Search Publications
A GMRT study of Seyfert galaxies NGC 4235 and NGC 4594: evidence of episodic activity?
Singh, V.; Ishwara-Chandra, C. H.; Kharb, P. +3 more
Low-frequency observations at 325 and 610 MHz have been carried out for two `radio-loud' Seyfert galaxies, NGC 4235 and NGC 4594 (Sombrero galaxy), using the Giant Meterwave Radio Telescope (GMRT). The 610 MHz total intensity and 325-610 MHz spectral index images of NGC 4235 tentatively suggest the presence of a `relic' radio lobe, most likely fro…
Analysis of Coronal Rain Observed by IRIS, HINODE/SOT, and SDO/AIA: Transverse Oscillations, Kinematics, and Thermal Evolution
Kohutova, P.; Verwichte, E.
Coronal rain composed of cool plasma condensations falling from coronal heights along magnetic field lines is a phenomenon occurring mainly in active region coronal loops. Recent high-resolution observations have shown that coronal rain is much more common than previously thought, suggesting its important role in the chromosphere-corona mass cycle…
NuSTAR reveals the extreme properties of the super-Eddington accreting supermassive black hole in PG 1247+267
Harrison, F. A.; Stern, D.; Zhang, W. W. +26 more
PG1247+267 is one of the most luminous known quasars at z ~ 2 and is a strongly super-Eddington accreting supermassive black hole (SMBH) candidate. We obtained NuSTAR data of this intriguing source in December 2014 with the aim of studying its high-energy emission, leveraging the broad band covered by the new NuSTAR and the archival XMM-Newton dat…
Compositional and spatial variations in Titan dune and interdune regions from Cassini VIMS and RADAR
Malaska, Michael J.; Solomonidou, Anezina; Le Gall, Alice +4 more
Dunes cover about 15 % of Titan's visible surface, and represent one of the largest reservoirs of hydrocarbon solids on Titan (Rodriguez, S. et al. [2014]. Icarus 230, 168-179; Lopes, R.M.C. et al. [2016]. Icarus 270, 162-182.). Herein, we use data from the Cassini spacecraft to derive constraints on the compositional and regional variability of T…
Gaia Data Release 1. On-orbit performance of the Gaia CCDs at L2
Prusti, T.; Mora, A.; Brown, A. G. A. +19 more
The European Space Agency's Gaia satellite was launched into orbit around L2 in December 2013 with a payload containing 106 large-format scientific CCDs. The primary goal of the mission is to repeatedly obtain high-precision astrometric and photometric measurements of one thousand million stars over the course of five years. The scientific value o…
Rosetta lander Philae - Landing performance and touchdown safety assessment
Jurado, Eric; Ulamec, Stephan; Biele, Jens +2 more
This paper describes the simulation and analysis work on Rosetta lander Philae's touchdown dynamics which was done to support its Landing Site Selection Process. The simulation part consists of a numerical multi-body simulation to describe Philae's touchdown dynamics. Suitable performance metrics in conjunction with Monte Carlo trajectory data fro…
A Very Compact Dense Galaxy Overdensity with δ ≃ 130 Identified at z ∼ 8: Implications for Early Protocluster and Cluster Core Formation
Ouchi, Masami; Harikane, Yuichi; Ishigaki, Masafumi
We report the first identification of a compact dense galaxy overdensity at z∼ 8 called A2744z8OD. A2744z8OD consists of eight Y-dropout galaxies behind Abell 2744 that were originally pinpointed by Hubble Frontier Fields studies. However, so far, no studies have derived the basic physical quantities of structure formation or made comparisons with…
Galaxy clustering, CMB and supernova data constraints on ϕCDM model with massive neutrinos
Xu, Lixin; Chen, Yun
We investigate a scalar field dark energy model (i.e., ϕCDM model) with massive neutrinos, where the scalar field possesses an inverse power-law potential, i.e., V (ϕ) ∝ϕ-α (α > 0). We find that the sum of neutrino masses Σmν has significant impacts on the CMB temperature power spectrum and on the matter power spectrum. In…
Probing deep photospheric layers of the quiet Sun with high magnetic sensitivity
Franz, M.; Schmidt, W.; Solanki, S. K. +31 more
Context. Investigations of the magnetism of the quiet Sun are hindered by extremely weak polarization signals in Fraunhofer spectral lines. Photon noise, straylight, and the systematically different sensitivity of the Zeeman effect to longitudinal and transversal magnetic fields result in controversial results in terms of the strength and angular …
The evolution of the Sun's birth cluster and the search for the solar siblings with Gaia
Brown, A. G. A.; Antoja, T.; Portegies Zwart, S. +3 more
We use self-consistent numerical simulations of the evolution and disruption of the Sun's birth cluster in the Milky Way potential to investigate the present-day phase-space distribution of the Sun's siblings. The simulations include the gravitational N-body forces within the cluster and the effects of stellar evolution on the cluster population. …