Millimeter-wave polarization of protoplanetary disks: alignment or - PowerPoint PPT Presentation

Millimeter-wave polarization of protoplanetary disks: alignment or scattering? ALMA Band 7 (870 µm) ALMA Band 3 (3.1 mm) HL Tau l p Stephens et al. 2017 Kataoka et al. 2017 Scattering Alignment Akimasa Kataoka (NAOJ) T. Muto (Kogakuin U.), M. Momose, T. Tsukagoshi (Ibaraki U.), H.Nagai (NAOJ), M. Fukagawa (Nagoya U.), H. Shibai (Osaka U.), T. Hanawa (Chiba U.), K. Murakawa (Osaka-S.), Kees Dullemond, Adriana Pohl (Heidelberg) � ´ � ~ ´ s ´ = + - s =

Star and disk formation time (years) molecular envelope + disk cloud core -10^6 Infalling envelope Disk -10^5 ~300 AU Out fm ow Out fm ow B68, ~10^4AU Elias 2-24 (Perez+ 2016) (Alves+ 2001) Disk protostar formation Infalling envelope ~25,000 AU L1527, envelope:10^4 AU, 10^5 disk:10^2 AU (Tobin+ 2012) HL Tau (ALMA+ 2015) protoplanetary disks 10^6 e.g., TW Hya (Andrews+ 2016) HD 142527 (Fukagawa+ 2013) Akimasa Kataoka (NAOJ)

Polarization of star-disk system Envelope , ~10^4 AU time (years) B B -10^6 -10^5 a d IRAS 4A(Girart et al. 2006) Ser-emb 8 (Hull et al. 2017) � protostar > s s = formation � ´ � � ´ � � 2 � embedded disks , ~10^2 AU protoplanetary disks , ~10^2 AU B b � � E E 10^5 b � º � º pr L1527 (Segura-Cox+ 2015) 10^6 100 AU 100 AU cf) non-detection of disks with SMA HD 142527 HL Tau HD 163296, TW Hya, GM Aur, DG Tau (Kataoka et al. 2016b) (Kataoka et al. 2017) (Hughes et al. 2009, 2013) Akimasa Kataoka (NAOJ)

SED of a protoplanetary disk • TW Hya ( M star = 0.6 M ⊙ , T eff = 4000 K) MIR Scattered Light (sub-)mm star 1 2 3 4 a b c d Distance in AU 1 10 100 1 T urbulent Mixing (radial or vertical) disk 0.35 mm 3.0 mm ALMA Vertical Settling 2 3 Radial Drift 10 µm VLTI/MATISSE a) Sticking 4 b) Bouncing EELT 2 µm 10 µm c) Fragmentation with mass transfer d) Fragmentation JWST/MIRI Menu et al. 2014 Testi et al. 2014 • The millimeter emission is thermal dust emission from the disk. • How can we polarize the thermal dust emission? Akimasa Kataoka (NAOJ)

Polarization mechanisms 1. Alignment of elongated dust grains with magnetic fields Magnetic Field Linear polarization e.g., Lazarian and Hoang 2007 2. The self-scattering of thermal dust emission Kataoka et al. 2015 3. Alignment of elongated dust grains with radiation fields Tazaki, Lazarian et al. 2017 Akimasa Kataoka (NAOJ)

Dust is big in disks 0.1 μ m 1m 1mm 1km 10 2-4 km dust opacity 10 5 a max =1 µ m, κ abs 10 4 a max =1 µ m, κ sca a max =100 µ m, κ abs 10 3 κ abs,sca [cm 2 /g] a max =100 µ m, κ sca 10 2 scattering 10 1 > absorption 10 0 10 -1 10 -2 10 -3 10 0 10 1 10 2 10 3 10 4 λ [ µ m] Akimasa Kataoka (NAOJ)

Light source of scattering IR scattered light example (face-on, PI) disk Infrared Pohl et al. 2017 radio scattered light (self-scattering) ? millimeter Akimasa Kataoka (NAOJ)

Polarization due to scattering incident light (unpolarized) a dust grain an observer an observer an observer http://sites.sinauer.com/animalcommunication2e/chapter05.02.html Akimasa Kataoka (NAOJ)

Polarization due to scattering thermal dust emission of other dust grains a dust grain Horizontal Polarization The observer is you. (the line of sight is perpendicular to the plane of this slide) Akimasa Kataoka (NAOJ)

Polarization due to scattering Horizontal Polarization Akimasa Kataoka (NAOJ)

Polarization due to scattering Unpolarized Akimasa Kataoka (NAOJ)

Polarization due to scattering Unpolarized Akimasa Kataoka (NAOJ)

Polarization due to scattering Vertical Polarization Akimasa Kataoka (NAOJ)

Protoplanetary disks HD142527 A IRS 48 Fukagawa et al. 2013 van der Marel et al. 2013 Perez et al. 2014 MEM model HD 97048 HL Tau TW Hya 1.0 1.0 0.5 0.5 0.0 0.0 − 0.5 − 0.5 − 1.0 − 1.0 1.0 1.0 0.5 0.5 0.0 0.0 − 0.5 − 0.5 − 1.0 − 1.0 ∆α [arcseconds] Andrews et al. 2016 ALMA Partnership 2015 van der Plas et al. 2016 Anisotropic thermal emission at mm wavelengths Akimasa Kataoka (NAOJ)

self-scattering in a protoplanetary disk Akimasa Kataoka (NAOJ)

self-scattering in a protoplanetary disk Akimasa Kataoka (NAOJ)

Theoretical prediction Polarization fraction [%] Stokes I (continuum) I [mJy/arcsec 2 ] P[%] P[%] 10 3 3.00 ring @ 170AU, d=140pc 2 2 2 2.50 10 2 1 1 1 2.00 [arcsec] [arcsec] [arcsec] 0 0 1.50 0 10 1 1.00 -1 -1 -1 0.50 -2 -2 -2 λ =870µm λ =870µm 10 0 0.00 -2 -2 -1 -1 0 0 1 1 2 2 -2 -1 0 1 2 [arcsec] [arcsec] [arcsec] The polarization degree is as high as 2.5% → detectable with ALMA Anisotropy → net polarization Kataoka, et al., 2015 Akimasa Kataoka (NAOJ)

ALMA observation of HD 142527 flip 100 AU 100 AU • Flip of polarization vectors • Change of the direction of radiative flux - evidence of the self- scattering (Kataoka et al. 2015) Kataoka, et al., 2016b Akimasa Kataoka (NAOJ)

Conditions of dust grains for polarization ・ For efficient scattering λ =870 µ m (ALMA Band 7) 1.4 (grain size) >~ λ P ω 1.2 P 90 Albedo 1 ・ For efficient polarization 0.8 (grain size) <~ λ 0.6 P 0.4 0.2 0 There is a grain size which -0.2 contributes most to the 0.001 0.01 0.1 1 Maximum grain size [cm] grain size [cm] polarized emission If (grain size) ~ λ /2 π , the polarized emission due to dust scattering is the strongest Akimasa Kataoka (NAOJ)

Grain size constraints by polarization Expected polarization degree (scalable) 1.2 7 mm 3.1 mm (Band 1) 1 (Band 3) 0.87 mm (Band 7) 0.34 mm 0.8 (Band 10) 0.6 0.4 0.2 0 0.001 0.01 0.1 1 Maximum grain size [cm] Kataoka, et al., 2015 Multi-wave polarization → constraints on the grain size Akimasa Kataoka (NAOJ)

Yang, Li, et al. 2016 See also Kataoka et al. 2016a self-scattering in an inclined disk i =45° Akimasa Kataoka (NAOJ) (disk, edge-on view)

HL Tau pol. - prediction λ =870 µ m • i = 47° (ALMA Partnership 2015) • The polarization vectors are parallel to the minor axis Kataoka, et al., 2016a (see also Yang et al. 2016) Akimasa Kataoka (NAOJ)

HL Tau polarization with ALMA 100 AU 100 AU • We find the azimuthal polarization vectors at 3.1 mm wavelength Kataoka, et al., 2017 Akimasa Kataoka (NAOJ)

HL Tau polarization 100 AU 100 AU Kataoka, et al., 2017 data from Stephens et al., 2014 • The polarization vectors at 1.3 mm are parallel to the minor axis • The polarization vectors at 3.1 mm are in the azimuthal direction wavelength-dependent polarization in mm range Akimasa Kataoka (NAOJ)

ALMA observation: HL Tau ALMA Partnership 2014 Kataoka et al. 2017 Stephens et al. 2017 Akimasa Kataoka (NAOJ fellow)

Polarization mechanisms 1. Alignment of elongated dust grains with magnetic fields Magnetic Field Thermal emission Linear polarization e.g., Lazarian and Hoang 2007 2. The self-scattering of thermal dust emission Kataoka et al. 2015 3. Alignment of elongated dust grains with radiation fields Tazaki, Lazarian et al. 2017 Akimasa Kataoka (NAOJ)

Alignment with radiation fields a~100 µm aligned with rad. fields Figure 5. n of E -vector is plotted as the white bar. Left and right panels represent mid-infrare Tazaki, Lazarian et al. 2017 Akimasa Kataoka (NAOJ)

Polarization mechanisms alignment with B-fields self-scattering alignment with radiation • Toroidal magnetic • Inclination-induced • Grains are needed to fields are assumed scattering -> parallel be big (~>100um) to the minor axis • Radiation gradient is • Grain size is a ~ λ /2 π : in the radial direction. strong wavelength dependence Akimasa Kataoka (NAOJ)

Wavelength dependence alignment with B-fields self-scattering alignment with radiation self-scattering mixture alignment with radiation Stephens et al. 2017 (see also Kataoka et al. 2017) Akimasa Kataoka (NAOJ)

Total polarization fraction 100 AU 100 AU integrating no polarization 0.5% <0.1% We can extract the self-scattering components Akimasa Kataoka (NAOJ)

HL Tau polarization Kataoka, et al., 2017 The maximum grain size is ~ 70 µm Akimasa Kataoka (NAOJ)

Star and disk formation Molecular Protostar and cloud cores protoplanetary disk Timescale ~10 4-6 years ~10 6-7 years ~0.1 pc ~100 AU =20,000 AU Spatial scale ~1 arcsec ~ 200 arcsec magnetic fields grain growth Key physics A.Isella or turbulence? Akimasa Kataoka (NAOJ)

10µm polarization Surface brightness (log[Jy/arcsec 2 ]) • Inner part - grains are aligned -0.5 0.0 0.5 1.0 1.5 2.0 with poloidal B-fields at Offset (AU) -200 -100 0 100 200 surface 06 ″ 06 ″ AB Aur @ 10 µ m • Inner part - grains are aligned 200 • Outer part - the self-scattering- with poloidal B-fields at induced polarization surface 05 ″ 05 ″ 100 Declination (J2000) cf) NIR polarization 100 50 0 -50 -100 -150 Offset (AU) • Outer part - the self- -0.5 0 0.5 1 0 scattering-induced Dec. offset (arcsecond) 04 ″ 04 ″ polarization -100 30 ° 33 ′ 03 ″ 30 ° 33 ′ 03 ″ -200 N 2% E 0.5 0 -0.5 -1 04 h 55 m 45.95 s 04 h 55 m 45.95 s 45.85 s 45.85 s 45.75 s 45.75 s R.A. offset (arcsecond) Right Ascension (J2000) Dan Li, et al., 2016 Hashimoto et al., 2011 Akimasa Kataoka (NAOJ)