Showing papers by "Bärbel S. Koribalski published in 2014"
TL;DR: In this paper, the authors proposed a new analytic function, named the "busy function", that can be used to accurately describe the characteristic double-horn HI profile of many galaxies, including the Tully-Fisher relation and the HI mass function.
Abstract: Accurate parametrization of galaxies detected in the 21-cm HI emission is of fundamental importance to the measurement of commonly used indicators of galaxy evolution, including the Tully-Fisher relation and the HI mass function. Here, we propose a new analytic function, named the 'busy function', that can be used to accurately describe the characteristic double-horn HI profile of many galaxies. The busy function is a continuous, differentiable function that consists of only two basic functions, the error function, erf(x), and a polynomial, vertical bar x vertical bar(n), of degree n >= 2. We present the basic properties of the busy function and illustrate its great flexibility in fitting a wide range of HI profiles from the Gaussian profiles of dwarf galaxies to the broad, asymmetric double-horn profiles of spiral galaxies. Applications of the busy function include the accurate and efficient parametrization of observed HI spectra of galaxies and the construction of spectral templates for simulations and matched-filtering algorithms. We demonstrate the busy function's power by automatically fitting it to the HI spectra of 1000 galaxies from the HI Parkes All-Sky Survey (HIPASS) Bright Galaxy Catalog, using our own C/C++ implementation, and comparing the resulting parameters with the catalogued ones. We also present two methods for determining the uncertainties of observational parameters derived from the fit.
62 citations
TL;DR: In this article, the authors performed a deep X-ray observation of the galaxies NGC1512 and NGC 1510 with XMM-Newton to gain information on the population of Xray sources and diffuse emission in a system of interacting galaxies.
Abstract: The galaxy NGC1512 is interacting with the smaller galaxy NGC1510 and shows a peculiar morphology, characterised by two extended arms immersed in an HI disc whose size is about four times larger than the optical diameter of NGC1512. For the first time we performed a deep X-ray observation of the galaxies NGC1512 and NGC1510 with XMM-Newton to gain information on the population of X-ray sources and diffuse emission in a system of interacting galaxies. We identified and classified the sources detected in the XMM-Newton field of view by means of spectral analysis, hardness-ratios calculated with a Bayesian method, X-ray variability, and cross-correlations with catalogues in optical, infrared, and radio wavelengths. We also made use of archival Swift (X-ray) and Australia Telescope Compact Array (radio) data to better constrain the nature of the sources detected with XMM-Newton. We detected 106 sources in the energy range of 0.2-12 keV, out of which 15 are located within the D_25 regions of NGC1512 and NGC1510 and at least six sources coincide with the extended arms. We identified and classified six background objects and six foreground stars. We discussed the nature of a source within the D_25 ellipse of NGC1512, whose properties indicate a quasi-stellar object or an intermediate ultra-luminous X-ray source. Taking into account the contribution of low-mass X-ray binaries and active galactic nuclei, the number of high-mass X-ray binaries detected within the D_25 region of NGC1512 is consistent with the star formation rate obtained in previous works based on radio, infrared optical, and UV wavelengths. We detected diffuse X-ray emission from the interior region of NGC1512 with a plasma temperature of kT=0.68(0.31-0.87) keV and a 0.3-10 keV X-ray luminosity of 1.3E38 erg/s, after correcting for unresolved discrete sources.
9 citations
01 Jul 2014
TL;DR: In this article, the authors present results from individual galaxy studies and galaxy surveys in the Local Universe with particular emphasis on the spatially resolved properties of neutral hydrogen gas, and use new 3D visualisation tools to present multi-wavelength data, aided by tilted-ring models of the warped galaxy disks.
Abstract: Here I present results from individual galaxy studies and galaxy surveys in the Local Universe with particular emphasis on the spatially resolved properties of neutral hydrogen gas. The 3D nature of the data allows detailed studies of the galaxy morphology and kinematics, their relation to local and global star formation as well as galaxy environments. I use new 3D visualisation tools to present multi-wavelength data, aided by tilted-ring models of the warped galaxy disks. Many of the algorithms and tools currently under development are essential for the exploration of upcoming large survey data, but are also highly beneficial for the analysis of current galaxy surveys.
5 citations
01 Dec 2014
TL;DR: SoFiA is a flexible source finding pipeline designed to detect and parameterise sources in 3D spectral-line data cubes using wavelet denoising, spatial and spectral smoothing, source mask optimisation, spectral profile fitting, and calculation of the reliability of detections.
Abstract: SoFiA is a flexible source finding pipeline designed to detect and parameterise sources in 3D spectral-line data cubes. SoFiA combines several powerful source finding and parameterisation algorithms, including wavelet denoising, spatial and spectral smoothing, source mask optimisation, spectral profile fitting, and calculation of the reliability of detections. In addition to source catalogues in different formats, SoFiA can also generate a range of output data cubes and images, including source masks, moment maps, sub-cubes, position-velocity diagrams, and integrated spectra. The pipeline is controlled by simple parameter files and can either be invoked on the command line or interactively through a modern graphical user interface.
3 citations