Evolution of the Dark Matter Distribution with 3-D Weak Lensing

We present a direct detection of the growth of large-scale structure, using weak gravitational lensing and photometric redshift data from the COMBO-17 survey. We use deep R-band imaging of two 0.25 square degree fields, affording shear estimates for over 52000 galaxies; we combine these with photometric redshift estimates from our 17 band survey, in order to obtain a 3-D shear field. We find theoretical models for evolving matter power spectra and correlation functions, and fit the corresponding shear correlation functions to the data as a function of redshift. We detect the evolution of the power at the 7.7 sigma level given minimal priors, and measure the rate of evolution for 0<z<1. We also fit correlation functions to our 3-D data as a function of cosmological parameters sigma_8 and Omega_Lambda. We find joint constraints on Omega_Lambda and sigma_8, demonstrating an improvement in accuracy by a factor of 2 over that available from 2D weak lensing for the same area.Comment: 11 pages, 4 figures; submitted to MNRA

The merger rate of massive galaxies

We calculate the projected two point correlation function for samples of luminous and massive galaxies in the COMBO-17 photometric redshift survey, focusing particularly on the amplitude of the correlation function at small projected radii and exploring the constraints such measurements can place on the galaxy merger rate. For nearly volume-limited samples with 0.4<z<0.8, we find that 4+/-1% of luminous M_B<-20 galaxies are in close physical pairs (with real space separation of <30 proper kpc). The corresponding fraction for massive galaxies with M_*>2.5e10 M_sun is 5+/-1%. Incorporating close pair fractions from the literature, the 2dFGRS and the SDSS, we find a fairly rapid evolution of the merger fraction of massive galaxies between z=0.8 and the present day. Assuming that the major merger timescale is of order the dynamical timescale for close massive galaxy pairs, we tentatively infer that ~50% (70%) of all galaxies with present-day masses M_*>5e10 M_sun (remnants of mergers between galaxies with M_*>2.5e10 M_sun) have undergone a major merger since z=0.8(1): major mergers between massive galaxies are a significant driver of galaxy evolution over the last eight billion years.Comment: ApJ, in press. 8 pages, 3 figures. Expanded discussion section with explicit discussion of merger fraction vs. close pair fraction. Change of typical close pair timescale results in increased inferred merger rat

Star Formation and the Growth of Stellar Mass

Recent observations have demonstrated a significant growth in the integrated stellar mass of the red sequence since z=1, dominated by a steadily increasing number of galaxies with stellar masses M* < 10^11 M_sun. In this paper, we use the COMBO-17 photometric redshift survey in conjunction with deep Spitzer 24 micron data to explore the relationship between star formation and the growth of stellar mass. We calculate `star formation rate functions' in four different redshift slices, splitting also into contributions from the red sequence and blue cloud for the first time. We find that the growth of stellar mass since z=1 is consistent with the integrated star formation rate. Yet, most of the stars formed are in blue cloud galaxies. If the stellar mass already in, and formed in, z<1 blue cloud galaxies were to stay in the blue cloud the total stellar mass in blue galaxies would be dramatically overproduced. We explore the expected evolution of stellar mass functions, finding that in this picture the number of massive M* > 3x10^10 M_sun blue galaxies would also be overproduced; i.e., most of the new stars formed in blue cloud galaxies are in the massive galaxies. We explore a simple truncation scenario in which these `extra' blue galaxies have their star formation suppressed by an unspecified mechanism or mechanisms; simple cessation of star formation in these extra blue galaxies is approximately sufficient to build up the red sequence at M*<10^11 M_sun.Comment: 9 Pages; ApJ in pres

Fjernmålingsbasert kartlegging og overvåking av tidevannssonen

Source at https://www.miljodirektoratet.no/publikasjoner/2021/mai-2021/satellite-based-national-intertidal-zone-mapping-of-continental-norway-with-sentinel-12/The report describes updated methods that were originally developed in Haarpaintner & Davids (2020) to map the intertidal zone, in terms of atmospheric exposure, type and areal extent, based on radar and optical high resolution (10m) satellite imagery from Sentinel-1A/B (C-band synthetic aperture radar, C-SAR) and Sentinel-2A/B (multi-spectral instruments) of the European Copernicus Program. It further presents the application of the method to create products covering the whole Norwegian coast, and describes some limitations and error sources. The project resulted in a first version of national products of the intertidal zone area, type and its atmospheric exposure

Prevalence of Neuropathy and Peripheral Arterial Disease and the Impact of Treatment in People With Screen-Detected Type 2 Diabetes

OBJECTIVE: There is limited evidence on how intensive multifactorial treatment (IT) improves outcomes of diabetes when initiated in the lead time between detection by screening and diagnosis in routine clinical practice. We examined the effects of early detection and IT of type 2 diabetes in primary care on the prevalence of diabetic peripheral neuropathy (DPN) and peripheral arterial disease (PAD) 6 years later in a pragmatic, cluster-randomized parallel group trial. RESEARCH DESIGN AND METHODS: A stepwise screening program in 190 general practices in Denmark was used to identify 1,533 people with type 2 diabetes. General practices were randomized to deliver either IT or routine care (RC) as recommended through national guidelines. Participants were followed for 6 years and measures of DPN and PAD were applied. RESULTS: We found no statistically significant effect of IT on the prevalence of DPN and PAD compared with RC. The prevalence of an ankle brachial index ≤0.9 was 9.1% (95% CI 6.0–12.2) in the RC arm and 7.3% (5.0–9.6) in the IT arm. In participants tested for vibration detection threshold and light touch sensation, the prevalence of a least one abnormal test was 34.8% (26.7–43.0) in the RC arm and 30.1% (24.1–36.1) in the IT arm. CONCLUSIONS: In a population with screen-detected type 2 diabetes, we did not find that screening followed by IT led to a statistically significant difference in the prevalence of DPN and PAD 6 years after diagnosis. However, treatment levels were high in both groups

GEMS: Galaxy Evolution from Morphologies and SEDs

GEMS, Galaxy Evolution from Morphologies and SEDs, is a large-area (800 arcmin2) two-color (F606W and F850LP) imaging survey with the Advanced Camera for Surveys on HST. Centered on the Chandra Deep Field South, it covers an area of ~28'x28', or about 120 Hubble Deep Field areas, to a depth of m_AB(F606W)=28.3 (5sigma and m_AB(F850LP)=27.1 (5sigma) for compact sources. In its central ~1/4, GEMS incorporates ACS imaging from the GOODS project. Focusing on the redshift range 0.2<=z<=1.1, GEMS provides morphologies and structural parameters for nearly 10,000 galaxies where redshift estimates, luminosities and SEDs exist from COMBO-17. At the same time, GEMS contains detectable host galaxy images for several hundred faint AGN. This paper provides an overview of the science goals, the experiment design, the data reduction and the science analysis plan for GEMS.Comment: 24 pages, TeX with 6 eps Figures; to appear in ApJ Supplement. Low resolution figures only. Full resolution at http://zwicky.as.arizona.edu/~rix/Misc/GEMS.ps.g