Resolved Stellar Populations in the Near IR

June 07th, 2011 Frontier Science Opportunities with JWST - STScI

Resolved Stellar Populations in the Near IRJason Kalirai (STScI)


Outline- Frontier science opportunities for JWST in the arena of resolved stellar populations.- Characteristics of JWST that will enable this science.- Some hints from Hubble.- Synergies with HST, LSST, and GSMT.


Carina Nebula - NASA, ESA, N. Smith (UC Berkeley), and the Hubble Heritage Team (STScI/AURA)

Hubble Space Telescope ACS/WFC - STScI-PRC07-16A

Resolved Stellar Populations in the Near IR

Science Opportunities1.) Calibrate the infrared color-magnitude diagram.2.) Increase the sensitivity of main-sequence turnoff fitting methods .

3.) Complete the stellar inventory.4.) Resolve distant galaxies into individual stars.


JWST Characteristics1.) Superb sensitivity at near-infrared wavelengths.2.) Multiple imaging and spectroscopic modes with fine sampling.3.) High spatial resolution.4.) Large fields of view.



100 microns10 microns1 microns

Wavelength

Light

gath

eri

ng p

ow

er

0.1 microns

(Mir

ror

Are

a)

HST

JWST

Spitzer

Light Gathering PowerJWST = 25 m2 ; Hubble = 4.5 m2 ; Spitzer = 0.6 m2


Resolved Stellar Populations in the Near IRJWST Sensitivity and Imaging Modes (see poster by J. Rigby)


Hubble (D = 2.4 M) ACS @ 0.5 m = 0.043’’ WFC3 @ 1.6 m = 0.138’’

Diffraction Limits of Hubble, Spitzer, and JWST at various wavelengths (Minimum angular separation of a source that can be resolved)

Spitzer (D = 0.8 M) IRAC @ 3.6 m = 0.93” IRAC @ 8.0 m = 2.06” MIPS @ 24 m = 6.18”

JWST (D = 6.5 M) NIRCam @ 2 m = 0.063’’ NIRCam @ 4 m = 0.126’’ MIRI @ 10 m = 0.317’’ MIRI @ 20 m = 0.635’’

But, Hubble pixels are 0.04 – 0.05” at <1 m and 0.13” at >1 m Spitzer pixels are 1.2” at <8 m and 2.55” at 24 m Hubble can not fully sample diffraction limit at optical or IR wavelengths Spitzer only reaches diffraction limit at > 24 microns

JWST NIRCam has two modules, with pixel size 0.0317” at <2.5 m and 0.0648 at >2.5 mJWST MIRI has pixel size of 0.11 arcsec JWST optimally samples the diffraction limit at 2 m, 4 m, and 7+ m

Best sampling demands a pixel size that is slightly finer than nyquist limit (/2D)(i.e., ~2 pixels should sample the diffraction limits given above)

Diffraction Limits



JWST Instruments: Imaging/Spectroscopic Modes and Fields of View

The Near Infrared Camera (NIRCam)- Visible and near infrared camera (0.6 – 5 micron)- 2.2 x 4.4 arcmin field of view, diffraction limited

The Near Infrared Spectrograph (NIRSpec)- Multi-object dispersive spectrograph (1 – 5 micron)- 3.4 x 3.4 arcmin field of view with 0.1 arcsec pixels- R = 1000 and 2700 gratings and R = 100 prism

The Mid Infrared Instrument (MIRI)- Mid-infrared camera and slit spectrograph (5 – 28 microns)- 1.9 x 1.4 arcmin imaging field of view with 0.11 arcsec pixels- R = 100 slit spectrograph (5 – 10 micron) and IFU (R = 3000)

The Tunable Filter Imager (TFI)- Selectable R = 100 tunable filters for imaging (1.5 – 5 micron)- 2.2 x 2.2 arcmin field of view

NIRCam

NIRSpec





Resolved stellar populations anchor our knowledge of the UniverseJWST Opportunity #1: Calibrate the infrared color-magnitude diagram.



- NIRSpec can be extremely effective at obtaining large (~10,000 stars) statistical samples of stellar spectra in dense fields. Depending on density, 10-40% of all stars can be recovered.

- This technique is very efficient because it can be done by reconfiguring the MSA only, without dithering. Sky background exposures are obtained “for free”.

- This technique could be employed in globular clusters, star forming regions, the Galactic disk, and the bulge - provided the user requires a statistical sampling of stars.

+ Targets in operable shutter x Targets outside shutters

NIRSpec MSA in Dense Stellar FieldsJason Tumlinson & Jay Anderson


Resolved stellar populations anchor our knowledge of the UniverseJWST Opportunity #1: Calibrate the infrared color-magnitude diagram.

Leads to better calibration of stellar evolution models at red wavelengths. Leads to smaller uncertainties in population synthesis models. Provides an improved interpretation of light from distant galaxies.




Star clusters are excellent tracers of parent population star formation historiesJWST Opportunity #2: Increase the sensitivity of main-sequence turnoff fitting methods.



Sandage (1953) Buonanno et al. (1994)

The Color-Magnitude DiagramMessier 3 (Photographic plates from 200”)



The Milky Way’s Globular Clusters

M80NGC 2808

M55

NGC 6397

M92 Omega Cen



The Milky Way’s Globular Clusters

Resolved Stellar Populations in the Near IRThe Current State of the ArtThe HST/ACS Survey of Galactic Globular Clusters (Sarajedini et al. 2007)- Homogenous photometry and reduction.- V and I optical filters.- Modeled consistently with updated physics.- Large sample of 60+ clusters.


Resolved Stellar Populations in the Near IRThe Current State of the ArtThe HST/ACS Survey of Galactic Globular Clusters (Sarajedini et al. 2007)- Homogenous photometry and reduction.- V and I optical filters.- Modeled consistently with updated physics.- Large sample of 60+ clusters.

NGC 6362 - Dotter et al. (2010) Dotter et al. (2010)


Main-Sequence Turnoff Fitting

JWST Offers - Well separated filters in .- Superb sensitivity.- Larger field of view.- Diffraction limited.

Transform current optical survey to panchromatic study. Calibration and tests of stellar evolution models into the IR. More sensitive mapping of star formation spreads.


T. Brown (priv communication)


Star clusters are excellent tracers of parent population star formation historiesJWST Opportunity #2: Increase the sensitivity of main-sequence turnoff fitting methods.

Provides opportunity to probe <0.5 Gyr relative age spreads in clusters. Establishes more sensitive absolute age diagnostics.



Co-spatial populations are excellent hunting grounds JWST Opportunity #3: Complete the stellar inventory.



Based on HST/ACS and HST/WFC3 Data Collected as a Part of GO-11677 (PI H. Richer)UBC: Harvey RicherAMNH: Mike Shara, David Zurek HIA/NRC: Greg Fahlman, Peter StetsonSwinburne: Jarrod HurleySTScI: Jay Anderson, Aaron Dotter UBC: Jeremy Heyl, Ryan Goldsbury, Kristen WoodleyUCLA: Brad Hansen, Mike Rich, David ReitzelUW: Ivan King



Resolved Stellar Populations in the Near IRACS/WFC visible color-magnitude diagram


Resolved Stellar Populations in the Near IRWFC3/IR color-magnitude diagram


Resolved Stellar Populations in the Near IRWFC3/UVIS and IR color-magnitude diagrams (1 HST orbit per filter)


Resolved Stellar Populations in the Near IRA panchromatic data set: The color-magnitude relation


Co-spatial populations are excellent hunting grounds JWST Opportunity #3: Complete the stellar inventory. Measure the initial mass function and its dependency on environment. Characterize the hydrogen burning limit and probe sub-stellar regimes.


Apr 04th, 2011 University of British Columbia

Brown et al. (2003) Field(126 HST/ACS Orbits)


Ultra-deep imagingJWST Opportunity #4: Resolve distant galaxies into individual stars.



Brown et al. (2003) mF606W – mF814W

M31

N185 N147

M33

M33

N205

M31 dSphs

30 kpc 90 kpc 150 kpc

PAndAS M31 Map(McConnachie et al.)

60 kpc

N

E

SPLASH Project CollaboratorsUCSC: Raja GuhathakurtaCaltech: Evan KirbyCambridge: Andreea FontColumbia: Kathryn JohnstonJapan: Masashi Chiba & Mikito TanakaSTScI: Tom BrownUC Irvine: James Bullock, Joe Wolf, Erik TollerudUCSC: Kirsten Howley, Claire DormanUMass: Mark FardalUVa: Steve Majewski, Ricky Patterson, Rachael BeatonUW: Karrie GilbertYale: Marla Geha



Observational Design- Keck II 10 meter telescope (on Mauna Kea)- DEIMOS spectrograph (R = 6000, FOV = 16’ x 4’, l = 6000 – 9000 Ang, # = 200 stars)



Observational Design- Keck II 10 meter telescope (on Mauna Kea)- DEIMOS spectrograph (R = 6000, FOV = 16’ x 4’, l = 6000 – 9000 Ang, # = 200 stars)


Recent Results (SPLASH + PAndAS + Other)- Discovered M31’s stellar halo and measured its SB (Guhathakurta et al. 2006; Irwin et al. 2006)- Measured the spatial extent of the halo - R > 150 kpc (Gilbert et al. 2006; Ibata et al. 2007)


Observational Design- Keck II 10 meter telescope (on Mauna Kea)- DEIMOS spectrograph (R = 6000, FOV = 16’ x 4’, = 6000 – 9000 Ang, # = 200 stars)


Recent Results (SPLASH + PAndAS + Other)- Discovered M31’s stellar halo and measured its SB (Guhathakurta et al. 2006; Irwin et al. 2006)- Measured the spatial extent of the halo - R > 150 kpc (Gilbert et al. 2006; Ibata et al. 2007)- Characterized the halo metallicity distribution function (Kalirai et al. 2006; Chapman et al. 2006)


Observational Design- Keck II 10 meter telescope (on Mauna Kea)- DEIMOS spectrograph (R = 6000, FOV = 16’ x 4’, = 6000 – 9000 Ang, # = 200 stars)


Recent Results (SPLASH + PAndAS + Other)- Discovered M31’s stellar halo and measured its SB (Guhathakurta et al. 2006; Irwin et al. 2006)- Measured the spatial extent of the halo - R > 150 kpc (Gilbert et al. 2006; Ibata et al. 2007)- Characterized the halo metallicity distribution function (Kalirai et al. 2006; Chapman et al. 2006)- Discovered and characterized new substructures (Ibata et al. 2007; McConnachie et al. 2009; Kalirai et al. 2006; Gilbert et al. 2007; 2009a; 2009b; Fardal et al. 2007; 2008; 2009; Guhathakurta et al. 2006)- Measured the SFH in M31’s disk, spheroid, and stream (Brown et al. 2003; 2005; 2007; 2008)


Future Observational Design in for Samples of Galaxies- LSST wide-field imaging (substructure)- GSMT spectroscopy (kinematics, abundances)- JWST ultradeep imaging (SFHs)


- A view of the nearby universe, with galaxies at their true distances. Concentric circles correspond to hypothetical observing programs of 10, 100, and 1000 hours.

- At a given distance, JWST will be nearly six times faster than HST for this type of work.

- For a given exposure time, JWST can explore galaxies about 50% further away than those available to HST.

T. Brown (priv communication)



Ultra-deep imagingJWST Opportunity #4: Resolve distant galaxies into individual stars. Enable direct age measurements for components of samples of galaxies.


Carina Nebula - NASA, ESA, N. Smith (UC Berkeley), and the Hubble Heritage Team (STScI/AURA)

Hubble Space Telescope ACS/WFC - STScI-PRC07-16A


Science Opportunities1.) Calibrate the infrared color-magnitude diagram.2.) Increase the sensitivity of main-sequence turnoff fitting methods .

3.) Complete the stellar inventory.4.) Resolve distant galaxies into individual stars.


Resolved Stellar Populations in the Near IR

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