Showing papers by "Jesús Falcón-Barroso published in 2014"
University of Tokyo1, University of Wisconsin-Madison2, University of Toronto3, University of Kentucky4, University of Texas at Austin5, University of Washington6, University of St Andrews7, University of Portsmouth8, European Southern Observatory9, University of Nottingham10, National Autonomous University of Mexico11, University of Pittsburgh12, University of Cambridge13, New Mexico State University14, Carnegie Institution for Science15, University of Sydney16, New York University17, University of Utah18, University of Oxford19, University of California, Santa Cruz20, Max Planck Society21, Claude Bernard University Lyon 122, École normale supérieure de Lyon23, Texas Christian University24, University of Iowa25, Princeton University26, Case Western Reserve University27, University of La Laguna28, Chinese Academy of Sciences29, Academia Sinica30, University of Manchester31, Macquarie University32, Australian Astronomical Observatory33, Yale University34, Lawrence Berkeley National Laboratory35, University of Potsdam36, University of Victoria37, University of Groningen38
TL;DR: MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) as mentioned in this paper employs dithered observations with 17 fiber-bundle integral field units that vary in diameter from 12'' (19 fibers) to 32'' (127 fibers).
Abstract: We present an overview of a new integral field spectroscopic survey called MaNGA (Mapping Nearby Galaxies at Apache Point Observatory), one of three core programs in the fourth-generation Sloan Digital Sky Survey (SDSS-IV) that began on 2014 July 1. MaNGA will investigate the internal kinematic structure and composition of gas and stars in an unprecedented sample of 10,000 nearby galaxies. We summarize essential characteristics of the instrument and survey design in the context of MaNGA's key science goals and present prototype observations to demonstrate MaNGA's scientific potential. MaNGA employs dithered observations with 17 fiber-bundle integral field units that vary in diameter from 12'' (19 fibers) to 32'' (127 fibers). Two dual-channel spectrographs provide simultaneous wavelength coverage over 3600-10300 A at R ~ 2000. With a typical integration time of 3 hr, MaNGA reaches a target r-band signal-to-noise ratio of 4-8 (A–1 per 2'' fiber) at 23 AB mag arcsec–2, which is typical for the outskirts of MaNGA galaxies. Targets are selected with M * 109 M ☉ using SDSS-I redshifts and i-band luminosity to achieve uniform radial coverage in terms of the effective radius, an approximately flat distribution in stellar mass, and a sample spanning a wide range of environments. Analysis of our prototype observations demonstrates MaNGA's ability to probe gas ionization, shed light on recent star formation and quenching, enable dynamical modeling, decompose constituent components, and map the composition of stellar populations. MaNGA's spatially resolved spectra will enable an unprecedented study of the astrophysics of nearby galaxies in the coming 6 yr.
1,104 citations
Spanish National Research Council1, National Autonomous University of Mexico2, National Institute of Astrophysics, Optics and Electronics3, Complutense University of Madrid4, Autonomous University of Madrid5, Universidade Federal de Santa Catarina6, University of St Andrews7, University of La Laguna8, Instituto Superior Técnico9, Leibniz Institute for Astrophysics Potsdam10, Academy of Sciences of the Czech Republic11, Masaryk University12, Max Planck Society13, University of Sydney14, Australian Astronomical Observatory15, University of Porto16
TL;DR: In this paper, the authors presented the largest and most homogeneous catalog of H ii regions and associations compiled so far, consisting of more than 7000 ionized regions, extracted from 306 galaxies observed by the CALIFA survey.
Abstract: We present the largest and most homogeneous catalog of H ii regions and associations compiled so far The catalog comprises more than 7000 ionized regions, extracted from 306 galaxies observed by the CALIFA survey We describe the procedures used to detect, select, and analyze the spectroscopic properties of these ionized regions In the current study we focus on characterizing of the radial gradient of the oxygen abundance in the ionized gas, based on the study of the deprojecteddistribution of H ii regions We found that all galaxies without clear evidence of an interaction present a common gradient in the oxygen abundance, with a characteristic slope of α_O/H = −01 dex/r_e between 03 and 2 disk effective radii (r_e), and a scatter compatible with random fluctuations around this value, when the gradient is normalized to the disk effective radius The slope is independent of morphology, the incidence of bars, absolute magnitude, or mass Only those galaxies with evidence of interactions and/or clear merging systems present a significantly shallower gradient, consistent with previous results The majority of the 94 galaxies with H ii regions detected beyond two disk effective radii present a flattening in the oxygen abundance The flattening is statistically significant We cannot provide a conclusive answer regarding the origin of this flattening However, our results indicate that its origin is most probably related to the secular evolution of galaxies Finally, we find a drop/truncation of the oxygen abundance in the inner regions for 26 of the galaxies All of them are non-interacting, mostly unbarred Sb/Sbc galaxies This feature is associated with a central star-forming ring, which suggests that both features are produced by radial gas flows induced by resonance processes Our result suggests that galaxy disks grow inside-out, with metal enrichment driven by the local star formation history and with a small variation galaxy-by-galaxy At a certain galactocentric distance, the oxygen abundance seems to be correlated well with the stellar mass density and total stellar mass of the galaxies, independently of other properties of the galaxies Other processes, such as radial mixing and inflows/outflows seem to have a limited effect on shaping of the radial distribution of oxygen abundances, although they are not ruled out
474 citations
Leibniz Institute for Astrophysics Potsdam1, European Southern Observatory2, Spanish National Research Council3, University of La Laguna4, Complutense University of Madrid5, Masaryk University6, Max Planck Society7, University of St Andrews8, Heidelberg University9, National Autonomous University of Mexico10, INAF11, University of Vienna12, University of Sydney13, Centre national de la recherche scientifique14, Universidade Federal de Santa Catarina15, Paris Diderot University16, University of Chile17, University of Copenhagen18, Academy of Sciences of the Czech Republic19, National Institute of Astrophysics, Optics and Electronics20, Autonomous University of Madrid21, Royal Military College of Canada22
TL;DR: In this paper, the authors describe the selection procedure and statistical properties of the galaxy sample used by the Calar Alto Legacy Integral Field Area (CALIFA) survey, a public legacy survey of 600 galaxies using integral field spectroscopy.
Abstract: We describe and discuss the selection procedure and statistical properties of the galaxy sample used by the Calar Alto Legacy Integral Field Area (CALIFA) survey, a public legacy survey of 600 galaxies using integral field spectroscopy. The CALIFA "mother sample" was selected from the Sloan Digital Sky Survey (SDSS) DR7 photometric catalogue to include all galaxies with an r-band isophotal major axis between 45 '' and 79 : 2 '' and with a redshift 0 : 005 M-r > -23 : 1 and over a stellar mass range between 10(9.7) and 10(11.4) M-circle dot. In particular, within these ranges, the diameter selection does not lead to any significant bias against - or in favour of - intrinsically large or small galaxies. Only below luminosities of M-r = -19 (or stellar masses < 10(9.7) M-circle dot) is there a prevalence of galaxies with larger isophotal sizes, especially of nearly edge-on late-type galaxies, but such galaxies form < 10% of the full sample. We estimate volume-corrected distribution functions in luminosities and sizes and show that these are statistically fully compatible with estimates from the full SDSS when accounting for large-scale structure. For full characterization of the sample, we also present a number of value-added quantities determined for the galaxies in the CALIFA sample. These include consistent multi-band photometry based on growth curve analyses; stellar masses; distances and quantities derived from these; morphological classifications; and an overview of available multi-wavelength photometric measurements. We also explore different ways of characterizing the environments of CALIFA galaxies, finding that the sample covers environmental conditions from the field to genuine clusters. We finally consider the expected incidence of active galactic nuclei among CALIFA galaxies given the existing pre-CALIFA data, finding that the final observed CALIFA sample will contain approximately 30 Sey2 galaxies.
258 citations
University of Tokyo1, University of Wisconsin-Madison2, University of Toronto3, University of Kentucky4, University of Texas at Austin5, University of Washington6, University of St Andrews7, University of Portsmouth8, European Southern Observatory9, University of Nottingham10, National Autonomous University of Mexico11, University of Pittsburgh12, University of Cambridge13, New Mexico State University14, Carnegie Institution for Science15, University of Sydney16, New York University17, University of Utah18, University of Oxford19, University of California, Santa Cruz20, Max Planck Society21, Claude Bernard University Lyon 122, École normale supérieure de Lyon23, Texas Christian University24, University of Iowa25, Princeton University26, Case Western Reserve University27, University of La Laguna28, Chinese Academy of Sciences29, Academia Sinica30, University of Manchester31, Macquarie University32, Australian Astronomical Observatory33, Yale University34, Lawrence Berkeley National Laboratory35, University of Potsdam36, University of Victoria37, University of Groningen38
TL;DR: MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) as discussed by the authors employs dithered observations with 17 fiber-bundle integral field units that vary in diameter from 12" (19 fibers) to 32" (127 fibers).
Abstract: We present an overview of a new integral field spectroscopic survey called MaNGA (Mapping Nearby Galaxies at Apache Point Observatory), one of three core programs in the fourth-generation Sloan Digital Sky Survey (SDSS-IV) that began on 2014 July 1. MaNGA will investigate the internal kinematic structure and composition of gas and stars in an unprecedented sample of 10,000 nearby galaxies. We summarize essential characteristics of the instrument and survey design in the context of MaNGA's key science goals and present prototype observations to demonstrate MaNGA's scientific potential. MaNGA employs dithered observations with 17 fiber-bundle integral field units that vary in diameter from 12" (19 fibers) to 32" (127 fibers). Two dual-channel spectrographs provide simultaneous wavelength coverage over 3600-10300 A at R~2000. With a typical integration time of 3 hr, MaNGA reaches a target r-band signal-to-noise ratio of 4-8 (per A, per 2" fiber) at 23 AB mag per sq. arcsec, which is typical for the outskirts of MaNGA galaxies. Targets are selected with stellar mass greater than 1e9 Msun using SDSS-I redshifts and i-band luminosity to achieve uniform radial coverage in terms of the effective radius, an approximately flat distribution in stellar mass, and a sample spanning a wide range of environments. Analysis of our prototype observations demonstrates MaNGA's ability to probe gas ionization, shed light on recent star formation and quenching, enable dynamical modeling, decompose constituent components, and map the composition of stellar populations. MaNGA's spatially resolved spectra will enable an unprecedented study of the astrophysics of nearby galaxies in the coming 6 yr.
235 citations
Spanish National Research Council1, Universidade Federal de Santa Catarina2, Leibniz Institute for Astrophysics Potsdam3, University of La Laguna4, University of Copenhagen5, INAF6, Max Planck Society7, University of Vienna8, University of Sydney9, University of Cambridge10, Complutense University of Madrid11, Heidelberg University12
TL;DR: In this article, the authors studied the radial structure of the stellar mass surface density and stellar population age as a function of the total stellar mass and morphology for a sample of 107 galaxies from the CALIFA survey.
Abstract: We have studied the radial structure of the stellar mass surface density (μ∗) and stellar population age as a function of the total stellar mass and morphology for a sample of 107 galaxies from the CALIFA survey. We applied the fossil record method based on spectral synthesis techniques to recover the star formation history (SFH), resolved in space and time, in spheroidal and disk dominated galaxies with masses from 10^9 to 10^12 M_⊙. We derived the half-mass radius, and we found that galaxies are on average 15% more compact in mass than in light. The ratio of half-mass radius to half-light radius (HLR) shows a dual dependence with galaxy stellar mass; it decreases with increasing mass for disk galaxies, but is almost constant in spheroidal galaxies. In terms of integrated versus spatially resolved properties, we find that the galaxy-averaged stellar population age, stellar extinction, and μ_∗ are well represented by their values at 1 HLR. Negative radial gradients of the stellar population ages are present in most of the galaxies, supporting an inside-out formation. The larger inner (≤1 HLR) age gradients occur in the most massive (10^11 M_⊙) disk galaxies that have the most prominent bulges; shallower age gradients are obtained in spheroids of similar mass. Disk and spheroidal galaxies show negative μ∗ gradients that steepen with stellar mass. In spheroidal galaxies, μ∗ saturates at a critical value (~7 × 10^2 M_⊙/pc^2 at 1 HLR) that is independent of the galaxy mass. Thus, all the massive spheroidal galaxies have similar local μ_∗ at the same distance (in HLR units) from the nucleus. The SFH of the regions beyond 1 HLR are well correlated with their local μ_∗, and follow the same relation as the galaxy-averaged age and μ_∗; this suggests that local stellar mass surface density preserves the SFH of disks. The SFH of bulges are, however, more fundamentally related to the total stellar mass, since the radial structure of the stellar age changes with galaxy mass even though all the spheroid dominated galaxies have similar radial structure in μ_∗. Thus, galaxy mass is a more fundamental property in spheroidal systems, while the local stellar mass surface density is more important in disks.
193 citations
National Institute of Astrophysics, Optics and Electronics1, University of St Andrews2, University of Granada3, Spanish National Research Council4, National Autonomous University of Mexico5, INAF6, University of Sydney7, Complutense University of Madrid8, Universidade Federal de Santa Catarina9, Academy of Sciences of the Czech Republic10, University of Porto11, Max Planck Society12, Leibniz Institute for Astrophysics Potsdam13
TL;DR: In this paper, a comparative study of the stellar metallicity and age distributions in a sample of 62 nearly face-on, spiral galaxies with and without bars, using data from the CALIFA survey is presented.
Abstract: While studies of gas-phase metallicity gradients in disc galaxies are common, very little has been done towards the acquisition of stellar abundance gradients in the same regions. We present here a comparative study of the stellar metallicity and age distributions in a sample of 62 nearly face-on, spiral galaxies with and without bars, using data from the CALIFA survey. We measure the slopes of the gradients and study their relation with other properties of the galaxies. We find that the mean stellar age and metallicity gradients in the disc are shallow and negative. Furthermore, when normalized to the effective radius of the disc, the slope of the stellar population gradients does not correlate with the mass or with the morphological type of the galaxies. In contrast to this, the values of both age and metallicity at ~2.5 scale lengths correlate with the central velocity dispersion in a similar manner to the central values of the bulges, although bulges show, on average, older ages and higher metallicities than the discs. One of the goals of the present paper is to test the theoretical prediction that non-linear coupling between the bar and the spiral arms is an efficient mechanism for producing radial migrations across significant distances within discs. The process of radial migration should flatten the stellar metallicity gradient with time and, therefore, we would expect flatter stellar metallicity gradients in barred galaxies. However, we do not find any difference in the metallicity or age gradients between galaxies with and without bars. We discuss possible scenarios that can lead to this lack of difference.
176 citations
University of Chile1, Instituto Superior Técnico2, Paris Diderot University3, European Southern Observatory4, Spanish National Research Council5, National Autonomous University of Mexico6, University of Pittsburgh7, University of La Laguna8, University of Sydney9, University of Porto10, Max Planck Society11, Macquarie University12, Australian Astronomical Observatory13, University of St Andrews14, Complutense University of Madrid15, University of Zaragoza16, National Institute of Astrophysics, Optics and Electronics17
TL;DR: In this article, optical integral field spectroscopy (IFS) of nearby supernova (SN) host galaxies (0.04, 2.01, and 97.95% in these intervals) was used to estimate that the low-mass galaxies produce ten times fewer SNe Ia and three times fewer CC SNe than the high-mass group.
Abstract: We use optical integral field spectroscopy (IFS) of nearby supernova (SN) host galaxies (0.005 2.4 Gyr, respectively) than the massive SN Ia hosts (0.04%, 2.01%, and 97.95% in these intervals). We estimate that the low-mass galaxies produce ten times fewer SNe Ia and three times fewer CC SNe than the high-mass group. Therefore the ratio between the number of CC SNe and SNe Ia is expected to increase with decreasing galaxy mass. CC SNe tend to explode at positions with younger stellar populations than the galaxy average, but the galaxy properties at SNe Ia locations are one average the same as the global galaxy properties.
106 citations
TL;DR: In this paper, the authors used optical IFS of nearby SN host galaxies provided by the CALIFA Survey with the goal of finding correlations in the environmental parameters at the location of different SN types.
Abstract: [Abridged] We use optical IFS of nearby SN host galaxies provided by the CALIFA Survey with the goal of finding correlations in the environmental parameters at the location of different SN types. We recover the sequence in association of different SN types to the star-forming regions by using several indicators of the ongoing and recent SF related to both the ionized gas and the stellar populations. While the total ongoing SF is on average the same for the three SN types, SNe Ibc/IIb tend to happen closer to star-forming regions and occur in higher SF density locations compared to SNe II and SNe~Ia, the latter showing the weakest correlation. SNe~Ia host galaxies have on average masses that are $\sim$0.3-0.8~dex higher than CC SNe hosts due to a larger fraction of old stellar populations in the SNe~Ia hosts. Using the recent SN~Ia delay-time distribution and the SFHs of the galaxies, we show that the SN~Ia hosts in our sample should presently produce a factor 2 more SNe~Ia than the CC~SN hosts. Since both types are in hosts with similar SF rate and hence similar CC~SN rate, this can explain the mass difference between the SN~Ia and CC~SN hosts, and reinforce the finding that at least part of SNe~Ia should originate from very old progenitors. Comparing the mean SFH of the eight least massive galaxies to that of the massive SF SN~Ia hosts we find that the low-mass galaxies formed their stars over more extended time than the massive SN~Ia hosts. We estimate that the low-mass galaxies should produce by a factor of 10 less SNe~Ia, and a factor of 3 less CC~SNe than the high-mass group. Therefore the ratio between the number of CC~SNe and SNe~Ia is expected to increase with decreasing the galaxy mass. CC~SNe tend to explode at positions with younger stellar populations than the galaxy average, but the galaxy properties at SNe~Ia locations are one average the same as the global ones.
99 citations
University of Oulu1, University of Turku2, Heidelberg University3, Kapteyn Astronomical Institute4, University College London5, University of California, Santa Cruz6, Carnegie Institution for Science7, University of Vienna8, University of La Laguna9, Spanish National Research Council10, Aix-Marseille University11, University of Utah12, Paris Diderot University13
TL;DR: In this paper, a nearly magnitude-complete sample of 121 Virgo cluster early types with deep near-infrared images from the SMAKCED project was used to fit two-dimensional models with optional inner and outer components, as well as bar and lens components, to the galaxy images.
Abstract: The fraction of star-forming to quiescent dwarf galaxies varies from almost infinity in the field to zero in the centers of rich galaxy clusters. What is causing this pronounced morphology-density relation? What do quiescent dwarf galaxies look like when studied in detail, and what conclusions can be drawn about their formation mechanism? Here we study a nearly magnitude-complete sample (-19
86 citations
Spanish National Research Council1, Autonomous University of Madrid2, National Institute of Astrophysics, Optics and Electronics3, Leibniz Institute for Astrophysics Potsdam4, Complutense University of Madrid5, University of Cambridge6, Instituto Superior Técnico7, University of St Andrews8, University of La Laguna9, University of Granada10, University of Porto11, Ruhr University Bochum12, University of Vienna13, University of Sydney14, Australian Astronomical Observatory15, Macquarie University16, Max Planck Society17
TL;DR: In this paper, the authors explored the capability of the CALIFA survey and a hypothetical higher redshift survey to reproduce the properties of a sample of objects observed with better spatial resolution at lower redshift.
Abstract: Context. Over the past decade, 3D optical spectroscopy has become the preferred tool for understanding the properties of galaxies and is now increasingly used to carry out galaxy surveys. Low redshift surveys include SAURON, DiskMass, ATLAS3D, PINGS, and VENGA. At redshifts above 0.7, surveys such as MASSIV, SINS, GLACE, and IMAGES have targeted the most luminous galaxies to study mainly their kinematic properties. The on-going CALIFA survey (z ∼ 0.02) is the first of a series of upcoming integral field spectroscopy (IFS) surveys with large samples representative of the entire population of galaxies. Others include SAMI and MaNGA at lower redshift and the upcoming KMOS surveys at higher redshift. Given the importance of spatial scales in IFS surveys, the study of the effects of spatial resolution on the recovered parameters becomes important. Aims. We explore the capability of the CALIFA survey and a hypothetical higher redshift survey to reproduce the properties of a sample of objects observed with better spatial resolution at lower redshift. Methods. Using a sample of PINGS galaxies, we simulated observations at different redshifts. We then studied the behaviour of different parameters as the spatial resolution degrades with increasing redshift. Results. We show that at the CALIFA resolution, we are able to measure and map common observables in a galaxy study: the number and distribution of H ii regions (Hα flux structure), the gas metallicity (using the O3N2 method), the gas ionization properties (through the [N ii]/Hα and [O iii]/Hβ line ratios), and the age of the underlying stellar population (using the D4000 index). This supports the aim of the survey to characterise the observable properties of galaxies in the Local Universe. Our analysis of simulated IFS data cubes at higher redshifts highlights the importance of the projected spatial scale per spaxel as the most important figure of merit in the design of an integral field survey.
82 citations
Fulbright & Jaworski1, Carnegie Institution for Science2, University of California, Santa Cruz3, Kapteyn Astronomical Institute4, Centre national de la recherche scientifique5, Heidelberg University6, University of La Laguna7, Spanish National Research Council8, Max Planck Society9, Korea Astronomy and Space Science Institute10, European Southern Observatory11, École normale supérieure de Lyon12, Swinburne University of Technology13, University of Utah14, Complutense University of Madrid15, University of Vienna16, University of Oulu17, University of Turku18, University College London19
TL;DR: In this paper, a sample of 39 dwarf early-type (dE) galaxies in the Virgo cluster studied as part of the SMAKCED stellar absorption-line spectroscopy and imaging survey is presented.
Abstract: We present spatially resolved kinematics and global stellar populations and mass-to-light ratios for a sample of 39 dwarf early-type (dE) galaxies in the Virgo cluster studied as part of the SMAKCED stellar absorption-line spectroscopy and imaging survey. This sample is representative of the early-type population in the Virgo cluster in the absolute magnitude range -19.0 < M-r < -16.0 and of all morphological subclasses found in this galaxy population. For each dE, we measure the rotation curve and velocity dispersion profile and fit an analytic function to the rotation curve. We study the significance of the departure of the rotation curve from the best-fit analytic function (poorly fit) and of the difference between the approaching and receding sides of the rotation curve (asymmetry). Our sample includes two dEs with kinematically decoupled cores that have been previously reported. We find that 62 +/- 8% (23 out of the 39) of the dEs have a significant anomaly in their rotation curve. Analysis of the images reveals photometric anomalies for most galaxies. However, there is no clear correlation between the significance of the photometric and kinematic anomalies. We measure age-sensitive (H-beta and H-gamma A) and metallicity sensitive (Fe4668 and Mgb) Lick spectral indices in the LIS-5 angstrom system. This population of galaxies exhibits a wide range of ages and metallicities; we also find that 4 dEs show clear evidence of emission partially filling in the Balmer absorption lines. Finally, we estimate the total masses and dark matter fractions of the dEs and plot them in the mass-size, themass-velocity dispersion, and the fundamental plane scaling relations. The dEs seem to be the bridge between massive early-type galaxies and dSphs, and have a median total mass within the R-e of logM(e) = 9.1 +/- 0.2 and a median dark matter fraction within the R-e of f(DM) = 46 +/- 18%. Any formation model for the dE galaxy class must account for this diversity of kinematic and photometric anomalies and stellar populations.
TL;DR: In this paper, the authors present the dynamical analysis of a sample of 12 dwarf elliptical (dE) galaxies for which they have obtained SAURON large-scale two-dimensional spectroscopic data.
Abstract: We present the dynamical analysis of a sample of 12 dwarf elliptical (dE) galaxies for which we have obtained SAURON large-scale two-dimensional spectroscopic data. We construct Jeans axisymmetric models and obtain total dynamical masses enclosed within one effective radius. We use the obtained values to show that the validity of the dynamical scaling relations of massive early-type galaxies can be extended to these low-mass systems, except that dEs seem to contain relatively larger fraction of dark matter in their inner parts. We then demonstrate that dE galaxies have lower angular momenta than the present-day analogues of 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. This requires a transformation mechanism that is not only able to lower the angular momentum but also one that needs to account for increased stellar concentration. Additionally, we match the dark matter fraction of our galaxies to their location in the Virgo Cluster and see that galaxies in the cluster outskirts tend to have a higher dark-to-stellar matter ratio. Transformation due to tidal harassment is able to expain all of the above, unless the dE progenitors were already compact and had lower angular momenta at higher redshifts.
University of California, Santa Cruz1, Carnegie Institution for Science2, Fulbright & Jaworski3, Max Planck Society4, Centre national de la recherche scientifique5, University of Utah6, Spanish National Research Council7, University of La Laguna8, University of Vienna9, University of Oulu10, Heidelberg University11, University of Turku12, Paris Diderot University13
TL;DR: In this article, the authors presented evidence for kinematically decoupled cores (KDCs) in two dwarf early-type (dE) galaxies in the Virgo cluster, VCC 1183 and VCC 1453.
Abstract: We present evidence for kinematically decoupled cores (KDCs) in two dwarf early-type (dE) galaxies in the Virgo cluster, VCC 1183 and VCC 1453, studied as part of the SMAKCED stellar absorption-line spectroscopy and imaging survey. These KDCs have radii of 1.''8 (0.14 kpc) and 4.''2 (0.33 kpc), respectively. Each of these KDCs is distinct from the main body of its host galaxy in two ways: (1) inverted sense of rotation and (2) younger (and possibly more metal-rich) stellar population. The observed stellar population differences are probably associated with the KDC, although we cannot rule out the possibility of intrinsic radial gradients in the host galaxy. We describe a statistical analysis method to detect, quantify the significance of, and characterize KDCs in long-slit rotation curve data. We apply this method to the two dE galaxies presented in this paper and to five other dEs for which KDCs have been reported in the literature. Among these seven dEs, there are four significant KDC detections, two marginal KDC detections, and one dE with an unusual central kinematic anomaly that may be an asymmetric KDC. The frequency of occurrence of KDCs and their properties provide important constraints on the formation history of their hostmore » galaxies. We discuss different formation scenarios for these KDCs in cluster environments and find that dwarf-dwarf wet mergers or gas accretion can explain the properties of these KDCs. Both of these mechanisms require that the progenitor had a close companion with a low relative velocity. This suggests that KDCs were formed in galaxy pairs residing in a poor group environment or in isolation whose subsequent infall into the cluster quenched star formation.« less
TL;DR: In this paper, the authors used the cross-correlation technique to obtain the radial velocity of the dominant gaseous component and derived the main kinematic parameters directly from the radial velocities with no assumptions on the internal motions.
Abstract: This work provides an overall characterization of the kinematic behavior of the ionized gas of the galaxies included in the Calar Alto Legacy Integral field Area (CALIFA), offering kinematic clues to potential users of this survey for including kinematical criteria for specific studies. From the first 200 galaxies observed by CALIFA, we present the 2D kinematic view of the 177 galaxies satisfying a gas detection threshold. After removing the stellar contribution, we used the cross-correlation technique to obtain the radial velocity of the dominant gaseous component. The main kinematic parameters were directly derived from the radial velocities with no assumptions on the internal motions. Evidence of the presence of several gaseous components with different kinematics were detected by using [OIII] profiles. Most objects in the sample show regular velocity fields, although the ionized-gas kinematics are rarely consistent with simple coplanar circular motions. 35% of the objects present evidence of a displacement between the photometric and kinematic centers larger than the original spaxel radii. Only 17% of the objects in the sample exhibit kinematic lopsidedness when comparing receding and approaching sides of the velocity fields, but most of them are interacting galaxies exhibiting nuclear activity. Early-type galaxies in the sample present clear photometric-kinematic misaligments. There is evidence of asymmetries in the emission line profiles suggesting the presence of kinematically distinct gaseous components at different distances from the nucleus. This work constitutes the first determination of the ionized gas kinematics of the galaxies observed in the CALIFA survey. The derived velocity fields, the reported kinematic peculiarities and the identification of the presence of several gaseous components might be used as additional criteria for selecting galaxies for specific studies.
TL;DR: In this paper, a near-infrared (H-and K-band) integral field observations of the inner 700 pc of the active spiral galaxy NGC 613, obtained with SINFONI on the Very Large Telescope, were used to determine the dominant excitat ion mechanisms in different regions within their field-of-view.
Abstract: We present near-infrared (H- and K-band) integral-field observations of the inner �700 pc of the active spiral galaxy NGC 613, obtained with SINFONI on the Very Large Telescope. We use emission-line ratios to determine the dominant excitat ion mechanisms in different regions within our field-of-view, in particular the active nucleus a nd the star-forming circum-nuclear ring. Diagnostic diagrams involving [FeII] and H2 fluxes indicate that the gas is not only photoionized by the AGN in the nucleus of NGC 613, but also shock-heated. On the other hand, the emission line ratios measured in the “hot spots” al ong the ring are fully consistent with them being young star forming regions. We find no sign of r adial gas transport from the ring into the core region dominated by the AGN. The ring morphology appears disturbed by a radial outflow of material from the AGN, which is confirmed by the existence of a weak jet in archival radio maps. However, this jet does not seem to have any significant effect on the morphology of the large (�8×10 7 M⊙) reservoir of molecular gas that has accumulated inside the central �100 pc. Such a concentration of molecular gas around an AGN is unusual, and supports a scenario in which star formation is recurrent and episodic in spiral galaxies. In this context, NGC 613 appears to be in final stages of the gas accumu lation phase, and is likely to undergo a nuclear starburst in the near future.
University of St Andrews1, University of Edinburgh2, Autonomous University of Madrid3, National Institute of Astrophysics, Optics and Electronics4, Spanish National Research Council5, University of La Laguna6, University of Copenhagen7, INAF8, Leibniz Institute for Astrophysics Potsdam9, Heidelberg University10, University of Helsinki11, Max Planck Society12, Paris Diderot University13, Universidade Federal de Santa Catarina14, Ruhr University Bochum15, Institut d'Astrophysique de Paris16, University of Cambridge17, European Southern Observatory18, National Autonomous University of Mexico19, University of Vienna20, University of Sydney21, Complutense University of Madrid22, University of Granada23, Macquarie University24, Australian Astronomical Observatory25
TL;DR: In this article, optical integral field spectroscopy (IFS) observations of the Mice, a major merger between two massive (≳10^11 M_⊙) gas-rich spirals NGC 4676A and B, observed between first passage and final coalescence.
Abstract: We present optical integral field spectroscopy (IFS) observations of the Mice, a major merger between two massive (≳10^11 M_⊙) gas-rich spirals NGC 4676A and B, observed between first passage and final coalescence. The spectra provide stellar and gas kinematics, ionised gas properties, and stellar population diagnostics, over the full optical extent of both galaxies with ~1.6 kpc spatial resolution. The Mice galaxies provide a perfect case study that highlights the importance of IFS data for improving our understanding of local galaxies. The impact of first passage on the kinematics of the stars and gas has been significant, with strong bars most likely induced in both galaxies. The barred spiral NGC 4676B exhibits a strong twist in both its stellar and ionised gas disk. The edge-on disk galaxy NGC 4676A appears to be bulge free, with a strong bar causing its “boxy” light profile. On the other hand, the impact of the merger on the stellar populations has been minimal thus far. By combining the IFS data with archival multiwavelength observations we show that star formation induced by the recent close passage has not contributed significantly to the total star formation rate or stellar mass of the galaxies. Both galaxies show bicones of high ionisation gas extending along their minor axes. In NGC 4676A the high gas velocity dispersion and Seyfert-like line ratios at large scaleheight indicate a powerful outflow. Fast shocks (vs ~ 350 km s^-1) extend to ~6.6 kpc above the disk plane. The measured ram pressure (P/k = 4.8 × 10^6 K cm^-3) and mass outflow rate (~8−20 M_⊙ yr^-1) are similar to superwinds from local ultra-luminous infrared galaxies, although NGC 4676A only has a moderate infrared luminosity of 3 × 10^10 L_⊙. Energy beyond what is provided by the mechanical energy of the starburst appears to be required to drive the outflow. Finally, we compare the observations to mock kinematic and stellar population maps extracted from a hydrodynamical merger simulation. The models show little enhancement in star formation during and following first passage, in agreement with the observations. We highlight areas where IFS data could help further constrain the models.
TL;DR: In this article, the stellar angular momentum of galaxies across the Hubble sequence from the CALIFA survey is investigated, and it is shown that the location of spiral galaxies in this diagram is significantly different.
Abstract: We investigate the stellar angular momentum of galaxies across the Hubble sequence from the CALIFA survey. The distribution of CALIFA elliptical and lenticular galaxies in the $\lambda_{\rm Re}-\epsilon_{\rm e}$ diagram is consistent with that shown by the Atlas$^\mathrm{3D}$ survey. Our data, however, show that the location of spiral galaxies in this diagram is significantly different. We have found two families of spiral galaxies with particularly peculiar properties: (a) spiral galaxies with much higher $\lambda_{\rm Re}$ values than any elliptical and lenticular galaxy; (b) low-mass spiral galaxies with observed $\lambda_{\rm Re}$ values much lower than expected for their apparent flattening. We use these two families of objects to argue that (1) fading alone cannot explain the transformation of spiral to lenticular galaxies, and (2) that those low-mass spiral galaxies are in fact dark matter dominated, which explains the unusually low angular momentum.
TL;DR: In this article, the authors analyzed the unphysical mass discrepancy between galaxies and their stellar masses at all redshifts and found that the discrepancy grows as galaxies depart from the present-day relation between stellar mass and size: the more compact a galaxy, the larger its mass discrepancy.
Abstract: For many massive compact galaxies, their dynamical masses ($M_\mathrm{dyn} \propto \sigma^2 r_\mathrm{e}$) are lower than their stellar masses ($M_\star$). We analyse the unphysical mass discrepancy $M_\star / M_\mathrm{dyn} > 1$ on a stellar-mass-selected sample of early-type galaxies ($M_\star \gtrsim 10^{11} \ \mathrm{M_\odot}$) at redshifts $z \sim 0.2$ to $z \sim 1.1$. We build stacked spectra for bins of redshift, size and stellar mass, obtain velocity dispersions, and infer dynamical masses using the virial relation $M_\mathrm{dyn} \equiv K \ \sigma_\mathrm{e}^2 r_\mathrm{e} / G$ with $K = 5.0$; this assumes homology between our galaxies and nearby massive ellipticals. Our sample is completed using literature data, including individual objects up to $z \sim 2.5$ and a large local reference sample from the Sloan Digital Sky Survey (SDSS). We find that, at all redshifts, the discrepancy between $M_\star$ and $M_\mathrm{dyn}$ grows as galaxies depart from the present-day relation between stellar mass and size: the more compact a galaxy, the larger its $M_\star / M_\mathrm{dyn}$. Current uncertainties in stellar masses cannot account for values of $M_\star / M_\mathrm{dyn}$ above 1. Our results suggest that the homology hypothesis contained in the $M_\mathrm{dyn}$ formula above breaks down for compact galaxies. We provide an approximation to the virial coefficient $K \sim 6.0 \left[ r_\mathrm{e} / (3.185 \ \mathrm{kpc}) \right]^{-0.81} \left[ M_\star / (10^{11} \ \mathrm{M_\odot}) \right]^{0.45}$, which solves the mass discrepancy problem. A rough approximation to the dynamical mass is given by $M_\mathrm{dyn} \sim \left[ \sigma_\mathrm{e} / (200 \ \mathrm{km \ s^{-1}}) \right]^{3.6} \left[ r_\mathrm{e} / (3 \ \mathrm{kpc}) \right]^{0.35} 2.1 \times 10^{11} \ \mathrm{M_\odot}$.
Leibniz Institute for Astrophysics Potsdam1, European Southern Observatory2, Spanish National Research Council3, University of La Laguna4, Complutense University of Madrid5, Masaryk University6, Max Planck Society7, University of St Andrews8, Heidelberg University9, National Autonomous University of Mexico10, INAF11, University of Vienna12, University of Sydney13, Centre national de la recherche scientifique14, Universidade Federal de Santa Catarina15, Paris Diderot University16, University of Chile17, University of Copenhagen18, Academy of Sciences of the Czech Republic19, National Institute of Astrophysics, Optics and Electronics20, Autonomous University of Madrid21, Royal Military College of Canada22
TL;DR: In this paper, the authors describe the selection procedure and statistical properties of the galaxy sample used by the Calar Alto Legacy Integral Field Area Survey (CALIFA), a public legacy survey of 600 galaxies using integral field spectroscopy.
Abstract: We describe and discuss the selection procedure and statistical properties of the galaxy sample used by the Calar Alto Legacy Integral Field Area Survey (CALIFA), a public legacy survey of 600 galaxies using integral field spectroscopy. The CALIFA "mother sample" was selected from the Sloan Digital Sky Survey (SDSS) DR7 photometric catalogue to include all galaxies with an r-band isophotal major axis between 45" and 79.2" and with a redshift 0.005 Mr > -23.1 and over a stellar mass range between 10^9.7 and 10^11.4Msun. In particular, within these ranges, the diameter selection does not lead to any significant bias against - or in favour of - intrinsically large or small galaxies. Only below luminosities of Mr = -19 (or stellar masses < 10^9.7Msun) is there a prevalence of galaxies with larger isophotal sizes, especially of nearly edge-on late-type galaxies, but such galaxies form < 10% of the full sample. We estimate volume-corrected distribution functions in luminosities and sizes and show that these are statistically fully compatible with estimates from the full SDSS when accounting for large-scale structure. We also present a number of value-added quantities determined for the galaxies in the CALIFA sample. We explore different ways of characterizing the environments of CALIFA galaxies, finding that the sample covers environmental conditions from the field to genuine clusters. We finally consider the expected incidence of active galactic nuclei among CALIFA galaxies.
01 Jul 2014
TL;DR: In this article, the stellar angular momentum of galaxies across the Hubble sequence from the CALIFA survey was investigated, and two families of spiral galaxies with particularly peculiar properties were found: (a) spiral galaxies having much higher λRe values than any elliptical and lenticular galaxies; (b) low-mass spiral galaxies had observed λR values much lower than expected for their apparent flattening.
Abstract: We investigate the stellar angular momentum of galaxies across the Hubble sequence from the CALIFA survey. The distribution of CALIFA elliptical and lenticular galaxies in the λRe - ɛe diagram is consistent with that shown by the Atlas3D survey. Our data, however, show that the location of spiral galaxies in this diagram is significantly different. We have found two families of spiral galaxies with particularly peculiar properties: (a) spiral galaxies with much higher λRe values than any elliptical and lenticular galaxy; (b) low-mass spiral galaxies with observed λRe values much lower than expected for their apparent flattening. We use these two families of objects to argue that (1) fading alone cannot explain the transformation of spiral to lenticular galaxies, and (2) that those low-mass spiral galaxies are in fact dark matter dominated, which explains the unusually low angular momentum.
University of St Andrews1, University of Edinburgh2, Autonomous University of Madrid3, National Institute of Astrophysics, Optics and Electronics4, University of La Laguna5, Spanish National Research Council6, INAF7, University of Copenhagen8, Leibniz Institute for Astrophysics Potsdam9, Heidelberg University10, University of Helsinki11, Max Planck Society12, Paris Diderot University13, Universidade Federal de Santa Catarina14, Ruhr University Bochum15, Institut d'Astrophysique de Paris16, University of Cambridge17, European Southern Observatory18, National Autonomous University of Mexico19, University of Vienna20, University of Sydney21, Complutense University of Madrid22, University of Granada23, Australian Astronomical Observatory24, Macquarie University25
TL;DR: In this paper, optical integral field spectroscopy (IFS) observations of the Mice, a major merger between two massive (>10^11Msol) gas-rich spirals NGC4676A and B, observed between first passage and final coalescence.
Abstract: We present optical integral field spectroscopy (IFS) observations of the Mice, a major merger between two massive (>10^11Msol) gas-rich spirals NGC4676A and B, observed between first passage and final coalescence. The spectra provide stellar and gas kinematics, ionised gas properties and stellar population diagnostics, over the full optical extent of both galaxies. The Mice provide a perfect case study highlighting the importance of IFS data for improving our understanding of local galaxies. The impact of first passage on the kinematics of the stars and gas has been significant, with strong bars likely induced in both galaxies. The barred spiral NGC4676B exhibits a strong twist in both its stellar and ionised gas disk. On the other hand, the impact of the merger on the stellar populations has been minimal thus far: star formation induced by the recent close passage has not contributed significantly to the global star formation rate or stellar mass of the galaxies. Both galaxies show bicones of high ionisation gas extending along their minor axes. In NGC4676A the high gas velocity dispersion and Seyfert-like line ratios at large scaleheight indicate a powerful outflow. Fast shocks extend to ~6.6kpc above the disk plane. The measured ram pressure and mass outflow rate (~8-20Msol/yr) are similar to superwinds from local ULIRGs, although NGC4676A has only a moderate infrared luminosity of 3x10^10Lsol. Energy beyond that provided by the mechanical energy of the starburst appears to be required to drive the outflow. We compare the observations to mock kinematic and stellar population maps from a merger simulation. The models show little enhancement in star formation during and following first passage, in agreement with the observations. We highlight areas where IFS data could help further constrain the models.
01 Jul 2014
TL;DR: In this paper, the authors present the dynamical and stellar population analysis of 12 dwarf elliptical galaxies (dEs) observed using the SAURON IFU (WHT, La Palma) and demonstrate that dEs have lower angular momenta than their presumed late-type progenitors.
Abstract: We 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.
01 Jan 2014
TL;DR: In this paper, the authors presented the largest and most homogeneous catalog of H ii regions and associations compiled so far, consisting of more than 7000 ionized regions, extracted from 306 galaxies observed by the CALIFA survey.
Abstract: We present the largest and most homogeneous catalog of H ii regions and associations compiled so far. The catalog comprises more than 7000 ionized regions, extracted from 306 galaxies observed by the CALIFA survey. We describe the procedures used to detect, select, and analyze the spectroscopic properties of these ionized regions. In the current study we focus on characterizing of the radial gradient of the oxygen abundance in the ionized gas, based on the study of the deprojected distribution of H ii regions. We found that all galaxies without clear evidence of an interaction present a common gradient in the oxygen abundance, with a characteristic slope of αO/H = −0.1 dex/re between 0.3 and 2 disk effective radii (re), and a scatter compatible with random fluctuations around this value, when the gradient is normalized to the disk effective radius. The slope is independent of morphology, the incidence of bars, absolute magnitude, or mass. Only those galaxies with evidence of interactions and/or clear merging systems present a significantly shallower gradient, consistent with previous results. The majority of the 94 galaxies with H ii regions detected beyond two disk effective radii present a flattening in the oxygen abundance. The flattening is statistically significant. We cannot provide a conclusive answer regarding the origin of this flattening. However, our results indicate that its origin is most probably related to the secular evolution of galaxies. Finally, we find a drop/truncation of the oxygen abundance in the inner regions for 26 of the galaxies. All of them are non-interacting, mostly unbarred Sb/Sbc galaxies. This feature is associated with a central star-forming ring, which suggests that both features are produced by radial gas flows induced by resonance processes. Our result suggests that galaxy disks grow inside-out, with metal enrichment driven by the local star formation history and with a small variation galaxy-by-galaxy. At a certain galactocentric distance, the oxygen abundance seems to be correlated well with the stellar mass density and total stellar mass of the galaxies, independently of other properties of the galaxies. Other processes, such as radial mixing and inflows/outflows seem to have a limited effect on shaping of the radial distribution of oxygen abundances, although they are not ruled out.
01 Jul 2014
TL;DR: In this paper, the stellar content of three galactic bulges with the high resolution gratings (R=7000) of the WiFeS integral field unit was studied to better understand their formation and evolution.
Abstract: We 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.