The planned new generation of extremely large telescopes requires highly efficient algorithms for its adaptive optics systems. We present a new reconstruction approach for multi-conjugate adaptive ...optics or multi-object adaptive optics that computes the mirror shapes without the use of matrix-vector multiplications. The method solves the involved subproblems-wavefront reconstruction, atmospheric tomography and determination of the mirror shapes-sequently. In this paper, we focus on highly efficient algorithms for the atmospheric tomography and the computation of the mirror shape. Finally, we estimate the complexity of the method and provide some numerical examples, including a comparison of our approach to the standard Tikhonov regularization and minimum variance reconstructors.
Abstract
BL Lac objects emitting in the very high energy (VHE) regime are unique tools to peer into the properties of the extragalactic background light (EBL). However, due to the typical absence of ...features in their spectra, the determination of their redshifts has proven challenging. In this work, we exploit the superb spatial resolution delivered by the new Advanced Rayleigh guided Ground layer adaptive Optics System (ARGOS) at the Large Binocular Telescope to detect the host galaxy of HESS J1943+213, a VHE emitting BL Lac shining through the Galaxy. Deep H-band imaging collected during the ARGOS commissioning allowed us to separate the contribution of the nuclear emission and to unveil the properties of the host galaxy with unprecedented detail. The host galaxy is well fitted by a Sérsic profile with index of n ∼ 2 and total magnitude of HHost ∼ 16.15 mag. Under the assumption that BL Lac host galaxies are standard candles, we infer a redshift of z ∼ 0.21. In the framework of the current model for the EBL, this value is in agreement with the observed dimming of the VHE spectrum due to the annihilation of energetic photons on the EBL
ARGOS at the LBT Rabien, S.; Angel, R.; Barl, L. ...
Astronomy & astrophysics,
01/2019, Volume:
621
Journal Article
Peer reviewed
Open access
Having completed its commissioning phase, the Advanced Rayleigh guided Ground-layer adaptive Optics System (ARGOS) facility is coming online for scientific observations at the Large Binocular ...Telescope (LBT). With six Rayleigh laser guide stars in two constellations and the corresponding wavefront sensing, ARGOS corrects the ground-layer distortions for both LBT 8.4 m eyes with their adaptive secondary mirrors. Under regular observing conditions, this set-up delivers a point spread function (PSF) size reduction by a factor of 2–3 compared to a seeing-limited operation. With the two LUCI infrared imaging and multi-object spectroscopy instruments receiving the corrected images, observations in the near-infrared can be performed at high spatial and spectral resolution. We discuss the final ARGOS technical set-up and the adaptive optics performance. We show that imaging cases with ground-layer adaptive optics (GLAO) are enhancing several scientific programmes, from cluster colour magnitude diagrams and Milky Way embedded star formation, to nuclei of nearby galaxies or extragalactic lensing fields. In the unique combination of ARGOS with the multi-object near-infrared spectroscopy available in LUCI over a 4 × 4 arcmin field of view, the first scientific observations have been performed on local and high-z objects. Those high spatial and spectral resolution observations demonstrate the capabilities now at hand with ARGOS at the LBT.
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FMFMET, NUK, UL, UM, UPUK
The planned new generation of extremely large telescopes (ELT) requires highly efficient algorithms for its adaptive optics systems. Recently, a new iterative reconstruction approach for multi ...conjugate adaptive optics (MCAO) and multi object adaptive optics (MOAO) was introduced that computes the mirror corrections without the use of matrix-vector multiplications. The method splits the MCAO/MOAO problem into three subproblems - wavefront reconstruction, atmospheric tomography and mirror deformation - sequently. If an AO system uses laser guide stars, then the reconstruction methods have to be extended in order to consider the cone effect and the tip/tilt indetermination. For the reconstruction of an atmosphere with correct tip/tilt we assume that additional measurements from a tip/tilt sensor are available, and propose two iterative reconstruction methods for the atmosphere. In the first approach, the tip/tilt reconstruction is included into the atmospheric tomography, whereas in the second approach the tip/tilt is reconstructed separately and added to the atmosphere after the atmospheric tomography. Both algorithms are tested numerically. The reconstruction quality of our methods is evaluated for ELT.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
6.
ARGOS at the LBT Rabien, S.; Angel, R.; Barl, L. ...
Astronomy and astrophysics (Berlin),
01/2019, Volume:
621
Journal Article, Web Resource
Peer reviewed
Open access
Having completed its commissioning phase, the Advanced Rayleigh guided Ground-layer adaptive Optics System (ARGOS) facility is coming online for scientific observations at the Large Binocular ...Telescope (LBT). With six Rayleigh laser guide stars in two constellations and the corresponding wavefront sensing, ARGOS corrects the ground-layer distortions for both LBT 8.4 m eyes with their adaptive secondary mirrors. Under regular observing conditions, this set-up delivers a point spread function (PSF) size reduction by a factor of 2–3 compared to a seeing-limited operation. With the two LUCI infrared imaging and multi-object spectroscopy instruments receiving the corrected images, observations in the near-infrared can be performed at high spatial and spectral resolution. We discuss the final ARGOS technical set-up and the adaptive optics performance. We show that imaging cases with ground-layer adaptive optics (GLAO) are enhancing several scientific programmes, from cluster colour magnitude diagrams and Milky Way embedded star formation, to nuclei of nearby galaxies or extragalactic lensing fields. In the unique combination of ARGOS with the multi-object near-infrared spectroscopy available in LUCI over a 4 × 4 arcmin field of view, the first scientific observations have been performed on local and high- z objects. Those high spatial and spectral resolution observations demonstrate the capabilities now at hand with ARGOS at the LBT.
Full text
Available for:
FMFMET, NUK, UL, UM, UPUK
Aims. Gravitationally lensed systems allow a detailed view of galaxies at high redshift. High spatial- and spectral-resolution measurements of arc-like structures can offer unique constraints on the ...physical and dynamical properties of high-z systems. Methods. We present near-infrared spectra centred on the gravitational arcs of six known z ∼ 2 lensed star-forming galaxies of stellar masses of 109−11 M⊙ and star formation rate (SFR) in the range between 10 and 400 M⊙ yr−1. Ground layer adaptive optics (AO)-assisted observations are obtained at the Large Binocular Telescope (LBT) with the LUCI spectrographs during the commissioning of the ARGOS facility. We used MOS masks with curved slits to follow the extended arched structures and study the diagnostic emission lines. LBT observations are used to demonstrate the spectroscopic capabilities of ARGOS. Results. Combining spatially resolved kinematic properties across the arc-like morphologies, emission line diagnostics and archival information, we distinguish between merging and rotationally supported systems, and reveal the possible presence of ejected gas. For galaxies that have evidence for outflows, we derive outflow energetics and mass-loading factors compatible with those observed for stellar winds in local and high-z galaxies. We also use flux ratio diagnostics to derive gas-phase metallicities. The low signal-to-noise ratio in the faint Hβ and nitrogen lines allows us to derive an upper limit of ≈0.15 dex for the spatial variations in metallicity along the slit for the lensed galaxy J1038. Conclusions. Analysed near-infrared spectra presented here represent the first scientific demonstration of performing AO-assisted multi-object spectroscopy with narrow curved-shape slits. The increased angular and spectral resolution, combined with the binocular operation mode with the 8.4 m wide eyes of LBT, will allow the characterisation of kinematic and chemical properties of a large sample of galaxies at high-z in the near future.
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FMFMET, NUK, UL, UM, UPUK
We aim to refine the sample of isolated early-type galaxies in the AMIGA catalogue via high resolution imaging. Here we report the result from a pilot study investigating two candidates, KIG 685 and ...KIG 895, in K-band with the laser guide star and wavefront sensing facility ARGOS} at LBT. Observations, obtained during commissioning time, achieved a PSF of ~0.25". We present the data reduction and the PSF analysis from the best closed loop exposures to investigate the galaxies' morphological structure, including their nuclear region. We used PROFILER for the decomposition of the azimuthal 1D light distribution and GALFIT for the 2D analysis, accounting for ARGOS's PSF. KIG 685 was found to be a S0 galaxy and has been modeled with two Sersic components representing a pseudo-bulge (n_{1D}=2.87+-0.21, n_{2D}=2.29+-0.10) and a disk (n_{1D}=0.95+-0.16, n_{2D}=0.78+-0.10). Nearly symmetric ring/shell-like structures emerge after subtracting the GALFIT model from the image. KIG 895 shows a clear irregular arm-like structure, in which the northern outer arm is reminiscent of a tail. The galaxy body is a disk, best fitted by a single Sersic profile (n_{1D}=1.22+-0.1; n_{2D}=1.32+-0.12), i.e. KIG 895 is a bulge-less very late-type spiral. ARGOS high resolution images clearly revealed interaction signatures in KIG 895. We suggest that the ring/shell like residuals in KIG 685, a "bona fide" early-type galaxy, point towards a past accretion event.
A&A 618, A36 (2018) Gravitationally lensed systems allow a detailed view of galaxies at high
redshift. High spatial- and spectral-resolution measurements of arc-like
structures can offer unique ...constraints on the physical and dynamical
properties of high-z systems. We present near-infrared spectra centred on the
gravitational arcs of six known z ~ 2 lensed star-forming galaxies of stellar
masses of 10^9-10^11 Msun and star formation rate (SFR) in the range between 10
and 400 Msun/yr. Ground layer adaptive optics (AO)-assisted observations are
obtained at the Large Binocular Telescope (LBT) with the LUCI spectrographs
during the commissioning of the ARGOS facility. We used MOS masks with curved
slits to follow the extended arched structures and study the diagnostic
emission lines. Combining spatially resolved kinematic properties across the
arc-like morphologies, emission line diagnostics and archival information, we
distinguish between merging and rotationally supported systems, and reveal the
possible presence of ejected gas. For galaxies that have evidence for outflows,
we derive outflow energetics and mass-loading factors compatible with those
observed for stellar winds in local and high-z galaxies. We also use flux ratio
diagnostics to derive gas-phase metallicities. The low signal-to-noise ratio in
the faint H$\beta$ and nitrogen lines allows us to derive an upper limit of ~
0.15 dex for the spatial variations in metallicity along the slit for the
lensed galaxy J1038. Analysed near-infrared spectra presented here represent
the first scientific demonstration of performing AO-assisted multi-object
spectroscopy with narrow curved-shape slits. The increased angular and spectral
resolution, combined with the binocular operation mode with the 8.4-m-wide eyes
of LBT, will allow the characterisation of kinematic and chemical properties of
a large sample of galaxies at high-z in the near future.
Having completed its commissioning phase, the Advanced Rayleigh guided Ground-layer adaptive Optics System (ARGOS) facility is coming online for scientific observations at the Large Binocular ...Telescope (LBT). With six Rayleigh laser guide stars in two constellations and the corresponding wavefront sensing, ARGOS corrects the ground-layer distortions for both LBT 8.4m eyes with their adaptive secondary mirrors. Under regular observing conditions, this set-up delivers a point spread function (PSF) size reduction by a factor of ~2--3 compared to a seeing-limited operation. With the two LUCI infrared imaging and multi-object spectroscopy instruments receiving the corrected images, observations in the near-infrared can be performed at high spatial and spectral resolution. We discuss the final ARGOS technical set-up and the adaptive optics performance. We show that imaging cases with ground-layer adaptive optics (GLAO) are enhancing several scientific programmes, from cluster colour magnitude diagrams and Milky Way embedded star formation, to nuclei of nearby galaxies or extragalactic lensing fields. In the unique combination of ARGOS with the multi-object near-infrared spectroscopy available in LUCI over a 4x4 arcmin field of view, the first scientific observations have been performed on local and high-z objects. Those high spatial and spectral resolution observations demonstrate the capabilities now at hand with ARGOS at the LBT.
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