The Planetary Nebula Spectrograph: The Green Light for Galaxy Kinematics

Douglas, N. G.; Arnaboldi, M.; Freeman, K. C.; Kuijken, Konrad; Merrifield, M. R.; Romanowsky, Aaron J.; Taylor, Keith; Capaccioli, M.; Axelrod, T. S.; Gilmozzi, R.; Hart, John; Bloxham, Gabe; Jones, Dkioioio D F

doi:10.1086/342765

Cited by 94 publications

(83 citation statements)

References 32 publications

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“…This has been possible thanks to dedicated observational campaigns and instrumentation (such as the PN.Spectrograph, Douglas et al 2002). Observations of PNe probe the photometric and kinematic profiles of the starlight well beyond the effective radius, where the surface-brightness would be too low ).…”

Section: Introductionmentioning

confidence: 99%

Dynamical models of elliptical galaxies – II. M87 and its globular clusters

Agnello

Evans

Romanowsky

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We study the Globular Cluster (GC) system of the nearby elliptical galaxy M87 using the newly available dataset with accurate kinematics provided by Strader et al. (2011). We find evidence for three distinct sub-populations of GCs in terms of colours, kinematics and radial profiles. We show that a decomposition into three populations -blue, intermediate and red GCs -is statistically preferred to one with two or four populations. The existence of three components has been suggested before, but here we are able to identify them robustly and relate them to the stellar profile. We exploit the sub-populations to derive dynamical constraints on the mass and Dark Matter (DM) content of M87 out to ∼ 100 kpc. We deploy a class of global mass-estimators, developed in Paper I, obtaining mass measurements at different locations. The DM fraction in M87 changes from ≈0.2 at the effective radius of the stellar light (0.02• or 6 kpc) to ≈0.95 at the distance probed by the most extended, blue GCs (0.47• or 135 kpc).We supplement this analysis with virial decompositions, which exploit the dynamical model to produce a separation into multiple components. These yield the luminous mass as 5.511 M ⊙ and the dark matter within 135 kpc as 8.0The inner DM density behaves as ρ ∼ r −γ with γ ≈ 1.6. This is steeper than the cosmologically preferred cusp of ρ ∼ r −1 (Dubinski & Carlberg; Navarro, Frenk & White), and may provide evidence of dark matter contraction. Finally, we combine the GC separation into three sub-populations with the Jeans equations, obtaining information on the orbital structure of the GC system. The centrally concentrated red GCs exhibit tangential anisotropy, consistent with the depletion of radial orbits by tidal shredding. The most extended blue GCs have an isotropic velocity dispersion tensor in the central parts, which becomes more tangential moving outwards, consistent with adiabatic contraction of the DM halo.

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Section: Introductionmentioning

confidence: 99%

Dynamical models of elliptical galaxies – II. M87 and its globular clusters

Agnello

Evans

Romanowsky

et al. 2014

Monthly Notices of the Royal Astronomical Society

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“…The PN Spectrograph (PN.S) is an instrument on the William Herschel Telescope dedicated to measuring PN velocities in nearby galaxies (Douglas et al 2002). The pupil is split in half before being dispersed in opposite directions in twin spectrographs.…”

Section: Introductionmentioning

confidence: 99%

Counter-dispersed slitless-spectroscopy technique: planetary nebula velocities in the halo of NGC 1399

McNeil

Arnaboldi

Freeman³

et al. 2010

A&A

Self Cite

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Aims. Using a counter-dispersed slitless spectroscopy technique, we detect and measure the line-of-sight velocities of 187 planetary nebulae (PNe) around one of the nearest cD galaxies, NGC 1399, with FORS1 on the VLT. Methods. We describe the method for identifying and classifying the emission-line sources and the procedure for computing their J2000 coordinates and velocities. The number of PN detections and the errors in the velocity measurements (37 km s −1 ) indicate that this technique is comparable to other methods. Results. We present the spatial distribution of the PNe and a basic analysis of their velocities. The PN two-dimensional velocity field shows marginal rotation consistent with other studies. We also find a low-velocity substructure in the halo and a flatter velocity-dispersion profile compared to previous observations that extends to ∼400 . The detection of a low-velocity subcomponent underscores the importance of discrete velocity tracers for the detection of un-mixed components. Conclusions. The new velocity-dispersion profile is in good agreement with revised velocity dispersions for the red globular clusters in NGC 1399. The outer parts of this profile are consistent with one of the dynamical models, which corresponds to a circular velocity of 340 km s −1 and a rescaled B-band mass-to-light ratio of 20 at 7 radius. These measurements trace the kinematics of the outer halo and disentangle the heterogenous populations in the Fornax Cluster core. The new data set the stage for a revised dynamical model of the outer halo of NGC 1399.

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“…Furthermore, clues on angular momentum alignment could change when looking at the halo regions of these systems. Preliminary results on PNe radial velocity fields of NGC 3379 and NGC 4494 from the Planetary Nebula Spectrograph, (PN.S, Douglas et al 2002), have revealed that there is a tilt of the major kinematical axis of the PNe sample with respect to the stellar long-slit data as it is clearly shown in Fig. 1.…”

Section: Introductionmentioning

confidence: 87%

A detailed view on the kinematics of candidate intermediate luminosity early‐type galaxies with a lack of dark matter

Covone¹,

Napolitano²

2004

Astron Nachr

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Abstract. In several nearby L ∼ L * early-type galaxies, recent observations at large radii have shown indications of a lack of dark matter, substantially at odds with the prediction from the Cold Dark Matter (CDM) hierarchical merger models. Here we discuss a pilot observational project for the study of the internal kinematical and dynamical properties of this remarkable sample of galaxies. Using the VIMOS-IFU in its high spectral resolution mode, it would be possible to investigate the regions up to ∼ 1.2 Re, taking advantage of the much larger field of view and telescope diameter. This will allow to disclose the presence of any kinematical substructures which could affect the conclusion on the mass modeling and definitely clarify the inner structure of this particular class of early-type galaxies.

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The Planetary Nebula Spectrograph: The Green Light for Galaxy Kinematics

Cited by 94 publications

References 32 publications

Dynamical models of elliptical galaxies – II. M87 and its globular clusters

Dynamical models of elliptical galaxies – II. M87 and its globular clusters

Counter-dispersed slitless-spectroscopy technique: planetary nebula velocities in the halo of NGC 1399

A detailed view on the kinematics of candidate intermediate luminosity early‐type galaxies with a lack of dark matter

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