Volker Knierim

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.

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.

LUCIFER status report: summer 2008

LUCIFER is a NIR spectrograph and imager (wavelength range 0.9 to 2.5 micron) for the Large Binocular Telescope (LBT) on Mt. Graham, Arizona, working at cryogenic temperatures of less than 70K. Two instruments are built by a consortium of five German institutes and will be mounted at the bent Gregorian foci of the two individual telescope mirrors. Three exchangable cameras are available for imaging and spectroscopy: two of them are optimized for seeing-limited conditions, a third camera for the diffraction limited case will be used with the LBT adaptive secondary mirror working. Up to 33 exchangeable masks are available for longslit or multi-object spectroscopy (MOS) over the full field of view (FOV). Both MOS-units (LUCIFER 1 and LUCIFER 2) and the auxiliary cryostats together with the control electronics have been completed. The observational software-package is in its final stage of preparation. After the total integration of LUCIFER 1 extensive tests were done for all electro-mechanical functions and the verification of the instrument started. The results of the tests are presented in detail and are compared with the specifications.

The development process of the LUCIFER control software

In this paper we present the software development process and history of the LUCIFER (LBT NIR spectroscopic Utility with Camera and Integral- Field Unit for Extragalactic Research) multi-mode near-infrared instrument, which is one of the first light instruments of the LBT on Mt. Graham, Arizona. The software is realised as a distributed system in Java using its remote method invocation service (RMI). We describe the current status of the software and give an overview of the planned computer hardware architecture.

Lucifer VR: a virtual instrument for the LBT

Lucifer VR is a virtually realized instrument that was build in order to allow improved pre-integration software tests, training of observers as well as providing educational access. Beside testing the instrument hardware in combination with e.g. a telescope simulator, software tests need to be done. A virtual instrument closes the gap between regression tests and testing the control software with the integrated instrument. Lucifer VR allows much earlier tests and reduces the amount of time needed to combine the software with the hardware. By modeling the instrument in a simulator, motion times can be calculated very easily and the position of all instrument units can be traced. Especially when using complex mechanisms like a MOS unit a virtual instrument makes software development less time consuming. Lucifer VR consists of three parts; one for handling the communication, another to simulate the hardware and finally a part to visualize the whole instrument in three dimensions.

The LUCIFER control software

The successful roll-out of the control software for a complex NIR imager/spectrograph with MOS calls for flexible development strategies due to changing requirements during different phases of the project. A waterfall strategy used in the beginning has to change to a more iterative and agile process in the later stages. The choice of an appropriate program language as well as suitable software layout is crucial. For example the software has to accomplish multiple demands of different user groups, including a high level of flexibility for later changes and extensions. Different access levels to the instrument are mandatory to afford direct control mechanisms for lab operations and inspections of the instrument as well as tools to accomplish efficient science observations. Our hierarchical software structure with four layers of increasing abstract levels and the use of an object oriented language ideally supports these requirements. Here we describe our software architecture, the software development process, the different access levels and our commissioning experiences with LUCIFER 1.