bluuebunny/crossref_metadata_2025_split huggingface dataset:
The origin of metallicity gradients in massive galaxies at large radii
Authors: Hirschmann Michaela , Naab Thorsten 
Published: February 2015

AbstractWe investigate the origin of stellar metallicity gradients in massive galaxies at large radii (r > 2 Reff) using ten cosmological zoom simulations of halos with 6 × 1012M⊙ < Mhalo < 2 × 1013M⊙. The simulations follow metal cooling and enrichment from SNII, SNIa and AGB winds. We explore the differential impact of an empirical model for galactic winds that reproduces the evolution of the mass-metallicity relation. At larger radii, the galaxies become more dominated by stars accreted from satellite galaxies in major and minor mergers. In the wind model, fewer stars are accreted, but they are significantly more metal poor resulting in steep global metallicity (〈 ▽ Zstars 〉= -0.35 dex/dex) gradients in agreement with observations. Metallicity gradients of models without winds are inconsistent with observations. For the wind model, stellar accretion is steepening existing in-situ metallicity gradients by about 0.2 dex by the present day and is required to match observed gradients. Metallicity gradients are significantly steeper for systems, which have accreted stars in minor mergers. In contrast, galaxies with major mergers have relatively flat gradients, confirming previous results. We highlight the importance of stellar accretion for stellar population properties of massive galaxies at large radii, which provide important constraints for formation models.
DYNAMO Survey: An Upclose View of Clumpy Galaxies
Authors: Fisher David ,   the DYNAMO Team
Published: February 2015

AbstractWe highlight recent results on the DYNAMO survey of turbulent, clumpy disks galaxies found at z=0.1. Bright star forming DYNAMO galaxies are found to be very similar in properties to star forming galaxies in the high redshift Universe. Typical star formation rates of turbulent DYNAMO galaxies range 10-80 M⊙ yr−1. Roughly 2/3 of DYNAMO galaxies have Hα kinematics that are consistent with rotation. The typical gas velocity dispersion of DYNAMO galaxies is σHα ~ 20 - 60 km s−1. We show that, when convolved to the same resolution, maps of Hα emission in DYNAMO galaxies have essentially identical morphology as that of z ~ 1 - 3 galaxies. Finally, DYNAMO galaxies have high molecular gas fractions fmol ~ 20 - 35%. We note that DYNAMO galaxies are not dwarfs, typical masses are Mstar ~ 0.8 - 8 × 1010 M⊙. These data are all consistent with a scenario in which despite being at relatively low redshift the DYNAMO galaxies are forming stars similarly to that observed in the high-redshift Universe, that is to say star formation is occurring in very massive (Mclump ~ 109 M⊙), very large (rclump ~ 300 pc) clumps of gas.
Simulations on the survivability of Tidal Dwarf Galaxies
Authors: Ploeckinger Sylvia , Recchi Simone , Hensler Gerhard , Kroupa Pavel 
Published: February 2015

AbstractWe present detailed numerical simulations of the evolution of Tidal Dwarf Galaxies (TDGs) after they kinematically decouple from the rest of the tidal arm to investigate their survivability. Both the short-term (500 Myr) response of TDGs to the stellar feedback of different underlying stellar populations as well as the long-term evolution that is dominated by a time dependent tidal field is examined. All simulated TDGs survive until the end of the simulation time of up to 3 Gyr, despite their lack of a stabilising dark matter component.
Dwarf ellipticals in the eye of SAURON: dynamical & stellar population analysis in 3D
Authors: Ryś Agnieszka , Falcón-Barroso Jesús , van de Ven Glenn , Koleva Mina 
Published: February 2015

AbstractWe present the dynamical and stellar population analysis of 12 dwarf elliptical galaxies (dEs) observed using the SAURON IFU (WHT, La Palma). We demonstrate that dEs have lower angular momenta than their presumed late-type progenitors and we show that dE circular velocity curves are steeper than the rotation curves of galaxies with equal and up to an order of magnitude higher luminosity. Transformation due to tidal harassment is able to explain all of the above, unless the dE progenitors were already compact and had lower angular momenta at higher redshifts. We then look at the star formation histories (SFHs) of our galaxies and find that for the majority of them star formation activity was either still strong at a few Gyr of age or they experienced a secondary burst of star formation roughly at that time. This latter possibility would be in agreement with the scenario where tidal harassment drives the remaining gas inwards and induces a secondary star formation episode. Finally, one of our galaxies appears to be composed exclusively of an old population (≳12 Gyr). Combining this with our earlier dynamical results, we conclude that it either was ram-pressure stripped early on in its evolution in a group environment and subsequently tidally heated (which lowered its angular momentum and increased compactness), or that it evolved in situ in the cluster's central parts, compact enough to avoid tidal disruption.
Radial gradients in the SLUGGS survey
Authors: Foster Caroline ,   the SLUGGS collaboration
Published: February 2015

AbstractThe SAGES Legacy Unifying Galaxies and GlobularS (SLUGGS) survey probes the outskirts of early-type galaxies (ETGs). SLUGGS uses the DEIMOS spectrograph on Keck to simultaneously obtain globular cluster and spatially resolved galaxy spectra. The galaxy spectra allow for the reconstruction of kinematic maps out to ∼3 effective radii (Re), while globular clusters (GCs) push the galactocentric limit out to ∼8–10Re. Stellar population parameters (abundances) can also be recovered. This provides a unique dataset for exploring the outer gradients (abundance and/or kinematic transition). We briefly present recent and salient results of the SLUGGS survey so far.
Continuous Mid-Infrared Star Formation Rate Indicators
Authors: Battisti A. J. , Calzetti D. , Johnson B. D. , Elbaz D. 
Published: February 2015

AbstractWe present continuous, monochromatic star formation rate (SFR) indicators over the mid-infrared wavelength range of 6–70 μm. We use a sample of 58 star forming galaxies (SFGs) in the Spitzer-SDSS-GALEX Spectroscopic Survey (SSGSS) at z<0.2, for which there is a rich suite of multi-wavelength photometry and spectroscopy from the ultraviolet through to the infrared. The data from the Spitzer infrared spectrograph (IRS) of these galaxies, which spans 5–40 μm, is anchored to their photometric counterparts. The spectral region between 40-70 μm is interpolated using dust model fits to the IRS spectrum anchored by Spitzer 70 and 160 μm photometry. Since there are no sharp spectral features in this region, we expect these interpolations to be robust. This spectral range is calibrated as a SFR diagnostic using several reference SFR indicators to mitigate potential bias. Our band-specific continuous SFR indicators are found to be consistent with monochromatic calibrations in the local universe, as derived from Spitzer, WISE, and Herschel photometry. Additionally, in the era of the James Webb Space Telescope this will become a flexible tool, applicable to any SFG up to z∼3.
A Herschel and CARMA view of CO and [C ii] in Hickson Compact groups
Authors: Alatalo Katherine , Appleton Philip N. , Lisenfeld Ute 
Published: February 2015

AbstractUnderstanding the evolution of galaxies from the starforming blue cloud to the quiescent red sequence has been revolutionized by observations taken with Herschel Space Observatory, and the onset of the era of sensitive millimeter interferometers, allowing astronomers to probe both cold dust as well as the cool interstellar medium in a large set of galaxies with unprecedented sensitivity. Recent Herschel observations of of H2-bright Hickson Compact Groups of galaxies (HCGs) has shown that [C ii] may be boosted in diffuse shocked gas. CARMA CO(1–0) observations of these [C ii]-bright HCGs has shown that these turbulent systems also can show suppression of SF. Here we present preliminary results from observations of HCGs with Herschel and CARMA, and their [C ii] and CO(1–0) properties to discuss how shocks influence galaxy transitions and star formation.
The Narrow Line Region in 3D: mapping AGN feeding and feedback
Authors: Bergmann Thaisa Storchi 
Published: February 2015

AbstractEarly studies of nearby Seyfert galaxies have led to the picture that the Narrow Line Region is a cone-shaped region of gas ionized by radiation from a nuclear source collimated by a dusty torus, where the gas is in outflow. In this contribution, I discuss a 3D view of the NLR obtained via Integral Field Spectroscopy, showing that: (1) although the region of highest emission is elongated (and in some cases cone-shaped), there is also lower level emission beyond the “ionization cone”, indicating that the AGN radiation leaks through the torus; (2) besides outflows, the gas kinematics include also rotation in the galaxy plane and inflows; (3) in many cases the outflows are compact and restricted to the inner few 100pc; we argue that these may be early stages of an outflow that will evolve to an open-ended, cone-like one. Inflows are observed in ionized gas in LINERs, and in warm molecular gas in more luminous AGN, being usually found on hundred of pc scales. Mass outflow rates in ionized gas are of the order of a few M⊙ yr−1, while the mass inflow rates are of the order of tenths of M⊙ yr−1. Mass inflow rates in warm molecular gas are ≈ 4–5 orders of magnitude lower, but these inflows seem to be only tracers of more massive inflows in cold molecular gas that should be observable at mm wavelengths.
Investigating AGN/Starburst activities through ALMA multi-line observations in the mid-stage IR-bright merger VV 114
Authors: Saito Toshiki , Iono Daisuke , Yun Min S. , Ueda Junko , Espada Daniel , Hagiwara Yoshiaki , Imanishi Masatoshi , Motohara Kentaro , Nakanishi Kouichiro , Sugai Hajime , Tateuchi Ken , Lee Minju , Kawabe Ryohei 
Published: February 2015

AbstractWe present ALMA cycle 0 observations of the luminous merger VV 114. One of the main goals is to investigate mechanisms of molecular line ratio enhancement. Regions with the high 12CO (1–0)/13CO (1–0) and 12CO (3–2)/12CO (1–0) is located at a central filamentary structure (∼6 kpc) in VV 114. The filament consists of the eastern nucleus and the overlap region, where the galaxy disks are colliding. We also investigate these molecular line ratios on the Kennicutt-Schmidt law. VV 114 fills a gap between the “starburst” sequence and the “normal disk” sequence, and regions with the high ratios show the high ΣSFR and ΣH2. We suggest that the high ratios in VV 114 are due to star-forming activities in the both progenitor's nuclei and the merger-induced overlap region.
Why galaxies care about Type Ia supernovae?
Authors: Jiménez Noelia , Tissera Patricia B. , Matteucci Francesca 
Published: February 2015

AbstractWe implement the Single Degenerate (SD) scenario proposed for Type Ia Supernova (SNIa) progenitors in SPH simulations. We analyse the chemical evolution of bulge-type galaxies together with the observed correlations relating SNIa rates with the characteristics of the host galaxy, such as their SFR. The models reproduce the observed signatures shown by [O/Fe] ratios in the Galactic Bulge and the present day SNIa rates. Also, the observed correlation found by Sullivan et al. (2006) between SSFR (specific star formation rate) and the SNIa rate per unit of galaxy mass (SSNIaR), naturally arises. This analysis helps to set more stringent constraints to the galaxy formation models and gives some hint on the progenitor problem.
The Theory of Forming Submillimetre Galaxies
Authors: Narayanan Desika 
Published: February 2015

AbstractSubmillimetre-selected galaxies are the most luminous, heavily star-forming galaxies in the Universe. While this field has exploded observationally over the past decade and a half, theorists have struggled to develop a concordance model for their origin. Here, I review the major theoretical efforts in this field. I then present a newly developed model for the origin of this enigmatic population of galaxies.
Understanding the transformation of spirals to lenticulars
Authors: Johnston Evelyn J. , Aragón-Salamanca Alfonso , Merrifield Michael R. 
Published: February 2015

AbstractBy studying the individual star-formation histories of the bulges and discs of lenticular (S0) galaxies, it is possible to build up a sequence of events that leads to the cessation of star formation and the consequent transformation from the progenitor spiral. In order to separate the bulge and disc stellar populations, we spectroscopically decomposed long-slit spectra of Virgo Cluster S0s into bulge and disc components. Analysis of the decomposed spectra shows that the most recent star formation activity in these galaxies occurred within the bulge regions, having been fuelled by residual gas from the disc. These results point towards a scenario where the star formation in the discs of spiral galaxies are quenched, followed by a final episode of star formation in the central regions from the gas that has been funnelled inwards through the disc.
Galaxy Growth at Early Times from 3D Studies
Authors: Schreiber N. M. Förster ,   the SINS/zC-SINF & KMOS3D teams
Published: February 2015

AbstractSpatially- and spectrally-resolved studies have proven very powerful in exploring the processes driving baryonic mass assembly and star formation at redshifts z ∼ 1–3, the heyday of massive galaxy formation. This contribution presents selected key results from near-infrared integral field spectroscopic studies of z ∼ 1–3 galaxies, including from the SINS/zC-SINF and KMOS3D surveys with SINFONI and KMOS at the ESO Very Large Telescope, highlights synergies with observations at other wavelengths, and discusses some of the implications for early galaxy evolution from mass assembly to feedback processes.
The Evolution of Resolved Kinematics and Metallicity from Redshift 2.7 to 0.7 with LUCI, SINS/zC-SINF and KMOS3D
Authors: Wuyts Eva ,   the SINS/zC-SINF and KMOS3D Teams
Published: February 2015

AbstractThe KMOS3D survey will provide near-IR IFU observations of a mass-selected sample of ∼600 star-forming galaxies at 0.7<z<2.7 with the K-band Multi Object Spectrograph (KMOS) at the VLT. We present kinematic results for a first sample of ∼200 galaxies, focusing on the evolution of the gas velocity dispersion with redshift. Combined with existing measurements, we find an approximate (1+z) evolution from z∼4 to the present day, which can be understood from the co-evolution of the gas fraction and specific star formation rate (sSFR) in the the equilibrium picture of galaxy evolution.We combine the KMOS3D sample with data from the LUCI and SINFONI spectrographs, as well as multi-wavelength HST imaging from CANDELS, to address the relations between stellar mass, SFR, and the [N II]/Hα flux ratio as an indicator of gas-phase metallicity for a sample of 222 star-forming galaxies. We find a constant slope at the low-mass end of the mass-metallicity relation and can fully describe its redshift evolution through the evolution of the characteristic turnover mass where the relation begins to flatten at the asymptotic metallicity. At a fixed mass and redshift, our data do not show a correlation between the [N II]/Hα ratio and SFR.
Mapping and resolving galaxy formation at its peak epoch with Mahalo-Subaru and Gracias-ALMA
Authors: Kodama Tadayuki , Hayashi Masao , Koyama Yusei , Tadaki Ken-ichi , Tanaka Ichi , Shimakawa Rhythm , Suzuki Tomoko , Yamamoto Moegi 
Published: February 2015

AbstractMAHALO-Subaru (MApping HAlpha and Lines of Oxygen with Subaru) project aims to investigate how the star forming activities in galaxies are propagated as a function of time, mass, and environment. It employs a unique set of narrow-band filters on MOIRCS/Subaru to search for Ha emitters associated to the proto-clusters or in narrow redshift slices in the general field. We have shown not only filamentary/clumpy structures of all the proto-clusters but also very high star formation activities therein especially at z > 2. HST images from the CANDELS survey have revealed that nearly half of the Hα emitters in the field at z ∼ 2 have clumpy structures. Among them, “red dusty clumps” are preferentially found at or near the mass center of galaxies. Therefore, they are probably linked to the formation of bulge component. To explore physical states and the mode of star formation of those forming galaxies, we have started Gracias-ALMA project in full coordination with the Mahalo-Subaru project. We will resolve molecular gas contents and dusty star formation within these galaxies, and tell whether clumps are formed by gravitational instability of gas rich disks, and whether bulges are formed by clump migration or through galaxy-galaxy mergers.
An Excess of Dusty Starbursts at z = 2.2
Authors: Dannerbauer Helmut 
Published: February 2015

AbstractSearching for massive, dusty starbursts offers the great opportunity to trace galaxy overdensities and thus the cosmic web in the distant universe. I will present our APEX-LABOCA 870 μm imaging of the protocluster field of the radio galaxy MRC1138–262 — the so-called Spiderweb Galaxy — at z = 2.16, uncovering a large number of so-called submm galaxies (SMGs). The number counts already indicate an excess of SMGs compared to blank fields. Based on an exquisite multi-wavelength dataset, I will show that a large fraction of these massive, dusty starbursts are physically associated with the protocluster at z = 2.16. Finally, I will discuss both the properties of this starburst overdensity and their individual members.
A molecular scan in the Hubble Deep Field North
Authors: Decarli Roberto , Walter Fabian , Carilli Chris , Riechers Dominik 
Published: February 2015

AbstractOur understanding of galaxy evolution has traditionally been driven by pre-selection of galaxies based on their broad-band continuum emission. This approach is potentially biased, in particular against gas-rich systems at high-redshift which may be dust-obscured. To overcome this limitation, we have recently concluded a blind CO survey at 3mm in a region of the Hubble Deep Field North using the IRAM Plateau de Bure Interferometer. Our study resulted in 1) the discovery of the redshift of the bright SMG HDF850.1 (z = 5.183); 2) the discovery of a bright line identified as CO(2-1) arising from a BzK galaxy at z = 1.785, and of other 6 CO lines associated with various galaxies in the field; 3) the detection of a few lines (presumably CO(3-2) at z ∼ 2) with no optical/NIR/MIR counterparts. These observational results allowed us to expand the parameter space of galaxy properties probed so far in high-z molecular gas studies. Most importantly, we could set first direct constraints on the cosmic evolution of the molecular gas content of the universe. The present study represents a first, fundamental step towards an unbiased census of molecular gas in ‘normal’ galaxies at high-z, a crucial goal of extragalactic astronomy in the ALMA era.
Cold streams: detectability, relation to structure and characteristics
Authors: Goerdt Tobias 
Published: February 2015

AbstractCold gas streaming along the dark-matter filaments of the cosmic web is predicted to be the major provider of resources for disc buildup and star formation in massive galaxies in the early universe. We use hydrodynamical simulations to study to what extent these cold streams are traceable in the extended circum-galactic environment of galaxies via Ly alpha emission, Ly alpha absorption and selected low ionisation metal absorption lines. We predict the strength of the absorption signal produced by the streams and find that it is consistent with observations in high redshift galaxies. The characteristics of the Ly alpha emission of our simulated galaxies are similar in luminosity, morphology and extent to the observed Ly alpha blobs, with distinct kinematic features. We analyse the characteristics of the cold streams in simulations and present scaling relations for the amount of infall, its velocity, distribution and its clumpiness and compare our findings with observations.
Galaxy Mass Assembly with VLT & HST and lessons for E-ELT/MOSAIC
Authors: Hammer François , Flores Hector , Puech Mathieu 
Published: February 2015

AbstractThe fraction of distant disks and mergers is still debated, while 3D-spectroscopy is revolutionizing the field. However its limited spatial resolution imposes a complimentary HST imagery and a robust analysis procedure. When applied to observations of IMAGES galaxies at z = 0.4-0.8, it reveals that half of the spiral progenitors were in a merger phase, 6 billion year ago. The excellent correspondence between methodologically-based classifications of morphologies and kinematics definitively probes a violent origin of disk galaxies as proposed by Hammer et al. (2005). Examination of nearby galaxy outskirts reveals fossil imprints of such ancient merger events, under the form of well organized stellar streams. Perhaps our neighbor, M31, is the best illustration of an ancient merger, which modeling in 2010 leads to predict the gigantic plane of satellites discovered by Ibata et al. (2013). There are still a lot of discoveries to be done until the ELT era, which will open an avenue for detailed and accurate 3D-spectroscopy of galaxies from the earliest epochs to the present.
Investigating the evolution of merger remnants from the formation of gas disks
Authors: Ueda Junko , Iono Daisuke , Yun Min S. , Crocker Alison F. , Narayanan Desika , Komugi Shinya , Espada Daniel , Hatsukade Bunyo , Kaneko Hiroyuki , Matsuda Yuichi , Tamura Yoichi , Wilner David J. , Kawabe Ryohei , Pan Hsi-An 
Published: February 2015

AbstractOur new compilation of interferometric CO data suggests that nuclear and extended molecular gas disks are common in the final stages of mergers. Comparing the sizes of the molecular gas disk and gas mass fractions to early-type and late-type galaxies, about half of the sample show similar properties to early-type galaxies, which have compact gas disks and low gas mass fractions. We also find that sources with extended gas disks and large gas mass fractions may become disk-dominated galaxies.
Molecular gas content in typical L* galaxies at z ∼ 1.5 − 3
Authors: Dessauges-Zavadsky Miroslava , Zamojski Michel , Schaerer Daniel , Combes Françoise , Egami Eiichi , Swinbank A. Mark , Richard Johan , Sklias Panos , Rawle Tim D. , Kneib Jean-Paul , Boone Frédéric , Blain Andrew 
Published: February 2015

AbstractTo extend the molecular gas measurements to typical L* star-forming galaxies (SFGs) at z ∼ 1.5 − 3, we have observed CO emission for five strongly-lensed galaxies selected from the Herschel Lensing Survey. The combined sample of our L* SFGs with CO-detected SFGs at z >1 from the literature shows a large spread in star formation efficiency (SFE). We find that this spread in SFE is due to variations of several physical parameters, primarily the specific star formation rate, but also stellar mass and redshift. An increase of the molecular gas fraction (fgas) is observed from z ∼ 0.2 to z ∼ 1.2, followed by a quasi non-evolution toward higher redshifts, as found in earlier studies. We provide the first measure of fgas of z >1 SFGs at the low-stellar mass end between 109.4 < M∗/M⊙ < 109.9, which shows a clear fgas upturn.
How to Simulate Galactic Outflows?
Authors: Barai Paramita 
Published: February 2015

AbstractA challenge in cosmological simulations is to formulate a physical model of star-formation (SF) and supernovae (SN) feedback which produces galactic outflows like that widely observed. In several models an outflow velocity (vout) and mass loading factor (η) are input to the sub-resolution recipe. We present results from our MUPPI model, which uses local properties of gas, and is able to develop galactic outflows whose properties correlate with global galaxy properties, consistent with observations; demonstrating a significant improvement in such work.