Vianak Naranjo

BLACK HOLE MASS ESTIMATES BASED ON C IV ARE CONSISTENT WITH THOSE BASED ON THE BALMER LINES

Using a sample of high-redshift lensed quasars from the CASTLES project with observed-frame ultraviolet or optical and near-infrared spectra, we have searched for possible biases between supermassive black hole (BH) mass estimates based on the C IV, Hα, and Hβ broad emission lines. Our sample is based upon that of Greene, Peng, & Ludwig, expanded with new near-IR spectroscopic observations, consistently analyzed high signal-to-noise ratio (S/N) optical spectra, and consistent continuum luminosity estimates at 5100 A. We find that BH mass estimates based on the full width at half-maximum (FWHM) of C IV show a systematic offset with respect to those obtained from the line dispersion, σ_l , of the same emission line, but not with those obtained from the FWHM of Hα and Hβ. The magnitude of the offset depends on the treatment of the He II and Fe II emission blended with C IV, but there is little scatter for any fixed measurement prescription. While we otherwise find no systematic offsets between C IV and Balmer line mass estimates, we do find that the residuals between them are strongly correlated with the ratio of the UV and optical continuum luminosities. This means that much of the dispersion in previous comparisons of C IV and Hβ BH mass estimates are due to the continuum luminosities rather than to any properties of the lines. Removing this dependency reduces the scatter between the UV- and optical-based BH mass estimates by a factor of approximately two, from roughly 0.35 to 0.18 dex. The dispersion is smallest when comparing the C IV σ l mass estimate, after removing the offset from the FWHM estimates, and either Balmer line mass estimate. The correlation with the continuum slope is likely due to a combination of reddening, host contamination, and object-dependent SED shapes. When we add additional heterogeneous measurements from the literature, the results are unchanged. Moreover, in a trial observation of a remaining outlier, the origin of the deviation is clearly due to unrecognized absorption in a low S/N spectrum. This not only highlights the importance of the quality of the observations, but also raises the question whether cases like this one are common in the literature, further biasing comparisons between C IV and other broad emission lines.

GRAVITY: getting to the event horizon of Sgr A*

We present the second-generation VLTI instrument GRAVITY, which currently is in the preliminary design phase. GRAVITY is specifically designed to observe highly relativistic motions of matter close to the event horizon of Sgr A*, the massive black hole at center of the Milky Way. We have identified the key design features needed to achieve this goal and present the resulting instrument concept. It includes an integrated optics, 4-telescope, dual feed beam combiner operated in a cryogenic vessel; near infrared wavefront sensing adaptive optics; fringe tracking on secondary sources within the field of view of the VLTI and a novel metrology concept. Simulations show that the planned design matches the scientific needs; in particular that 10µas astrometry is feasible for a source with a magnitude of K=15 like Sgr A*, given the availability of suitable phase reference sources.

CARMENES: Calar Alto high-resolution search for M dwarfs with exo-earths with a near-infrared Echelle spectrograph

CARMENES (Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Echelle Spectrographs) is a next-generation instrument to be built for the 3.5m telescope at the Calar Alto Observatory by a consortium of Spanish and German institutions. Conducting a five-year exoplanet survey targeting ~ 300 M stars with the completed instrument is an integral part of the project. The CARMENES instrument consists of two separate spectrographs covering the wavelength range from 0.52 to 1.7 μm at a spectral resolution of R = 85, 000, fed by fibers from the Cassegrain focus of the telescope. The spectrographs are housed in a temperature-stabilized environment in vacuum tanks, to enable a 1m/s radial velocity precision employing a simultaneous ThAr calibration.

GRAVITY: a four-telescope beam combiner instrument for the VLTI

GRAVITY is an adaptive optics assisted Beam Combiner for the second generation VLTI instrumentation. The instrument will provide high-precision narrow-angle astrometry and phase-referenced interferometric imaging in the astronomical K-band for faint objects. We describe the wide range of science that will be tackled with this instrument, highlighting the unique capabilities of the VLTI in combination with GRAVITY. The most prominent goal is to observe highly relativistic motions of matter close to the event horizon of Sgr A*, the massive black hole at center of the Milky Way. We present the preliminary design that fulfils the requirements that follow from the key science drivers: It includes an integrated optics, 4-telescope, dual feed beam combiner operated in a cryogenic vessel; near-infrared wavefrontsensing adaptive optics; fringe-tracking on secondary sources within the field of view of the VLTI and a novel metrology concept. Simulations show that 10 μas astrometry within few minutes is feasible for a source with a magnitude of mK = 15 like Sgr A*, given the availability of suitable phase reference sources (mK = 10). Using the same setup, imaging of mK = 18 stellar sources in the interferometric field of view is possible, assuming a full night of observations and the corresponding UV coverage of the VLTI.

LUCIFER1: performance results

LUCIFER1 is a NIR camera and spectrograph installed at the Large Binocular Telescope (LBT). Working in the wavelength range of 0.9-2.5micron, the instrument is designed for direct imaging and spectroscopy with 3 different cameras. A set of longslit masks as well as up to 23 user defined (MOS) masks are available. The set of user defined masks can be exchanged while the instrument is at operating temperature. Extensive tests have been done on the electro-mechanical functions, image motion due to flexure, optical quality, instrument software, calibration and especially on the multi-object spectroscopy. Also a detailed characterization of the instruments properties in the different observing modes has been carried out. Results are presented and compared to the specifications.

OVMS - the optical path difference and vibration monitoring system for the LBT and its interferometers

Characterisation, mitigation and correction of telescope vibrations have proven to be crucial for the performance of astronomical infrared interferometers. The project teams of the interferometers for the LBT, LINC-NIRVANA and LBTI, and LBT Observatory (LBTO) have embarked on a joint effort to implement an accelerometer-based vibration measurement system distributed over the optical elements of the LBT. OVMS, the Optical Path Difference and Vibration Monitoring System will serve to (i) ensure conditions suitable for adaptive optics (AO) and interferometric (IF) observations and (ii) utilize vibration information, converted into tip-tilt and optical path difference data, in the control strategies of the LBT adaptive secondary mirrors and the beam combining interferometers. The system hardware is mainly developed by Steward Observatorys LBTI team and its installation at the LBT is underway. The OVMS software development and associated computer infrastructure is the responsibility of the LINC-NIRVANA team at MPIA Heidelberg. Initially, the OVMS will fill a data archive provided by LBTO that will be used to study vibration data and correlate them with telescope movements and environmental parameters thereby identifiying sources of vibrations and to eliminate or mitigate them. Data display tools will help LBTO staff to keep vibrations within predefined thresholds for quiet conditions for AO and IF observations. Later-on real-time data from the OVMS will be fed into the control loops of the AO systems and IF instruments in order to permit the correction of vibration signals with frequencies up to 450 Hz.

LUCI in the sky: performance and lessons learned in the first two years of near-infrared multi-object spectroscopy at the LBT

LUCI (former LUCIFER) is the full cryogenic near-infrared multi-object spectrograph and imager at the LBT. It presently allows for seeing limited imaging and multi-object spectroscopy at R~2000-4000 in a 4x4arcmin2 FOV from 0.9 to 2.5 micron. We report on the instrument performance and the lessons learned during the first two years on sky from a technical and operational point of view. We present the upcoming detector upgrade to Hawaii-2 RG arrays and the operating modes to utilize the binocular mode, the LBT facility AO system for diffraction limited imaging as well as to use the wide-field AO correction afforded by the multi-laser GLAO System ARGOS in multi-object spectroscopy.

Vibration measurements at the Large Binocular Telescope (LBT)

The Large Binocular Telescope (LBT) is an international collaboration, with partners from the United States, Italy, and Germany. The telescope uses two 8.4-meter diameter primary mirrors to produce coherent images with the combined light along with adaptive optics. The correct functioning and optimum performance of the LBT is only achieved through a complex interplay of various optical elements. Each of these elements has its individual vibration behaviour, and therefore it is necessary to characterize the LBT as a distributed vibration system. LINC-NIRVANA is a near-infrared image-plane beam combiner with advanced, multi-conjugated adaptive optics, and one of the interferometric instruments for the Large Binocular Telescope (LBT). Its spectral range goes from 1.0 μm to 2.45 μm, therefore the requirements for the maximum optical path difference (OPD) are very tight (λ/10 ~ 100 nm). 1 During two dedicated campaigns, the vibrations introduced by various actuators were measured using different kinds of sensors. The evaluation of the obtained data allows an estimation of the frequency and amplitude contributions of the individual vibration sources. Until the final state of the LBT is reached, further measurements are necessary to optimize and adapt the equipment and also the investigated elements and configurations (measurement points and directions, number of sensors, etc.).

LINC-NIRVANA: the single arm MCAO experiment

LINC-NIRVANA is an imaging interferometer for the Large Binocular Telescope (LBT) and will make use of multi-conjugated adaptive optics (MCAO) with two 349 actuators deformable mirrors (DM), two 672 actuator deformable secondary mirrors and a total of 4 wavefront sensors (WFS) by using 8 or 12 natural guide stars each. The goal of the MCAO is to increase sky coverage and achieve a medium Strehl-ratio over the 2 arcmin field of view. To test the concepts and prototypes, a laboratory setup of one MCAO arm is being built. We present the layout of the MCAO prototype, planned and accomplished tests, especially for the used Xinetics DMs, and a possible setup for a test on sky with an existing 8m class telescope.

The ESPRI project: astrometric exoplanet search with PRIMA

PRIMA, the instrument for Phase-Referenced Imaging and Micro-arcsecond Astrometry at the VLTI, is currently being developed at ESO. PRIMA will implement the dual-feed capability, at first for two UTs or ATs, to enable simultaneous interferometric observations of two objects that are separated by up to 1 arcmin. PRIMA is designed to perform narrow-angle astrometry in K-band with two ATs as well as phase-referenced aperture synthesis imaging with instruments like Amber and Midi. In order to speed up the full implementation of the 10 microarcsec astrometric capability of the VLTI and to carry out a large astrometric planet search program, a consortium lead by the Observatoire de Genève, Max Planck Institute for Astronomy, and Landessternwarte Heidelberg, has built Differential Delay Lines for PRIMA and is developing the astrometric observation preparation and data reduction software. When the facility becomes fully operational in 2009, we will use PRIMA to carry out a systematic astrometric Exoplanet Search program, called ESPRI. In this paper, we describe the narrow-angle astrometry measurement principle, give an overview of the ongoing hardand software developments, and outline our anticipated astrometric exoplanet search program.