SAM sees the light

Tokovinin, Andreï; Tighe, R.; Schurter, Patricio; Cantarutti, Rolando; Bliek, N. van der; Martinez, Manuel; Mondaca, Eduardo; Montane, Andrés; Cortés, Wolnays Naudy

doi:10.1117/12.856407

Cited by 16 publications

(13 citation statements)

References 11 publications

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“…Several of our targets were re-observed in griz bands at the 4-m Southern Astrophysical Research Telescope (SOAR, Chile) during the science verification runs of the SOAR Adaptive Module (SAM) and the SAM Imager (SAMI; Tokovinin et al 2010Tokovinin et al , 2012. SAMI has a 3.…”

Section: Optical Imaging With Gemini/gmosmentioning

confidence: 99%

About AGN ionization echoes, thermal echoes and ionization deficits in low-redshift Lyα blobs

Schirmer

Malhotra

Levenson

et al. 2016

Mon. Not. R. Astron. Soc.

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We report the discovery of 14 Lyman-α blobs (LABs) at z ∼ 0.3, existing at least 4 − 7 billion years later in the Universe than all other LABs known. Their optical diameters are 20 − 70 kpc, and GALEX data imply Ly α luminosities of (0.4 − 6.3) × 10 43 erg s −1 . Contrary to high-z LABs, they live in low-density areas. They are ionized by AGN, suggesting that cold accretion streams as a power source must deplete between z = 2 and z = 0.3. We also show that transient AGN naturally explain the ionization deficits observed in many LABs: Their Ly α and X-ray fluxes decorrelate below 10 6 years because of the delayed escape of resonantly scattering Ly α photons. High Ly α luminosities do not require currently powerful AGN, independent of obscuration. Chandra X-ray data reveal intrinsically weak AGN, confirming the luminous optical nebulae as impressive ionization echoes. For the first time, we also report mid-infrared thermal echoes from the dusty tori. We conclude that the AGN have faded by 3 − 4 orders of magnitude within the last 10 4−5 years, leaving fossil UV, optical and thermal radiation behind. The host galaxies belong to the group of previously discovered Green Bean galaxies (GBs). Gemini optical imaging reveals smooth spheres, mergers, spectacular outflows and ionization cones. Because of their proximity and high flux densities, GBs are perfect targets to study AGN feedback, mode switching and the Ly α escape. The fully calibrated, coadded optical FITS images are publicly available.

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Section: Optical Imaging With Gemini/gmosmentioning

confidence: 99%

About AGN ionization echoes, thermal echoes and ionization deficits in low-redshift Lyα blobs

Schirmer

Malhotra

Levenson

et al. 2016

Mon. Not. R. Astron. Soc.

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“…The exception to this rule is the low-altitude Rayleigh LGS system, such as those employed in the GLAS [6] and SAM [7] projects. For multi-WFS tomographic systems, the combination of the wavefront signals from natural guide stars (NGS) and laser guide stars (LGS) required to perform tomography places additional processing load on the real-time control system (RTCS).…”

Section: Introductionmentioning

confidence: 91%

Tests of open-loop LGS tomography with CANARY

et al. 2012

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CANARY is an on-sky demonstrator adaptive optics (AO) system that in 2010 provided the first on-sky demonstration of open-loop tomographic adaptive optics correction using natural guide stars (NGS). Phase B of the CANARY experiment aims to extend the instrument from its original configuration by also measuring wavefronts from four offaxis Rayleigh laser guide stars (LGS). This upgrade allows CANARY to perform tomographic wavefront sensing over a 2.5arcminute field of view using any mix of up to seven off-axis wavefront sensors (four LGS and three NGS) simultaneously. AO correction within CANARY is performed on-axis along a single line of sight using a 52-actuator deformable mirror being controlled in open-loop. Here we give an overview of the Phase B LGS system, discuss the calibration of a mixed NGS/LGS tomographic system and present the recent laboratory and on-sky results from the Phase B commissioning.

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“…The temporal power spectrum W 4 (f ) of the time sequences was computed with Equ. (6). An example, of the power spectrum of a data set acquisioned at 444Hz is plotted in log-log scale on the left in Figure 1.…”

Section: Implementation Detailsmentioning

confidence: 99%

“…FADE was introduced as a stand-alone monitor using a 36-cm telescope 3 and tested for AO loop data of a 4m telescope with SOAR Adaptive Module (SAM). 5,6 This work is the first step of an effort to implement FADE for NAOS in order to demonstrate the suitability of the method for large scale telescopes. The coherence time was computed directly from AO loop data using the deformable mirror (DM) voltages provided by Adaptive Optics NIR Instrument NAOS-CONICA (NACO).…”

Section: Introductionmentioning

confidence: 99%

Atmospheric parameter estimation from AO wavefront sensing data: application of the FADE method with NACO

Brunner

Girard

2014

SPIE Proceedings

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The performance of a ground based telescope can depend greatly on the coherence time, a site and time varying parameter determining the required reaction bandwidth of an Adaptive Optics system. Recently, Fast Defocus (FADE), a method which measures the coherence time from defocus fluctuations in a small telescope introduced by atmospheric turbulence has been presented. In this work, FADE was implemented for the Nasmyth Adaptive Optics System (NAOS) of the VLT's UT4 to demonstrate suitability for large scale telescopes. Estimates of the coherence time for an examplary set of AO loop data were compared to results obtained with the DIMM and MASS instruments, showing good agreement which justify a future in depth analysis for large AO loop data samples provided by NAOS as well as the VLT's Spectro-Polarimetric High-contrast Exoplanet Research (SPHERE) instrument.

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SAM sees the light

Cited by 16 publications

References 11 publications

About AGN ionization echoes, thermal echoes and ionization deficits in low-redshift Lyα blobs

About AGN ionization echoes, thermal echoes and ionization deficits in low-redshift Lyα blobs

Tests of open-loop LGS tomography with CANARY

Atmospheric parameter estimation from AO wavefront sensing data: application of the FADE method with NACO

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