Institution
Netherlands Institute for Space Research
Facility•Utrecht, Netherlands•
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.
Topics: Galaxy, Neutron star, Stars, Spectral line, Luminosity
Papers published on a yearly basis
Papers
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University of Padua1, Open University2, INAF3, University of the Western Cape4, University of Edinburgh5, Paris Diderot University6, University of Paris-Sud7, Jet Propulsion Laboratory8, California Institute of Technology9, Imperial College London10, University of Colorado Boulder11, European Space Agency12, University of California, Irvine13, Virginia Tech14, Institut d'Astrophysique de Paris15, Cardiff University16, Aix-Marseille University17, Valparaiso University18, UK Astronomy Technology Centre19, University of Sussex20, University College London21, Rutherford Appleton Laboratory22, University of La Laguna23, Spanish National Research Council24, University of Oxford25, University of British Columbia26, Curtin University27, Netherlands Institute for Space Research28, Durham University29, University of Copenhagen30
TL;DR: In this paper, the authors used wide-area surveys over 39 deg^2 by the HerMES (Herschel Multi-tiered Extragalactic Survey) collaboration, performed with the Herschel Observatory SPIRE multiwavelength camera, to estimate the low-redshift, 0.02 \lt z \lt 0.5, monochromatic luminosity functions (LFs) of galaxies at 250, 350 and 500 μm.
Abstract: We used wide-area surveys over 39 deg^2 by the HerMES (Herschel Multi-tiered Extragalactic Survey) collaboration, performed with the Herschel Observatory SPIRE multiwavelength camera, to estimate the low-redshift, 0.02 \lt z \lt 0.5, monochromatic luminosity functions (LFs) of galaxies at 250, 350 and 500 μm. Within this redshift interval, we detected 7087 sources in five independent sky areas, \tilde40 per cent of which have spectroscopic redshifts, while for the remaining objects photometric redshifts were used. The SPIRE LFs in different fields did not show any field-to-field variations beyond the small differences to be expected from cosmic variance. SPIRE flux densities were also combined with Spitzer photometry and multiwavelength archival data to perform a complete spectral energy distribution fitting analysis of SPIRE detected sources to calculate precise k-corrections, as well as the bolometric infrared (IR; 8-1000 μm) LFs and their low-z evolution from a combination of statistical estimators. Integration of the latter prompted us to also compute the local luminosity density and the comoving star formation rate density (SFRD) for our sources, and to compare them with theoretical predictions of galaxy formation models. The LFs show significant and rapid luminosity evolution already at low redshifts, 0.02 \lt z \lt 0.2, with L_\IR\^\*\ \prop (1+z)^\6.0\plusmn 0.4\ and Φ _\IR\^\*\ \prop (1+z)^\-2.1\plusmn 0.4\, L_\250\^\*\ \prop (1+z)^\5.3\plusmn 0.2\ and Φ _\250\^\*\ \prop (1+z)^\-0.6\plusmn 0.4\ estimated using the IR bolometric and the 250 μm LFs, respectively. Converting our IR LD estimate into an SFRD assuming a standard Salpeter initial mass function and including the unobscured contribution based on the UV dust-uncorrected emission from local galaxies, we estimate an SFRD scaling of SFRD_0 + 0.08z, where SFRD_0 ∼e (1.9 \plusmn 0.03) × 10^-2 [M_⊙ Mpc^-3] is our total SFRD estimate at z \tilde 0.02.
51 citations
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TL;DR: This article conducted a global inverse analysis of 2010-2018 GOSAT observations to better understand the factors controlling atmospheric methane and its accelerating increase over the 2010 -2018 period, and showed large 2010−2018 increases in anthropogenic methane emissions over South Asia, tropical Africa, and Brazil, coincident with rapidly growing livestock populations in these regions.
Abstract: . We conduct a global inverse analysis of 2010–2018 GOSAT
observations to better understand the factors controlling
atmospheric methane and its accelerating increase over the 2010–2018
period. The inversion optimizes anthropogenic methane emissions and their
2010–2018 trends on a 4 ∘ × 5 ∘
grid, monthly regional wetland emissions, and annual hemispheric
concentrations of tropospheric OH (the main sink of methane). We use an
analytical solution to the Bayesian optimization problem that provides
closed-form estimates of error covariances and information content for the
solution. We verify our inversion results with independent methane
observations from the TCCON and NOAA networks. Our inversion successfully
reproduces the interannual variability of the methane growth rate inferred
from NOAA background sites. We find that prior estimates of fuel-related
emissions reported by individual countries to the United Nations are too
high for China (coal) and Russia (oil and gas) and too low for Venezuela
(oil and gas) and the US (oil and gas). We show large 2010–2018 increases in
anthropogenic methane emissions over South Asia, tropical Africa, and
Brazil, coincident with rapidly growing livestock populations in these
regions. We do not find a significant trend in anthropogenic emissions over
regions with high rates of production or use of fossil methane, including the US,
Russia, and Europe. Our results indicate that the peak methane growth rates
in 2014–2015 are driven by low OH concentrations (2014) and high fire
emissions (2015), while strong emissions from tropical (Amazon and tropical
Africa) and boreal (Eurasia) wetlands combined with increasing anthropogenic
emissions drive high growth rates in 2016–2018. Our best estimate is that
OH did not contribute significantly to the 2010–2018 methane trend other
than the 2014 spike, though error correlation with global anthropogenic
emissions limits confidence in this result.
51 citations
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TL;DR: In this paper, the presence and strength of the 69 {μ$}m emission band of the crystalline silicate forsterite was analyzed in terms of position and shape to derive the temperature and composition of the dust by comparison to laboratory spectra.
Abstract: Context. We have analysed far-infrared spectra of 32 circumstellar disks around Herbig Ae/Be and T Tauri stars obtained within the Herschel key programme Dust, Ice and Gas in Time (DIGIT). The spectra were taken with the Photodetector Array Camera and Spectrometer (PACS) on board the Herschel Space Observatory. In this paper we focus on the detection and analysis of the 69 {$μ$}m emission band of the crystalline silicate forsterite.
Aims: This work aims at providing an overview of the 69 {$μ$}m forsterite bands present in the DIGIT sample. We use characteristics of the emission band (peak position and FWHM) to derive the dust temperature and to constrain the iron content of the crystalline silicates. With this information, constraints can be placed on the spatial distribution of the forsterite in the disk and the formation history of the crystalline grains.
Methods: The 69 {$μ$}m forsterite emission feature is analysed in terms of position and shape to derive the temperature and composition of the dust by comparison to laboratory spectra of that band. The PACS spectra are combined with existing Spitzer IRS spectra and we compare the presence and strength of the 69 {$μ$}m band to the forsterite bands at shorter wavelengths.
Results: A total of 32 disk sources have been observed. Out of these 32, 8 sources show a 69 {$μ$}m emission feature that can be attributed to forsterite. With the exception of the T Tauri star AS 205, all of the detections are for disks associated with Herbig Ae/Be stars. Most of the forsterite grains that give rise to the 69 {$μ$}m bands are found to be warm (~{}100-200 K) and iron-poor (less than ~{}2% iron). AB Aur is the only source where the emission cannot be fitted with iron-free forsterite requiring approximately 3-4% of iron.
Conclusions: Our findings support the hypothesis that the forsterite grains form through an equilibrium condensation process at high temperatures. The large width of the emission band in some sources may indicate the presence of forsterite reservoirs at different temperatures. The connection between the strength of the 69 and 33 {$μ$}m bands shows that at least part of the emission in these two bands originates fom the same dust grains. We further find that any model that can explain the PACS and the Spitzer IRS observations must take the effects of a wavelength dependent optical depth into account. We find weak indications of a correlation of the detection rate of the 69 {$μ$}m band with the spectral type of the host stars in our sample. However, the sample size is too small to obtain a definitive result. Appendix A is available in electronic form at http://www.aanda.org
51 citations
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TL;DR: In this paper, a mid-IR interferometric survey of the circumstellar environment of a specific class of post-asymptotic giant branch (post-AGB) binaries is presented.
Abstract: Aims. We present a mid-IR interferometric survey of the circumstellar environment of a specific class of post-asymptotic giant branch (post-AGB) binaries. For this class the presence of a compact dusty disk has been postulated on the basis of various spatially unresolved measurements. The aim is to determine the angular extent of the N -band emission directly and to resolve the compact circumstellar structures.Methods. Our interferometric survey was performed with the MIDI instrument on the VLTI. In total 19 different systems were observed using variable baseline configurations. Combining all the visibilities at a single wavelength at 10.7 μ m, we fitted two parametric models to the data: a uniform disk and a ring model mimicking a temperature gradient. We compared our observables of the whole sample, with synthetic data computed from a grid of radiative transfer models of passively irradiated disks in hydrostatic equilibrium. These models are computed with a Monte Carlo code that has been widely applied to describe the structure of protoplanetary disks around young stellar objects (YSO). Results. The spatially resolved observations show that the majority of our targets cluster closely together in the distance-independent size-colour diagram, and have extremely compact N -band emission regions. The typical uniform disk diameter of the N -band emission region is ~40 mas, which corresponds to a typical brightness temperature of 400–600 K. The resolved objects display very similar characteristics in the interferometric observables and in the spectral energy distributions. Therefore, the physical properties of the disks around our targets must be similar. Our results are discussed in the light of recently published sample studies of YSOs to compare quantitatively the secondary discs around post-AGB stars to the ones around YSOs. Conclusions. Our high-angular-resolution survey further confirms the disk nature of the circumstellar structures present around wide post-AGB binaries. The grid of protoplanetary disk models covers very well the observed objects. Much like for young stars, the spatially resolved N -band emission region is determined by the hot inner rim of the disk. Continued comparisons between post-AGB and protoplanetary disks will help to understand grain growth and disk evolution processes, and to constrain planet formation theories. These second-generation disks are an important missing ingredient in binary evolution theory of intermediate-mass stars.
51 citations
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Delft University of Technology1, Netherlands Institute for Space Research2, Nagoya University3, Graduate University for Advanced Studies4, University of Tokyo5, University of Electro-Communications6, Cardiff University7, Hokkaido University8, Moscow State Pedagogical University9, Japan Aerospace Exploration Agency10, Saitama University11, KEK12, Leiden University13
TL;DR: In this paper, the authors present the design and astronomical spectra of an intrinsically scalable, integrated superconducting spectrometer, which combines the multiplexing advantage of microwave kinetic inductance detectors (MKIDs)7 with planar super-conducting filters for dispersing the signal in a single, small, small integrated circuit and demonstrates the two key applications of this type: as an efficient redshift machine and as a fast multi-line spectral mapper of extended areas.
Abstract: Ultra-wideband, three-dimensional (3D) imaging spectrometry in the millimeter–submillimeter (mm–submm) band is an essential tool for uncovering the dust-enshrouded portion of the cosmic history of star formation and galaxy evolution1–3. However, it is challenging to scale up conventional coherent heterodyne receivers4 or free-space diffraction techniques5 to sufficient bandwidths (≥1 octave) and numbers of spatial pixels2,3 (>102). Here, we present the design and astronomical spectra of an intrinsically scalable, integrated superconducting spectrometer6, which covers 332–377 GHz with a spectral resolution of F/ΔF ~ 380. It combines the multiplexing advantage of microwave kinetic inductance detectors (MKIDs)7 with planar superconducting filters for dispersing the signal in a single, small superconducting integrated circuit. We demonstrate the two key applications for an instrument of this type: as an efficient redshift machine and as a fast multi-line spectral mapper of extended areas. The line detection sensitivity is in excellent agreement with the instrument design and laboratory performance, reaching the atmospheric foreground photon noise limit on-sky. The design can be scaled to bandwidths in excess of an octave, spectral resolution up to a few thousand and frequencies up to ~1.1 THz. The miniature chip footprint of a few cm2 allows for compact multi-pixel spectral imagers, which would enable spectroscopic direct imaging and large-volume spectroscopic surveys that are several orders of magnitude faster than what is currently possible1–3. By using a superconducting integrated circuit to filter incoming millimetre, submillimetre and far-infrared light from distant galaxies, a prototype spectrometer holds promise for wideband spectrometers that are small, sensitive and scalable to wideband spectroscopic imagers.
51 citations
Authors
Showing all 756 results
Name | H-index | Papers | Citations |
---|---|---|---|
George Helou | 144 | 662 | 96338 |
Alexander G. G. M. Tielens | 115 | 722 | 51058 |
Gijs Nelemans | 102 | 433 | 83486 |
Jelle Kaastra | 90 | 677 | 28093 |
Christian Frankenberg | 79 | 286 | 19353 |
Jeroen Homan | 72 | 354 | 15499 |
Nanda Rea | 72 | 446 | 19881 |
Mariano Mendez | 70 | 372 | 14475 |
Jorick S. Vink | 70 | 311 | 18826 |
Peter G. Jonker | 67 | 384 | 28363 |
Michael W. Wise | 64 | 271 | 19580 |
George Heald | 64 | 375 | 16261 |
Pieter R. Roelfsema | 64 | 257 | 18759 |
F. F. S. van der Tak | 63 | 314 | 16781 |
Norbert Werner | 63 | 254 | 10741 |