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Global properties of `ordinary` early-type galaxies: photometry and spectroscopy of stars and globular clusters in NGC 4494

FOSTER, Caroline; SPITLER, Lee R.; ROMANOWSKY, Aaron J.; FORBES, Duncan A.; POTA, Vincenzo; BEKKI, Kenji; STRADER, Jay; PROCTOR, Robert N.; ARNOLD, Jacob A.; BRODIE, Jean P.
Fonte: WILEY-BLACKWELL Publicador: WILEY-BLACKWELL
Tipo: Artigo de Revista Científica
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We present a comprehensive analysis of the spatial, kinematic and chemical properties of stars and globular clusters (GCs) in the `ordinary` elliptical galaxy NGC 4494 using data from the Keck and Subaru telescopes. We derive galaxy surface brightness and colour profiles out to large galactocentric radii. We compare the latter to metallicities derived using the near-infrared Calcium Triplet. We obtain stellar kinematics out to similar to 3.5 effective radii. The latter appear flattened or elongated beyond similar to 1.8 effective radii in contrast to the relatively round photometric isophotes. In fact, NGC 4494 may be a flattened galaxy, possibly even an S0, seen at an inclination of similar to 45 degrees. We publish a catalogue of 431 GC candidates brighter than i(0) = 24 based on the photometry, of which 109 are confirmed spectroscopically and 54 have measured spectroscopic metallicities. We also report the discovery of three spectroscopically confirmed ultra-compact dwarfs around NGC 4494 with measured metallicities of -0.4 less than or similar to [Fe/H] less than or similar to -0.3. Based on their properties, we conclude that they are simply bright GCs. The metal-poor GCs are found to be rotating with similar amplitude as the galaxy stars...

The globular cluster kinematics and galaxy dark matter content of NGC 3923

Norris, Mark A.; Gebhardt, Karl; Sharples, Ray M.; Raul Faifer, Favio; Bridges, Terry; Forbes, Duncan A.; Forte, Juan C.; Zepf, Stephen E.; Beasley, Michael A.; Hanes, David A.; Proctor, Robert; Kannappan, Sheila J.
Fonte: WILEY-BLACKWELL; MALDEN Publicador: WILEY-BLACKWELL; MALDEN
Tipo: Artigo de Revista Científica
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This paper presents further results from our spectroscopic study of the globular cluster (GC) system of the group elliptical NGC 3923. From observations made with the GMOS instrument on the Gemini South Telescope, an additional 50 GC and ultra-compact dwarf (UCD) candidates have been spectroscopically confirmed as members of the NGC 3923 system. When the recessional velocities of these GCs are combined with the 29 GC velocities reported previously, a total sample of 79 GC/UCD velocities is produced. This sample extends to over 6 arcmin (>6 R-e similar to 30 kpc) from the centre of NGC 3923 and is used to study the dynamics of the GC system and the dark matter content of NGC 3923. It is found that the GC system of NGC 3923 displays no appreciable rotation, and that the projected velocity dispersion is constant with radius within the uncertainties. The velocity dispersion profiles of the integrated light and GC system of NGC 3923 are indistinguishable over the region in which they overlap. We find some evidence that the diffuse light and GCs of NGC 3923 have radially biased orbits within similar to 130 arcsec. The application of axisymmetric orbit-based models to the GC and integrated light velocity dispersion profiles demonstrates that a significant increase in the mass-to-light ratio (from M/L-V = 8 to 26) at large galactocentric radii is required to explain this observation. We therefore confirm the presence of a dark matter halo in NGC 3923. We find that dark matter comprises 17.5(-4.5)(+7.3) per cent of the mass within 1 R-e...

Mass profile and dynamical status of the z ~ 0.8 galaxy cluster LCDCS 0504

Guennou, L.; Biviano, A.; Adami, C.; Limousin, M.; Neto, Gastao Cesar Bierrenbach Lima; Mamon, G. A.; Ulmer, M. P.; Gavazzi, R.; Cypriano, Eduardo Serra; Durret, F.; Clowe, D.; LeBrun, V.; Allam, S.; Basa, S.; Benoist, C.; Cappi, A.; Halliday, C.; Ilbert,
Fonte: EDP Sciences; Les Ulis Publicador: EDP Sciences; Les Ulis
Tipo: Artigo de Revista Científica
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Constraints on the mass distribution in high-redshift clusters of galaxies are currently not very strong. Aims. We aim to constrain the mass profile, M(r), and dynamical status of the z ∼ 0.8 LCDCS 0504 cluster of galaxies that is characterized by prominent giant gravitational arcs near its center. Methods. Our analysis is based on deep X-ray, optical, and infrared imaging as well as optical spectroscopy, collected with various instruments, which we complemented with archival data. We modeled the mass distribution of the cluster with three different mass density profiles, whose parameters were constrained by the strong lensing features of the inner cluster region, by the X-ray emission from the intracluster medium, and by the kinematics of 71 cluster members. Results. We obtain consistent M(r) determinations from three methods based on kinematics (dispersion-kurtosis, caustics, and MAMPOSSt), out to the cluster virial radius, 1.3 Mpc and beyond. The mass profile inferred by the strong lensing analysis in the central cluster region is slightly higher than, but still consistent with, the kinematics estimate. On the other hand, the X-ray based M(r) is significantly lower than the kinematics and strong lensing estimates. Theoretical predictions from ΛCDM cosmology for the concentration–mass relation agree with our observational results...

Infrared mergers and infrared quasi-stellar objects with galactic winds - II. NGC 5514 : two extranuclear starbursts with LINER properties and a supergiant bubble in the rupture phase

Lipari, Sebastian; Mediavilla, Evencio; Garcia-Lorenzo, B.; Díaz, Rubén Joaquín; Acosta-Pulido, J.; Agüero, Maria Paz; Taniguchi, Y.; Dottori, Horacio Alberto; Terlevich, Roberto
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
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A study of the morphology, kinematics and ionization structure of the infrared (IR) merger NGC5514 is presented. This study is based mainly on INTEGRAL two-dimensional (2D) spectroscopy (obtained at the 4.2-m William Herschel Telescope, WHT), plus optical and near-IR images. Clear evidence of two extranuclear starbursts with young outflows (OFs) and low-ionization nuclear emission region (LINER) activity are reported. One of these OFs has generated a supergiant bubble and the other is associated with an extended complex of H II regions. In the galactic bubble it was found that: (i) the [S II], Hα, [NII], [O I] and [O III] emissionline maps show a bubble with a distorted ellipsoidal shape, with major and minor axes of ~ 6.5 kpc [13.6 arcsec; at position angle (PA) = 120◦ ± 10◦] and ~ 4.5 kpc (9.6 arcsec); (ii) these maps depict four main knots, a very strong one and three others more compact and located at the border; (iii) the centre of the bubble is located at ~ 4.1 kpc (8.5 arcsec) to the west of the main nucleus; (iv) the WHT spectra show, in this area, two strong components: blue and red emission-line systems, probably associated with emission from the near and far side of the external shell, for which the mean OF velocities were measured as VOF blue = (−320 ± 20) km s−1 and V OF red = (+265 ± 25) km s−1; (v) these two components depict LINER properties...

An atlas of calcium triplet spectra of active galaxies

Garcia-Rissmann, Aurea; Neme, Luis Rodolfo Vega; Asari, Natalia Vale; Fernandes Junior, Roberto Cid; Schmitt, Henrique Roberto; González Delgado, Rosa M.; Storchi-Bergmann, Thaisa
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
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We present a spectroscopic atlas of active galactic nuclei covering the region around the λλ8498, 8542, 8662 calcium triplet (CaT). The sample comprises 78 objects, divided into 43 Seyfert 2s, 26 Seyfert 1s, three starburst and six normal galaxies. The spectra pertain to the inner ~ 300 pc in radius, and thus sample the central kinematics and stellar populations of active galaxies. The data are used to measure stellar velocity dispersions (σ ) with both cross-correlation and direct fitting methods. These measurements are found to be in good agreement with each other and with those in previous studies for objects in common. The CaT equivalent width is also measured.We find average values and sample dispersions of WCaT of 4.6 ± 2.0, 7.0 ± 1.0 and 7.7 ± 1.0 Å for Seyfert 1s, Seyfert 2s and normal galaxies, respectively.We further present an atlas of [S III]λ9069 emission-line profiles for a subset of 40 galaxies. These data are analysed in a companion paper which addresses the connection between stellar and narrow-line region kinematics, the behaviour of the CaT equivalent width as a function of σ , activity type and stellar population properties.

Kinematics and physical properties of southern interacting galaxies : the minor merger AM 2306–721

Krabbe, Angela Cristina; Pastoriza, Miriani Griselda; Winge, Claudia; Rodrigues, Irapuan; Ferreiro, Diego L.
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
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We present an observational study about the effects of the interactions in the kinematics, stellar population and abundances of the components of the galaxy pair AM2306-721. Rotation curves for the main and companion galaxies were obtained, showing a deprojected velocity amplitude of 175 and 185 km s-ˡ, respectively. The interaction between the main and companion galaxies was modelled using numerical N-body/hydrodynamical simulations, with the result indicating that the current stage of the merger would be about 250 Myr after perigalacticum. The spatial variation in the distribution of the stellar-population components in both galaxies was analysed by fitting combinations of stellar-population models of different age groups. The central region of main galaxy is dominated by an old (5–10 Gyr) population, while significant contributions from a young (200 Myr) and intermediate (1 Gyr) components are found in the disc, and being enhanced in the direction of the tidal features. The stellar population of the companion galaxy is overall much younger, being dominated by components with 1 Gyr or less, quite widely spread over the whole disc. Spatial profiles of the oxygen abundance were obtained from a grid of photoionization models using the R23 line ratio. The disc of the main galaxy shows a clear radial gradient...

2D stellar population and gas kinematics of the inner 1.5 kpc of the post-starburst quasar SDSS J0210−0903

Sanmartim, David; Storchi-Bergmann, Thaisa; Brotherton, Mike
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
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Post-starburst quasars (PSQs) are hypothesized to represent a stage in the evolution of massive galaxies in which the star formation has been recently quenched due to the feedback of the nuclear activity. In this paper, our goal is to test this scenario with a resolved stellar population study of the PSQ J0210−0903, as well as of its emitting gas kinematics and excitation. We have used optical integral field spectroscopy obtained with the Gemini Multi-Object Spectrograph instrument at a velocity resolution of ≈120 km s-ˡ and a spatial resolution of ≈0.5 kpc. We find that old stars dominate the luminosity (at 4700 Å) in the inner 0.3 kpc (radius), while beyond this region (at ≈0.8 kpc) the stellar population is dominated by both intermediate-age and young ionizing stars. The gas emission-line ratios are typical of Seyfert nuclei in the inner 0.3 kpc, where an outflow is observed. Beyond this region, the line ratios are typical of low-ionization nuclear emission-line regions and may result from the combination of diluted radiation from the nucleus and ionization from young stars. The gas kinematics show a combination of rotation in the plane of the galaxy and outflows, observed with a maximum blueshift of−670 km s-ˡ. We have estimated a mass outflowrate in ionized gas in the range 0.3–1.1Mʘ yr-ˡ and a kinetic power for the outflow of ˙Eout ≈ 1.4–5.0 × 1040 erg s-ˡ ≈ 0.03–0.1 per cent × Lbol. This outflow rate is two orders of magnitude higher than the nuclear accretion rate of ≈8.7 × 10−3Mʘ yr−1...

Some effects of galaxy structure and dynamics on the Fundamental Plane

Graham, A.W; Colless, Matthew
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Artigo de Revista Científica Formato: 2958574 bytes; application/pdf
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We examine the effects on the Fundamental Plane (FP) of structural departures from an R^1/4 galaxy light profile. We also explore the use of spatial (i.e., volumetric) as well as projected galaxy parameters. We fit the Sersic R^1/n law to the V-band light profiles of 26 E/S0 Virgo galaxies, where n is a shape parameter that allows for structural differences amongst the profiles. The galaxy light profiles show a trend of systematic departures from a de Vaucouleurs R^1/4 law, in the sense that n increases with increasing effective half-light radius R_e. This results in R_e, and the associated mean surface brightness within this radius, having systematic biases when constructed using an R^1/4 law. Adjustments to the measured velocity dispersion are also made, based upon the theoretical velocity dispersion profile shapes of the different R^1/n light profiles, constructed assuming spherical symmetry and isotropic pressure support. We construct the FP for the case when structural homology is assumed (specifically, an R^1/4 law is fitted to all galaxies) and central velocity dispersions, sigma_0, are used. The plane we obtain is R_e~sigma^1.33+/-0.10 _0Sigma^-0.79+/-0.11 _e, where Sigma_e is the mean surface brightness within the projected effective radius R_e. This agrees with the FP obtained by others...

Kinematics and stellar populations in active galaxies: the LINER NGC 4579 (M58)

Palacios, J.; García Vargas, M.L.; Díaz, Angeles I.; Terlevich, Roberto; Terlevich, Elena
Fonte: EDP Sciences Publicador: EDP Sciences
Tipo: Artigo de Revista Científica
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This is an electronic version of an article published in Astronomy and Astrophysics. Palacios, J., García-Vargas, M.L., Diaz, A., Terlevich, R. and E. Terlevich. Kinematics and stellar populations in active galaxies: the LINER NGC 4579 (M58). Astronomy and Astrophysics 323 (1997): 749-761

Modelling the [Fe II]  λ1.644 μm outflow and comparison with H₂ and H+ kinematics in the inner 200 pc of NGC 1068

Barbosa, F. K. B.; Storchi-Bergmann, T.; McGregor, P.; Vale, T. B.; Rogemar Riffel, A.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
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We map the kinematics of the inner (200 pc) narrow-line region (NLR) of the Seyfert 2 galaxy NGC 1068 using the instrument Near-infrared Integral Field Spectrograph and adaptive optics at the Gemini North telescope. Channel maps and position–velocity diagrams are presented at a spatial resolution of ≅8 pc and spectral resolution ∼5300 in the emission lines [Fe II] λ1.644 μm, H₂ λ2.122 μm and Brγ. The [Fe II] emission line provides a better coverage of the NLR outflow than the previously used [O III] λ5007 emission line, extending beyond the area of the bipolar cone observed in Brγ and [O III]. This is mainly due to the contribution of the redshifted channels to the north-east of the nucleus, supporting its origin in a partial ionized zone with additional contribution from shocks of the outflowing gas with the galactic disc. We modelled the kinematics and geometry of the [Fe II] emitting gas finding good agreement with the data for outflow models with conical and lemniscate (or hourglass) geometry. We calculate a mass outflow rate of 1.9⁺²ˍ₁ M⊙ yr⁻¹ but a power for the outflow of only 0.08 per cent LBol. The molecular (H₂) gas kinematics is completely distinct from that of [Fe II] and Brγ...

Insights on the Milky Way bulge formation from the correlations between kinematics and metallicity

BABUSIAUX, C.; GOMEZ, A.; HILL, V.; ROYER, F.; ZOCCALI, M.; ARENOU, F.; FUX, R.; LECUREUR, A.; SCHULTHEIS, M.; BARBUY, B.; MINNITI, D.; ORTOLANI, S.
Fonte: EDP SCIENCES S A Publicador: EDP SCIENCES S A
Tipo: Artigo de Revista Científica
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Context. Two main scenarios for the formation of the Galactic bulge are invoked, the first one through gravitational collapse or hierarchical merging of subclumps, the second through secular evolution of the Galactic disc. Aims. We aim to constrain the formation of the Galactic bulge through studies of the correlation between kinematics and metallicities in Baade's Window (l = 1 degrees, b = -4 degrees) and two other fields along the bulge minor axis (l = 0 degrees, b = -6 degrees and b = -12 degrees). Methods. We combine the radial velocity and the [Fe/H] measurements obtained with FLAMES/GIRAFFE at the VLT with a spectral resolution of R = 20 000, plus for the Baade's Window field the OGLE-II proper motions, and compare these with published N-body simulations of the Galactic bulge. Results. We confirm the presence of two distinct populations in Baade's Window found in Hill et al. (2010, A&A, submitted): the metal-rich population presents bar-like kinematics while the metal-poor population shows kinematics corresponding to an old spheroid or a thick disc. In this context the metallicity gradient along the bulge minor axis observed by Zoccali et al. (2008, A&A, 486, 177), visible also in the kinematics, can be related to a varying mix of these two populations as one moves away from the Galactic plane...

The VLT LBG Redshift Survey - III. The clustering and dynamics of Lyman-break galaxies at z~3

Bielby, R.; Hill, M. D.; Shanks, T.; Crighton, N. H. M.; Infante, L.; Bornancini, Carlos Guillermo; Francke, H.; Héraudeau, P.; Garcia Lambas, Diego Rodolfo; Metcalfe, N.; Minniti, Dante; Padilla, Nelson David; Theuns, T.; Tummuangpak, P.; Weilbacher, P.
Fonte: Wiley-blackwell Publishing, Inc Publicador: Wiley-blackwell Publishing, Inc
Tipo: info:eu-repo/semantics/article; info:ar-repo/semantics/artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
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We present a catalogue of 2135 galaxy redshifts from the VLT LBG Redshift Survey (VLRS), a spectroscopic survey of z ~ 3 galaxies in wide fields centred on background quasi-stellar objects. We have used deep optical imaging to select galaxies via the Lyman-break technique. Spectroscopy of the Lyman-break galaxies (LBGs) was then made using the Very Large Telescope (VLT) Visible Multi-Object Spectrograph (VIMOS) instrument, giving a mean redshift of z = 2.79. We analyse the clustering properties of the VLRS sample and also of the VLRS sample combined with the smaller area Keck-based survey of Steidel et al. From the semiprojected correlation function, wp(σ), for the VLRS and combined surveys, we find that the results are well fit with a single power-law model, with clustering scale lengths of r0 = 3.46 ± 0.41 and 3.83 ± 0.24 h-1 Mpc, respectively. We note that the corresponding combined ξ(r) slope is flatter than for local galaxies at γ = 1.5-1.6 rather than γ = 1.8. This flat slope is confirmed by the z-space correlation function, ξ(s), and in the range 10 < s < 100 h-1Mpc the VLRS shows an ~2.5 sigma excess over the Lambda cold dark matter linear prediction. This excess may be consistent with recent evidence for non-Gaussianity in clustering results at z ~ 1. We then analyse the LBG z-space distortions using the 2D correlation function...

Supermassive black holes in the Sbc spiral galaxies NGC 3310, NGC 4303 and NGC 4258⋆

Pastorini, Guia; Marconi, Alessandro; Capetti, Alessandro; Axon, David; Alonso-Herrero, Almudena; Atkinson, John; Batcheldor, Dan; Carollo, C. Marcella; Collett, James; Dressel, Linda; Hughes, Mark; Duccio, Machetto; Maciejewski, Witold; Sparks, William;
Fonte: Astronomy and Astrophysics Publicador: Astronomy and Astrophysics
Tipo: Artigo de Revista Científica
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We have undertaken an HST Space Telescope Imaging Spectrograph survey of 54 late type spiral galaxies to study the scaling relations between black holes and their host spheroids at the low mass end. Our aim is to measure black hole masses or to set upper limits for a sizeable sample of spiral galaxies. In this paper we present new Space Telescope Imaging Spectrograph (STIS) observations of three spiral galaxies, NGC 4303, NGC 3310 and NGC 4258. The bright optical emission lines Hα λ 6564Å, [NII] λλ 6549, 6585Å and [SII] λλ 6718, 6732Å were used to study the kinematics of the ionized gas in the nuclear region of each galaxy with a ∼ 0.07′′ spatial resolution. Our STIS data for NGC 4258 were analyzed in conjunction with archival ones to compare the gas kinematical estimate of the black hole mass with the accurate value from H20-maser observations. In NGC 3310, the observed gas kinematics is well matched by a circularly rotating disk model but we are only able to set an upper limit to the BH mass which, taking into account the allowed disk inclinations, varies in the range 5.0 × 106 − 4.2 × 107M ⊙ at the 95% confidence level. In NGC 4303 the kinematical data require the presence of a BH with mass MBH = (5.0)+0.87 −2.26 × 106M ⊙ (for a disk inclination i = 70 deg) but the weak agreement between data and disk model does not allow us to consider this measurement completely reliable. If the allowed inclination values are taken into account...

Dynamics of the globular cluster system associated with M87 (NGC 4486). II. Analysis

Cote, Patrick; McLaughlin, Dean; Hanes, David; Bridges, Terry; Geisler, Doug; Merritt, David; Hesser, James; Harris, Gretchen; Lee, Myung
Fonte: Astrophysical Journal Publicador: Astrophysical Journal
Tipo: Pré-impressão Formato: 1278433 bytes; application/pdf
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We present a dynamical analysis of the globular cluster system associated with M87 (= NGC 4486), the cD galaxy near the dynamical center of the Virgo cluster. The analysis utilizes a new spectroscopic and photometric database which is described in a companion paper (Hanes et al. 2001). Using a sample of 278 globular clusters with measured radial velocities and metallicities, and new surface density profiles based on wide-field Washington photometry, we study the dynamics of the M87 globular cluster system both globally — for the entire cluster sample — and separately — for the metal-rich and metal-poor globular cluster samples. This constitutes the largest sample of radial velocities for pure Population II tracers yet assembled for any galaxy. Our principal findings are ummarized as follows: (1) Surface density profiles constructed from our Washington photometry reveal the metal-poor cluster system to be more spatially extended than its metal-rich counterpart, consistent with earlier findings based on HST imaging in the central regions of the galaxy. Beyond a radius of R ≃ 1.5Re (10 kpc), the metal-poor component dominates the total globular cluster system. (2) When considered in their entirety, each of the combined, metal-poor and metal-rich globular cluster samples (278...

Resolving the shocks in radio galaxy nebulae: HST and radio imaging of 3C 171, 3C 277.3, and PKS 2250-41

Tilak, Avanti; O'Dea, Christopher; Tadhunter, Clive; Willis, Karen; Morganti, Raffaella; Baum, Stefi; Koekemoer, Anton; Dallacasa, Daniele
Fonte: Astronomical Journal Publicador: Astronomical Journal
Tipo: Artigo de Revista Científica Formato: 897724 bytes; application/pdf
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We present the results of HST/WFPC2 medium and narrow band imaging and VLA and MERLIN2 radio imaging of three powerful radio galaxies: 3C 171, 3C 277.3, and PKS 2250-41. We obtained images of the rest frame [OIII] 5007 and [OII] 3727 line emission using the Linear Ramp Filters on WFPC2. The correlations between the emission line morphology and the [OIII]/[OII] line ratios with the radio emission seen in ground based observations are clarified by the HST imaging. We confirm that the radio lobes and hot-spots are preferentially associated with lower ionization gas. 3C 171 exhibits high surface brightness emission line gas mainly along the radio source axis. The lowest ionization gas is seen at the Eastern hot spot. In 3C 277.3 there is bright high ionization gas (and continuum) offset just to the east of the radio knot K1. Our observations are consistent with previous work suggesting that this emission is produced by precursor gas ionized by the shock being driven into the cloud by the deflected radio jet. In PKS 2250-41 we resolve the emission line arc which wraps around the outer rim of the western lobe. The lower ionization [OII] emission is nested just interior to the higher ionization [OIII] emission suggesting that we have resolved the cooling region behind the bow shock. We also detect possible continuum emission from the secondary hot-spot. Thus...

Emission-line properties of 3CR radio galaxies III: origins and implications of the velocity fields

Baum, Stefi; McCarthy, Patrick
Fonte: Astrophysical Journal Publicador: Astrophysical Journal
Tipo: Artigo de Revista Científica Formato: 224097 bytes; application/pdf
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We present the results of an analysis of the large scale velocity fields of the ionized gas associated with powerful radio galaxies. Long-slit spectra of 52 objects provide a sample of resolved velocities that span a wide range of redshifts, radio and emission-line luminosities. Line widths reaching 1000 km s−1 and resolved velocity fields with amplitudes of up 1500 km s−1 are found on scales from 10 to 100 kpc in the environments of radio galaxies at redshifts larger than 0.5. The global velocities and FWHM are of comparable amplitudes in the FRII sources, while the FRI sources have FWHM values that are larger than their resolved velocity fields. We find evidence for systematically larger line widths and velocity field amplitudes at z > 0.6. Several of the largest amplitude systems contain two galaxies with small projected separations. All of the > 1000 km s−1 systems occur in objects at z > 0.6 and all have comparable radio and [OII] sizes. There is a weak correlation of off-nuclear line widths and velocity field with the ratio of the radio and emission-line sizes, but it is of low statistical significance and there is a very large dispersion. The change in properties at redshifts above z ~ 0.6 could reflect a difference in environments of the host galaxies...

Gas kinematics and the black hole mass at the center of the radio galaxy NGC 4335

Kleijn, Gijs; van der Marel, Roeland; de Zeeuw, P. Tim; Noel-Storr, Jacob; Baum, Stefi
Fonte: Astronomical Journal Publicador: Astronomical Journal
Tipo: Artigo de Revista Científica Formato: 582699 bytes; application/pdf
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We investigate the kinematics of the central gas disk of the radio-loud elliptical galaxy NGC 4335, derived from Hubble Space Telescope (HST) long-slit spectroscopic observations of Ha+ [Nii] along three parallel slit positions. The observed mean velocities are consistent with a rotating thin disk. We model the gas disk in the customary way, taking into account the combined potential of the galaxy and a putative black hole with massM., as well as the influence on the observed kinematics of the point-spread function and finite slit width. This sets a 3 upper limit of 108 M on M.. The velocity dispersion at r<~0.5" is in excess of that predicted by the thin rotating disk model. This does not invalidate the model if the excess dispersion is caused by localized turbulent motion in addition to bulk circular rotation. However, if instead the dispersion is caused by the black hole (BH) potential then the thin disk model provides an underestimate of M.. A BH mass M. ~ 6 x10^8 M is inferred by modeling the central gas dispersion as due to an isotropic spherical distribution of collisionless gas cloudlets. The stellar kinematics for NGC 4335 are derived from a ground-based (William Herschel Telescope=ISIS) long-slit observation along the galaxy major axis. A two-integral model of the stellar dynamics yieldsM. >~ 3 x 10^9 M . However...

The Globular Cluster System of NGC 5128. II. Ages, Metallicities, Kinematics, and Formation

Peng, Eric W; Ford, Holland C; Freeman, Kenneth
Fonte: IOP Publishing Publicador: IOP Publishing
Tipo: Artigo de Revista Científica
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We present a study of the nearby postmerger giant elliptical galaxy NGC 5128 (Centaurus A), in which we use the properties of its globular cluster (GC) and planetary nebula (PN) systems to constrain its evolution. Using photometric and spectroscopic data

The Planetary Nebula System and Dynamics in the Outer Halo of NGC 5128

Peng, Eric W; Ford, Holland C; Freeman, Kenneth
Fonte: IOP Publishing Publicador: IOP Publishing
Tipo: Artigo de Revista Científica
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The halos of elliptical galaxies are faint and difficult to explore, but they contain vital clues to both structure and formation. We present the results of an imaging and spectroscopic survey for planetary nebulae (PNe) in the nearby elliptical NGC 5128. We extend the work of Hui and coworkers well into the halo of the galaxy - out to distances of 100 and 50 kpc along the major and minor axes. We now know of 1141 PNe in NGC 5128, 780 of which are confirmed. Of these 780 PNe, 349 are new from this survey, and 148 are at radii beyond 20 kpc. PNe exist at distances up to 80 kpc (∼15re), showing that the stellar halo extends to the limit of our data. This study represents by far the largest kinematic study of an elliptical galaxy to date, both in the number of velocity tracers and in radial extent. We confirm the large rotation of the PNe along the major axis and show that it extends in a disklike feature into the halo. The rotation curve of the stars flattens at ∼100 km s-1 with V/σ between 1 and 1.5 and with the velocity dispersion of the PNe falling gradually at larger radii. The two-dimensional velocity field exhibits a zero-velocity contour with a pronounced twist, showing that the galaxy potential is likely triaxial in shape...

The Various Kinematics of Dwarf Irregular Galaxies in Nearby Groups and their Dark Matter Distributions

Cote, Stephanie; Carignan, C; Freeman, Kenneth
Fonte: University of Chicago Press Publicador: University of Chicago Press
Tipo: Artigo de Revista Científica
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Eight dwarf irregular galaxies, in the two nearby groups of galaxies Sculptor and Centaurus A (at 2.5 Mpc and 3.5 Mpc), have been imaged in neutral hydrogen (H I) with the Australia Telescope and the Very Large Array. These galaxies have absolute magnitudes ranging from MB = -15.7 to -11.3. Yet they are mostly rotationally supported, with maximum velocities going from 19 to 67 km s-1. Multicomponent mass models have been fitted to the rotation curves to investigate the properties of their dark matter halos and the scaling laws of dark matter halo parameters. Dwarf galaxies have, on average, a higher dark to luminous mass ratio, as well as higher dark halo central densities than spiral galaxies. They have a larger dispersion of their dark matter properties both in terms of their total dark matter amount and of their dark halo parameters, compared to spiral galaxies. It is therefore very difficult to predict a dwarf galaxy rotation curve shape based only on its optical properties. Dwarfs are not well fitted by cold dark matter (CDM) halos of the type proposed by Navarro, Frenk, & White, even for ACDM models with Ω0 as low as 0.3. For two of our dwarfs we also have Hα rotation curves confirming the H I velocities, so the discrepancy with the CDM models cannot be attributed to beam-smearing effects.