The Metallicity Distribution of Intracluster Stars in Virgo

Williams, Benjamin F.; Ciardullo, Robin; Durrell, Patrick R.; Vinciguerra, M.; Feldmeier, John J.; Jacoby, George H.; Sigurd̵sson, Steinn; Hippel, Ted von; Ferguson, Henry C.; Tanvir, N. R.; Arnaboldi, M.; Gerhard, Ortwin; Aguerri, J. A. L.; Freeman, K. C.

doi:10.1086/510149

Cited by 105 publications

(158 citation statements)

References 64 publications

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“…We speculate that α 2.5,ICL is a factor 2 larger than α 2.5,M 87 because of different metallicity distributions in the ICL and the M 87 halo, with a larger fraction of metal-poor stars in the intracluster component, as shown by Williams et al (2007). 6. ICL and the dynamics of the Virgo cluster core…”

Section: The Luminosity-specific Pn Number For the M 87 Halo And The mentioning

confidence: 84%

“…The measured α 2.5 parameter for the ICL is in the observed range for old stellar populations; 5. The metallicity distribution of the RGB stars associated with the ICL in the Williams et al (2007) field is broad, with a peak at about 0.1 solar, and the best model of Williams et al (2007) indicates an old stellar population (>10 Gyr).…”

Section: Implications For the Formation Of The Iclmentioning

confidence: 99%

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The edge of the M 87 halo and the kinematics of the diffuse light in the Virgo cluster core

Doherty¹,

Arnaboldi²,

Das

et al. 2009

A&A

133

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Aims. We study the kinematics and dynamics of the extreme outer halo of M 87, the central galaxy in the Virgo cluster, and its transition to the intracluster light (ICL). Methods. We present high resolution FLAMES/VLT spectroscopy of intracluster planetary nebula (PN) candidates, targeting three new fields in the Virgo cluster core with surface brightness down to μ B = 28.5. Based on the projected phase space information (sky positions and line-of-sight velocities) we separate galaxy and cluster components in the confirmed PN sample. We then use the spherical Jeans equation and the total gravitational potential as traced by the X-ray emission to derive the orbital distribution in the outer stellar halo of M 87. We determine the luminosity-specific PN number for the M 87 halo and the ICL from the photometric PN catalogs and sampled luminosities, and discuss the origin of the ICL in Virgo based on its measured PN velocities. Results. We confirm a further 12 PNs in Virgo, five of which are bound to the halo of M 87, and the remainder are true intracluster planetary nebulas (ICPNs). The M 87 PNs are confined to the extended stellar envelope of M 87, within a projected radius of ∼160 kpc, while the ICPNs are scattered across the whole surveyed region between M 87 and M 86, supporting a truncation of M 87's luminous outer halo at a 2σ level. The line-of-sight velocity distribution of the M 87 PNs at projected radii of 60 kpc and 144 kpc shows (i) no evidence for rotation of the halo along the photometric major axis; and (ii) that the velocity dispersion decreases in the outer halo, down to σ last = 78 ± 25 km s −1 at 144 kpc. The Jeans model for the M 87 halo stars fits the observed line-of-sight velocity dispersion profile only if the stellar orbits are strongly radially anisotropic (β 0.4 at r 10 kpc increasing to 0.8 at the outer edge), and if additionally the stellar halo is truncated at 150 kpc average elliptical radius. The α-parameters for the M 87 halo and the ICL are in the range of values observed for old (>10 Gyr) stellar populations. Conclusions. Both the spatial segregation of the PNs at the systemic velocity of M 87 and the dynamical model support that the stellar halo of M 87 ends at ∼150 kpc. We discuss several possible explanations for the origin of this truncation but are unable to discriminate between them: tidal truncation following an earlier encounter of M 87 with another mass concentration in the Virgo core, possibly around M 84, early AGN feedback effects, and adiabatic contraction due to the cluster dark matter collapsing onto M 87. From the spatial and velocity distribution of the ICPNs we infer that M 87 and M 86 are falling towards each other and that we may be observing them just before the first close pass. The new PN data support the view that the core of the Virgo cluster is not yet virialized but is in an ongoing state of assembly, and that massive elliptical galaxies are important contributors to the ICL in the Virgo cluster.

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Section: The Luminosity-specific Pn Number For the M 87 Halo And The mentioning

confidence: 84%

Section: Implications For the Formation Of The Iclmentioning

confidence: 99%

The edge of the M 87 halo and the kinematics of the diffuse light in the Virgo cluster core

Doherty¹,

Arnaboldi²,

Das

et al. 2009

A&A

133

View full text Add to dashboard Cite

show abstract

“…Another similarly deep probe of the RGB population in the Virgo region has been published by Williams et al (2007). Their HST/ACS target field (from program GO-10131) is located in the intracluster region between M 87 and M 86, approximately 180 kpc projected distance from each of these two giants.…”

Section: The Dataset and Preliminary Processingmentioning

confidence: 98%

“…For our two outer zones, there are 761 stars in the 0.7-mag region just above the TRGB, versus 4467 stars in the 0.5-mag region just below it. For field contamination, comparison with the photometry of Williams et al (2007) and Madrid et al (2009) suggests that < ∼ 40 foreground stars are present, a negligible contribution. The number of faint, small and misidentified background galaxies is harder to assess without an adjacent control field to rely on, but comparison with the similar ACS (V, I) Leo field data of Harris et al (2007a) suggests very conservatively N gal < ∼ 50, also negligible.…”

Section: Determining the Trgb And Fiducial Distancementioning

confidence: 99%

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The inner halo of M 87: a first direct view of the red-giant population

Bird

Harris

Blakeslee

et al. 2010

A&A

141

109

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An unusually deep (V, I) imaging dataset for the Virgo supergiant M 87 with the Hubble Space Telescope ACS successfully resolves its brightest red-giant stars, reaching M I (lim) = −2.5. After assessing the photometric completeness and biasses, we use this material to estimate the metallicity distribution for the inner halo of M 87, finding that the distribution is very broad and likely to peak near [m/H] −0.4 and perhaps higher. The shape of the MDF strongly resembles that of the inner halo for the nearby giant E galaxy NGC 5128. As a byproduct of our study, we also obtain a preliminary measurement of the distance to M 87 with the TRGB (red-giant branch tip) method; the result is (m− M) 0 = 31.12± 0.14 (d = 16.7± 0.9 Mpc). Averaging this result with three other recent techniques give a weighted mean d(M 87) = (16.4 ± 0.5) Mpc.

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Metal Enrichment Processes

Schindler

Diaferio

Clusters of Galaxies

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The Metallicity Distribution of Intracluster Stars in Virgo

Cited by 105 publications

References 64 publications

The edge of the M 87 halo and the kinematics of the diffuse light in the Virgo cluster core

The edge of the M 87 halo and the kinematics of the diffuse light in the Virgo cluster core

The inner halo of M 87: a first direct view of the red-giant population

Metal Enrichment Processes

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