Million Element Integral Field Unit Design Study

Transcription

1 Million Element Integral Field Unit Design Study Simon Morris, Robert Content, Cedric Lacey (University of Durham, UK) AURA contract No GEM00303

2 Milestone 1 Prepare and present a PowerPoint presentation describing the preliminary optical concept with performance predictions, along with a status report on the science case work. Contractor shall make the presentation at a teleconference no less than one week after the PowerPoint presentation has been made available to AURA.

3 Plan for Presentation 1. Preliminary Optical Concept 2. Status Report of Science Case Overview of 3D Deep Field Science Specific calculations for Lyman α emitters

4 Preliminary Optical Concept Million Element Integral Field Unit 5 x 5 arcmin field of view x arcsec sampling nm full coverage (R~500) in 4 exposures R ~ 500 and 1500 (2 pixel) 24 spectrographs (8k x 8k detectors) ~1.6x10 9 pixels in cameras

5 From 8m to ELT MEIFU What Change Field Pixel Length Lens Width before after Total Spectr. arcmin arcsec m m mm Nothing x Pixel(µm) x # spectrog x Detector(K) x F-Ratio Camera x

6 Optical Principle cylindrical foreoptics IFU spectrograph Fore-optics magnify the focal plane anamorphically onto the first (rectangular) lenslet array which acts as the image slicer Cylindrical microlens arrays to divide the input focal plane into micro-slices Second lenslet array demagnifies (anamorphically) the slices onto the input focal plane of the spectrograph and puts the pupil onto the grating horizontal cylindrical microlens arrays vertical cylindrical microlens arrays

7 GSMT MEIFUS Focal Planes Magnifying optics Pickoff mirror F/28 x F/98 F/15 Microlens optics Spectra are dispersed at an angle (19 deg) to avoid spectral overlap Spectra are 200 x 12 pixels on detector (0.092 arcsec per pixel) Inter-spectrum gaps are 22 pixels (spectral) and 3 pixels (spatial) Spectrograph F/4.4 F/1.8

8 Comparison between a standard lenslet array system and a microslice system Integral Field Unit Spectrograph Input Detector Dot image sytem Microslice image system

9 200 millimeters Pickoff mirrors GSMT MEIFUS Telescope or derotator focal plane Twenty four pickoff mirrors in the telescope focal plane reflect the light to the 24 toroidal mirrors of the reimaging optics. The figure above shows the 4 pickoffs on 1/6 of the field. The light from each pickoff is sent in a different direction by its toroidal mirror (left).

10 400 millimeters Principle of the fore-optics: Each pickoff mirror in the focal plane sends the light to a toroidal mirror that redirects it to the fore-optics (here represented by paraxial lenses). The first set of lenses is divergent in the vertical direction, the second set is convergent. We have the opposite in the horizontal direction. The magnification is then much larger in the vertical direction than the horizontal transforming the elongated sub-field into a nearly square one. Top view

11 Grating (VPH or grism) Optics to change when changing of band Draft design of spectrograph of GSMT MEIFUS 200 millimeters

12 Status Report of Science Case Overview of 3D Deep Field Science

13 Simulated NGST Image (Im 2001) 2 x2 10 hr exposure

14 Reionisation Highest possible z line emitters, both SFR and AGN excited, UV background measurement from Lyα Fluorescence

15 Dave et al University of Durham Astronomical Instrumentation Group The relationship between Galaxies and diffuse gas Column density of neutral hydrogen through a 200 km s -1 slice of the LCDM simulation volume at z=3,2,1.5,1,0.5, and 0 (from top left to bottom right panels). Red corresponds to N H = cm -2, orange to N H = cm -2, yellow to N H = cm -2, and white to N H >10 16 cm -2

16 Feedback Winds from star forming galaxies, gas stripping in groups and clusters of galaxies

17 Emission line versus Continuum morphology

18 Identification of X-ray, MIR and submm targets Chandra XMM HST ACS SIRTF NGST Imaging SCUBA ALMA (17 x 17 arcmin) (30 arcmin diameter) (3.3 x 3.3 arcmin) (5.1 x 5.1 arcmin) (4 x 4 arcmin) (2.3 arcmin diameter) (12 arcsec diameter, but will mosaic?)

19 Serendipity

20 Status Report of Science Case Specific calculations for Lyman α emitters

21 High z Lyman α Emitters Ellis et al. z=5.6 lensed Lyman Alpha emitters Brighter object observed I=26, lensed by factor ~33

22 Dawson et al. 2002, astro-ph/

23 Lyman α Emitters Surface Density z delta z flux lim (1) Surface Density (2) reference year E Stiavelli et al E Warren & Moller E Moller & Fynbo E Steidel et al E Kudritzki et al E Cowie & Hu E Cowie & Hu ? 6.9 Cowie & Hu x E Rhoads et al large? 2.3 Dawson et al E Rhoads&Malhotra 2001 (1) Ergs cm -2 s -1 (2) Number (Square arcminute) -1 ( z=1) -1

24 Emission Line Sensitivity Calculation Natural Seeing Exposure 4x8 hours (~10 5 seconds), sky I= % sky-to-hard-disk throughput 50% of object flux in 0.6x0.6 arcsec box All of line flux in 2 spectral pixels (1.7 nm) 5σ Detection for 3x10-19 ergs cm -2 s -1 Z=6 (Observed λ=851.2 nm) gives 1x10 41 ergs s -1 luminosity Would need 4x4 nights to survey nm wavelength range (2.45<z<6.49) for full 5x5 arcminute field

25 Emission Line Sensitivity Calculation AO corrected and diffraction limited Assumption as in previous slide, except: 50% of object flux in 0.2x0.2 arcsec box 5σ Detection for 1x10-19 ergs cm -2 s -1 Z=6 (Observed λ=851.2 nm) gives 3x10 40 ergs s -1 luminosity 50% of object flux in 0.006x0.006 arcsec box (50% EE diameter for 30m Airy Pattern at 790 nm) N.B. this also implies a different plate scale to sample this properly. 5σ Detection for 3x10-21 ergs cm -2 s -1 Z=6 (Observed λ=851.2 nm) gives 1x10 39 ergs s -1 luminosity

26 Baugh et al. Semi-analytic Model for galaxy formation Greyscale= dark matter Dots=galaxies (colour=colour) You are here

27 Semi-analytic surface density prediction

28 Semi-analytic surface density prediction

29 Semi-analytic continuum mag prediction

30 Lyα emitters, 25% complete? What are we selecting? Log (Number Mpc -3 ) LBG, 80% complete? Log(SFR M /yr)

31 A Census of Star Formation Push both fainter into the luminosity function and over a larger continuous range in redshift Lyman alpha emitters (2.5<z<6.75) [OII] emitters (0.13<z<1.52) faint H alpha emitters (0<z<0.43)

32 Milestone 2, delivery Prepare and present a PowerPoint presentation describing the mechanical packaging concept, including the feasibility of the design, along with a status report on the science case work. Contractor shall make the presentation at a teleconference no less than one week after the PowerPoint presentation has been made available to AURA.

33 The End

34 A few bonus slides in case questions are asked about survey strategy

35 How to survey nm (R=500) over 5x5 arcmin in 4 exposures nm nm nm nm

36 Spatial element intensity distribution when adding images taken at % 12.5 % 50% 12.5 % % Since a spatial element on the sky (the rectangle that gives one spectrum) is 0.09 x 0.18, adding images taken at 90 from each other gives a spatial element with a core 0.09 x 0.09.

37 Example of separation of the field in space and wavelength 0.42 to 0.51 µm or 0.51 to 0.62 µm or 0.62 to 0.75 µm 12 red and 12 blue spectrographs 0.51 to 0.62 µm or 0.62 to 0.75 µm or 0.75 to 0.91 µm 5.8 arcmin Examples of how the field can be separated in wavelength. Two images rotated 180 are necessary to cover 0.42 to 0.62 µm. The same is true for 0.62 to 0.91 µm.