2015A&A...579A.135L


C.D.S. - SIMBAD4 rel 1.7 - 2019.12.06CET14:52:22

2015A&A...579A.135L - Astronomy and Astrophysics, volume 579A, 135-135 (2015/7-1)

The outer regions of the giant Virgo galaxy M 87 Kinematic separation of stellar halo and intracluster light.

LONGOBARDI A., ARNABOLDI M., GERHARD O. and HANUSCHIK R.

Abstract (from CDS):

We present a spectroscopic study of a sample of 287 planetary nebulas (PNs) around the brightest cluster galaxy (BCG) M87 in Virgo A, of which 211 are located between 40kpc and 150kpc from the galaxy centre. With these data we can distinguish the stellar halo from the co-spatial intracluster light (ICL) and study both components separately. We obtained PN velocities with a high resolution FLAMES/VLT survey targeting eight fields in a total area of ∼0.4deg2. We identified PNs from their narrow and symmetric redshifted λ5007Å [OIII] emission line, the presence of the second λ4959Å [OIII] emission line, and the absence of significant continuum. We implement a robust technique to measure the halo velocity dispersion from the projected phase-space to identify PNs associated with the M87 halo and ICL. Using photometric magnitudes, we construct PN luminosity functions (PNLFs), which are complete down to m5007=28.8. The velocity distribution of the spectroscopically confirmed PNs is bimodal, containing a narrow component centred on the systemic velocity of the BCG and an off-centred broader component, which we identify as halo and ICL, respectively. We find that 243 PNs are part of the velocity distribution of the M87 halo, while the remaining subsample of 44 PNs are intracluster PNs (ICPNs). Halo and ICPNs have different spatial distributions: the number density of halo PNs follow the galaxy's surface brightness profile, whereas the ICPNs are characterised by a shallower power-law profile, IICL∝Rγ with γ in the range [-0.34,-0.04]. No evidence is found for an asymmetry in the halo and ICPN density distributions when the NW and SE fields are studied separately. A study of the composite PN number density profile confirms the superposition of different PN populations associated with the M87 halo and the ICL, characterised by different PN specific numbers α. We derive αhalo=1.06x10–8 NPNL–1☉,bol and αICL=2.72x10–8 NPN L–1☉,bol, respectively. The M87 halo PNLF has fewer bright PNs and a steeper slope towards faint magnitudes than the ICPNLF, and both are steeper than the standard PNLF for the M31 bulge. Moreover, the ICPNLF has a dip at ∼1-1.5 mag fainter than the bright cut-off, reminiscent of the PNLFs of systems with extended star formation history, such as M33 or the Magellanic clouds. The BCG halo of M87 and the Virgo ICL are dynamically distinct components with different density profiles and velocity distributions. Moreover, the different α-parameter values and PNLF shapes of the halo and ICL indicate distinct parent stellar populations, consistent with the existence of a gradient towards bluer colours at large radii. These results reflect the hierarchical build-up of the Virgo cluster.

Abstract Copyright:

Journal keyword(s): galaxies: clusters: general - galaxies: clusters: individual: Virgo cluster - galaxies: halos - galaxies: individual: M87 - planetary nebulae: general

Simbad objects: 17

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Number of rows : 17

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 10604 1
2 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 9131 1
3 M 33 GiG 01 33 50.904 +30 39 35.79 6.17 6.27 5.72     ~ 5031 1
4 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 5398 1
5 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14374 1
6 NAME Hydra I Cluster ClG 10 36 36.0 -27 31 04           ~ 765 1
7 NGC 3311 BiC 10 36 42.821 -27 31 42.02   11.93 10.93 10.00 9.67 ~ 264 2
8 M 86 GiG 12 26 11.814 +12 56 45.49 10.32 9.83 8.90   7.50 ~ 997 1
9 NAME Vir I ClG 12 26 32.1 +12 43 24   10.00 8.49     ~ 5667 0
10 M 87 BiC 12 30 49.42338230 +12 23 28.0438581 10.16 9.59 8.63   7.49 ~ 6045 3
11 2MASS J12355084+2623430 * 12 35 50.8546931203 +26 23 42.890456192           ~ 1 0
12 ACO 1656 ClG 12 59 48.7 +27 58 50           ~ 4113 2
13 NGC 4889 BiC 13 00 08.097 +27 58 37.29 12.93 13.0 11.30 11.652 10.906 ~ 629 1
14 ACO 2199 ClG 16 28 37.0 +39 31 28           ~ 1086 1
15 3C 338.0 QSO 16 28 38.2443686587 +39 33 04.231770853   12.78 11.78     ~ 690 5
16 NGC 6822 G 19 44 56.199 -14 47 51.29   18 8.1     ~ 1408 0
17 NAME Local Group GrG ~ ~           ~ 6696 0

    Equat.    Gal    SGal    Ecl

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2019.12.06-14:52:22

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