6 research outputs found
The EFIGI catalogue of 4458 nearby galaxies with morphology II. Statistical properties along the Hubble sequence
The EFIGI catalogue of 4458 galaxies provides a reference database of the
morphological properties of nearby galaxies, with 16 shape attributes
describing their various dynamical components, their texture and environment,
and with a dense sampling of all Hubble types. This catalogue allows us to
derive a quantitative description of the Hubble Sequence in terms of the
specific morphological features of the various types. The variations of the
EFIGI morphological attributes with type confirm that the visual Hubble
sequence is a decreasing sequence of bulge-to-total ratio and an increasing
sequence of disk contribution to the total flux. There is nevertheless a large
dispersion of approximately 5 types for a given bulge-to-total ratio, due to
the fact that the Hubble sequence is primarily based on the strength and pitch
angle of the spiral arms, independently from the bulge-to-total ratio. The
grand spiral design is also related to a steep decrease in visible dust from
types Sb to Sbc-Sc. In contrast, the scattered and giant HII regions show
different strength variation patterns; hence, they do not appear to directly
participate in the establishment of the Hubble sequence. The distortions from a
symmetric profile also incidentally increase along the sequence. Bars and inner
rings are frequent and occur in 41% and 25% of disk galaxies resp. Outer rings
are twice less frequent than inner rings, and outer pseudo-rings occur in 11%
of barred galaxies. Finally, we find a smooth decrease in mean surface
brightness and intrinsic size along the Hubble sequence. The largest galaxies
are cD, Ellipticals and Sab-Sbc spirals, whereas Sd and later spirals are
nearly twice smaller. S0 are intermediate in size, and Im, cE and dE are
confirmed as small objects. Dwarf spiral galaxies of type Sa to Scd are rare in
the EFIGI catalogue, we only find 2 such objects.Comment: Accepted for publication in Astronomy and Astrophysics, 22 pages, 10
tables, 19 colour figures. Data available at http://www.efigi.or
KiDS+2dFLenS+GAMA: testing the cosmological model with the EG statistic
We present a new measurement of EG, which combines measurements of weak gravitational lensing, galaxy clustering, and redshift-space distortions. This statistic was proposed as a consistency test of General Relativity (GR) that is insensitive to linear, deterministic galaxy bias, and the matter clustering amplitude. We combine deep imaging data from KiDS with overlapping spectroscopy from 2dFLenS, BOSS DR12, and GAMA and find EG(z = 0.267) = 0.43 ± 0.13 (GAMA), EG(z = 0.305) = 0.27 ± 0.08 (LOWZ+2dFLOZ), and EG(z = 0.554) = 0.26 ± 0.07 (CMASS+2dFHIZ). We demonstrate that the existing tension in the value of the matter density parameter hinders the robustness of this statistic as solely a test of GR. We find that our EG measurements, as well as existing ones in the literature, favour a lower matter density cosmology than the cosmic microwave background. For a flat CDM Universe, we find m(z = 0) = 0.25 ± 0.03. With this paper, we publicly release the 2dFLenS data set at: http://2dflens.swin.edu.au
Severity dependent distribution of impairments in PSP and CBS: Interactive visualizations
BACKGROUND: Progressive supranuclear palsy (PSP) -Richardson's Syndrome and Corticobasal Syndrome (CBS) are the two classic clinical syndromes associated with underlying four repeat (4R) tau pathology. The PSP Rating Scale is a commonly used assessment in PSP clinical trials; there is an increasing interest in designing combined 4R tauopathy clinical trials involving both CBS and PSP. OBJECTIVES: To determine contributions of each domain of the PSP Rating Scale to overall severity and characterize the probable sequence of clinical progression of PSP as compared to CBS. METHODS: Multicenter clinical trial and natural history study data were analyzed from 545 patients with PSP and 49 with CBS. Proportional odds models were applied to model normalized cross-sectional PSP Rating Scale, estimating the probability that a patient would experience impairment in each domain using the PSP Rating Scale total score as the index of overall disease severity. RESULTS: The earliest symptom domain to demonstrate impairment in PSP patients was most likely to be Ocular Motor, followed jointly by Gait/Midline and Daily Activities, then Limb Motor and Mentation, and finally Bulbar. For CBS, Limb Motor manifested first and ocular showed less probability of impairment throughout the disease spectrum. An online tool to visualize predicted disease progression was developed to predict relative disability on each subscale per overall disease severity. CONCLUSION: The PSP Rating Scale captures disease severity in both PSP and CBS. Modelling how domains change in relation to one other at varying disease severities may facilitate detection of therapeutic effects in future clinical trials
Herschel-ATLAS: statistical properties of Galactic cirrus in the GAMA-9 Hour Science Demonstration Phase Field
The definitive version can be found at : http://onlinelibrary.wiley.com/ Copyright Wiley-BlackwellWe study the spectral energy distribution (SED) and the power spectrum of Galactic cirrus emission observed in the 14 deg2 Science Demonstration Phase field of the Herschel-ATLAS using Herschel and IRAS data from 100 to 500 mu m. We compare the Spectral and Photometric Imaging Receiver (SPIRE) 250, 350 and 500 mu m maps with IRAS 100-mu m emission, binned in 6-arcmin pixels. We assume a modified blackbody SED with dust emissivity parameter beta (F proportional to lambda-beta) and a single dust temperature T-d, and find that the dust temperature and emissivity index varies over the science demonstration field as and 1 , and similar values of beta, ranging from 1.4 +/- 0.5 to 1.9 +/- 0.5. We show that T-d and beta associated with diffuse cirrus emission are anti-correlated and can be described by the relationship: beta(T-d) = NT alpha(d) with [N = 116 +/- 38, alpha = -1.4 +/- 0.1]. The strong correlation found in this analysis is not just limited to high-density clumps of cirrus emission as seen in previous studies, but is also seen in diffuse cirrus in low-density regions. To provide an independent measure of T-d and beta, we obtain the angular power spectrum of the cirrus emission in the IRAS and SPIRE maps, which is consistent with a power spectrum of the form P(k) = P-0(k/k(0))gamma, where gamma = 2.6 +/- 0.2 for scales of 50-200 arcmin in the SPIRE maps. The cirrus rms fluctuation amplitude at angular scales of 100 arcmin is consistent with a modified blackbody SED with and beta = ! 1.3 +/- 0.2, in agreement with the values obtained above.Peer reviewe