13 research outputs found

    A 10 kpc Scale Seyfert Galaxy Outflow: HST/COS Observations of IRAS F22456-5125

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    We present analysis of the UV-spectrum of the low-z AGN IRAS-F22456-5125 obtained with the Cosmic Origins Spectrograph on board the Hubble Space Telescope. The spectrum reveals six main kinematic components, spanning a range of velocities of up to 800 km s-1, which for the first time are observed in troughs associated with CII, CIV, NV, SiII, SiIII, SiIV and SIV. We also obtain data on the OVI troughs, which we compare to those available from an earlier FUSE epoch. Column densities measured from these ions allow us to derive a well-constrained photoionization solution for each outflow component. Two of these kinematic components show troughs associated with transitions from excited states of SiII\ and CII. The number density inferred from these troughs, in combination with the deduced ioinization parameter, allows us to determine the distance to these outflow components from the central source. We find these components to be at a distance of ~ 10 kpc. The distances and the number densities derived are consistent with the outflow being part of a galactic wind.Comment: 52 pages, 15 figures, accepted for publication in ApJ March 25, 201

    BAL phosphorus abundance and evidence for immense ionic column densities in quasar outflows: VLT X-Shooter observations of quasar SDSS J1512+1119

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    We present spectroscopic analysis of the broad absorption line outflow in quasar SDSS J1512+1119. In particular, we focus our attention on a kinematic component in which we identify PV and SIV/SIV* absorption troughs. The shape of the unblended phosphorus doublet troughs and the three SIV/SIV* troughs allow us to obtain reliable column density measurements for these two ions. Photoionization modelling using these column densities and those of HeI* constrain the abundance of phosphorus to the range of 0.5-4 times the solar value. The total column density, ionization parameter and metalicity inferred from the PV and SIV column densities leads to large optical depth values for the common transition observed in BAL outflows. We show that the true CIV optical depth, is about 1000 times greater in the core of the absorption profile than the value deduced from its apparent optical depth.Comment: Accepted for publication in ApJ on August 26, 2012; 33 pages, 8 figure

    Development of full-field deflectometry for characterization of free-form mirrors for space applications

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    We demonstrate that full-field deflectometry is a viable alternative to interferometry for the characterization of free-form mirrors. Deflectometry does not require the use of a CGH. Instead of measuring the surface height map, the deflectometer measures the surface slopes in two orthogonal directions using the phase-shifting Schlieren method [1]. The surface height map is then reconstructed by integration of the slope maps. We present two instruments. The first one can be mounted in the lathe for in situ measurement. The second is adapted for the characterization of large concave mirrors

    Galactic-scale absorption outflow in the low-luminosity quasar IRAS F04250-5718: Hubble space telescope/cosmic origins spectrograph observations

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    We present absorption line analysis of the outflow in the quasar IRAS F04250?5718. Far-ultraviolet data from the Cosmic Origins Spectrograph on board the Hubble Space Telescope reveal intrinsic narrow absorption lines from high ionization ions (e.g., C iv, N v, and O vi) as well as low ionization ions (e.g., Cii and Si iii). We identify three kinematic components with central velocities ranging from ??50 to ??230 km s?1. Velocity-dependent, nonblack saturation is evident from the line profiles of the high ionization ions. From the non-detection of absorption from a metastable level of C ii, we are able to determine that the electron number density in the main component of the outflow is 30 cm?3. Photoionization analysis yields an ionization parameter log UH ? ?1.6 ± 0.2, which accounts for changes in the metallicity of the outflow and the shape of the incident spectrum. We also consider solutions with two ionization parameters. If the ionization structure of the outflow is due to photoionization by the active galactic nucleus, we determine that the distance to this component from the central source is 3 kpc. Due to the large distance determined for the main kinematic component, we discuss the possibility that this outflow is part of a galactic wind.We acknowledge support from NASA STScI grants GO 11686 and GO 12022 as well as NSF grant AST 0837880. We thank Pat Hall for insightful suggestions and discussions. J.I.G.-S. and C.B. acknowledge financial support from the Spanish Ministerio de Ciencia e Innovacion under project AYA2008-06311-C02-02

    Freeform Grating-Based Hyperspectral Instruments: When SmallSat Solutions Benefit to Big Missions

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    Hyperspectral Earth Observation is a fast-growing field requiring high performing imaging spectrometers. Since 2010, the European Space Agency has initiated a series of developments demonstrating the feasibility of miniaturized hyperspectral instruments on mini-and nano-satellites[1]. Among them, ELOIS and CHIMA are two innovative full Aluminum instruments based on diffraction gratings ruled on a freeform surface (FFG : Free-Form Grating). That solution offers a reduction of about a factor of 4 in volume with respect to a Offner-Chrisp spectrometers with equivalent performances. The Spectrometers combines three promising new technologies for future hyperspectral instruments: complex blazed grating, freeform optics and backside-illuminated hyperspectral CMOS sensor. With an image space F-number of 2.1, ELOIS is also one of the fastest instrument of this type. The ratio between Swath and Ground Sampling Distance is about twice as big as currently planned hyperspectral missions. Breadboards of these spectro-imagers, limited to the visible and NIR spectra, has been manufactured and tested. This breadboard program confirmed the achievement of the challenging design specifications. Based on these demonstrations, a complete payload is now developed to cover the VNIR and SWIR spectral ranges (400nm to 2450 nm) with a spectral resolution of 10 nm. The proposed technologies are now studied in the context of the “Copernicus Space Component Expansion” program. Six candidate missions have been identified by the European Commission (EC) as priorities for implementation in the coming years. Among them, the CHIME mission (Copernicus Hyperspectral Imaging Mission for Environment) aims to provide precise spectroscopic measurements in the VNIR/SWIR spectral range. Those data will be used to derive quantitative surface characteristics supporting the monitoring, implementation and improvement of a range of policies in the domain of raw materials, agriculture, soils, food security, biodiversity, environmental degradation and hazards, inland and coastal waters, snow, forestry and the urban environment
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