1,170 research outputs found
Larger in the disc of isolated active spiral galaxies than in their non-active twins
We present a comparison of the spin parameter , measured in a
region dominated by the galaxy disc, between 20 pairs of nearby
(0.005z0.03) seemingly isolated twin galaxies differing in nuclear
activity. We find that 80--82% of the active galaxies show higher values of
than their corresponding non-active twin(s), indicating larger
rotational support in the AGN discs. This result is driven by the 11 pairs of
unbarred galaxies, for which 100% of the AGN show larger than their
twins. These results can be explained by a more efficient angular momentum
transfer from the inflowing gas to the disc baryonic matter in the case of the
active galaxies. This gas inflow could have been induced by disc or bar
instabilities, although we cannot rule out minor mergers if these are prevalent
in our active galaxies. This result represents the first evidence of
galaxy-scale differences between the dynamics of active and non-active isolated
spiral galaxies of intermediate stellar masses (10
M) in the Local Universe.Comment: 11 pages, 7 figures. Accepted for publication in A&A Letter
Acute Impacts of Different Types of Exercise on Circulating α-Klotho Protein Levels
[EN] Elevated plasma α-klotho (αKl) protects against several ageing phenotypes and has been proposed as a biomarker of a good prognosis for different diseases. The beneficial health effects of elevated plasma levels of soluble αKl (SαKl) have been likened to the positive effects of exercise on ageing and chronic disease progression. It has also been established that molecular responses and adaptations differ according to exercise dose. The aim of this study is to compare the acute SαKl response to different exercise interventions, cardiorespiratory, and strength exercise in healthy, physically active men and to examine the behavior of SαKl 72h after acute strength exercise.S
Dissecting galactic bulges in space and time I: The importance of early formation scenarios vs. secular evolution
This article has been accepted for publication in Monthly Notices Royal Astronomical Society ©: 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reservedThe details of bulge formation via collapse, mergers, secular processes or their interplay remain unresolved. To start answering this question and quantify the importance of distinct mechanisms, we mapped a sample of three galactic bulges using data from the integral field spectrograph WiFeS on the ANU's 2.3-m telescope in Siding Spring Observatory. Its highresolution gratings (R ~ 7000) allow us to present a detailed kinematic and stellar population analysis of their inner structures with classical and novel techniques. The comparison of those techniques calls for the necessity of inversion algorithms in order to understand complex substructures and separate populations. We use line-strength indices to derive single stellar population equivalent ages and metallicities. Additionally, we use full spectral fitting methods, here the code STECKMAP, to extract their star formation histories. The high quality of our data allows us to study the 2D distribution of different stellar populations (i.e. young, intermediate and old). We can identify their dominant populations based on these age-discriminated 2D light and mass contribution. In all galactic bulges studied, at least 50 per cent of the stellar mass already existed 12 Gyr ago, more than currently predicted by simulations. A younger component (age between ~1 and ~8 Gyr) is also prominent and its present day distribution seems to be affected much more strongly by morphological structures, especially bars, than the older one. This in-depth analysis of the three bulges supports the notion of increasing complexity in their evolution, likely to be found in numerous bulge structures if studied at this level of detail, which cannot be achieved by mergers alone and require a non-negligible contribution of secular evolutionMKS acknowledges the support of the Instituto
de Astrofísica de Canarias via an Astrophysicist Resident
fellowship and Ignacio Martín-Navarro, Andra Stroe and Stéphane
Courteau for useful discussions. RC acknowledges the Ministerio
de Ciencia e Innovación by means of their FPI program (grant AYA-
2010-21322-C03-03 and AYA-2013-48226-C3-3-P). JFB acknowledges
support from the Ramón y Cajal Program and from the FP7
Marie Curie Actions of the European Commission, via the Initial
Training Network DAGAL under REA grant agreement number
289313. TRL thanks the support of the Spanish Ministerio de Educación,
Cultura y Deporte by means of the FPU fellowship. This research
has been supported by the Spanish Ministry of Economy and
Competitiveness (MINECO; grants AYA2010-21322-C03-02 and
AYA2009-11137) and by the Spanish Ministry of Science and Innovation
(MICINN; grants AYA2011-24728 and Consolider-Ingenio
CSD2010-00064) and by the Junta de Andalucía (FQM-108
Observational hints of radial migration in disc galaxies from CALIFA
Context. According to numerical simulations, stars are not always kept at their birth galactocentric distances but they have a tendency to migrate. The importance of this radial migration in shaping galactic light distributions is still unclear. However, if radial migration is indeed important, galaxies with different surface brightness (SB) profiles must display differences in their stellar population properties.
Aims: We investigate the role of radial migration in the light distribution and radial stellar content by comparing the inner colour, age, and metallicity gradients for galaxies with different SB profiles. We define these inner parts, avoiding the bulge and bar regions and up to around three disc scale lengths (type I, pure exponential) or the break radius (type II, downbending; type III, upbending).
Methods: We analysed 214 spiral galaxies from the CALIFA survey covering different SB profiles. We made use of GASP2D and SDSS data to characterise the light distribution and obtain colour profiles of these spiral galaxies. The stellar age and metallicity profiles were computed using a methodology based on full-spectrum fitting techniques (pPXF, GANDALF, and STECKMAP) to the Integral Field Spectroscopic CALIFA data.
Results: The distributions of the colour, stellar age, and stellar metallicity gradients in the inner parts for galaxies displaying different SB profiles are unalike as suggested by Kolmogorov-Smirnov and Anderson-Darling tests. We find a trend in which type II galaxies show the steepest profiles of all, type III show the shallowest, and type I display an intermediate behaviour.
Conclusions: These results are consistent with a scenario in which radial migration is more efficient for type III galaxies than for type I systems, where type II galaxies present the lowest radial migration efficiency. In such a scenario, radial migration mixes the stellar content, thereby flattening the radial stellar properties and shaping different SB profiles. However, in light of these results we cannot further quantify the importance of radial migration in shaping spiral galaxies, and other processes, such as recent star formation or satellite accretion, might play a role
No direct coupling between bending of galaxy disc stellar age and light profiles as seen from CALIFA
Recent theoretical and observational works claim the existence of galaxies with a characteristic age profile consisting on a negative radial trend followed by a smooth age upturn in its outskirts (``U-shape''). This shape has been generally related to down-bending light distributions; however, the existence of a real link between observed Surface Brightness (SB) profiles and changes in stellar properties such as age is still unclear
CO-CAVITY pilot survey:Molecular gas and star formation in void galaxies
We present the first molecular gas mass survey of void galaxies. We compare
these new data together with data for the atomic gas mass and star formation
rate () from the literature to those of galaxies in filaments and
walls in order to better understand how molecular gas and star formation are
related to the large-scale environment. We observed at the IRAM 30 m telescope
the CO(1-0) and CO(2-1) emission of 20 void galaxies selected from the Void
Galaxy Survey (VGS), with a stellar mass range from to . We detected 15 objects in at least one CO line. We
compared the molecular gas mass (), the star formation efficiency
(), the atomic gas mass, the molecular-to-atomic gas
mass ratio, and the specific star formation rate (sSFR) of the void galaxies
with two control samples of galaxies in filaments and walls, selected from
xCOLD GASS and EDGE-CALIFA, for different stellar mass bins and taking the star
formation activity into account. The results for the molecular gas mass for a
sample of 20 voids galaxies allowed us to make a statistical comparison to
galaxies in filaments and walls for the first time.Comment: 24 pages, 15 figures, accepted in A&A, language corrected versio
- …