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Multi-IFU spectroscopyon the LBT
Andreas Kelz, [email protected] Institut Potsdam
2nd Gen Science with the LBT workshop, Ringeberg, 18.7.2008
A. Kelz: Multi-IFU Spectroscopy on LBT, Ringberg workshop, 18. July 2008
3D- and fiber-spectroscopy projects at
AIP
PMAS MUSE VIRUS STELLA & 3.5m CA 8m VLT 9m HET 6dF/RAVE
A. Kelz: Multi-IFU Spectroscopy on LBT, Ringberg workshop, 18. July 2008
PMAS
www.caha.es/pmas
PMAS: Roth, Kelz, et al., 2005, PASP 117, 620
Lens-array-IFU:256 spectra,
8“ to 16“ FoV, spectrophotometry
options: + nod & shuffle,
+ Fabry-Perot Etalon+ polarimetry
PPak-IFU: Fiberbundle, 382 spectra,
wide FoV:74“ x 64“
+ simul. calibrat.
PPak: Kelz, Verheijen, et al., 2006, PASP, 118, 129
PMAS features 2 IFUsand a spectrograph
corrected from 340-900nm
A. Kelz: Multi-IFU Spectroscopy on LBT, Ringberg workshop, 18. July 2008
Science example with the PPak-IFU: the Disk Mass Project
P. I. Marc Verheijen
Right: UGC 463: re-constructed from the PMAS data cube between 450-600 nm, 1.35“/pixel. Left: POSS image for comparison. Note, that
despite the coarse sampling the basic morphology is reconstructed well.
using E3D
Aim: to measure the velocity distributions of face-on spirals to constrain dark matter contribution.
A. Kelz: Multi-IFU Spectroscopy on LBT, Ringberg workshop, 18. July 2008
Advantage: Spatial binning
99 x 108 arcsec
HST/WFPC-2
NGC3982
gaining S/N in particular for the fainter outer parts of galaxies by spatial binning of spaxels
in azimuth.Credit: M. Verheijen, Kapteyn Institute, Groningen
PPak-FoV
74 x 65 arcsec
A. Kelz: Multi-IFU Spectroscopy on LBT, Ringberg workshop, 18. July 2008
Science example: clusters, gravitational lenses
6 hours integration with PPakLambda: 460-780nm
de-blended to 1“/pixel
3 hrs HST image (re-sampled to seeing conditions)
Sanchez & Cardiel et al 2007
Abell2218
A. Kelz: Multi-IFU Spectroscopy on LBT, Ringberg workshop, 18. July 2008
Advantage: multi-plex information
3 dither pointings yielded 993 spectra 455 monochromatic plus various
polychromatic images
Sanchez & Cardiel et al 2007
A. Kelz: Multi-IFU Spectroscopy on LBT, Ringberg workshop, 18. July 2008
Science example: large fields – mapping the Orion nebula
Sanchez et al. 2006
Line ratio and abundance maps7.5 arcmin
10600 spaxel (spectra)
A. Kelz: Multi-IFU Spectroscopy on LBT, Ringberg workshop, 18. July 2008
Science example: Luminosity Function of Ly galaxies
Peter Schuecker (MPE)Ralf Bender (USM/MPE)Ulrich Hopp (USM/MPE)Ralf Köhler (USM)
Karl Gebhard (UT)Gary Hill (UT)Philipp McQueen (UT)
Matthias Steinmetz (AIP)
Peter Weilbacher (AIP)Joris Gerssen (AIP)
-> Baryon oscillations(HETDEX)
A. Kelz: Multi-IFU Spectroscopy on LBT, Ringberg workshop, 18. July 2008
Astronet Infrastructure Roadmap
8.2.3 Ground-based, Small Scale:
Wide-Field, Multiplexed Spectrograph.
There is an extremely strong scientific case for the development of such an instrument which could be placed at one of a number of existing 8-10m class telescopes (see Section 4.3.2). Such a project was therefore given high scientific priority. The term “wide-field” here means a FOV of at least 1.5 degrees (goal 3 degrees) in order to provide simultaneous spectroscopic observations of thousands of objects over a FOV matched to the scientific requirements, comparable to that envisaged for the next generation wide field imagers, e.g. the LSST. The primary science drivers are the determination of the equation of state of Dark Energy, the study of stellar populations over a large fraction of the history of the Universe, and the study of the structure and formation of the Galaxy and Local Group by determining in a quantitative manner the kinematical and chemical signatures of the different stellar components.
A. Kelz: Multi-IFU Spectroscopy on LBT, Ringberg workshop, 18. July 2008
IFU capabilities at 8-10m
VLT: VIMOS-IFU, SINFONI, FLAMES-IF (in operation) KMOS, MUSE, SPHERE (2nd Generation)
Gemini: GMOS
Keck: OSIRIS
GTC: FRIDA, SIDE
LBT:
(… but all have relatively small fields, e.g. MUSE has 90,000 spaxels but 1‘ x 1‘ FoV …)
A. Kelz: Multi-IFU Spectroscopy on LBT, Ringberg workshop, 18. July 2008
Multi-IFUsN
GC
6946,
LB
C
PPak-styleIFU‘s in dense
configuration
A. Kelz: Multi-IFU Spectroscopy on LBT, Ringberg workshop, 18. July 2008
Multi-IFU Spectrograph for LBT-Gregorian
LBT
Gregorian station: usable FoV: 10‘ (evt. up to 24‘ ?) F/15 beam + focal red. to ~F/5
7 deployable IFUs each IFU: - ~ 250-300 fibers- 1/3 fill factor - size of ~1.5 arcmin
total no. of fibers: ~ 1750 - 2100
10‘
60‘‘-90‘‘
A. Kelz: Multi-IFU Spectroscopy on LBT, Ringberg workshop, 18. July 2008
Example: Stellar populations
M101 (10‘ x 10‘), each IFU: 90‘‘ x 90‘‘
A. Kelz: Multi-IFU Spectroscopy on LBT, Ringberg workshop, 18. July 2008
Example: Galaxies & Mergers
M51 (10‘ x 10‘), each IFU: 90‘‘ x 90‘‘
A. Kelz: Multi-IFU Spectroscopy on LBT, Ringberg workshop, 18. July 2008
Example: Galaxy clusters, gravitational lenses, ...
Abell1185 (10‘ x 10‘), each IFU: 90‘‘ x 90‘‘
the deployable IFUs can be set on different targets.
field #1 field #2
A. Kelz: Multi-IFU Spectroscopy on LBT, Ringberg workshop, 18. July 2008
VIRUS-IFU: layout
– IFU format: hexagonal packed
– Dense-pack design with 1/3 fill factor
– 3 dither exp. to fill the field– 200-250 fibers / IFU – Fiber core diameters:
200-300 microns – Step-index quartz
broadband multimode fibers
– Mapping from IFU to slit: either row by row or random
VIRUS P.I. G.Hill, McDonald Obs.
A. Kelz: Multi-IFU Spectroscopy on LBT, Ringberg workshop, 18. July 2008
VIRUS-IFU input head design
– Small mount design allows ¼ packing fraction – Precision mount with capillary tubing or
precision mask to set matrix (design and manufacture at AIP)
6 mm
11.5 mm
A. Kelz: Multi-IFU Spectroscopy on LBT, Ringberg workshop, 18. July 2008
Fiber bundle developments at AIP
Built and under development at AIP: PPak, VIRUS-P1, VIRUS-P2, …, V-Wendelstein
A. Kelz: Multi-IFU Spectroscopy on LBT, Ringberg workshop, 18. July 2008
1 fixed central IFU and 8 deployable IFUs using R- or x-y positioners with a densest IFU fill factor of ¼ advantage: relative „simple“ simulataneous positioning, medium-sized units allow industrial replication at affordable prices.
8 positioners with
R-stages (or x-y stages)
IFU placement
VIRUS IFU-Spectrograph Modified replicated integral field
spectrographs (VIRUS-type) – Inexpensive fiber-fed unit IFS – Each with ~250 fibers .– Visible wavelength coverage
VIRUS Prototype
VIRUS design by: P. MacQueen
McDonald Observatory
IFU-Spectrograph placement at LBT
IFUs and positioner at direct Gregorian focal station - less complex than prime focus, - place stages & bundles in AGW-type ring structure
Spectrograph placementa)at Gregorian station but with grav. stable mount (issues: size, weight, space) b)on the ground (issues: fiber length and effects due to bending, location) c)use MODS (but off-telescope)
© McDonald Observatory
© McDonald Observatory
A. Kelz: Multi-IFU Spectroscopy on LBT, Ringberg workshop, 18. July 2008
Further options …
- use extended FoV (up to 24‘ ?) at Gregorian focus with/without a corrector lens (vignetting, PSF) ?
- option to connect IFU fiber bundles to stationary MODS on the ground (fiber length & numbers of fibers, calibration, ADC) ?
- IFUs at prime foci (evt. at f/4.5 trapped Cass. Focus) + long fiber lengths (plate scale, space, corrector,… ?)
- use of photonic technologies, such as photonic crystal fibers, fiber bragg gratings, arrayed waveguide gratings, miniaturized spectrographs, …
- innovation center for fiber-based spectroscopy (innoFSPEC) and Astrophotonic related R&D at AIP.
A. Kelz: Multi-IFU Spectroscopy on LBT, Ringberg workshop, 18. July 2008
About innoFSPECThe Potsdam Center for Fiber-based Spectroscopy and Sensing innoFSPEC is a joint initiative of the Astrophysical Institute Potsdam (AIP) and the University of Potsdam, Dept. Physical Chemistry & Interdisciplinary Photonics Center (UPPC), whose goal is to create a national center of excellence.
The primary research fields of innoFSPEC are- Fiber-coupled multichannel spectroscopy (AWG, PCF, FBG, replicable-miniaturized MCS, …) - Optical fiber-based sensing
innoFSPEC requested funding for- 2 research groups with 2 associated-professorships - 6 postdocs and 6 PhD student positions - 1 center manager and 1referent assistant - funding for personal, infrastructure, equipment, travel, etc… - in total: 7.7 M€ granted for 5 years (2008-in total: 7.7 M€ granted for 5 years (2008-20142014) )
innoFSPEC excellence centerinnoFSPEC excellence center
www.innofspec-potsdam.de