15 research outputs found
Integral Field Spectroscopy: a disruptive innovation for observations of Planetary Nebulae and the PNLF
A quarter of a century has passed since the observing technique of integral
field spectroscopy (IFS) was first applied to planetary nebulae (PNe). Progress
after the early experiments was relatively slow, mainly because of the limited
field-of-view (FoV) of first generation instruments.With the advent of MUSE at
the ESO Very Large Telescope, this situation has changed. MUSE is a wide
field-of-view, high angular resolution, one-octave spanning optical integral
field spectrograph with high throughput. Its major science mission has enabled
an unprecedented sensitive search for Ly{\alpha} emitting galaxies at redshift
up to z=6.5. This unique property can be utilized for faint objects at low
redshift as well. It has been demonstrated that MUSE is an ideal instrument to
detect and measure extragalactic PNe with high photometric accuracy down to
very faint magnitudes out to distances of 30 Mpc, even within high surface
brightness regions of their host galaxies. When coupled with a differential
emission line filtering (DELF) technique, MUSE becomes far superior to
conventional narrow-band imaging, and therefore MUSE is ideal for accurate
Planetary Nebula Luminosity Function (PNLF) distance determinations. MUSE
enables the PNLF to become a competitive tool for an independent measure of the
Hubble constant, and stellar population studies of the host galaxies that
present a sufficiently large number of PNe.Comment: 12 pages, 8 figures, to appear in proceedings of IAU Symposium 384
"Planetary Nebulae", Krakow, September 4-8, 202
The halo of M 105 and its group environment as traced by planetary nebula populations: I. Wide-field photometric survey of planetary nebulae in the Leo i group
Context. M 105 (NGC 3379) is an early-type galaxy in the Leo I group. The Leo I group is the nearest group that contains all main galaxy types and can thus be used as a benchmark to study the properties of the intra-group light (IGL) in low-mass groups.
Aims. We present a photometric survey of planetary nebulae (PNe) in the extended halo of the galaxy to characterise its PN populations and investigate the presence of an extended PN population associated with the intra-group light.
Methods. We use PNe as discrete stellar tracers of the diffuse light around M 105. These PNe were identified on the basis of their bright [OâŻIII]5007 A emission and the absence of a broad-band continuum using automated detection techniques. We compare the PN number density profile with the galaxy surface-brightness profile decomposed into metallicity components using published photometry of the Hubble Space Telescope in two halo fields.
Results. We identify 226 PNe candidates within a limiting magnitude of m5007,âlimâ=â28.1 from our Subaru-SuprimeCam imaging, covering 67.6 kpc (23 effective radii) along the major axis of M 105 and the halos of NGC 3384 and NGC 3398. We find an excess of PNe at large radii compared to the stellar surface brightness profile from broad-band surveys. This excess is related to a variation in the luminosity-specific PN number α with radius. The α-parameter value of the extended halo is more than seven times higher than that of the inner halo. We also measure an increase in the slope of the PN luminosity function at fainter magnitudes with radius.
Conclusions. We infer that the radial variation of the PN population properties is due to a diffuse population of metal-poor stars ([M/H] < â1.0) following an exponential profile, in addition to the M 105 halo. The spatial coincidence between the number density profile of these metal-poor stars and the increase in the α-parameter value with radius establishes the missing link between metallicity and the post-asymptotic giant branch phases of stellar evolution. We estimate that the total bolometric luminosity associated with the exponential IGL population is 2.04â
xâ
109âLâ as a lower limit. The lower limit on the IGL fraction is thus 3.8%. This work sets the stage for kinematic studies of the IGL in low-mass groups
Planetary nebula spectrograph survey of s0 galaxy kinematics - ii. Clues to the origins of s0 galaxies
The stellar kinematics of the spheroids and discs of S0 galaxies contain clues to their formation histories. Unfortunately, it is difficult to disentangle the two components and to recover their stellar kinematics in the faint outer parts of the galaxie
Intracluster Planetary Nebulae in Virgo: Photometric selection, spectroscopic validation and cluster depth
We have imaged an empty area of 34'x34' one and a half degree north of the
Virgo cluster core to survey for intracluster planetary nebula candidates. We
have implemented and tested a fully automatic procedure for the selection of
emission line objects in wide-field images, based on the on-off technique from
Ciardullo and Jacoby. Freeman et al. have spectroscopically confirmed a sample
of intracluster planetary nebulae in one Virgo field. We use the photometric
and morphological properties of this sample to test our selection procedure. In
our newly surveyed Virgo field, 75 objects were identified as best candidates
for intracluster PNe.
The luminosity function of the spectroscopically confirmed PNe shows a
brighter cut-off than the planetary nebula luminosity function for the inner
regions of M87. Such a brighter cut-off is also observed in the newly surveyed
field and indicates a smaller distance modulus, implying that the front end of
the Virgo cluster is closer to us by a significant amount: 14% closer (2.1 Mpc)
than M87 for the spectroscopic field, using the PN luminosity function distance
of 14.9 Mpc to M87, and 19% closer (2.8 Mpc) than M87 for the newly surveyed
field. Independent distance indicators (Tully-Fisher relation for Virgo spirals
and surface brightness fluctuations for Virgo ellipticals) agree with these
findings.
From these two Virgo cluster fields there is no evidence that the surface
luminosity density for the diffuse stellar component in the cluster decreases
with radius. The luminosity surface density of the diffuse stellar population
is comparable to that of the galaxies.Comment: 30 pages, 8 figures, accepted for pubblication in A
Galaxy populations in the Hydra i cluster from the VEGAS survey:I. Optical properties of a large sample of dwarf galaxies
At ~50 Mpc, the Hydra I cluster of galaxies is among the closest cluster in
the z=0 Universe, and an ideal environment to study dwarf galaxy properties in
a cluster environment. We exploit deep imaging data of the Hydra I cluster to
construct a new photometric catalog of dwarf galaxies in the cluster core,
which is then used to derive properties of the Hydra I cluster dwarf galaxies
population as well as to compare with other clusters. Moreover, we investigate
the dependency of dwarf galaxy properties on their surrounding environment. The
new Hydra I dwarf catalog contains 317 galaxies with luminosity between
-18.5<<-11.5 mag, a semi-major axis larger than ~200 pc (a=0.84 arcsec),
of which 202 are new detections, previously unknown dwarf galaxies in the Hydra
I central region. We estimate that our detection efficiency reaches 50% at the
limiting magnitude =-11.5 mag, and at the mean effective surface
brightness =26.5 mag/. We present the standard
scaling relations for dwarf galaxies and compare them with other nearby
clusters. We find that there are no observational differences for dwarfs
scaling relations in clusters of different sizes. We study the spatial
distribution of galaxies, finding evidence for the presence of substructures
within half the virial radius. We also find that mid- and high-luminosity
dwarfs (<-14.5 mag) become on average redder toward the cluster center,
and that they have a mild increase in with increasing clustercentric
distance, similar to what is observed for the Fornax cluster. No clear
clustercentric trends are reported with surface brightness and S\'ersic index.
Considering galaxies in the same magnitude-bins, we find that for high and
mid-luminosity dwarfs (<-13.5 mag) the g-r color is redder for the
brighter surface brightness and higher S\'ersic n index objects.Comment: Accepted for publication in A&A. 25 pages, 21 figure
Virgo's Intracluster Globular Clusters as Seen by the Advanced Camera for Surveys
We report the discovery of 4 candidate intracluster globular clusters (IGCs)
in a single deep HST ACS field of the Virgo Cluster. We show that each cluster
is roughly spherical, has a magnitude near the peak of the Virgo globular
cluster luminosity function, has a radial profile that is best-fit by a King
model, and is surrounded by an excess of point sources which have the colors
and magnitudes of cluster red giant stars. Despite the fact that two of our IGC
candidates have integrated colors redder than the mean of the M87 globular
cluster system, we propose that all of the objects are metal-poor with [M/H] <
-1. We show that the tidal radii of our intracluster globulars are all larger
than the mean for Milky Way clusters, and suggest that the clusters have
undergone less tidal stress than their Galactic counterparts. Finally, we
normalize our globular cluster observations to the luminosity of intracluster
stars, and derive a value of S_N ~ 6 for the specific frequency of Virgo
intracluster globular clusters. We use these data to constrain the origins of
Virgo's intracluster population, and suggest that globular clusters in our
intracluster field have a different origin than globular clusters in the
vicinity of M87. In particular, we argue that dwarf elliptical galaxies may be
an important source of intracluster stars.Comment: 24 pages, 1 table, 5 figures, accepted for publication in Ap
Looking into the faintEst WIth MUSE (LEWIS): on the nature of ultra-diffuse galaxies in the Hydra-I cluster.I. Project description and preliminary results
Looking into the faintEst WIth MUSE (LEWIS) is an ESO large observing
programme aimed at obtaining the first homogeneous integral-field spectroscopic
survey of 30 extremely low-surface brightness (LSB) galaxies in the Hydra I
cluster of galaxies, with MUSE at ESO-VLT. The majority of LSB galaxies in the
sample (22 in total) are ultra-diffuse galaxies (UDGs). The distribution of
systemic velocities Vsys ranges between 2317 km/s and 5198 km/s and is centred
on the mean velocity of Hydra I (Vsys = 3683 46 km/s). Considering the
mean velocity and the velocity dispersion of the cluster, 17 out of 20 targets
are confirmed cluster members. To assess the quality of the data and
demonstrate the feasibility of the science goals, we report the preliminary
results obtained for one of the sample galaxies, UDG11. For this target, we
derived the stellar kinematics, including the 2-dimensional maps of
line-of-sight velocity and velocity dispersion, constrained age and
metallicity, and studied the globular cluster (GC) population hosted by the
UDG. Results are compared with the available measurements for UDGs and dwarf
galaxies in literature. By fitting the stacked spectrum inside one effective
radius, we find that UDG11 has a velocity dispersion km/s,
it is old ( Gyr), metal-poor ([M/H]=-1.170.11 dex) and has a total
dynamical mass-to-light ratio M, comparable to those observed for
classical dwarf galaxies. The spatially resolved stellar kinematics maps
suggest that UDG11 does not show a significant velocity gradient along either
major or minor photometric axes. We find two GCs kinematically associated with
UDG11. The estimated total number of GCs in UDG11, corrected for the
spectroscopic completeness limit, is , which
corresponds to a GC specific frequency of .Comment: Accepted for publication in Astronomy and Astrophysic
Toward Precision Cosmology with Improved Planetary Nebula Luminosity Function Distances Using VLT-MUSE. II. A Test Sample from Archival Data
Thanks to the MUSE integral field spectrograph on board the Very Large Telescope (VLT), extragalactic distance measurements with the [O iii ] λ 5007 planetary nebula luminosity function (PNLF) are now possible out to âŒ40 Mpc. Here we analyze the VLT/MUSE data for 20 galaxies from the ESO public archive to identify the systemsâ planetary nebulae (PNe) and determine their PNLF distances. Three of the galaxies do not contain enough PNe for a robust measure of the PNLF, and the results for one other system are compromised of the galaxyâs internal extinction. However, we obtain robust PNLF distances for the remaining 16 galaxies, two of which are isolated and beyond 30 Mpc in a relatively unperturbed Hubble flow. From these data, we derive a Hubble constant of 74.2 ± 7.2 (stat) ±3.7 (sys) km s ^â1 Mpc ^â1 , a value that is very similar to that found from other quality indicators (e.g., Cepheids, the tip of the red giant branch, and surface brightness fluctuations). At present, the uncertainty is dominated by the small number of suitable galaxies in the ESO archive and their less-than-ideal observing conditions and calibrations. Based on our experience with these systems, we identify the observational requirements necessary for the PNLF to yield a competitive value for H _0 that is independent of the Type Ia supernova distance scale
Dynamics of Stars and Globular Clusters in Galaxy Halos
We have obtained kinematical data in the halos of the giant ellipticals M49 and M87. These include globular cluster velocities in M49 to 10 R_eff and planetary nebula velocities in M49 and M87 to 4 R_eff. We report initial results, including dynamical comparisons between the diffuse stellar components and globular cluster systems
Constraining the internal dynamics of stellar systems using the NMAGIC particle code
NMAGIC is a parallel implementation of our made-to-measure (2M2M) algorithm for constructing N-particle models of stellar systems from observational data, which extends earlier ideas by Syer & Tremaine (1996). The2M2M algorithm properly accounts for observational errors, is flexible, and can be applied to various systems and geometries. We show its ability to reproduce the internal dynamics of an oblate isotropic rotator model and report on the modeling of the dark matter (DM) halo of NGC 3379 combining SAURON and PN.S kinematic data. The2M2M algorithm is practical, reliable and can be applied to various dynamical systems without symmetry restrictions. We conclude that2M2M holds great promise for unraveling the internal dynamics of bulges