Netherlands Institute for Space Research

About: Netherlands Institute for Space Research is a facility organization based out in Utrecht, Netherlands. It is known for research contribution in the topics: Galaxy & Neutron star. The organization has 737 authors who have published 3026 publications receiving 106632 citations. The organization is also known as: SRON & Space Research Organisation Netherlands.

Athena: ESA's X‐ray observatory for the late 2020s

Abstract: This research was supported by the Spanish Ministry of Economy and Competitiveness, ESP2014-53672-C3-1-P and AYA2015-64346-C2-1-P.

Thermal desorption of circumstellar and cometary ice analogs

Abstract: Context. Thermal annealing of interstellar ices takes place in sever al stages of star formation. Knowledge of this process comes from a combination of astronomical observations and laboratory simulations under astrophysically relevant conditions. Aims. For the first time we present the results of temperature progr ammed desorption (TPD) experiments with pre-cometary ice analogs composed of up to five molecular components: H 2O, CO, CO2, CH3OH, and NH3. Methods. The experiments were performed with an ultra-high vacuum chamber. A gas line with a novel design allows the controlled preparation of mixtures with up to five molecular components . Volatiles desorbing to the gas phase were monitored using a quadrupole mass spectrometer, while changes in the ice structure and composition were studied by means of infrared spectroscopy. Results. The TPD curves of water ice containing CO, CO2, CH3OH, and NH3 present desorption peaks at temperatures near those observed in pure ice experiments, volcano desorption peaks after water ice crystallization, and co-desorption peaks w ith water. Desorption peaks of CH3OH and NH3 at temperatures similar to the pure ices takes place when their abundance relative to water is above ∼ 3 % in the ice matrix. We found that CO, CO2, and NH3 also present co-desorption peaks with CH3OH, which cannot be reproduced in experiments with binary water-rich ice mixtures. These are extensively used in the study of thermal desorption of interstellar ices. Conclusions. These results reproduce the heating of circumstellar ices i n hot cores and can be also applied to the late thermal evolution of comets. In particular, TPD curves represent a benchmark for the analysis of the measurements that mass spectrometers on board the ESA-Rosetta cometary mission will perform on the coma of comet 67P/Churyumov-Gerasimenko, which will be active before the arrival of Rosetta according to our predictions.

The star formation rate density from z = 1 to 6

Abstract: We use 3035 Herschel-SPIRE 500 μm sources from 203 deg² of sky in the HerMES Lockman, ES1 and XMM-LSS areas to estimate the star formation rate density at z = 0–6 500 μm sources are associated first with 350 and 250 μm sources, and then with Spitzer 24 μm sources from the SWIRE photometric redshift catalogue The infrared and submillimetre data are fitted with a set of radiative-transfer templates corresponding to cirrus (quiescent) and starburst galaxies Lensing candidates are removed via a set of colour–colour and colour–redshift constraints Star formation rates are found to extend from <1 to 20 000 M⊙ yr−1 Such high values were also seen in the all-sky IRAS Faint Source Survey Star formation rate functions are derived in a series of redshift bins from 0 to 6, combined with earlier far-infrared estimates, where available, and fitted with a Saunders et al (1990) functional form The star formation rate density as a function of redshift is derived and compared with other estimates There is reasonable agreement with both infrared and ultraviolet estimates for z < 3, but we find higher star formation rate densities than ultraviolet estimates at z = 3–6 Given the considerable uncertainties in the submillimetre estimates, we cannot rule out the possibility that the ultraviolet estimates are correct But the possibility that the ultraviolet estimates have seriously underestimated the contribution of dust-shrouded star formation can also not be excluded

The First Swift Intensive AGN Accretion Disk Reverberation Mapping Survey

Abstract: Swift intensive accretion disk reverberation mapping of four AGN yielded light curves sampled ~200–350 times in 0.3–10 keV X-ray and six UV/optical bands. Uniform reduction and cross-correlation analysis of these data sets yields three main results: (1) The X-ray/UV correlations are much weaker than those within the UV/optical, posing severe problems for the lamp-post reprocessing model in which variations in a central X-ray corona drive and power those in the surrounding accretion disk. (2) The UV/optical interband lags are generally consistent with $\tau \propto {\lambda }^{4/3}$ as predicted by the centrally illuminated thin accretion disk model. While the average interband lags are somewhat larger than predicted, these results alone are not inconsistent with the thin disk model given the large systematic uncertainties involved. (3) The one exception is the U band lags, which are on average a factor of ~2.2 larger than predicted from the surrounding band data and fits. This excess appears to be due to diffuse continuum emission from the broad-line region (BLR). The precise mixing of disk and BLR components cannot be determined from these data alone. The lags in different AGN appear to scale with mass or luminosity. We also find that there are systematic differences between the uncertainties derived by JAVELIN versus more standard lag measurement techniques, with JAVELIN reporting smaller uncertainties by a factor of 2.5 on average. In order to be conservative only standard techniques were used in the analyses reported herein.

A candidate circumbinary Keplerian disk in G35.20-0.74 N: A study with ALMA

Abstract: We report on ALMA observations of continuum and molecular line emission with 0 ''4 resolution towards the high-mass star-forming region G3520-074 N Two dense cores are detected in typical hot-core tracers (e g, CH3CN) that reveal velocity gradients In one of these cores, the velocity field can be fitted with an almost edge-on Keplerian disk rotating about a central mass of similar to 18 M-circle dot This finding is consistent with the results of a recent study of the CO first overtone bandhead emission at 23 mu m towards G3520-074 N The disk radius and mass are greater than or similar to 2500 au and similar to 3 M-circle dot To reconcile the observed bolometric luminosity (similar to 3x10(4) L-circle dot) with the estimated stellar mass of 18 M-circle dot, we propose that the latter is the total mass of a binary system