bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of the loss of boundary conditions for the diffusive Hamilton–Jacobi equation
Authors: Porretta Alessio , Souplet Philippe
Published: March 2017

We consider the diffusive Hamilton–Jacobi equation, with superquadratic Hamiltonian, homogeneous Dirichlet conditions and regular initial data. It is known from [4] (Barles–DaLio, 2004) that the problem admits a unique, continuous, global viscosity solution, which extends the classical solution in case gradient blowup occurs. We study the question of the possible loss of boundary conditions after gradient blowup, which seems to have remained an open problem till now.

Our results show that the issue strongly depends on the initial data and reveal a rather rich variety of phenomena. For any smooth bounded domain, we construct initial data such that the loss of boundary conditions occurs everywhere on the boundary, as well as initial data for which no loss of boundary conditions occurs in spite of gradient blowup. Actually, we show that the latter possibility is rather exceptional. More generally, we show that the set of the points where boundary conditions are lost, can be prescribed to be arbitrarily close to any given open subset of the boundary.
Postoperative Pain Self‐Management Behavior in Patients Who Underwent Total Knee or Hip Arthroplasty
Authors: Zhu Ning‐Ning , Xu Pei‐Pei , Lei Ting‐Ting , Sun Ting , Chan Sally Wai‐Chi
Published: March 2017

The self‐management of acute postoperative pain is not well researched. This cross‐sectional study investigates postoperative pain and pain self‐management behavior. We recruited 127 patients who underwent total knee or total hip arthroplasty in an acute care hospital. We measured postoperative pain intensity and pain self‐management behavior for three postoperative days. The results showed that the participants experienced mild and moderate pain intensity and perceived moderate to severe pain interference, which influenced their mood, sleep patterns, ability to walk, and performance of general activities and rehabilitation exercises. Female participants reported significantly higher pain intensity and lower pain self‐management behavior; highly educated participants reported significantly lower pain intensity and higher self‐management behavior. Pain intensity scores had a significant negative correlation with the total self‐management behavior score (r = −0.719, P < .01). Health care professionals must consider patients’ demographic characteristics when providing education and support regarding pain self‐management for postoperative pain control.
A General Algebraic Semantics for Sentential Logics
Authors: Font Josep Maria , Jansana Ramon
Published: March 2017

Since their inception, the Perspectives in Logic and Lecture Notes in Logic series have published seminal works by leading logicians. Many of the original books in the series have been unavailable for years, but they are now in print once again. In this volume, the seventh publication in the Lecture Notes in Logic series, Font and Jansana develop a very general approach to the algebraization of sentential logics and present its results on a number of particular logics. The authors compare their approach, which uses abstract logics, to the classical approach based on logical matrices and the equational consequence developed by Blok, Czelakowski, Pigozzi and others. This monograph presents a systematized account of some of the work on the algebraic study of sentential logics carried out by the logic group in Barcelona in the 1970s.
The Value of Switching Production Options in a Flexible Biorefinery
Authors: Hossiso Kassu Wamisho , Ripplinger David
Published: March 2017

This study analyses the value of a switching option in a flexible biorefinery plant that produces ethanol and sugar juice in a single plant using energy beets. A real-options approach is used to compute threshold prices and optimal switching decision rules for switching between sugar and ethanol production modes. The analysis shows that it is economically optimal to keep producing ethanol then switching to sugar juice, given the stochastic price parameters of the two products.
Operative Landscape at Canadian Neurosurgery Residency Programs
Authors: Tso Michael K. , Dakson Ayoub , Ahmed Syed Uzair , Bigder Mark , Elliott Cameron , Guha Daipayan , Iorio-Morin Christian , Kameda-Smith Michelle , Lavergne Pascal , Makarenko Serge , Taccone Michael S. , Wang Bill , Winkler-Schwartz Alexander , Sankar Tejas , Christie Sean D.
Published: March 2017

Background Currently, the literature lacks reliable data regarding operative case volumes at Canadian neurosurgery residency programs. Our objective was to provide a snapshot of the operative landscape in Canadian neurosurgical training using the trainee-led Canadian Neurosurgery Research Collaborative. Methods: Anonymized administrative operative data were gathered from each neurosurgery residency program from January 1, 2014, to December 31, 2014. Procedures were broadly classified into cranial, spine, peripheral nerve, and miscellaneous procedures. A number of prespecified subspecialty procedures were recorded. We defined the resident case index as the ratio of the total number of operations to the total number of neurosurgery residents in that program. Resident number included both Canadian medical and international medical graduates, and included residents on the neurosurgery service, off-service, or on leave for research or other personal reasons. Results: Overall, there was an average of 1845 operative cases per neurosurgery residency program. The mean numbers of cranial, spine, peripheral nerve, and miscellaneous procedures were 725, 466, 48, and 193, respectively. The nationwide mean resident case indices for cranial, spine, peripheral nerve, and total procedures were 90, 58, 5, and 196, respectively. There was some variation in the resident case indices for specific subspecialty procedures, with some training programs not performing carotid endarterectomy or endoscopic transsphenoidal procedures. Conclusions: This study presents the breadth of neurosurgical training within Canadian neurosurgery residency programs. These results may help inform the implementation of neurosurgery training as the Royal College of Physicians and Surgeons residency training transitions to a competence-by-design curriculum.
UNIVERSAL ROSSER PREDICATES
Authors: KIKUCHI MAKOTO , KURAHASHI TAISHI
Published: March 2017

Gödel introduced the original provability predicate in the proofs of Gödel’s incompleteness theorems, and Rosser defined a new one. They are equivalent in the standard model ${\mathbb N}$ of arithmetic or any nonstandard model of ${\rm PA} + {\rm Con_{PA}} $, but the behavior of Rosser’s provability predicate is different from the original one in nonstandard models of ${\rm PA} + \neg {\rm Con_{PA}} $. In this paper, we investigate several properties of the derivability conditions for Rosser provability predicates, and prove the existence of a Rosser provability predicate with which we can define any consistent complete extension of ${\rm PA}$ in some nonstandard model of ${\rm PA} + \neg {\rm Con_{PA}} $. We call it a universal Rosser predicate. It follows from the theorem that the true arithmetic ${\rm TA}$ can be defined as the set of theorems of ${\rm PA}$ in terms of a universal Rosser predicate in some nonstandard model of ${\rm PA} + \neg {\rm Con_{PA}} $. By using this theorem, we also give a new proof of a theorem that there is a nonstandard model M of ${\rm PA} + \neg {\rm Con_{PA}} $ such that if N is an initial segment of M which is a model of ${\rm PA} + {\rm Con_{PA}} $ then every theorem of ${\rm PA}$ in N is a theorem of $\rm PA$ in ${\mathbb N}$. In addition, we prove that there is a Rosser provability predicate such that the set of theorems of $\rm PA$ in terms of the Rosser provability predicate is inconsistent in any nonstandard model of ${\rm PA} + \neg {\rm Con_{PA}} $.
THE FIELD OF p-ADIC NUMBERS WITH A PREDICATE FOR THE POWERS OF AN INTEGER
Authors: MARIAULE NATHANAËL
Published: March 2017

In this paper, we prove the decidability of the theory of ℚp in the language (+, −,⋅, 0, 1, Pn(n ∈ ℕ)) expanded by a predicate for the multiplicative subgroup nℤ (where n is a fixed integer). There are two cases: if $v_p \left( n \right) > 0$ then the group determines a cross-section and we get an axiomatization of the theory and a result of quantifier elimination. If $v_p \left( n \right) = 0$, then we use the Mann property of the group to get an axiomatization of the theory.
DEGREES OF CATEGORICITY ON A CONE VIAη-SYSTEMS
Authors: CSIMA BARBARA F. , HARRISON-TRAINOR MATTHEW
Published: March 2017

We investigate the complexity of isomorphisms of computable structures on cones in the Turing degrees. We show that, on a cone, every structure has a strong degree of categoricity, and that degree of categoricity is${\rm{\Delta }}_\alpha ^0 $-complete for someα. To prove this, we extend Montalbán’sη-system framework to deal with limit ordinals in a more general way. We also show that, for any fixed computable structure, there is an ordinalαand a cone in the Turing degrees such that the exact complexity of computing an isomorphism between the given structure and another copy${\cal B}$in the cone is a c.e. degree in${\rm{\Delta }}_\alpha ^0\left( {\cal B} \right)$. In each of our theorems the cone in question is clearly described in the beginning of the proof, so it is easy to see how the theorems can be viewed as general theorems with certain effectiveness conditions.
HANDMADE DENSITY SETS
Authors: CAROTENUTO GEMMA
Published: March 2017

Given a metric space (X , d), equipped with a locally finite Borel measure, a measurable set $A \subseteq X$ is a density set if the points where A has density 1 are exactly the points of A. We study the topological complexity of the density sets of the real line with Lebesgue measure, with the tools—and from the point of view—of descriptive set theory. In this context a density set is always in $\Pi _3^0$. We single out a family of true $\Pi _3^0$ density sets, an example of true $\Sigma _2^0$ density set and finally one of true $\Pi _2^0$ density set.
GENERIC EXISTENCE OF MAD FAMILIES
Authors: GUZMÁN-GONZÁLEZ OSVALDO , HRUŠÁK MICHAEL , MARTÍNEZ-RANERO CARLOS AZAREL , RAMOS-GARCÍA ULISES ARIET
Published: March 2017

In this note we study generic existence of maximal almost disjoint (MAD) families. Among other results we prove that Cohen-indestructible families exist generically if and only if b = c. We obtain analogous results for other combinatorial properties of MAD families, including Sacks-indestructibility and being +-Ramsey.
COMPUTING STRENGTH OF STRUCTURES RELATED TO THE FIELD OF REAL NUMBERS
Authors: IGUSA GREGORY , KNIGHT JULIA F. , SCHWEBER NOAH DAVID
Published: March 2017

In [8], the third author defined a reducibility$\le _w^{\rm{*}}$that lets us compare the computing power of structures of any cardinality. In [6], the first two authors showed that the ordered field of reals${\cal R}$lies strictly above certain related structures. In the present paper, we show that$\left( {{\cal R},exp} \right) \equiv _w^{\rm{*}}{\cal R}$. More generally, for the weak-looking structure${\cal R}$ℚconsisting of the real numbers with just the ordering and constants naming the rationals, allo-minimal expansions of${\cal R}$ℚare equivalent to${\cal R}$. Using this, we show that for any analytic functionf,$\left( {{\cal R},f} \right) \equiv _w^{\rm{*}}{\cal R}$. (This is so even if$\left( {{\cal R},f} \right)$is noto-minimal.)
TURING DEGREE SPECTRA OF DIFFERENTIALLY CLOSED FIELDS
Authors: MARKER DAVID , MILLER RUSSELL
Published: March 2017

The degree spectrum of a countable structure is the set of all Turing degrees of presentations of that structure. We show that every nonlow Turing degree lies in the spectrum of some differentially closed field (of characteristic 0, with a single derivation) whose spectrum does not contain the computable degree 0. Indeed, this is an equivalence, for we also show that if this spectrum contained a low degree, then it would contain the degree 0. From these results we conclude that the spectra of differentially closed fields of characteristic 0 are exactly the jump-preimages of spectra of automorphically nontrivial graphs.
Gender Regimes in Ontario Nursing Homes: Organization, Daily Work, and Bodies
Authors: Storm Palle , Braedley Susan , Chivers Sally
Published: March 2017

Aujourd’hui, des hommes, ainsi que des personnes immigrantes, travaillent dans le secteur des soins de longue durée. Cette nouvelle donne modifie profondément le stéréotype du travailleur de ce secteur, soit une femme d’un certain âge née au Canada. Bien que toujours minoritaires, on en sait peu sur les expériences de travail des hommes qui prodiguent des soins de longue durée, ainsi que sur les dilemmes et les opportunités auxquels ils font face en raison de leur genre. Cet article examine comment le personnel de deux centres d’hébergement et de soins de longue durée ontariens perçoit les travailleurs masculins de ce secteur. S’appuyant sur une méthode ethnographique rapide, qui comprend à la fois des entrevues et des observations, nous avons constaté que le style de gestion de ces établissements entraîne des répercussions significatives sur l’intégration et l’acceptation des travailleurs masculins. Dans un centre d’hébergement doté d’une organisation du travail rigide et laissant peu de place au pouvoir décisionnel des travailleurs, les travailleurs masculins sont perçus négativement. Au contraire, dans des centres d’hébergement dotés d’une organisation du travail plus flexible qui met l’emphase sur une approche relationnelle du care, les travailleurs masculins sont perçus plus positivement. Finalement, des processus de racialisation influencent également les relations de genre dans les centres d’hébergement et de soins de longue durée.
A scaffolding approach to coreference resolution integrating statistical and rule-based models
Authors: LEE HEEYOUNG , SURDEANU MIHAI , JURAFSKY DAN
Published: March 2017

We describe a scaffolding approach to the task of coreference resolution that incrementally combines statistical classifiers, each designed for a particular mention type, with rule-based models (for sub-tasks well-matched to determinism). We motivate our design by an oracle-based analysis of errors in a rule-based coreference resolution system, showing that rule-based approaches are poorly suited to tasks that require a large lexical feature space, such as resolving pronominal and common-noun mentions. Our approach combines many advantages: it incrementally builds clusters integrating joint information about entities, uses rules for deterministic phenomena, and integrates rich lexical, syntactic, and semantic features with random forest classifiers well-suited to modeling the complex feature interactions that are known to characterize the coreference task. We demonstrate that all these decisions are important. The resulting system achieves 63.2 F1 on the CoNLL-2012 shared task dataset, outperforming the rule-based starting point by over seven F1 points. Similarly, our system outperforms an equivalent sieve-based approach that relies on logistic regression classifiers instead of random forests by over four F1 points. Lastly, we show that by changing the coreference resolution system from relying on constituent-based syntax to using dependency syntax, which can be generated in linear time, we achieve a runtime speedup of 550 per cent without considerable loss of accuracy.
On the evolution of simulated galaxies: the mass dependence in metallicity gradients
Authors: Miranda Maider , Sánchez-Blázquez Patricia , Brook Chris B. , Gibson Brad K.
Published: March 2017

Making use of a fiducial set of simulated disc galaxies spanning a wide range of mass, we examine the influence of stellar mass in the radial metallicity gradients and compare to observational trends from Ho et al. (2015).
The spectacular 200 kpc-wide disk of the Malin 1 giant low surface brightness galaxy
Authors: Boissier Samuel
Published: March 2017

Malin 1 is the best example among giant low surface brightness galaxies. New observations of this object in 6 broad-bands allow us for the first time to perform a pan-chromatic study of the stellar population in its 200 kpc wide disk. We observe a spiral structure revealing a star forming disk. The colors indicate a long history with a low efficiency of star formation. It is well reproduced by a model of disk galaxy making it similar to the disk of the Milky Way or other nearby spirals, except for its extremely large angular momentum.
Supermassive black holes hidden in the outskirts of galaxies
Authors: Mieske Steffen
Published: March 2017

Ultra-Compact dwarf galaxies, which inhabit the outskirts of galaxies, may conceal a significant population of hitherto overlooked super-massive black holes.
Gas accretion from the cosmic web feeding disk galaxies
Authors: Almeida J. Sánchez , Olmo-García A. , Elmegreen B. G. , Muñoz-Tuñón C. , Elmegreen D. M. , Filho M. E. , Pérez-Montero E. , Amorín R.
Published: March 2017

Disk galaxies in cosmological numerical simulations grow by accreting gas from the cosmic web. This gas reaches the external disk, and then spirals in dragged along by tidal forces and/or disk instabilities. The importance of gas infall is as clear from numerical simulations as it is obscure to observations. Extremely metal poor (XMP) galaxies seem to be the best example we have of the gas accretion process at work. They have large off-center starbursts which show significant metallicity drop compared with the host galaxy. This observation is naturally explained as a gas accretion event caught in the act. We present preliminary results of the kinematical properties of the metal poor starbursts in XMPs, which suggest that the starbursts are kinematically decoupled entities within the host galaxy.
The radial extent of the Galactic thick disk
Authors: Bensby Thomas
Published: March 2017

Based on observational data from the fourth internal data release of the Gaia-ESO Survey we probe the abundance structure in the Milky Way stellar disk as a function of galactocentric radius and height above the plane. We find that the inner and outer Galactic disks have different chemical signatures. The stars in the inner Galactic disk show abundance signatures of both the thin and thick disks, while the stars in the outer Galactic disk resemble in majority the abundances seen in the thin disk. Assuming that the Galactic thick disk can be associated with the α-enriched population, this can be interpreted as that the thick disk density drops drastically beyond a galactocentric radius of about 10 kpc. This is in agreement with recent findings that the thick disk has a short scale-length, shorter than that of the the thin disk.
HST Observations Reveal the Curious Geometry of Circumgalactic Gas
Authors: Kacprzak Glenn G. , Muzahid Sowgat , Churchill Christopher W. , Nielsen Nikole M. , Charlton Jane C.
Published: March 2017

We have discovered that warm gas flows along galaxy major and minor axes detected out to 200 kpc. Our results are derived from a sample of HST-imaged isolated galaxies with nearby background quasars used to probe their 105K CGM detected in HST/COS UV spectra (traced by Ovi absorption). We constrain the geometry of the gas to reside between 20-40 degrees of the projected major axis and within 60 degrees of the projected minor axis, with little-to-no gas found in between. Furthermore, strong absorption systems tend to be found along the minor axes of star-forming galaxies. All of our results are consistent with the current view of the CGM originating from major axis-fed inflows/recycled gas and from minor axis-driven outflows.
Are “U-shape” age profiles a universal feature in spiral galaxies?
Authors: Florido Estrella , Ruiz-Lara Tomás , Few Gareth , Gibson Brad , Pérez Isabel , Minchev Ivan , Sánchez-Blázquez Patricia
Published: March 2017

In this work we study the effect of satellite accretion on the building-up of the radial stellar age distribution in the discs of spiral galaxies. In addition, we analyse its effect on other chemical and dynamical properties of these systems up to their outskirts.
UV-IR color profiles of the outer regions of 2K nearby S4G galaxies
Authors: Bouquin Alexandre Y. K. , de Paz Armando Gil
Published: March 2017

We present our new, spatially-resolved, photometry in FUV and NUV from images obtained by GALEX, and IRAC1 (3.6 μm) photometry obtained by the Spitzer Space Telescope. We analyzed the surface brightness profiles μFUV, μNUV, μ[3.6], as well as the radial evolution of the (FUV-NUV), (FUV - [3.6]), and (NUV - [3.6]) colors in the Spitzer Survey of Stellar Structures in Galaxies (S4G) galaxies (d < 40 Mpc) sample. We defined the GALEX Blue Sequence (GBS) and GALEX Red Sequence (GBR) from the (FUV - NUV) versus (NUV - [3.6]) color-color diagram, populated by late-type star forming galaxies and quiescent early-type galaxies respectively. While most disk becomes radially bluer for GBS galaxies, and stay constant for GRS galaxies, a large fraction ( > 50%) of intermediary GALEX Green Valley (GGV) galaxies’ outer disks are becoming redder. An outside-in quenching mechanism such as environmentally-related mechanisms such as starvation or ram-pressure-stripping could explain our results.
Resolving the stellar outskirts of six Milky Way-like galaxies beyond the Local Group
Authors: Monachesi A. , Bell E. F. , Radburn-Smith D. J. , Harmsen B. , de Jong R. S. , Bailin J. , Holwerda B. W. , Streich D.
Published: March 2017

Models of galaxy formation in a hierarchical universe predict substantial scatter in the halo-to-halo stellar properties, owing to stochasticity in galaxies’ merger histories. Currently, only few detailed observations of galaxy’s halos are available, mainly for the Milky Way and M31. The Galaxy Halos, Outer disks, Substructure, Thick disks and Star clusters (GHOSTS) HST survey is the largest study to date of the resolved stellar populations in the outskirts of disk galaxies and its observations offer a direct test of model predictions. Here we present the results we obtain for six highly inclined nearby Milky Way-mass spiral galaxies. We find a great diversity in the properties of their stellar halos.
The IAC stripe82 legacy project
Authors: Román Javier , Fliri Juergen , Trujillo Ignacio
Published: March 2017

We present new deep co-adds of data taken within Stripe 82 of the Sloan Digital Sky Survey (SDSS), especially stacked to reach the faintest surface brightness limits of this data set. Our reduction puts special emphasis on preserving the characteristics of the background (sky + diffuse light) in the input images using a non-aggressive sky subtraction strategy, resulting in an exquisite quality on extremely faint structures. The IAC Stripe 82 co-adds offer a rather unique possibility to study the low surface brightness Universe like stellar haloes and disc truncations, low surface brightness, tidal galactic interactions, extremely faint dwarf galaxies, intra-cluster light or diffuse light from galactic dust. The imaging data is publicly available at http://www.iac.es/proyecto/stripe82/.
The frequency and properties of young tidal dwarf galaxies in nearby groups
Authors: Lee-Waddell K. , Spekkens K. , Chandra P. , Patra N. , Cuillandre J.-C. , Wang J. , Haynes M. P. , Cannon J. , Stierwalt S. , Sick J. , Giovanelli R.
Published: March 2017

We present the results of a multi-wavelength investigation of the dwarf galaxy populations in three interacting galaxy groups: NGC 871/6/7, NGC 3166/9, NGC 4725/47. Using degree-scale Giant Metrewave Radio Telescope Hi mosaics and deep optical photometry from the Canada-France-Hawaii Telescope, we measured the Hi and stellar properties of the gas-rich low-mass group members to classify each one as a classical dwarf galaxy, a short-lived tidal knot or a tidal dwarf galaxy (TDG). Our observations detect several dwarf irregulars and various tidal knots. We identify four potentially long-lived tidal objects in the three groups, implying that TDGs are not readily produced. The tidal objects examined in this small survey also appear to have a wider variety of properties than TDGs formed in current simulations.
Could magnetic fields produce outwards stellar migration?
Authors: Battaner Eduardo , Florido Estrella , Zurita Almudena , Guijarro Ana , Ruiz-Lara Tomás , Pérez Isabel
Published: March 2017

We propose a qualitative explanation for the light radial profile of a spiral galaxy based on the quantitative magnetic model of truncations (Battaner et al. 2002) in which when stars are born (hence the magnetic force acting on the progenitor gas cloud is no longer at work) migrate to larger orbits or escape.
Breaking the disc-halo degeneracy in NGC 1291 using hydrodynamic simulations
Authors: Fragkoudi Francesca , Athanassoula E. , Bosma A.
Published: March 2017

We present a pilot study on the nearby massive galaxy NGC 1291, in which we aim to constrain the dark matter in the inner regions, by obtaining a dynamical determination of the disc mass-to-light ratio (M/L). To this aim, we model the bar-induced dust lanes in the galaxy, using hydrodynamic gas response simulations. The models have three free parameters, the M/L of the disc, the bar pattern speed and the disc height function. We explore the parameter space to find the best fit models, i.e. those in which the morphology of the shocks in the gas simulations matches the observed dust lanes. The best-fit models suggest that the M/L of NGC 1291 agrees with that predicted by stellar population synthesis models in the near-infrared (≈ 0.6M⊙/L⊙), which leads to a borderline maximum disc for this galaxy. The bar rotates fast, with corotation radius ⩽ 1.4 times the bar length. Additionally, we find that the height function has a significant effect on the results, and can bias them towards lower or higher M/L.
Probing the low surface brightness outskirts of Milky Way dSphs: Sextans
Authors: Cicuéndez Luis , Battaglia Giuseppina , Irwin Mike , McMonigal Brendan , Lewis Geraint , Bate Nick
Published: March 2017

Faint dwarf galaxies such as those found around the Milky Way (MW) display the largest known dynamical mass-to-light ratios (up to several 100s M⊙/L⊙). However, tidal interaction with the MW may impact the dynamical equilibrium in the outer parts of some of these objects, and partly affect the derived dynamical M/L. Assessing this is crucial for the study of the dark matter content of these galaxies. A clear sign of ongoing tidal disturbance would be the presence of tidal tails. These are expected to be low surface brightness features, hence difficult to detect from star counts in systems where contamination is also present, e.g. from foreground MW stars. At present we have searched for these sorts of tidal features in the Sextans dwarf spheroidal galaxy (dSph), by adopting the Matched Filter Method (e.g. Rockosi et al. 2002), a very efficient technique to decontaminate stellar density maps with a high ratio of contamination versus source density (dwarf galaxies outer regions or ultra faint dwarf galaxies). We also calculate structural parameters from the position of stars without requiring spatial binning (Richardson et al. 2011), through a Bayesian MCMC (Foreman-Mackey et al. 2013).
Ultra-deep imaging of nearby galaxy outskirts from the ground
Authors: Trujillo Ignacio
Published: March 2017

We show how present-day 10 meter class telescopes can provide broadband imaging 1.5-2 mag deeper than most previous results within a reasonable amount of time ( ~ 8h on source integration). We illustrate the ability of the 10.4 m Gran Telescopio de Canarias (GTC) telescope to produce imaging with a limiting surface brightness of 31.5 mag/arcsec2 (3σ in 10 × 10 arcsec boxes). We explore the stellar halos of nearby galaxies obtaining surface brightness radial profiles down to μr ~ 33 mag/arcsec2. This depth is similar to that obtained using star counts techniques of Local Group galaxies, but is achieved at a distance where this technique is unfeasible.
The Missing Satellite Problem Outside of the Local Group
Authors: Tanaka Masayuki , Chiba Masashi , Komiyama Yutaka , Tanaka Mikito , Okamoto Sakurako , Okamoto Takashi
Published: March 2017

We report on the first results from our pilot observation of nearby galaxies with Hyper Suprime-Cam. We have observed two galaxies with mass similar to that of the Milky Way Galaxy and measured the abundance of their satellite galaxies in order to address the missing satellite problem outside of the Local Group. We find that (1) the abundance of dwarf galaxies is smaller by a factor of two than the prediction from one of the current hydro-dynamical simulations and (2) there is a large halo to halo scatter. Our results highlight the importance of a statistical sample of nearby galaxies to address the missing satellite problem.
GASP: Gas stripping and the outskirts of galaxies as a function of environment
Authors: Poggianti Bianca ,   the GASP team
Published: March 2017

We present GASP, an ongoing ESO Large Program with MUSE aiming to study gas removal processes from galaxies at low redshift. GASP targets 100 galaxies with tails, tentacles and one-sided debris. MUSE data allows a detailed investigation of the ionized stripped gas, as well as of the gas and stars within the galaxy out to large distances from the galaxy center. We show the first results for two of the GASP galaxies that are striking cluster jellyfish galaxies of stellar masses ~ 1011M⊙.
On the origin of Sérsic profiles of galaxies and Einasto profiles of dark-matter halos
Authors: Nipoti Carlo
Published: March 2017

The surface-brightness profiles of galaxies I(R) and the density profiles of dark-matter halos ρ(r) are well represented by the same analytic function, named after either Sérsic, I∝e−(R/R*)1/m, or Einasto, ρ∝e−(r/r*)α, where R* and r* are characteristic radii. Systems with high Sérsic index m (or low Einasto index α) have steep central profiles and shallow outer profiles, while systems with low m (or high α) have shallow central profiles and steep profiles in the outskirts. We present the results of idealized numerical experiments which suggest that the origin of these profiles can be traced back to the initial density fluctuation field: high-α (low-m) systems form in smooth regions via few mergers, while low-α (high-m) systems form in clumpy regions via several mergers.
Gas Kinematics in the Multiphase Circumgalactic Medium
Authors: Nielsen Nikole M. , Kacprzak Glenn G. , Churchill Christopher W. , Murphy Michael T. , Muzahid Sowgat , Charlton Jane C. , Evans Jessica L.
Published: March 2017

We use high-resolution Keck, VLT, or Hubble Space Telescope spectra of background quasars to examine the kinematic properties of the multiphase, metal-enriched circumgalactic medium in the outskirts of galaxies at 0.08 < zgal < 1.0, focusing on the low-ionization Mgii and high-ionization Ovi doublets. The absorption kinematics of low-ionization gas in the circumgalactic medium depend strongly on the star formation activity and the location about the host galaxy, where the largest velocity dispersions are associated with blue, face-on galaxies probed along the minor axis. Conversely, high-ionization gas kinematics are independent of galaxy star formation activity and orientation.
Resolved Stellar Populations of the interacting galaxies of the M81 group
Authors: Okamoto Sakurako , Arimoto Nobuo , Ferguson Annette M.N. , Bernard Edouard J. , Irwin Mike J. , Yamada Yoshihiko , Utsumi Yousuke
Published: March 2017

We present the results from the state-of-the-art wide-field survey of the M81 galaxy group that we are conducting with Hyper Suprime-Cam on Subaru Telescope. Our photometry reaches about 2 mag below the tip of the red giant branch (RGB) and reveals the spatial distribution of both old and young stars over an area of 5°2around the M81. The young main-sequence (MS) stars closely follow the HI distribution and can be found in a stellar stream between M81 and NGC 3077 and in numerous outlying stellar associations. Our survey also reveals for the first time the very extended (>2 × R25) halos of RGB stars around M81, M82, and NGC 3077, as well as faint tidal streams that link these systems. The gravitational interactions between M81, M82 and NGC 3077 galaxies induced star formation in tidally stripped gas, and also significantly perturbed the older stellar components leading to disturbed halo morphologies.
Modelling the outskirts of galaxies in a cosmological context
Authors: Cooper Andrew P.
Published: March 2017

Current data broadly support trends of galaxy surface brightness profile amplitude and shape with total stellar mass predicted by state-of-the-art ΛCDM cosmological simulations, although recent results show signs of interesting discrepancies, particularly for galaxies less massive than the Milky Way. Here I discuss how perhaps the largest contribution to such discrepancies can be inferred almost directly from how well a given model agrees with the observed present-day galaxy stellar mass function.
Recent star formation in the Hi dominated outer regions of early-type galaxies
Authors: Yıldız Mustafa K. , Serra Paolo , Peletier Reynier F. , Oosterloo Tom A. , Duc Pierre-Alain
Published: March 2017

Context

According to the ATLAS3D project, about 20 percent of all nearby early-type galaxies (D < 42 Mpc; MK < -21.5 mag; stellar mass Mstars ≳ 6 × 109 M⊙) outside clusters are surrounded by a disc or ring of low-column-density neutral hydrogen (Hi) gas with typical radii of tens of kpc, much larger than the stellar body.

Aims

Our aim is to understand the impact of these gas systems on the host galaxies, in particular, whether there is any recent star formation related to the Hi and effect of recent star formation on the host early-type galaxies.

Methods and sample

We analyse the distribution of star formation out to large radii by using resolved Hi images together with UV and optical images. We calculate the UV-UV and UV-optical colours in two apertures, 1-3 and 3-10 Reff. Using FUV emission as a proxy for star formation, we also estimate the integrated star formation rate in the outer regions. Our sample consists of 18 Hi-rich galaxies as well as 55 control galaxies where no Hi has been detected. We select the control sample galaxies to match the Hi-rich galaxies in stellar mass, environment, distance and stellar kinematics.

Results

In half of the Hi-rich galaxies the radial UV profile changes slope at the position of the Hi radial profile peak. We find that the FUV-NUV and UV-optical colours in the first and second apertures of the Hi-rich galaxies are on average 0.5 and 0.8 mag bluer than the Hi-poor ones, respectively. We also find that the Hi-rich early-type galaxies have colour gradients that are almost 2 times stronger than the Hi-poor ones. we estimate the integrated star formation rate in the outer regions (R > 1 Reff) to be on average ~ 6.1×10−3 M⊙ yr−1 for the Hi-rich galaxies. We find that the gas depletion time in the outermost region (3-10 Reff) is ~ 80 Gyrs, which is similar to that estimated for the outskirts of spirals.

Conclusions

Studying the stellar populations in early type galaxies with and without Hi, we find that galaxies with Hi generally show UV and UV-Optical colours in the outer parts that are bluer than those of early-type galaxies without Hi. This shows that the Hi is actively involved in recent star formation. The star formation rate in the outer regions is too low to build a stellar disc, and therefore change the morphology of the host even when integrated over several Gyrs. Star formation in outermost regions does not depend on the type of the galaxies.
Outskirts of spiral galaxies
Authors: Bresolin Fabio
Published: March 2017

I present an overview of the recent star formation activity in the outer disks of spiral galaxies, from the observational standpoint, with emphasis on the gas content, the star formation law, the metallicity and the stellar populations.
Chemical Abundances of Seven Outer Halo M31 Globular Clusters from the Pan-Andromeda Archaeological Survey
Authors: Sakari Charli M.
Published: March 2017

Observations of stellar streams in M31’s outer halo suggest that M31 is actively accreting several dwarf galaxies and their globular clusters (GCs). Detailed abundances can chemically link clusters to their birth environments, establishing whether or not a GC has been accreted from a satellite dwarf galaxy. This talk presents the detailed chemical abundances of seven M31 outer halo GCs (with projected distances from M31 greater than 30 kpc), as derived from high-resolution integrated-light spectra taken with the Hobby Eberly Telescope. Five of these clusters were recently discovered in the Pan-Andromeda Archaeological Survey (PAndAS)—this talk presents the first determinations of integrated Fe, Na, Mg, Ca, Ti, Ni, Ba, and Eu abundances for these clusters. Four of the target clusters (PA06, PA53, PA54, and PA56) are metal-poor ([Fe/H] < -1.5), α-enhanced (though they are possibly less alpha-enhanced than Milky Way stars at the 1 sigma level), and show signs of star-to-star Na and Mg variations. The other three GCs (H10, H23, and PA17) are more metal-rich, with metallicities ranging from [Fe/H] = -1.4 to -0.9. While H23 is chemically similar to Milky Way field stars, Milky Way GCs, and other M31 clusters, H10 and PA17 have moderately-low [Ca/Fe], compared to Milky Way field stars and clusters. Additionally, PA17’s high [Mg/Ca] and [Ba/Eu] ratios are distinct from Milky Way stars, and are in better agreement with the stars and clusters in the Large Magellanic Cloud (LMC). None of the clusters studied here can be conclusively linked to any of the identified streams from PAndAS; however, based on their locations, kinematics, metallicities, and detailed abundances, the most metal-rich PAndAS clusters H23 and PA17 may be associated with the progenitor of the Giant Stellar Stream, H10 may be associated with the SW Cloud, and PA53 and PA56 may be associated with the Eastern Cloud.
The mass-metallicity relation of absorption selected high-redshift galaxies
Authors: Christensen Lise , Møller P. , Rhodin Henrik , Krogager Jens-Kristian , Fynbo Johan P.U.
Published: March 2017

Strong absorption lines in quasar spectra primarily probe low-mass galaxies and detecting these in emission has previously been difficult. Dedicated surveys for the host galaxies of damped Lyman-α (DLA) systems have often resulted in non-detections and upper limits. Targeting the most metal-rich absorbers has proven to be a viable method, because these galaxies are brighter. By combining DLA metallicities and deriving host galaxy stellar masses, we find that metal-rich DLAs (with >10% solar metallicity) and their host galaxies follow the same redshift-dependent scaling relation between stellar mass and metallicity as luminosity-selected galaxies. We derive a prediction for an absorber galaxy mass that depends on the DLA metallicity.
The observed peripheral growth of disc galaxies from z ~ 1
Authors: Gadotti Dimitri A. , Sachdeva Sonali , Saha Kanak , Singh Harinder P.
Published: March 2017

Using images from the Hubble Space Telescope and Sloan Digital Sky Survey, we have computed both parametric and non-parametric measures, and examined the evolution in size, concentration, stellar mass, effective stellar mass density and asymmetry for a sample of 600 disc galaxies from z ~ 1 till z ~ 0. We find that disc galaxies have gained more than 50 per cent of their present stellar mass over the last 8 Gyr. Also, the increase in disc size is found to be peripheral. While the average total (Petrosian) radius almost doubles from z ~ 1 to z ~ 0, the average effective (half-light) radius undergoes a marginal increase in comparison. This indicates that galaxies grow more substantially in their outskirts, and is consistent with the inside-out growth picture. The substantial increase in mass and size indicates that accretion of external material has been a dominant mode of galaxy growth, where the circumgalactic environment plays a significant role.
Star formation at low rates - the impact of lacking massive stars on stellar feedback
Authors: Hensler Gerhard , Steyrleithner Patrick , Recchi Simone
Published: March 2017

Due to their low masses dwarf galaxies experience low star-formation rates resulting in stellar cluster masses insufficient to fill the initial mass function (IMF) to the uppermost mass. Numerical simulations usually do not account for the completeness of the IMF, but treat a filed IMF by numbers, masses, and stellar feedback by fractions. To ensure that only entire stars are formed, we consider an IMF filled from the lower-mass regime and truncated where at least one entire massive star is formed.

By 3D simulations we investigate the effects of two possible IMFs on the evolution of dwarf galaxies: filled vs. truncated IMF. For the truncated IMF the star-formation self-regulation is suppressed, while the energy release by typeII supernovae is larger, both compared to the filled IMF. Moreover, the abundance ratios of particular elements yielded from massive and intermediate-mass stars differ significantly between the two IMF distributions.
Real & Simulated IFU Observations of Low-Mass Early-Type Galaxies: Environmental Influence Probed for Cluster Galaxies
Authors: Sybilska Agnieszka , Łokas Ewa Luiza , Fouquet Sylvain
Published: March 2017

We combine high-quality IFU data with a new set of numerical simulations to study low-mass early type galaxies (dEs) in dense environments. Our earlier study of dEs in the Virgo cluster has produced the first large-scale maps of kinematic and stellar population properties of dEs in those environments (Ryś et al. 2013, 2014, 2015). A quantitative discrimination between various (trans)formation processes proposed for these objects is, however, a complex issue, requiring a priori assumptions about the progenitors of galaxies we observe and study today. To bridge this gap between observations and theoretical predictions, we use the expertise gained in the IFU data analysis to look “through the eye of SAURON” at our new suite of high-resolution N-body simulations of dEs in the Virgo cluster. Mimicking the observers perspective as closely as possible, we can also indicate the existing instrumental and viewer limitations regarding what we are/are not able to detect as observers.
Kinematics of the outskirts of S0 galaxies from PNe and GCs
Authors: Cortesi A. , de Oliveira C. Mendes
Published: March 2017

The stellar kinematics of the discs of S0 galaxies (as obtained using planetary nebulae, PNe, and integrated stellar light data) is comparable to that of spiral galaxies, with similar flat rotation curves and falling velocity dispersion profiles, but they present a larger amount of random motions. The only other tracer available to probe the kinematics of individual early-type galaxies are globular clusters (GCs). GCs’ formation is intimately connected to a galaxy major star forming event(s) and GCs are, therefore, good proofs of galaxy formation histories. We directly compare a sample of PNe, GCs, and stellar velocities out to 4 effective radii, in the S0 galaxies NGC 2768 and NGC 1023. In particular, we test a new method for studying GC properties and we find that these two lenticular galaxies are consistent with being formed through different formation mechanisms.
Why do disk galaxies present a common gas-phase metallicity gradient?
Authors: Chang R. , Zhang Shuhui , Shen Shiyin , Yin Jun , Hou Jinliang
Published: March 2017

CALIFA data show that isolated disk galaxies present a common gas-phase metallicity gradient, with a characteristic slope of -0.1dex/re between 0.3 and 2 disk effective radius re (Sanchez et al. 2014). Here we construct a simple model to investigate which processes regulate the formation and evolution.
Studying dark matter haloes with Schwarzschild modeling
Authors: Kowalczyk Klaudia , Łokas Ewa L. , Valluri Monica
Published: March 2017

We present a study exploring the reliability of recovering the mass and velocity anisotropy profiles of dark matter haloes using the Schwarzschild method of modeling galaxies.
Green Bank Telescope OH Observations of Smith’s Cloud: Evidence Of A Lack Of Chemistry
Authors: Minter Anthony
Published: March 2017

Smith’s Cloud is a large few × 106 Solar Mass cloud which will impact the Milk Way disk in about 35 Million Years (Lockman et al., 2008). Green Bank Telescope OH observations indicate that there are no molecules present in Smith’s Cloud, and thus there is no active ongoing chemistry in Smith’s Cloud.
On the colors of barlenses and their link to B/P bulges
Authors: Endoqui Martín Herrera , Laurikainen Eija , Salo Heikki , Knapen Johan H.
Published: March 2017

Barlenses are morphological features present in barred galaxies with morphological types between S0 and Sb. Recently, they have been suggested to be the more face-on counterparts of the boxy/peanut bulges generally observed in edge-on galaxies. In this work we test this idea by looking at the orientations and colors of barlenses, and by comparing them with those of the bars and disks in the same galaxies. We find that barlenses have colors which are similar to those of bars, and also similar to those of elliptical galaxies.
Search for molecular gas in XUV disk of M83
Authors: Morokuma-Matsui Kana , Koda Jin , Takekoshi Tatsuya , Saito Masao , Nakanishi Hiroyuki , Boissier Samuel , Madore Barry F. , Boselli Alessandro , de Paz Armando Gil , Thilker David , Yagi Masafumi , Sorai Kazuo , Kuno Nario
Published: March 2017

We report a non-detection of CO(J=1-0) emission from one of the brightest Hii regions in the extended UV (XUV) disks of M 83 with on-source integration time of 11 hours.
A survey of molecular clouds in the outer Galaxy with the highest spatial resolution
Authors: Matsuo Mitsuhiro , Minamidani Tetsuhiro , Umemoto Tomofumi , Nishimura Atsushi , Nakanishi Hiroyuki , Kuno Nario , Fujita Shinji , Tosaki Tomoka , Tsuda Yuya , Yamagishi Mitsuyoshi , Kohno Mikito ,   the FUGIN team
Published: March 2017

We report a recent result of the FUGIN project, a Galactic plane CO survey using the Nobeyama 45-m Telescope and the FOREST receiver. In the third galactic quadrant, 42 square degrees are observed and 4752 molecular clouds are detected. Among them, 12 clouds are located at R (distance from the Galactic center) > 16 kpc. Molecular clouds at R < 16 kpc trace the Local, Perseus, and Outer arms.
Investigation into the Origin of Age-Velocity dispersion Relation by High Resolution Simulation
Authors: Kumamoto Jun , Baba Junichi , Saitoh Takayuki R.
Published: March 2017

We focused on the stellar age-velocity dispersion relation (AVR). We performed the N-body/SPH simulations to investigate the origin of AVR. As a results, we found that AVR is not consistent with simple stellar heating.
Evolving sparse stellar populations
Authors: Bruzual Gustavo , C. Gladis Magris , Hernández-Pérez Fabiola
Published: March 2017

We examine the role that stochastic fluctuations in the IMF and in the number of interacting binaries have on the spectro-photometric properties of sparse stellar populations as a function of age and metallicity.