J/A+A/620/A111 Confirmed PN in M87 outer regions (Longobardi+, 2018)
Kinematics of the outer halo of M87 as mapped by planetary nebulae.
Longobardi A., Arnaboldi M., Gerhard O., Pulsoni C., Soeldner-Rembold I.
<Astron. Astrophys. 620, A111 (2018)>
=2018A&A...620A.111L 2018A&A...620A.111L (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Planetary nebulae
Keywords: galaxies: clusters: individual: Virgo cluster - galaxies: halos -
galaxies: individual: M87 - planetary nebulae: general
Abstract:
We present a kinematic study of a sample of 298 planetary nebulas
(PNs) in the outer halo of the central Virgo galaxy M87 (NGC 4486).
The line-of-sight velocities of these PNs are used to identify
sub-components, to measure the angular momentum content of the main
M87 halo, and to constrain the orbital distribution of the stars at
these large radii.
We use Gaussian mixture modelling to statistically separate distinct
velocity components and identify the M87 smooth halo component, its
unrelaxed substructures, and the intra-cluster (IC) PNs. We compute
probability weighted velocity and velocity dispersion maps for the
smooth halo, and its specific angular momentum profile (λR)
and velocity dispersion profile.
The classification of the PNs into smooth halo and ICPNs is supported
by their different PN luminosity functions. Based on a K-S test, we
conclude that the ICPN line-of-sight velocity distribution (LOSVD) is
consistent with the LOSVD of the galaxies in Virgo subcluster A. The
surface density profile of the ICPNS at 100kpc radii has a shallow
logarithmic slope, -αICL~=-0.8, dominating the light at the
largest radii. Previous B-V colour and resolved star metallicity data
indicate masses for the ICPN progenitor galaxies of a few
x108M☉. The angular momentum-related λR profile for
the smooth halo remains below 0.1, in the slow rotator regime, out to
135kpc average ellipse radius (170kpc major axis distance). Combining
the PN velocity dispersion measurements for the M87 halo with
literature data in the central 15kpc, we obtain a complete velocity
dispersion profile out to Ravg=135kpc. The σhalo profile
decreases from the central 400km/s to about 270km/s at 2-10kpc, then
rises again to ~=300±50km/s at 50-70kpc to finally decrease sharply
to σhalo∼100km/s at Ravg=135kpc. The steeply decreasing outer
σhalo profile and the surface density profile of the smooth
halo can be reconciled with the circular velocity curve inferred from
assuming hydrostatic equilibrium for the hot X-ray gas. Because this
rises to vc,X∼700km/s at 200kpc, the orbit distribution of the
smooth M87 halo is required to change strongly from approximately
isotropic within Ravg∼60kpc to very radially anisotropic at the
largest distances probed.
The extended LOSVD of the PNs in the M87 halo allows the
identification of several subcomponents: the ICPNs, the "crown"
accretion event, and the smooth M87 halo. In galaxies likeM87, the
presence of these sub-components needs to be taken into account to
avoid systematic biases in estimating the total enclosed mass. The
dynamical structure inferred from the velocity dispersion profile
indicates that the smooth halo of M87 steepens beyond Ravg=60kpc
and becomes strongly radially anisotropic, and that the velocity
dispersion profile is consistent with the X-ray circular velocity
curve at these radii without non-thermal pressure effects.
Description:
tableb1.dat contains the information about the spectroscopically
confirmed Planetary Nebulae (PNs) in the outer regions of M87. This
catalogue is the result of the PN photometric and spectroscopic
surveys carried out with Suprime-Cam@Subaru and FLAMES@VLT,
respectively, and presented in Longobardi et al. (2013A&A...558A..42L 2013A&A...558A..42L;
L13) and Longobardi et al. (2015A&A...579A.135L 2015A&A...579A.135L; L15a). From the
repeated observations of the same candidates in different FLAMES plate
configurations we estimated the median deviation of velocity
measurements to be 4.2km/s, and the hole distribution covers a range
of 0.6<ΔV<16.2km/s. In case of repeated observations the given
heliocentric velocity has been estimated from the spectrum with the
highest S/N. L15a discussed a statistical approach to determine the
fraction of misclassified PNs based on the analysis of stacked PN
spectra. They determined that 2% of the entire sample (7 PNs) could
represent misclassified spectra (for more details see L15a).
The table is divided in three parts:
1) PNs that have higher probability of belonging to the smooth halo
component and PNs that have high probability to belong to the 'crown'
structure (indicated by an *) (Longobardi et al., 2015A&A...579L...3L 2015A&A...579L...3L),
2) PNs that have higher probability to belong to the additional ICL
component as determined in this work (see Sect. 2, and
3) PNS that have been assigned to the ICL component by Longobardi et al.
(2015A&A...579A.135L 2015A&A...579A.135L).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb1.dat 79 298 Catalogue of spectroscopically confirmed
Planetary Nebulae in the outer regions of M87
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See also:
J/ApJ/492/62 : M87 planetary nebulae (Ciardullo+, 1998)
Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 25 A25 --- ID PN identifier according to the IAU regulations
(M87PNJHHMMSS.ss+DDMMSS.s)
27- 33 A7 --- Field ID Field (1)
34 A1 --- n_Field [*] Note on Field (2)
36- 43 F8.4 deg RAdeg Right ascension (J2000)
45- 51 F7.4 deg DEdeg Declination (J2000)
53- 59 F7.1 km/s Vlos Line-of-sight velocity corrected for
heliocentric velocity
61- 64 F4.1 mag 5007mag Measured 5007 magnitudes from Longobardi et al.
(2013A&A...558A..42L 2013A&A...558A..42L)
66- 68 F3.1 --- Gamma Probability to belong to the main M87 halo
70- 72 A3 --- [OIII]D [yes/-- ] Flag indicating the detection (yes)
or not (--) of the [OIII] Doublet
73 A1 --- n_[OIII]D [ab] Note on [OIII]Doublet (3)
76- 79 F4.1 --- S/N S/N per resolution element for the redshifted
[OIII] lambda 5007 Angstrom emission line
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Note (1): ID following conventions in Longobardi et al. (2015A&A...579A.135L 2015A&A...579A.135L.
FCJ and F7 are data from Doherty et al. (2009A&A...502..771D 2009A&A...502..771D)
Note (2): * for PNs that have higher probability of belonging to the smooth halo
component and PNs that have high probability to belong to the 'crown'
structure (Longobardi et al., 2015A&A...579L...3L 2015A&A...579L...3L).
Note (3): Notes as follows:
a = The Doppler-shifted [OIII]] lambda 4959 Angstrom emission line falls
at a shorter wavelength than the blue edge of the FLAMES filter
b = Spectrum deprecated in the wavelength region around the Doppler-shifted
[OIII]] lambda 4959 Angstrom emission line
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Acknowledgements:
Alessia Longobardi, alongobardi(at)pku.edu.cn
(End) Patricia Vannier [CDS] 03-Oct-2018