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Potential of TMT polarimetry Koji S. Kawabata (Hiroshima Univ., Japan) Polarized glass

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Index 1.Why Polarimetry? 2.Polarimetry Science Cases with TMT SNe, AGN jet 3.Idea for Instrumentation for polarimetry WFOS/Mobie, IRIS

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1. Why Polarimetry? Geometry of Light-scattering media (free electron, dust grain, etc) in distant point-like objects (Morphology: bipolar/clumply mass-loss, jet, disk) Magnetic Field (High-energy Electrons) Physical properties of scattaring matter / Extracting Light from Hidden source They are difficult to access by normal imaging and spectroscopy. Because we explore

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YSOs, Stars, ISM/IGM, SNe/GRBs, Exo-planets/Solar system, Extragalaxies, Currently, ~35 cases in various fields are listed. W. Skidmore et al. 2. Polarimetry Science Cases

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Case 1: Supernovae 5 http://snap.lbl.gov/multimedia/animations/ SNAP/LANL Light curve Spectrum Image Time Variation over ~100 days After Explosion tail peak

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free electron SN Polarization: Continuum light Polarization vector Spherical photosphere Aspherical photosphere Cancelled out and Unpolarized (p~0%) Not fully cannceled and Polarized (up to a few %; Hoeflich 1991 ) Surface integration of Stokes Q, U Polarization Pattern of Electron-scattering- dominated photosphere (Chandrasekhar 1960) Scattered light (polarized orthogonally to scattering plane) Incident light Pol. Dir.

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SN Polarization: Absorption Line Polarization vector Homogeneous ion distribution Homogeneously absorbed flux %pol. Inhomogeneous ion distribution Partially absorbed flux %pol. P Cyg prof. constant

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A few good samples. Tanaka+ (2012) Polarization features at absorption lines Subaru/FOCAS spectropolarimetry

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Probing 3D structure of SN photosphere Loop structure in QU diagram is an evidence that the ion distribution is NOT axisymmetric (2D asymmetric), but inhomogeneous (3D). Global mixing in expanding atphosphere? PA=0 PA=90 Tanaka+ 2012 See also Wang and Wheeler 2008; KSK+ 2002; Leonard+ 2002; Wang+ 2003 Tanaka+ 2012 2D (axi-symmetry) 3D (inhomogeneous)

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First principle 3D simulation (Takiwaki+ 2012) From 2-3D explosion models 500km EntropyDensity/Velocity 0.0015ms 0.0125ms 2D model (Suwa+ 2010) Multi-D effects (SASI/rotation, mixing instability) accelerate neutrino heating Asymmetric engine is expected In 2D model, shock front can expand! In 1D shock front stalls Blondin+ 04

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From late-time spectroscopy 5 out of 18 (28%) ES CC SNe showed double-peak profile in [O I] emission line. This high incidence is consistent with the prediction in case that all of the observed SNe are moderately asymmetric. Mazzali, KSK+ 05; Maeda, KSK+ 08. (cf. Modjaz+ 08; Taubenberger+ 09) Torus-like O(Mg)-rich ejecta equator double peaks polar (single peak) w/ GRB w/o GRB Emission line profile may depend on viewing angle. O-rich Maeda+ (2002) Fe(Ni)

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If the SN engine is bipolar associated with GRB jet, little or no polarization is expected; while, non-GRB hypernovae may show strong polarization New clue to the engine and massejection process of GRB-SN explosion with systematic observation with TMT GRB jet SN asphericity connection? Unpolarized Polarized GRB-associated hypernova non-GRB hypernova

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From X-ray SNR observation (Fesen+ 2006; Krause+ 2008) Imaging + Doppler projection (X-ray, IR, ground-based Opt); DeLaney+ 2010 220 Cas A, a young SNR ~330 years old; Type IIb SN (Seen) Ion distribution is inhomogeneous. How? Interaction with inhomogeneous CSM ? Already inhomogeneous at SN explosion ? Clue to engine

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Past line polarimetry for envelope-stripped core-collapse SNe with 8-10m telescopes 5 our of 6 type Ib/c SNe show loop (i.e. 3D) signs. SN IDTy pe Dist. (Mpc) Polarization Loop or 3D ? Tel./Instr.Ref. 2002apIc9.7Yes Subaru/FOCAS, Keck/LRISp, VLT/FORS1 KSK+ 02, Wang+02, Leonard+ 03 2005bfIb84Yes VLT/FORS1, Subaru/FOCAS Maund+ 07, Tanaka+ 09 2007grIc9.3No Subaru/FOCAS Tanaka+ 08 2008DIb32Yes VLT/FORS1 Maund+ 09 2009jfIb34Yes Subaru/FOCAS Tanaka+ 12 2009miIc30Yes Subaru/FOCAS Tanaka+ 12 Observation is restricted for nearest SNe (

Age of Next-Gen., Multi-wavelength Polarimetry up to high-energy photons is coming.. Hard X-ray: Astro-H (2015-) ISAS/JAXA NASA mm/sub-mm: ALMA ESO/NAOJ cm: SKA (2020?-) Univ. of Manchester 1.9 yr 2.3yr Optical 3-band polarization (p~0.1%) of millions of stars (100 times more samples than current catalog (e.g. Heiles 2000)

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Instrument capabilities planned for the first decade of TMT operations. The first three are early light instruments. InstrumentField of view / slit lengthSpectral resolution (m) Comments InfraRed Imager and Spectrometer (IRIS) 15imaging > 3500 5-100 (imaging) 0.8 2.5 0.6 5(goal) NFIRAOS Wide-field Optical spectrometer and imager (WFOS) >40 arcmin 2 >100 arcmin 2 (goal) Slit length>500 1000-5000 >7500 @0.75 (goal) 0.31-1.0 0.3-1.5(goal) Seeing-Limited (SL) InfraRed Multislit Spectrometer (IRMS) 2 arcmin field 46 deployable slits R=4660 @ 0.16 arcsec slit 0.95-2.45NFIRAOS Multi-IFU imaging spectrometer (IRMOS) 3 IFUs over >5 diameter field 2000-100000.8-2.5MOAO Mid-IR AO-fed Echelle Spectrometer (MIRES) 3 slit length 10 imaging 5000-100000 8-18 4.5-28(goal) MIRAO Planet Formation Instrument (PFI) 1 outer working angle, 0.05 inner working angle R100 1-2.5 1-5 (goal) 10 8 contrast 10 9 goal Near-IR AO-fed Echelle Spectrometer (NIRES) 2 slit length 20000-1000001-5NFIRAOS High-Resolution Optical Spectrometer (HROS) 5 slit length 50000 0.31-1.1 0.31-1.3(goal) SL Wide-field AO imager (WIRC) 30 imaging field 5-100 0.8-5.0 0.6-5.0(goal) NFIRAOS Courtesy TMT Observatory Corporation No Polarimetry Mode yet TMT instruments planned for first decade

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Why NOT Polarimetry with TMT? Essentially, polarimetry needs a number of photon in most scientific cases. (Requiring ~10 times larger S/N ratio than normal phot/spec) Potentially TMT can be a great polarimeter. Disadvantage Requiring extremely large optical components that have never been realized A few % instrumental polarization due to reflection at tertiary mirror Less image quality/sensitivity due to additional optical components Could these be compensated or compromised for some scientific cases?

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There would be two types of astronomers 1. People who like polarization so much. 2. People who do no like polarization so much. Bipolarity --- 2. is likely to be major... We (1.) may explore further possibility

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Required Field of View for TMT polarimetry cases Required FoVNumber of polarimetric scientific cases Single point-like source (604 From the list by Skidmore et al.

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3. Idea for Instrumentation Target : Two of three First light instruments

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Example: Polarimeter at 8-10m Tel. Subaru/FOCAS VLT/FORS Keck/LRIS ISAAC/VLT Naco/VLT Subaru/HiCIAO (Gemini/Michelle)

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Add-on-type polarimetry module 1 8-10m class optical: FOCAS/FORS/(LRIS) type FOCAS/Subaru Rotatable Half-wave plate (~120mm diam.) Beam splitter (~120mm cube) Focal mask (~175mm diam.) Filter 2 Filter 1 Grism Aux/Filter Retarder Polarizing prism ordinary ray + extraortdinary ray Polarization Module We (need to) insert two additional optical components in the beam.

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Pol. unit inserted in front of optical fiber HARPSpol ESO3.6m/HARPS (Mayor+ 2003) SEMPOL AAT3.9m/UCLES (Semel+ 1993) SOFIN-pol NOT2.6m/SOFIN (Pettersson+ 1998 Pol. unit for HARPSpol (Piskunov+ 2011) Pol. unit in SEMPOL (Semel+ 1993) Focal mirror/slit /4wave plate beam spliter Focal reducer Optical fiber (ord/ext) Add-on-type polarimetry module 2 Circular spectro-polarimetry with fiber-fed high-disp. spectrograph at 2-9m telescopes

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WFOS/Mobie case Mobie/WFOS Focal plane (mask) 550mm 1260mm

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Large Optical Components vs. Clearance Mobie/WFOS Focal plane (mask) Wave plate before mirror >550mm1260mm Beam splitter @pupil position >350mm 550mm 1260mm

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Possible solution for Mobie polarimetry Monolithic WP of ~150 available (A corp. in Japan) o e Mosaiced crystal Wire-grid

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Sufficient clearance in the optical train / holder / support of Mobie? Feasibility study needed. Add-on polarimetry with a restricted FoV (