94 research outputs found
Influence of galaxy stellar mass and observed wavelength on disc breaks in SG, NIRS0S, and SDSS data
Breaks in the surface brightness profiles in the outer regions of galactic
discs are thought to have formed by various internal and external processes,
and by studying the breaks we aim to better understand what processes are
responsible for the evolution of the outer discs. We use a large well-defined
sample to study how common the breaks are, and whether their properties depend
on galaxy stellar mass or observed wavelength. We study radial surface
brightness profiles of 753 galaxies, obtained from the images of
the Spitzer Survey of Stellar Structure in Galaxies (SG), and the
-band data from the Near InfraRed S0-Sa galaxy Survey (NIRS0S), covering a
wide range of galaxy morphologies and stellar masses. Optical SDSS or Liverpool
telescope data was used for 480 of these galaxies. We find that in low-mass
galaxies the single exponential discs (Type I) are most common, and that their
fraction decreases with increasing galaxy stellar mass. The fraction of
down-bending (Type II) discs increases with stellar mass, possibly due to more
common occurrence of bar resonance structures. The up-bending (Type III) discs
are also more common in massive galaxies. The observed wavelength affects the
scalelength of the disc of every profile type. Especially the scalelength of
the inner disc of Type II profiles increases from infrared to u-band on average
by a factor of . Consistent with the previous studies, we find that
Type II outer disc scalelengths () in late-type and low-mass galaxies are
shorter in bluer wavelengths, possibly due to stellar radial migration
populating the outer discs with old stars. In Type III discs are larger
in the u-band, hinting to the presence of young stellar population in the outer
disc. While the observed wavelength affects the disc parameters, it does not
significantly affect the profile type in our sample. (Abridged)Comment: 22 pages, 16 figures. Accepted for publication in Astronomy &
Astrophysic
Naisten virtsankarkailun nauhaleikkaukset
Vain ponnistukseen liittyvÀÀ virtsankarkailua voidaan korjata leikkauksella. Valikoiduille potilaille voidaan kĂ€yttÀÀ injektiohoitoa.Leikkaushoidolla paranee 62â97 % potilaista. Retropuubiset (TVT) ja transobturatoriset (TOT ja TVT-O) nauhaleikkaustekniikat ovat yhtĂ€ tehokkaita.Suomessa tehdÀÀn pÀÀasiassa vĂ€hĂ€n kajoavia nauhaleikkauksia. VĂ€littömiĂ€ leikkauskomplikaatioita ja myöhemmin ilmaantuvia virtsaamisongelmia on ollut vĂ€hĂ€n
Kinematics and dynamics of the M51-type galaxy pair NGC 3893/96 (KPG 302)
We study the kinematics and dynamics of the M51-type interacting galaxy pair
KPG 302 (NGC 3893/96). We analyse the distribution of the dark matter (DM) halo
of the main galaxy in order to explore possible differences between DM halos of
"isolated" galaxies and those of galaxies belonging to a pair. The velocity
field of each galaxy was obtained using scanning Fabry-Perot interferometry. A
two-dimensional kinematic and dynamical analysis of each galaxy and the pair as
a whole is done emphasizing the contribution of circular and non-circular
velocities. Non-circular motions can be traced on the rotation curves of each
galaxy allowing us to differentiate between motions associated to particular
features and motions that reflect the global mass distribution of the galaxy.
For the main galaxy of the pair, NGC 3893, optical kinematic information is
complemented with HI observations from the literature to build a
multi-wavelength rotation curve. We try to fit this curve with a
mass-distribution model using different DM halos. We find that the
multi-wavelength rotation curve of NGC 3893, "cleaned" from the effect of
non-circular motions, cannot be fitted neither by a pseudo-isothermal nor by a
NFW DM halo.Comment: Accepted for publication in A&A. 11 pages, 9 figures and 2 table
Evidence for the concurrent growth of thick discs and central mass concentrations from SG imaging
We have produced vertically integrated radial
luminosity profiles of 69 edge-on galaxies from the Spitzer Survey of Stellar
Structure in Galaxies (SG). We decomposed the luminosity profiles into a
disc and a central mass concentration (CMC). These fits, combined with
thin/thick disc decompositions from our previous studies, allow us to estimate
the masses of the CMCs, the thick discs, and the thin discs (, , and ). We obtained atomic
disc masses () from the literature. We then consider the
CMC and the thick disc to be dynamically hot components and the thin disc and
the gas disc to be dynamically cold components. We find that the ratio between
the mass of the hot components and that of the cold components,
, does not depend on the total galaxy mass as described
by circular velocities (). We also find that the higher the , the more concentrated the hot component of a galaxy. We suggest that our
results are compatible with having CMCs and thick discs built in a short and
early high star forming intensity phase. These components were born thick
because of the large scale height of the turbulent gas disc in which they
originated. Our results indicate that the ratio between the star forming rate
in the former phase and that of the formation of the thin disc is of the order
of 10, but the value depends on the duration of the high star forming intensity
phase.Comment: Accepted for publication in A&
Comparison of bar strengths in active and non-active galaxies
Bar strengths are compared between active and non-active galaxies for a
sample of 43 barred galaxies. The relative bar torques are determined using a
new technique (Buta and Block 2001), where maximum tangential forces are
calculated in the bar region, normalized to the axisymmetric radial force
field. We use JHK images of the 2 Micron All Sky Survey. We show a first clear
empirical indication that the ellipticies of bars are correlated with the
non-axisymmetric forces in the bar regions. We found that nuclear activity
appears preferentially in those early type galaxies in which the maximum bar
torques are weak and appear at quite large distances from the galactic center.
Most suprisingly the galaxies with the strongest bars are non-active. Our
results imply that the bulges may be important for the onset of nuclear
activity, but that the correlation between the nuclear activity and the early
type galaxies is not straightforward.Comment: MNRAS macro in tex format, 9 pages, 10 figure
Bar-induced perturbation strengths of the galaxies in the Ohio State University Bright Galaxy Survey (OSUBGS) I
This paper presents bar strength measurements for a sample of 180 galaxies,
based on the H-band images of the Ohio State University Bright Galaxy Survey
(Eskridge et al. 2002, ApJS, 143, 73). We use a gravitational bar torque
method, where the ratio of the maximum tangential force to the mean
axisymmetric radial force is used as a quantitative measure of the bar
strength. Based on our Fourier analysis we found that nearly 70 % of the
galaxies classified as SAB-types in the near-IR might actually be non-barred
systems. We also found that ovals are capable of inducing tangential forces at
some level. The measurements of this study are used by Buta et al. (AJ, 127,
279) for the analysis of the distribution of bar strengths in spiral galaxies,
and by Laurikainen et al. (ApJ, 607, 103) to study the connection between bar
strength and nuclear activity.Comment: Monthly Notices, in press. 24 pages, 8 figure
Halpha Kinematics of S4G Spiral Galaxies - III. Inner rotation curves
We present a detailed study of the shape of the innermost part of the
rotation curves of a sample of 29 nearby spiral galaxies, based on high angular
and spectral resolution kinematic Halpha Fabry-Perot observations. In
particular, we quantify the steepness of the rotation curve by measuring its
slope dRvc(0). We explore the relationship between the inner slope and several
galaxy parameters, such as stellar mass, maximum rotational velocity, central
surface brightness ({\mu}0), bar strength and bulge-to-total ratio. Even with
our limited dynamical range, we find a trend for low-mass galaxies to exhibit
shallower rotation curve inner slopes than high-mass galaxies, whereas steep
inner slopes are found exclusively in high-mass galaxies. This trend may arise
from the relationship between the total stellar mass and the mass of the bulge,
which are correlated among them. We find a correlation between the inner slope
of the rotation curve and the morphological T-type, complementary to the
scaling relation between dRvc(0) and {\mu}0 previously reported in the
literature. Although we find that the inner slope increases with the Fourier
amplitude A2 and decreases with the bar torque Qb, this may arise from the
presence of the bulge implicit in both A2 and Qb. As previously noted in the
literature, the more compact the mass in the central parts of a galaxy (more
concretely, the presence of a bulge), the steeper the inner slopes. We conclude
that the baryonic matter dominates the dynamics in the central parts of our
sample galaxies.Comment: 11 pages, 11 figures, accepted for publication in MNRA
The Fornax Deep Survey with the VST XII. Low surface brightness dwarf galaxies in the Fornax cluster
Context. Low surface brightness (LSB) dwarf galaxies in galaxy clusters are an interesting group of objects as their contribution to the galaxy luminosity function and their evolutionary paths are not yet clear. Increasing the completeness of our galaxy catalogs is crucial for understanding these galaxies, which have effective surface brightnesses below 23 mag arcsecâ2 (in optical). Progress is continuously being made via the performance of deep observations, but detection depth and the quantification of the completeness can also be improved via the application of novel approaches in object detection. For example, the Fornax Deep Survey (FDS) has revealed many faint galaxies that can be visually detected from the images down to a surface brightness level of 27 mag arcsecâ2, whereas traditional detection methods, such as using Source Extractor (SE), fail to find them.
Aims. In this work we use a max-tree based object detection algorithm (Max-Tree Objects, MTO) on the FDS data in order to detect previously undetected LSB galaxies. After extending the existing Fornax dwarf galaxy catalogs with this sample, our goal is to understand the evolution of LSB dwarfs in the cluster. We also study the contribution of the newly detected galaxies to the faint end of the luminosity function.
Methods. We test the detection completeness and parameter extraction accuracy of MTO using simulated and real images. We then apply MTO to the FDS images to identify LSB candidates. The identified objects are fitted with 2D SĂ©rsic models using GALFIT and classified as imaging artifacts, likely cluster members, or background galaxies based on their morphological appearance, colors, and structure.
Results. With MTO, we are able to increase the completeness of our earlier FDS dwarf catalog (FDSDC) 0.5â1 mag deeper in terms of total magnitude and surface brightness. Due to the increased accuracy in measuring sizes of the detected objects, we also add many small galaxies to the catalog that were previously excluded as their outer parts had been missed in detection. We detect 265 new LSB dwarf galaxies in the Fornax cluster, which increases the total number of known dwarfs in Fornax to 821. Using the whole cluster dwarf galaxy population, we show that the luminosity function has a faint-end slope of α = â1.38 ± 0.02. We compare the obtained luminosity function with different environments studied earlier using deep data but do not find any significant differences. On the other hand, the Fornax-like simulated clusters in the IllustrisTNG cosmological simulation have shallower slopes than found in the observational data. We also find several trends in the galaxy colors, structure, and morphology that support the idea that the number of LSB galaxies is higher in the cluster center due to tidal forces and the age dimming of the stellar populations. The same result also holds for the subgroup of large LSB galaxies, so-called ultra-diffuse galaxies
H-alpha kinematics of S4G spiral galaxies-II. Data description and non-circular motions
We present a kinematical study of 29 spiral galaxies included in the Spitzer
Survey of Stellar Structure in Galaxies, using Halpha Fabry-Perot data obtained
with the Galaxy Halpha Fabry-Perot System instrument at the William Herschel
Telescope in La Palma, complemented with images in the R-band and in Halpha.
The primary goal is to study the evolution and properties of the main
structural components of galaxies through the kinematical analysis of the FP
data, complemented with studies of morphology, star formation and mass
distribution. In this paper we describe how the FP data have been obtained,
processed and analysed. We present the resulting moment maps, rotation curves,
velocity model maps and residual maps. Images are available in FITS format
through the NASA/IPAC Extragalactic Database and the Centre de Donn\'ees
Stellaires. With these data products we study the non-circular motions, in
particular those found along the bars and spiral arms. The data indicate that
the amplitude of the non-circular motions created by the bar does not correlate
with the bar strength indicators. The amplitude of those non-circular motions
in the spiral arms does not correlate with either arm class or star formation
rate along the spiral arms. This implies that the presence and the magnitude of
the streaming motions in the arms is a local phenomenon.Comment: 23 pages, 14 figures, without appendices, accepted to be published in
MNRA
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