Search Publications
Mapping possible non-Gaussianity in the Planck maps
Bernui, A.; Rebouças, M. J.
Context. The study of the non-Gaussianity of the temperature fluctuations of cosmic background radiation (CMB) can be used to break the degeneracy between the inflationary models and to test alternative scenarios of the early universe. However, there are several sources of non-Gaussian contaminants in the CMB data, which make a convincing extracti…
Optical counterparts of ROSAT X-ray sources in two selected fields at low vs. high Galactic latitudes
Greiner, J.; Richter, G. A.
Context. The optical identification of large number of X-ray sources such as those from the ROSAT All-Sky Survey is challenging with conventional spectroscopic follow-up observations.
Aims: We investigate two ROSAT All-Sky Survey fields of size 10°× 10° each, one at galactic latitude b = 83° (26 Com), the other at b = -5° (γ Sge), in order to…
The FERRUM project: Experimental lifetimes and transition probabilities from highly excited even 4d levels in Fe ii
Nilsson, H.; Lundberg, H.; Hartman, H. +1 more
We report lifetime measurements of the 6 levels in the 3d6(5D)4d e6G term in Fe ii at an energy of 10.4 eV, and f-values for 14 transitions from the investigated levels. The lifetimes were measured using time-resolved laser-induced fluorescence on ions in a laser-produced plasma. The high excitation energy, and the…
The low energy magnetic spectrometer on Ulysses and ACE response to near relativistic protons
Filipe Maia, Dalmiro Jorge; Gonçalves, Patrícia; Morgado, Bruno +2 more
Aims: We show that the Heliosphere Instrument for Spectra Composition and Anisotropy at Low Energies (HISCALE) on board the Ulysses spacecraft and the Electron Proton Alpha Monitor (EPAM) on board the Advance Composition Explorer (ACE) spacecraft can be used to measure properties for ion populations with kinetic energies in excess of 1 GeV. T…
Proving strong magnetic fields near to the central black hole in the quasar PG0043+039 via cyclotron lines
Schartel, N.; Rodríguez-Pascual, P. M.; Santos-Lleó, M. +3 more
Context. The optical luminous quasar PG0043+039 has not been detected before in deep X-ray observations indicating the most extreme optical-to-X-ray slope index αox of all quasars.
Aims: This study aims to detect PG0043+039 in a deep X-ray exposure. Furthermore, we wanted to check out whether this object shows specific spectral pro…
Optical observations of comet 67P/Churyumov-Gerasimenko with the Nordic Optical Telescope. Comet activity before the solar conjunction
Snodgrass, C.; Schulz, R.; Nilsson, K. +4 more
Context. 67P/Churyumov-Gerasimenko (67P) is a short-period Jupiter-family comet that was chosen as a target for the Rosetta mission by the European Space Agency (ESA). Monitoring of 67P with the Nordic Optical Telescope (NOT; La Palma, Spain) intends to aid this mission by providing ground-based reference information about the overall activity of …
Infrared-faint radio sources remain undetected at far-infrared wavelengths. Deep photometric observations using the Herschel Space Observatory
Norris, R. P.; Leipski, C.; Spitler, L. R. +3 more
Context. Showing 1.4 GHz flux densities in the range of a few to a few tens of mJy, infrared-faint radio sources (IFRS) are a type of galaxy characterised by faint or absent near-infrared counterparts and consequently extreme radio-to-infrared flux density ratios up to several thousand. Recent studies showed that IFRS are radio-loud active galacti…
Mass-concentration relation and weak lensing peak counts
Maoli, R.; Scaramella, R.; Camera, S. +3 more
Context. The statistics of peaks in weak lensing convergence maps is a promising tool for investigating both the properties of dark matter haloes and constraining the cosmological parameters.
Aims: We study how the number of detectable peaks and its scaling with redshift depend upon the cluster's dark matter halo profiles and use peak statist…
Simulating charge transport to understand the spectral response of Swept Charge Devices
Narendranath, S.; Sreekumar, P.; Athiray, P. S. +1 more
Context. Swept Charge Devices (SCD) are novel X-ray detectors optimized for improved spectral performance without any demand for active cooling. The Chandrayaan-1 X-ray Spectrometer (C1XS) experiment onboard the Chandrayaan-1 spacecraft used an array of SCDs to map the global surface elemental abundances on the Moon using the X-ray fluorescence (X…
V342 Andromedae B is an eccentric-orbit eclipsing binary
Schwarzenberg-Czerny, A.; Bagińska, P.; Lehmann, H. +12 more
We present a photometric and spectroscopic study of the visual binary V342 Andromedae. Visual components of the system have angular separations of 3 arcseconds. We obtained two spectroscopic data sets. An examination of both the A and B component spectra reveals that the B component is a spectroscopic binary with an eccentric orbit. The orbital pe…