45 research outputs found
Imprint of the galactic acceleration scale on globular cluster systems: Galaxies in the Fornax Cluster
Dark matter is required in galaxies at galactocentric radii that are larger
than the -radius, which is where the gravitational acceleration generated
by baryons of the galaxy equals the constant ms
known as the galactic acceleration scale. It was found previously for massive
early-type galaxies that the radial number-density profiles of their globular
cluster (GC) systems follow broken power laws and the breaks occur at the
-radii. We have newly analyzed the distribution of GCs around galaxies in
the Fornax cluster in existing photometric catalogs. We found that 1) the
coincidence between -radii and the break radii of globular cluster systems
is valid for early-type galaxies of all masses and, 2) this also applies to the
red and blue sub-populations of GCs separately.Comment: 3 pages, 1 figure. To be published in Memorie della SAI
Cosmological constant and the fate of the DDM theory
We investigate the impact of the non-zero cosmological constant on the
classical decaying dark matter theory developed by the late Dennis Sciama. In
particular, we concentrate on the change in relevant values of cosmological
parameters in comparison to the high-precision estimates given by Sciama
(1997). It is shown that the appropriate changes in resulting parameter values
are such to make the DDM concept less plausible. This is in complete agreement
with recently reported observational results detrimental to this theory.Comment: 4 pages, 2 eps figures, uses AA latex styl
The galactic acceleration scale is imprinted on globular cluster systems of early-type galaxies of most masses and on red and blue globular cluster subpopulations
Context. Globular clusters carry information about the formation histories
and gravitational fields of their host galaxies. B\'ilek et al. (2019, BSR19
hereafter) reported that the radial profiles of volume number density of GCs in
GC systems (GCS) follow broken power laws, while the breaks occur approximately
at the radii. These are the radii at which the gravitational fields of
the galaxies equal the galactic acceleration scale ms known from the radial acceleration relation or the MOND
theory of modified dynamics.
Aims. Our main goals here are to explore whether the results of BSR19 hold
true for galaxies of a wider mass range and for the red and blue GCs
sub-populations.
Methods. We exploited catalogs of photometric GC candidates in the Fornax
galaxy cluster based on ground and space observations and a new catalog of
spectroscopic GCs of NGC 1399, the central galaxy of the cluster. For every
galaxy, we obtained the parameters of the broken power law density by fitting
the on-sky distribution of the GC candidates, while allowing for a constant
density of contaminants. The logarithmic stellar masses of our galaxy sample
span 8.0-11.4 .
Results. All investigated GCSs with a sufficient number of members show
broken power-law density profiles. This holds true for the total GC population
and the blue and red subpopulations. The inner and outer slopes and the break
radii agree well for the different GC populations. The break radii agree with
the radii typically within a factor of two for all GC color
subpopulations. The outer slopes correlate better with the radii than
with the galactic stellar masses. The break radii of NGC 1399 vary in azimuth,
such that they are greater toward and against the neighboring galaxy NGC 1404.Comment: 39 pages, ~15 pages main text, 33 figures, 12 tables. Accepted for
publication in A&
Dark matter in early-type galaxies: dynamical modelling of IC1459, IC3370, NGC3379 and NGC4105
We analyse long-slit spectra of four early-type galaxies which extend from ~1
to ~3 effective radii: IC1459, IC3370, NGC3379 and NGC4105. We have extracted
the full line-of-sight velocity distribution (in the case of NGC3379 we also
used data from the literature) which we model using the two-integral approach.
Using two-integral modelling we find no strong evidence for dark haloes, but
the fits suggest that three-integral modelling is necessary. We also find that
the inferred constant mass-to-light ratio in all four cases is typical for
early-type galaxies. Finally, we also discuss the constraints on the
mass-to-light ratio which can be obtained using X-ray haloes in the case of
IC1459, NGC3379 and NGC4105 and compare the estimated values with the
predictions from the dynamical modelling.Comment: 42 pages, 18 figures, accepted for publication in MNRA
MOND vs. Newtonian dynamics in early-type galaxies. The case of NGC 4649 (M60)
Context: Regarding the significant interest in both dark matter and the
application of MOND to early-type galaxies, we investigate the MOND theory by
comparing its predictions, for models of constant mass-to-light ratio, with
observational data of the early-type galaxy NGC 4649.
Aims: We study whether measurements for NGC 3379 and NGC 1399 are typical of
early-type systems and we test the assumption of a Newtonian constant M/L ratio
underlying most of the published models.
Methods: We employ the globular clusters of NGC 4649 as a mass tracer. The
Jeans equation is calculated for both MOND and constant mass-to-light ratio
assumptions. Spherical symmetry is assumed and the calculations are performed
for both isotropic and anisotropic cases.
Results: We found that both Jeans models with the assumption of a constant
mass-to-light ratio and different MOND models provide good agreement with the
observed values of the velocity dispersion. The most accurate fits of the
velocity dispersion were obtained for the mass-to-light ratio in the B-band,
which was equal to 7, implying that there is no need for significant amounts of
dark matter in the outer parts (beyond 3 effective radii) of this galaxy. We
also found that tangential anisotropies are most likely present in NGC 4649.Comment: 6 pages, 4 figure
SOME POSSIBLE EFFECTS OF CONSTRUCTION AND DEMOLITION WASTE LANDFILL ON THE ENVIRONMENT
In cases of inadequate waste management, there is a tendency for inappropriate
disposal of construction and demolition (C&D) waste, especially when its production surpasses the
capacities of official disposal sites. By disposing of C&D waste on the edge of the protected
natural area during the spring of 2021, a C&D landfill was formed near Reva pond, Belgrade. In
this work, the qualitative composition of C&D waste in the field was assessed, including chemical
analysis of landfill soil which was investigated by comparing its elemental composition with the
control soil by utilizing SEM-EDS analysis. The presence of various C&D waste components,
typical (concrete blocks, bricks, armature, glass shards, wood, soil of various origin) and atypical
(furniture, industrial-type glass shards, paint bottles and cans), indicated that waste disposal was
only partially controlled. Due to the high heterogeneity of the disposed soil, analysis can neither
confirm nor exclude the possibility of heavy metal contamination. Herbaceous plants are already
naturally colonizing the landfill; also, the aggressively spreading, heavy metal accumulator, honey
plant species - the False indigo bush (Amorpha fruticosa), is abundant in the area, and it is
expected that it will recultivate the landfill site. To get a full assessment of the landfill's impact on
local ecosystems, continuous monitoring is recommended
Measuring the non-thermal pressure in early type galaxy atmospheres: A comparison of X-ray and optical potential profiles in M87 and NGC1399
We compare the gravitational potential profiles of the elliptical galaxies
NGC 4486 (M87) and NGC 1399 (the central galaxy in the Fornax cluster) derived
from X-ray and optical data. This comparison suggests that the combined
contribution of cosmic rays, magnetic fields and micro-turbulence to the
pressure is ~10% of the gas thermal pressure in the cores of NGC 1399 and M87,
although the uncertainties in our model assumptions (e.g., spherical symmetry)
are sufficiently large that the contribution could be consistent with zero. In
the absence of any other form of non-thermal pressure support, these upper
bounds translate into upper limits on the magnetic field of ~10-20 muG at a
distance of 1'-2' from the centers of NGC1399 and M87. We show that these
results are consistent with the current paradigm of cool cluster cores, based
on the assumption that AGN activity regulates the thermal state of the gas by
injecting energy into the intra-cluster medium. The limit of ~10-20% on the
energy density in the form of relativistic protons applies not only to the
current state of the gas, but essentially to the entire history of the
intra-cluster medium, provided that cosmic ray protons evolve adiabatically and
that their spatial diffusion is suppressed.Comment: Accepted for MNRAS. 19 pages; 14 figures; expanded version in
response to comments from the refere
On the Correlations between Galaxy Properties and Supermassive Black Hole Mass
We use a large sample of upper limits and accurate estimates of supermassive
black holes masses coupled with libraries of host galaxy velocity dispersions,
rotational velocities and photometric parameters extracted from Sloan Digital
Sky Survey i-band images to establish correlations between the SMBH and host
galaxy parameters. We test whether the mass of the black hole, MBH, is
fundamentally driven by either local or global galaxy properties. We explore
correlations between MBH and stellar velocity dispersion sigma, bulge
luminosity, bulge mass Sersic index, bulge mean effective surface brightness,
luminosity of the galaxy, galaxy stellar mass, maximum circular velocity Vc,
galaxy dynamical and effective masses. We verify the tightness of the MBH-sigma
relation and find that correlations with other galaxy parameters do not yield
tighter trends. We do not find differences in the MBH-sigma relation of barred
and unbarred galaxies. The MBH-sigma relation of pseudo-bulges is also coarser
and has a different slope than that involving classical bulges. The MBH-bulge
mass is not as tight as the MBH-sigma relation, despite the bulge mass proving
to be a better proxy of MBH than bulge luminosity. We find a rather poor
correlation between MBH and Sersic index suggesting that MBH is not related to
the bulge light concentration. The correlations between MBH and galaxy
luminosity or mass are not a marked improvement over the MBH sigma relation. If
Vc is a proxy for the dark matter halo mass, the large scatter of the MBH-Vc
relation then suggests that MBH is more coupled to the baryonic rather than the
dark matter. We have tested the need for a third parameter in the MBH scaling
relations, through various linear correlations with bulge and galaxy
parameters, only to confirm that the fundamental plane of the SMBH is mainly
driven by sigma, with a small tilt due to the effective radius. (Abridged)Comment: 32 pages, 18 figures, 6 tables, accepted for publication in MNRA
Kinematic properties of early-type galaxy haloes using planetary nebulae
We present new planetary nebulae (PNe) positions, radial velocities, and
magnitudes for 6 early-type galaxies obtained with the Planetary Nebulae
Spectrograph, their two-dimensional velocity and velocity dispersion fields. We
extend this study to include an additional 10 early-type galaxies with PNe
radial velocity measurements available from the literature, to obtain a broader
description of the outer-halo kinematics in early-type galaxies. These data
extend the information derived from stellar kinematics to typically up to ~8
Re. The combination of photometry, stellar and PNe kinematics shows: i) good
agreement between the PNe number density and the stellar surface brightness in
the region where the two data sets overlap; ii) good agreement between PNe and
stellar kinematics; iii) that the mean rms velocity profiles fall into two
groups: with of the galaxies characterized by slowly decreasing profiles and
the remainder having steeply falling profiles; iv) a larger variety of velocity
dispersion profiles; v) that twists and misalignments in the velocity fields
are more frequent at large radii, including some fast rotators; vi) that outer
haloes are characterised by more complex radial profiles of the specific
angular momentum-related lambda_R parameter than observed within 1Re; vii) that
many objects are more rotationally dominated at large radii than in their
central parts; and viii) that the halo kinematics are correlated with other
galaxy properties, such as total luminosity, isophotal shape, total stellar
mass, V/sigma, and alpha parameter, with a clear separation between fast and
slow rotators.Comment: 36 pages, 21 figures, revised version for MNRA