Science Overview and the Key Design Space for MSE · • Science team charged with developing Science Reference Observations, that describe science programs that are high proﬁle,

Science Overview and the Key Design Space for MSE

Alan McConnachie !MSE Project Scientist First Annual MSE Science Team Meeting

http://mse.cfht.hawaii.edu

http://mse.cfht.hawaii.edu

Original Concept

MSE will:!• obtain efficiently very large numbers

(>106) of low- (R ~ 2 000), moderate- (R ~ 6 500) and high-resolution (R > 20 000) spectra !

• for faint (20 < g < 24) science targets !• over large areas of the sky (103 − 104

sq.deg ) !• spanning blue/optical to near-IR

wavelengths, 0.37 −> NIR (J or H band)!

• At the highest resolutions, it should have a velocity accuracy of <<1 km/s

• At low resolution, complete wavelength coverage should be possible in a single observation

Gaia: stellar astrophysics, stellar populations, Milky Way

Euclid, WFIRST… : extragalactic astrophysics and cosmology

eRosita: High energy astrophysics, clusters of galaxies…

TMT (and the other ELTS): General purpose, forefront science facilities, efficient target selection important for best use of facilities…

LSST: Wide field imaging for transients, MW and Cosmology

SKA: Spectral stacking; serious number of new objects with no OIR spectral data

Gaia: stellar astrophysics, stellar populations, Milky Way

Euclid, WFIRST… : extragalactic astrophysics and cosmology

eRosita: High energy astrophysics, clusters of galaxies…

TMT (and the other ELTS): General purpose, forefront science facilities, efficient target selection important for best use of facilities…

LSST: Wide field imaging for transients, MW and Cosmology

SKA: Spectral stacking; serious number of new objects with no OIR spectral data

•Within this context, consider the impact of a 10-m class version of SDSS at the best site on the planet. •And consider the popularity of those that have a major voice in deciding how it is deployed.

Competition is good for the soul

Competition is good for the soul

• AAT/HERMES • 4m class, optical• 3.14 sq.deg• 392 objects• R28000 (+ ~R50K)

• Mayall/DESI 4m class, optical7.1 sq.deg5000 objectsR4000

• Subaru/PFS• 8m class, opt+NIR (0.38 - 1.3um)• 1.25 sq.deg• 2400 objects• R2000/5000

• WHT/WEAVE 4m class, optical3.14 sq.deg1000 objectsR5000, 20000

• VLT/MOONS• 8m class, NIR (~0.8 - 1.8um)• 0.14 sq.deg• 1000 objects• R4000/20000

• Guo Shoujing/LAMOST4m class, optical19.6sq.deg FoV 4000 objectsR=1000 - 10000

• VISTA/4MOST 4m class, optical2.5 sq.deg2400 objectsR5000, 18000

• MSE is the only proposed, dedicated, large-aperture spectroscopic facility. Nevertheless, MSE must be positioned to be able to perform transformative, unique and high impact science

MSE Science Team & First Tasks

MSE Science Team & First Tasks• International Science Team with 84 members

• Australia - 12; Canada - 10; China - 8; France - 22; India - 10; USA - 7; Other - 15• ~30 - 40 present at this meeting

• Immediate (i.e., 2015) focus on completing drafts of key science foundational documentation. Revisit science baseline to ensure subsequent work is correctly focused:

• Detailed Science Case (DSC)• Science Requirements Document (SRD)

• Process for DSC and SRD development: • Science team charged with developing Science Reference Observations, that describe

science programs that are high profile, transformative in their field, and which are UNIQUELY POSSIBLE with MSE

• Constitutes a “Design Reference Mission” for MSE. Includes details on (e.g.) target selection, data requirements, calibration requirements, etc…

MSE Science Team & First Tasks• International Science Team with 84 members

• Australia - 12; Canada - 10; China - 8; France - 22; India - 10; USA - 7; Other - 15• ~30 - 40 present at this meeting

• Immediate (i.e., 2015) focus on completing drafts of key science foundational documentation. Revisit science baseline to ensure subsequent work is correctly focused:

• Detailed Science Case (DSC)• Science Requirements Document (SRD)

• Process for DSC and SRD development: • Science team charged with developing Science Reference Observations, that describe

science programs that are high profile, transformative in their field, and which are UNIQUELY POSSIBLE with MSE

• Constitutes a “Design Reference Mission” for MSE. Includes details on (e.g.) target selection, data requirements, calibration requirements, etc…

• Science requirements are then the range of capabilities that MSE must have in order to be able to conduct the SROs

• Science team split into three groups:• Stars, Low-z and High-z, coordinated by Babusiaux, Balogh and Driver, respectively• White papers submitted by science team members highlighting key science topics in October

2014• Submitted first draft of candidate SROs in January 2015. Typically ~6-8 per group

Driving science• SROs reviewed by Science Executive and Project Office.

• 12 SROs selected for continued development• These 12 SROs spawn the range of issues addressed by the science requirements

described in the Science Requirements Document

Driving science

The composition and dynamics of the faint Universe• Science Reference Observations include: !• SRO-1 Exoplanets and stellar velocity variability • SRO-2 Revealing the physics of rare stellar types• SRO-3 The formation and chemical evolution of the Galaxy• SRO-4 Unveiling cold dark matter substructure with precision stellar kinematics• SRO-5 The chemodynamical deconstruction of Local Group galaxies • SRO-6: The baryonic content and dark matter distribution of the nearest massive clusters • SRO-7: Galaxies and their environments in the nearby Universe• SRO-8: Multi-scale clustering and the halo occupation function• SRO-9: The chemical evolution of galaxies and AGN • SRO-10: Mapping the inner parsec of quasars through reverberation mapping• SRO-11: Linking galaxy evolution with the IGM through tomographic mapping• SRO-12: A peculiar velocity survey out to 1Gpc and the nature of the CMB dipole

• SROs reviewed by Science Executive and Project Office. • 12 SROs selected for continued development• These 12 SROs spawn the range of issues addressed by the science requirements

described in the Science Requirements Document

SRO-4: Unveiling CMD substructure with precision kinematics (Ibata)



+

SRO-8: Multi-scale clustering and the halo occupation function (Robotham)

• 8 photo-z selected survey cubes (300Mpc/h on a side) to probe the build-up of large scale structure, stellar mass, halo occupation and star formation out to a redshift of z=4!

• ~100% completeness per cube (1 dex below M* for first 4 cubes, beyond this limited by LSST photo-z accuracies)!

• Sensitivity to ~1.8um preferred. ~5 - 7 year observing program only possible on a dedicated facility

SRO-10: Mapping the inner parsec of quasars (Gallagher)

• ~60 observations of ~5000 quasars spread over ~years to map the structure and kinematics of the inner parsec around a large sample of supermassive black holes actively accreting during the peak quasar era!• (Compare with ~50 local, low-luminosity AGN that currently have high quality RM measurements; evolution as a function of z essentially unknown)!

• Calibration is key: Stable environment and well understood spectroscopic system essential.!!

SRO-10: Mapping the inner parsec of quasars (Gallagher)

• ~60 observations of ~5000 quasars spread over ~years to map the structure and kinematics of the inner parsec around a large sample of supermassive black holes actively accreting during the peak quasar era!• (Compare with ~50 local, low-luminosity AGN that currently have high quality RM measurements; evolution as a function of z essentially unknown)!

• Calibration is key: Stable environment and well understood spectroscopic system essential.!!

So what are the requirements

that flow from all these SROs???

Science Requirements I: A spectroscopic telescope


•Etendue!

• All SROs want to observe faint targets over fields of view from several to thousands of square degrees [e.g., “Nearby Galaxies and their environments”, 3200 + 100 sq. deg]!

• Requirement is equivalent to a 10m effective aperture and a 1.5 sq. degree FoV!

• 10m class essential to push to the faintest targets not accessible with smaller facilities

• Driver of all the SROs• See upcoming Sensitivity requirement

KEI’S PRESENTATION: MSE will is a 11.25m segmented Prime Focus Telescope with a 1.5 sq. degree FoV



•Multi-object Spectra• At first light, MSE will be be a MOS facility!

•Spatially resolved spectra• MSE will be able to host a suite of IFUs during

its lifetime (i.e. not a first light capability)

• Many compelling science programs need IFUs (e.g., “Dynamics of the dark and luminous cosmic-web during the last 3 billion years”)!

• For programmatic/cost/schedule reasons, it is expected that IFUs will be a second-light capability (likely feeding the same spectrographs as the MOS mode)• Informal MSE working group: Alessandro Boselli, Kevin Bundy (+MANGA team),

Scott Croom, Laura Ferrarese, Andrew Hopkins, Mike Hudson, Your-name-here?• Want to provide some initial science concepts by mid-Fall (e.g., number of IFUs,

sizes, spaxel size etc)

Science Requirements II: Operation at a range of spectral resolutions

Science Requirements II: Operation at a range of spectral resolutions

• High Resolution: Original requirement was R20K. Strong push by science team to change to R40000 (e.g., AAT/HERMES, ESO Gaia survey, UVES vs FLAMES).

• Very significant design specifications still need to be set (see later)

•Low Res: R~3000• (e.g., Evolution of galaxies, halos and structure

over 12Gyrs; “Mapping the Inner Parsec of Quasars with MSE”)

•Moderate Res: R~6500• (e.g., “A chemodynamical deconstruction of the

Local Group”; “Nearby Galaxies and their environments”; “Connecting high redshift galaxies to the IGM”

•High Res: R~XX000 (40K?)• Galactic Archaeology

Science Requirements III: Extremely multiplexed spectroscopy


• Original multiplexing spec inherited from WFMOS• Justifiable, e.g. space density of z<0.2 galaxies brighter than i~23 is

~2000/sq.deg• But without preselection of specific targets, the space density of

(extragalactic) targets brighter than i~24 (see later) is high (closer to ~1 per sq. arc min)

• Higher multiplexing = better

•Low & Moderate Res Multiplexing: both >3200 spectra/field

• or equivalent space density (0.59/sq.arcmin) if field is larger than 1.5 sq. deg


• Original multiplexing spec was N~800, inherited from WFMOS

• Lots of 4-m class surveys can target the disk

• Multiplexing req. based on space density of thick disk and halo stars with 16 < g < 21.5

•High Res Multiplexing: >1000 spectra/field

• or equivalent space density (0.18/sq.arcmin) if field is larger than 1.5 sq. deg

• Galactic Archaeology

Science Requirements IV: Broad wavelength range


• “Evolution of galaxies, halos and structures over 12Gyrs”, “Mapping the inner parsec of quasars with MSE”!

• Red-end cut-off set by technical and financial limitations, not by science!

• H band imposes very significant design challenges in terms of cost and complexity

•Low Res Wavelength Coverage: 0.36 —> at least 1.3um and with a very serious effort to get to 1.8um

• optimised for longward of 0.37um


• The total wavelength coverage in this range is anticipated to be approximately half that available at R3000. Use R6500 as a follow up to R3000 mode? !

• CaT region crucial (CaII Triplet region [8498, 8542, 8662A]). Also MgI 8806 (gravity-sensitive for dwarf-giant discrimination)• Any other red features, including NIR, for which moderate resolution is critically important? • Strong possibility that NIR will operate only at R~5000 (sky line considerations) !

• Blue wavelengths: • Target the bluest wavelength range of MSE (360 - 430nm; Blamner series, CaII HK, CN band

[3883], CH band [4320], SrII[4077, 4215], CaI [4227] ?• Any other features critically important? e.g. HBeta[4863] - NII[6583]?

•Moderate Res Wavelength Coverage: TBD• “The dark substructure of the Milky Way; A chemodynamical

deconstruction of the Local Group; Nearby galaxies and their environment; Connecting high redshift galaxies to their local IGM”


The major outstanding issue for the science requirements !

The Problem • Not possible to get full wavelength

coverage for 1000 objects at R~20-40K

• As resolution goes up, accuracy of chemical abundances improves = good

• As resolution goes up, number of species for which you can derive chemical abudances goes down (not to be found on your detector) = bad

0"

10"

20"

30"

40"

50"

60"

70"

400" 450" 500" 550" 600" 650" 700" 750" 800"

Range,'nm'

Central'Wavelength,'nm'

Wavelength'Range'for'1.2"'fibre'

R=20000"

R=30000"

R=40000"

R20K!!!R30K!!R40K

No slicing, 1.2 arcsec fibers!F/1.8 camera!Two CCDs wide per arm

•High Res Wavelength Coverage: TBD• Galactic Archaeology


• Right: spectral features visible in synthetic metal poor RGB star at R20K. • Grey is proposed wavelength

coverage from Feasibility Study • (426 - 491nm; 585 - 675nm)• ~17 chemical species!

• Consider R40K (~0.5 x previous wavelength coverage)• 449.5-482nm and 628-673nm

!• Elisabetta Caffau kindly ran a

spectral synthesis code using a real spectrum of HD122563 (metal-poor giant, stellar parameters in Cayrel et al. 2004) from UVES R40000, analyzing just the interval above


• Obtain metallicity and log(g) in agreement with Cayrel et al. 2004

• Teff low by >200K (a well known problem due to the available FeI lines in metal poor stars)

• Abundances obtained for the following species (9 in total, typical uncertainties of order 0.1 - 0.2 dex):

Fixed Vturb=2.0km/s!Derived Teff=4393.7 Logg=1.02!#############################! [X/H] Sigma [X/Fe] Sigma!Ca -2.68 0.0571 0.35 0.0946!Sc -3.08 NaN -0.05 NaN!Ti -2.78 0.0383 0.25 0.0846!Ti -2.79 0.1031 0.24 0.1833!Cr -3.15 0.0333 -0.13 0.0824!Cr -2.94 0.1600 0.08 0.2204!Mn -3.20 0.0114 -0.17 0.0763!Fe -3.02 0.0754 0.00 0.1066!Fe -3.03 0.1515 0.00 0.2142!Ni -2.94 0.0422 0.09 0.0864!Zn -2.88 0.0098 0.14 0.0760!Y -3.21 NaN -0.18 NaN!###############################







• Obtain metallicity and log(g) in agreement with Cayrel et al. 2004

• Teff low by >200K (a well known problem due to the available FeI lines in metal poor stars)

• Abundances obtained for the following species (9 in total, typical uncertainties of order 0.1 - 0.2 dex):

Fixed Vturb=2.0km/s!Derived Teff=4393.7 Logg=1.02!#############################! [X/H] Sigma [X/Fe] Sigma!Ca -2.68 0.0571 0.35 0.0946!Sc -3.08 NaN -0.05 NaN!Ti -2.78 0.0383 0.25 0.0846!Ti -2.79 0.1031 0.24 0.1833!Cr -3.15 0.0333 -0.13 0.0824!Cr -2.94 0.1600 0.08 0.2204!Mn -3.20 0.0114 -0.17 0.0763!Fe -3.02 0.0754 0.00 0.1066!Fe -3.03 0.1515 0.00 0.2142!Ni -2.94 0.0422 0.09 0.0864!Zn -2.88 0.0098 0.14 0.0760!Y -3.21 NaN -0.18 NaN!###############################






What is the fundamental (or, more likely, optimal) requirement on the high resolution mode in terms of

specific chemical species to be observed and/or total number of species to be observed?

!e.g. c.f. AAT/HERMES, 4MOST, Gyes

Science Requirements V: Targeting the faint Universe

Science Requirements V: Targeting the faint Universe

• Low res sensitivity: SNR=2 for m=24 in 1 hour (SNR=1 at <400nm)

• e.g.,Evolution of galaxies, halos and structure over 12Gyrs

• Moderate res sensitivity: SNR=2 for m=23.5 in 1 hour (SNR=1 at <400nm)

• e.g.,Nearby galaxies and their environment; The chemodynamical deconstruction of the Local Group

• High res sensitivity*: SNR=10 for m=20 in 1 hour (SNR=5 at <400nm)

• e.g.,Galactic Archaeology

*pending hi-res decisions

Science Requirements VI: Stable & calibrate-able


• Velocities at R3000: 20km/s at SNR=5• Velocities at R6500: 9km/s at SNR=5

• (standard velocity accuracy in both modes, no wavelength dependence)

• Velocities at RXX000*: 0.1km/s at SNR=30

• Velocity accuracy better than nominal

• Exoplanets and stellar velocity variability; “Revealing the physics of rare stellar types”; “The dark substructure of the Milky Way”

*pending hi-res decisions



• Relative Spectrophotometry• 3% at SNR=30• Mapping the inner parsec of

quasars

• Also required for stellar population analysis of extragalactic targets

• Accurate relative spectrophotometry is extremely hard• Requires precise knowledge of the relative transmission of all your system as a function

of wavelength to a very high level at all times• Requires precise knowledge of the amount of flux entering your system as a function of

wavelength ie where your source is relative to your fibers• The dedicated and stable nature of MSE is essential for spectrophotometry!

• Note that, ideally, you would like to have big fat fibres• [ Discussion on Friday ]



• Sky subtraction

• 0.5% accuracy away from sky lines (or limited by expected photon statistics)

• Residual noise consistent with variance from sky in regions of sky lines

• e.g. m=24 (SNR=2 limit in 1hr) is 3.3 mags fainter than median sky brightness in dark time (V=20.7mags/sq.arcsec)• so sky is ~20 times brighter than the object• 1% sky subtraction means 20% of flux in sky subtracted object spectrum is sky

!• Very good sky subtraction is hard; this requirement is pushing the limits of what can be

achieved with fiber fed systems• But good results achieved using advanced analysis procedures e.g., Principle

Component Analysis (see Sharp & Parkinson 2010); no plans for (e.g.) N&S• A lot of collective experience in the MSE science team to draw upon

The bottom line

* from Sugai et al. 2014 (SPIE); area based on “effective diameter of circle with area equal to patrol region of fibers"

MSE is the world’s only large aperture (>8m) observatory to be dedicated to spectroscopy at OIR wavelengths. Its first light capabilities will enable transformative science, and over its lifetime it will act as a premier platform for exploration of the faint Universe!

Outstanding Requirement Issues

Outstanding Requirement Issues• High spectral resolution mode

• Thursday science discussion topic?• Can we define a path forward at this meeting to resolve these questions?

• Data requirements• [ Friday data discussion ]• What data products does MSE need to provide as standard?

• Calibration requirements• [ Friday calibration discussion ]• Detailed calibration plans are next major focus for science

• Do the requirements reflect your science needs?• Primary focus of the science sessions today and tomorrow should be in identifying

key capabilities and ensuring these are accurately reflected by the science requirements

• Science Requirement Document will soon be put under configuration control (~September) and cross referenced to Detailed Science Case.

• Finalisation of these documents marks the end of the first set of tasks for the science team

As one door closes…

As one door closes…

• Next priorities for science team:• Integral field units

• concept and implementation strategy• Operations Concept

• how do we implement the science programs?• See discussion on Friday

• Calibration plan• See discussion on Friday• Set-up a calibration working group to advise the Project Office

• Data pipelines and concepts• Science simulations• MSE observing simulator• …lots to do :-)

Fin

Fin

Thank you…Questions?

Documents

Science Overview and the Key Design Space for MSE · • Science team charged with developing Science Reference Observations, that describe science programs that are high proﬁle,