build statistically large samples at high redshifts to constrain this evolution for the different accretion modes of AGN.
3D spectroscopy of Wolf-Rayet HII galaxies
Authors: Kehrig C. , Pérez-Montero E. , Vílchez J. M. , Brinchmann J. , Kunth D. , Durret F. , Iglesias-Páramo J. , Hernández-Fernández J. 
Published: February 2015

AbstractWolf-Rayet HII galaxies are local metal-poor star-forming galaxies, observed when the most massive stars are evolving from O stars to WR stars, making them template systems to study distant starbursts. We have been performing a program to investigate the interplay between massive stars and gas in WR HII galaxies using IFS. Here, we highlight some results from the first 3D spectroscopic study of Mrk 178,the closest metal-poor WR HII galaxy, focusing on the origin of the nebular HeII emission and the aperture effects on the detection of WR features.
News from the isolated ellipticals NGC 5812, NGC 7507, and NGC 7796
Authors: Richtler Tom , Salinas Ricardo , Lane Richard , Hilker Michael , Caso Juan Pablo , Bassino Lilia P. 
Published: February 2015

AbstractWe report on ongoing photometric and spectroscopic work on a sample of isolated elliptical galaxies. We investigate their globular cluster systems, and use the kinematics of globular clusters and the integrated galaxy light to constrain their dark halos, which are not found in the cases of NGC 5812 and NGC 7507.
Galactic bulges: the importance of early formation scenarios vs. secular evolution
Authors: Seidel Marja K. , Cacho R. , Ruiz-Lara T. , Falcón-Barroso J. , Pérez I. , Sánchez-Blázquez P. , Vogt F. P. A. , Ness M. , Freeman K. , Aniyan S. 
Published: February 2015

AbstractWe study the stellar content of three galactic bulges with the high resolution gratings (R=7000) of the WiFeS integral field unit in order to better understand their formation and evolution. In all cases we find that at least 50% of the stellar mass already existed 12 Gyrs ago, more than currently predicted by simulations. A younger component (age between ∼1 to ∼8 Gyrs) is also prominent and its present day distribution seems to be much more affected by morphological structures, especially bars, than the older one. This in-depth analysis supports the notion of increasing complexity in bulges which cannot be achieved by mergers alone, but requires a non-negligible contribution from secular evolution.
The beauty of resolution: The SN Ib factory NGC 2770 spatially resolved
Authors: Thöne C. C. , Christensen L. , Gorosabel J. , de Ugarte Postigo A. 
Published: February 2015

AbstractThe late-type spiral NGC 2770 hosted 3 Type Ib supernovae (SNe) in or next to star-forming regions in its outer spiral arms. We study the properties of the SN sites and the galaxy at different spatial resolutions to infer propeties of the SN progenitors and the SF history of the galaxy. Several 3D techniques are used and, for the first time, we present images of metallicity, shocks and stellar population ages from OSIRIS/GTC imaging with tunable narrowband filters.
3D Studies of Galaxies in Compact Groups
Authors: de Oliveira Claudia Mendes , Torres-Flores Sergio , Amram Philippe , Plana Henri , Epinat Benoit 
Published: February 2015

AbstractFabry-Perot data of compact group galaxies have been used to show that the Tully-Fisher relation in any photometric band, for galaxies with vmax > 100 km/s, is very similar to that for galaxies in other less dense environments. In the low-luminosity end, however, a few compact group galaxies fall above the relation apparently because they are too bright for their mass. Here we show that if the mass is properly computed from spectral energy distribution fitting or mass modelling, for the low-luminosity galaxies, their positions in the stellar-mass or baryonic Tully-Fisher relation are what is expected for a normal Tully-Fisher relation and the outlying positions observed in the B and K Tully-Fisher relation could be explained by brightening of the low-luminosity interacting galaxies due to strong star formation or AGN activity.
Models of AGN feedback
Authors: Combes Françcoise 
Published: February 2015

AbstractThe physical processes responsible of sweeping up the surrounding gas in the host galaxy of an AGN, and able in some circumstances to expel it from the galaxy, are not yet well known. The various mechanisms are briefly reviewed: quasar or radio modes, either momentum-conserving outflows, energy-conserving outflows, or intermediate. They are confronted to observations, to know whether they can explain the M-sigma relation, quench the star formation or whether they can also provide some positive feedback and how the black hole accretion history is related to that of star formation.
Kinematics of superdense galaxies in clusters
Authors: Moretti Alessia , Poggianti Bianca , Bettoni Daniela , Cappellari Michele , Fasano Giovanni ,   the WINGS team
Published: February 2015

AbstractWe present the first results obtained by analyzing the detailed kinematics of a subsample of 9 massive and compact galaxies found in the WINGS survey. The observed galaxies are very old (both luminosity and mass- weighted age are on average ≥ 10 Gyr), while they resemble more typical galaxies in the other characteristics. The total M/L ratio is determined using as free parameters the anisotropy β and the galaxy inclination i.
The Cosmic Skidmark: witnessing galaxy transformation at z = 0.19
Authors: Murphy David N. A. 
Published: February 2015

AbstractWe present an early-look analysis of the “Cosmic Skidmark”. Discovered following visual inspection of the Geach, Murphy & Bower (2011) SDSS Stripe 82 cluster catalogue generated by ORCA (an automated cluster algorithm searching for red-sequences; Murphy, Geach & Bower 2012), this z = 0.19 1.4L⋆ galaxy appears to have been caught in the rare act of transformation while accreting onto an estimated 1013–1014h−1 M⊙-mass galaxy group. SDSS spectroscopy reveals clear signatures of star formation whilst deep optical imaging reveals a pronounced 50 kpc cometary tail. Pending completion of our ALMA Cycle 2 and IFU observations, we show here preliminary analysis of this target.
Blowin' in the wind: both ‘negative’ and ‘positive’ feedback in an outflowing quasar at z∼1.6
Authors: Cresci Giovanni 
Published: February 2015

AbstractQuasar feedback in the form of powerful outflows is invoked as a key mechanism to quench star formation, preventing massive galaxies to over-grow and producing the red colors of ellipticals. On the other hand, some models are also requiring ‘positive’ AGN feedback, inducing star formation in the host galaxy through enhanced gas pressure in the interstellar medium. However, finding observational evidence of the effects of both types of feedback is still one of the main challenges of extragalactic astronomy, as few observations of energetic and extended radiatively-driven winds are available. We present SINFONI near infrared integral field spectroscopy of XID2028, an obscured, radio-quiet z=1.59 QSO, in which we clearly resolve a fast (1500 km/s) and extended (up to 13 kpc from the black hole) outflow in the [OIII] lines emitting gas, whose large velocity and outflow rate are not sustainable by star formation only. The narrow component of Hα emission and the rest frame U band flux show that the outflow position lies in the center of an empty cavity surrounded by star forming regions on its edge. The outflow is therefore removing the gas from the host galaxy (‘negative feedback’), but also triggering star formation by outflow induced pressure at the edges (‘positive feedback’). XID2028 represents the first example of a host galaxy showing both types of feedback simultaneously at work.
Is there a dependence in metallicity evolution on galaxy structures?
Authors: Kuchner U. , Maier C. , Ziegler B. , Verdugo M. , Czoske O. , Rosati P. , Balestra I. , Mercurio A. , Nonino M. ,   CLASH-, CLASH-VLT-team
Published: February 2015

AbstractWe investigate the environmental dependence of the mass-metallicty (MZ) relation and its connection to galaxy stellar structures and morphologies. In our studies, we analyze galaxies in massive clusters at z ∼ 0.4 from the CLASH (HST) and CLASH-VLT surveys and measure their gas metallicities, star-formation rates, stellar structures and morphologies. We establish the MZ relation for 90 cluster and 40 field galaxies finding a shift of ∼ − 0.3 dex in comparison to the local trends seen in SDSS for the majority of galaxies with logM < 10.5. We do not find significant differences of the distribution of 4 distinct morphological types that we introduce by our classification scheme (smooth, disc-like, peculiar, compact). Some variations between cluster and field galaxies in the MZ relation are visible at the high mass end. However, obvious trends for cluster specific interactions (enhancements or quenching of SFRs) are missing. In particular, galaxies with peculiar stellar structures that hold signs for galaxy interactions, are distributed in a similar way as disc-like galaxies - in SFRs, masses and O/H abundances. We further show that our sample falls around an extrapolation of the star-forming main sequence (the SFR-M∗ relation) at this redshift, indicating that emission-line selected samples do not have preferentially high star-formation rates (SFRs). However, we find that half of the high mass cluster members (M∗ > 1010M⊙) lie below the main sequence which corresponds to the higher mass objects that reach solar abundances in the MZ diagram.
Early-type galaxy formation: understanding the role of the environment
Authors: Demarco Ricardo , Rettura Alessandro , Lidman Chris , Nantais Julie , Jaffe Yara , Rosati Piero 
Published: February 2015

AbstractOne of the most characteristic features of galaxy clusters is the so-called “red sequence” (RS) of early-type galaxies. Since these galaxies are, in general, devoid of gas and dust, their red colors are mainly a consequence of their passive nature. However, the physical mechanisms responsible for quenching their star formation, thus originating the RS, are poorly understood. Environmental effects should play a significant role in the formation of the RS by transforming the observed galaxy properties from late to early-type ones. In this respect, we have initiated a KMOS program aimed at studying the kinematical structure of cluster galaxies at 0.8 < z < 1.7 in an effort to disentangle the physical mechanisms responsible for cluster galaxy evolution and the formation of the RS.
Spatially resolved Lyman-alpha emission from a virtual dwarf galaxy
Authors: Verhamme Anne 
Published: February 2015

AbstractIn the context of the first light of MUSE, Integral Field Unit (IFU) spectrograph of second generation installed recently at VLT, we compute mock IFU Lyman-alpha (lyα) observations of a virtual dwarf galaxy, to help understanding and interpreting forthcoming observations. This study is an extension of the work carried out in Verhamme et al. (2012), where we studied the spatially integrated lyα properties of a dwarf galaxy. With the same data, we now investigate the spatial variations of lyα spectra.
A low-luminosity type-1 QSO sample: Insight from integral-field spectroscopy
Authors: Busch Gerold , Smajić Semir , Moser Lydia , Valencia-S. Mónica , Zuther Jens , Scharwächter Julia , Eckart Andreas 
Published: February 2015

AbstractThe properties of the host galaxies of quasi-stellar objects (QSOs) are essential for the understanding of the suspected coevolution of central supermassive black holes (BHs) and their host galaxies. In Busch et al. (2014), we present a study of 20 low-luminosity type-1 QSOs (LLQSO; Busch et al.2012) that have been selected from the Hamburg/ESO survey for bright UV-excess QSOs (z ≤ 0.06). Performing careful decomposition of deep near-infrared J,H,K images, we found that the observed sources do not follow published MBH – Lbulge relations for inactive galaxies, supporting similar results found for type-1 AGN in the optical. This can be explained by overluminous bulges with very young stellar populations or undermassive black holes that are observed in a phase of growth. We use 3d-spectroscopy in the optical and near-infrared as a powerful tool to analyze gas and stellar kinematics, determine gas masses, star formation rate, trace underlying stellar continuum, etc. (e.g., Smajić et al.2014) and thereby constrain possible evolution scenarios. The results will be interpreted in the context of galaxy evolution and particularly the still unknown role of the AGN in this process. Here, we show first results for HE 1029-1831.
Fabry-Perot spectroscopy: a powerful method for detecting superbubbles in galaxy discs
Authors: Camps-Fariña A. , Beckman J. , Zaragoza-Cardiel J. , Font J. , Fathi K. 
Published: February 2015

AbstractWe present a new method for the detection and characterization of large scale expansion in galaxy discs based on Hα Fabry-Perot spectroscopy, taking advantage of the high spatial and velocity resolution of our instrument (GHαFaS). The method analyses multi-peaked emission line profiles to find expansion along the line of sight on a pixel-by-pixel basis. At this stage we have centred our attention on the large scale structures of expansive gas which show a coherent gradient of velocities from their centres as a result of both bubble shape and projection effect. The results show a wide range of expansion velocities in these superbubbles, ranging from 30-150 km/s, with the expected trend of finding the higher velocities in the more violent areas of the galaxies. We have applied the technique to the Antennae and M83, obtaining spectacular results, and used these to investigate to what extent kinematically derived ages can be found and used to characterize the ages of their massive star clusters.
Star Formation in the Local Universe from the CALIFA sample: calibration and contribution of disks to the SFR density
Authors: Catalán-Torrecilla Cristina , Gil de Paz Armando , Castillo-Morales África , Iglesias-Páramo Jorge , Sánchez Sebastián F. ,   CALIFA Collaboration
Published: February 2015

AbstractThe study of the star formation rate (SFR) is crucial for understanding the birth and evolution of the galaxies (Kennicutt 1998), with this aim in mind, we make use of a well-characterized sample of 380 nearby galaxies from the CALIFA survey that fill the entire color-magnitude diagram in the Local Universe. The availability of wide-field CALIFA IFS ensures a proper determination of the underlying stellar continuum and, consequently, of the extiction-corrected Hα luminosity. We compare our integrated Hα-based SFRs with single and hybrids tracers at other wavelengths found in the literature (Calzetti 2013). Then, we provide a new set of single-band and hybrid calibrators anchored to the extinction-corrected Hα luminosities. In the case of the hybrid calibrators we determine the best fitting aIR coefficients for different combinations of observed (UV or Hα) and dust-reprocessed (22μm or TIR) SFR contributions (where SFR ∝ Lobs + aIR × L[IR]). This analysis allow us to provide, for the first time, a set of hybrid calibrations for different morphological types and masses. These are particularly useful in case that the sample to be analyzed shows a different bias in terms of morphology or, more commonly, luminosity or stellar mass. We also study the dependence of this coefficient with color and ionized-gas attenuation. The distributions of aIR values are quite wide in all cases. We found that not single physical property can by itself explain the variation found in aIR.Finally, we explore the spatial distribution of the SFR by measuring the contribution of disks to the total SFR in the Local Universe. Our preliminary spatially-resolved analysis shows that the disk to total (disk + spheroidal component) SFR ratio is on average ∼ 88%. The use of the 2D spectroscopic data is critical to properly determine the Hα luminosity function and SFR density in the Local Universe per galaxy components, the ultimate goal of this project.
Metallicity gradients in the Milky Way thick disk as relic of a primordial distribution
Authors: Curir Anna , Serra Ana Laura , Lattanzi Mario G. , Spagna Alessandro , Re Fiorentin Paola , Diaferio Antonaldo 
Published: February 2015

AbstractWe examine the evolution induced by secular processes of an initial, cosmologically motivated, radial chemical distribution, in a barred and an unbarred disk.
A dust radiative transfer study of the edge-on spiral galaxy NGC 5908
Authors: De Geyter G. , Baes M. , Camps P. , Fritz J. , Viaene S. 
Published: February 2015

AbstractWe present a dust radiative transfer analysis of the edge-on spiral galaxy NGC 5908. In our previous analysis, it was found that the standard assumption of a double-exponential dust distribution resulted in a poor fit. We investigate the possibility of the dust being distributed in one or more rings. The parameters are constrained using FitSKIRT, a code used to automatically determine the best fitting radiative transfer model given a set of observations. We discuss the possible implications of this dust distribution on the predicted spectral energy distribution.