Searching for electromagnetic counterpart of LIGO gravitational waves in the Fermi GBM data with ADWO

The Fermi collaboration identified a possible electromagnetic counterpart of the gravitational wave event of September 14, 2015. Our goal is to provide an unsupervised data analysis algorithm to identify similar events in Fermi's Gamma-ray Burst Monitor CTTE data stream. We are looking for signals that are typically weak. Therefore, they can only be found by a careful analysis of count rates of all detectors and energy channels simultaneously. Our Automatized Detector Weight Optimization (ADWO) method consists of a search for the signal, and a test of its significance. We developed ADWO, a virtual detector analysis tool for multi-channel multi-detector signals, and performed successful searches for short transients in the data-streams. We have identified GRB150522B, as well as possible electromagnetic candidates of the transients GW150914 and LVT151012. ADWO is an independently developed, unsupervised data analysis tool that only relies on the raw data of the Fermi satellite. It can therefore provide a strong, independent test to any electromagnetic signal accompanying future gravitational wave observations.Comment: 4 pages and 4 figures, A&A Letters accepte

Revealing a strongly reddened, faint active galactic nucleus population by stacking deep co-added images

More than half of the sources identified by recent radio sky surveys have not been detected by wide-field optical surveys. We present a study, based on our co-added image stacking technique, in which our aim is to detect the optical emission from unresolved, isolated radio sources of the Very Large Array (VLA) Faint Images of the Radio Sky at Twenty-cm (FIRST) survey that have no identified optical counterparts in the Sloan Digital Sky Survey (SDSS) Stripe 82 co-added data set. From the FIRST catalogue, 2116 such radio point sources were selected, and cut-out images, centred on the FIRST coordinates, were generated from the Stripe 82 images. The already co-added cut-outs were stacked once again to obtain images of high signal-to-noise ratio, in the hope that optical emission from the radio sources would become detectable. Multiple stacks were generated, based on the radio luminosity of the point sources. The resulting stacked images show central peaks similar to point sources. The peaks have very red colours with steep optical spectral energy distributions. We have found that the optical spectral index α ν falls in the range -2.9 ≤ α ν ≤ -2.2 (Sν∝ναν), depending only weakly on the radio flux. The total integration times of the stacks are between 270 and 300h, and the corresponding 5σ detection limit is estimated to be about m r ≃ 26.6 mag. We argue that the detected light is mainly from the central regions of dust-reddened Type 1 active galactic nuclei. Dust-reddened quasars might represent an early phase of quasar evolution, and thus they can also give us an insight into the formation of massive galaxies. The data used in the paper are available on-line at http://www.vo.elte.hu/doublestacking. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS

PALLADIUM BASED CONTACTS TO GaAs AND InP

Au(85nm)/Pd(55nm) and Pd(55nm) metallizations were deposited on GaAs(lOO) and InP(100) substrates. The samples were heat treated in a scanning electron microscope (SEM) equipped with a quadrupole mass spectrometer. The simultaneous observation of the volatile component loss (in situ) by Evolved Gas Analysis (EGA) and the change in surface morphology by SEM during the heart treatment using a heating rate of 30°C/min were carried out. The interaction of the metallization with compound semiconductor substrates was observed after the heat treatment by transmission electron microscopy (TEM) using samples prepared by cross-sectional technique. In the course of the present work a large volatile component (arsenic and phosphorus) loss was observed for the samples coated by single layer metallization (at 410° C for Pd/GaAs and at 580°C for Pd/InP) and two peaks were registered in the case of Au/Pd metallization. In the latter case the cause of the second evaporation peak is the interaction between diffused gold and compound semiconductor. The SEM images of the surfaces demonstrate a significant change of the surface morphology at the singularities of the EGA curves. The grains grown into the semiconductors are shown by the cross-sectional images of the heat treated samples

Time-dependent properties of sunspot groups. I. Lifetime and asymmetric evolution

Aims. In this paper, we aim to study the time dependence of sunspot group areas in a large sample composed of various databases spanning over 130 years, used state-of-the-art statistical methods. Methods. For a carefully selected but unbiased sample, we use Bayesian modelling to fit the temporal evolution of the combined umbral and penumbral area of spot groups with a skew-normal function to determine the existence of any asymmetry in spot growth or decay. Our primary selection criteria guaranteed that only spot groups with a well-defined maximum area were taken into account. We also analysed the covariance of the resulting model parameters and their correlations with the physical parameters of the sunspots and the ongoing solar cycle. Results. Our results show that the temporal evolution of well-observed sunspot groups that reach at least 50 millionths of a solar hemisphere at their maximum can be fitted surprisingly well with our model. Furthermore, we show significant asymmetry – described by a skew parameter of fitted curves – between the growing and decaying phases of analysed sunspot groups. In addition, we found a weak correlation between the values of skew parameters and the maximum area of sunspot groups and their hemispherical latitude

Probing Spectroscopic Variability of Galaxies & Narrow-Line Active Galactic Nuclei in the Sloan Digital Sky Survey

Under the unified model for active galactic nuclei (AGNs), narrow-line (Type 2) AGNs are, in fact, broad-line (Type 1) AGNs but each with a heavily obscured accretion disk. We would therefore expect the optical continuum emission from Type 2 AGN to be composed mainly of stellar light and non-variable on the time-scales of months to years. In this work we probe the spectroscopic variability of galaxies and narrow-line AGNs using the multi-epoch data in the Sloan Digital Sky Survey (SDSS) Data Release 6. The sample contains 18,435 sources for which there exist pairs of spectroscopic observations (with a maximum separation in time of ~700 days) covering a wavelength range of 3900-8900 angstrom. To obtain a reliable repeatability measurement between each spectral pair, we consider a number of techniques for spectrophotometric calibration resulting in an improved spectrophotometric calibration of a factor of two. From these data we find no obvious continuum and emission-line variability in the narrow-line AGNs on average -- the spectroscopic variability of the continuum is 0.07+/-0.26 mag in the g band and, for the emission-line ratios log10([NII]/Halpha) and log10([OIII]/Hbeta), the variability is 0.02+/-0.03 dex and 0.06+/-0.08 dex, respectively. From the continuum variability measurement we set an upper limit on the ratio between the flux of varying spectral component, presumably related to AGN activities, and that of host galaxy to be ~30%. We provide the corresponding upper limits for other spectral classes, including those from the BPT diagram, eClass galaxy classification, stars and quasars.Comment: AJ accepte

The benefit of a mechanical needle stimulation pad in patients with chronic neck and lower back pain: Two randomized controlled pilot studies

Objectives. The objective was to investigate whether a treatment with a needle stimulation pad (NSP) changes perceived pain and/or sensory thresholds in patients with chronic neck (NP) and lower back pain (BP). Methods. 40 patients with chronic NP and 42 patients with chronic BP were equally randomized to either treatment or waiting list control group. The treatment group self-administered a NSP over a period of 14 days. Pain ratings were recorded on numerical rating scales (NRSs). Mechanical detection thresholds (MDTs) and pressure pain thresholds (PPTs) were determined at the site of maximal pain and in the adjacent region, vibration detection thresholds (VDT) were measured at close spinal processes. The Northwick Park Neck Pain Questionnaire (NPQ) and the Oswestry Disability Index (ODI) were utilized for the NP and BP study, respectively. Results. NRS ratings were significantly reduced for the treatment groups compared to the control groups (NP: P =. 021 and BP: P . 001), accompanied by a significant increase of PPT at pain maximum (NP: P =. 032 and BP: P =. 013). There was no effect on VDT and MDT. The NPQ showed also a significant improvement, but not the ODI. Conclusions. The mechanical NSP seems to be an effective treatment method for chronic NP and BP. © 2012 Claudia Hohmann et al