Polarimetry on M87. Outline of talk - Introduc8on: Accre8on Flow - SMA results - ALMA challenge. Keiichi Asada (ASIAA)

Transcription

1 Polarimetry on M87 Outline of talk - Introduc8on: Accre8on Flow - SMA results - ALMA challenge Keiichi Asada (ASIAA)

2 Introduction

3 M 87 and its Accretion Flows - Low-Luminosity AGNs are subclass of AGN. (L < 10-3 L edd ) - LLAGNs (Ho et al. 1997) are considered to accommodate RIAF - M 87 is categorized as LLAGN. LLAGN No Big Blue Bump (Ho et al. 2009)

4 Three types of RIAFs: Accretion flow of LLAGNs ADAF (Ichimaru 1977; Narayan & Yi 1995) ADIOS (Blandford & Begelman 1999) CDAF (Igumenshchev & Abramowicz 1999) Structure M ~ (r/r B ) 0 ~ (r/r B ) 0-1 ~ (r/r B ) 1 - Substan8al decrease of the mass accre8on rate can be expected for ADIOS and CDAF!! r B : Bondi radius (~ r s ) Mass Accre8on Rate is fundamental parameter to consider energy balance between L acc and L rad or L jet.

5 Probing Accretion Flow with SED fitting Yuan et al Very succeeded method for Sgr A* M ~ M! yr -1 (e.g., Narayan et al. 1995; Manmoto et al. 1997) SED can be contaminated/dominated by jet.

6 Probing Accretion Flow with Faraday Rotation Observer Agol 2000, Quataert & Gruzinov 2000, Bower et al. 2003, Marrone et al. 2006, Macquart et al Magnetized Plasma (RIAF) ~ K BH With RIAF model: n(r) ( r r s ) T (r) ( r r s ) 1 = 1/2 (ADAF) = 3/2 (CDAF) = 1/2 3/2 (ADIOS) Polarized emission (innermost AF or Jet) ~ K Marrone et al. 2006, ApJ, 640, 308

7 SMA Polarimetry towards Sgr A* Marrone et al. 2006, ApJ, 640, 308 RM observa8on with SMA towards Sgr A* - RM = (5.6 ± 0.7) 10 5 rad m -2 M = M! yr -1

8 M 87

9 M 87 (Virgo A*) - 1 st discovered relativistic jet - Low-Luminosity AGN - High Energy activities Importance of M 87 Cur8s 1918, Publica8ons of Lick Observatory 13, 31 Typical AGN with radia8vely inefficient accre8on flow (RIAF) Up to TeV gamma-ray Miss-aligned Blaser? - 2 nd largest apparent size of r s (radius of non-rotating BH) It contains all contents of AGN!! Best Source to understand AGN!!

10 Goal of the Greenland Telescope Project GRMHD model Pu et al. in prep. PdBI IRAM 30 m LMT Primary objec8ve: Image a shadow of black hole of M 87 with sub-millimeter VLBI observa8on includes Greenland Telescope, SMA/JCMT and phased ALMA at 230, 345 GHz and higher frequency.

11 In the case of M 87 - Apply the same scheme to M 87 Back light would be innermost jet, not AF - With Chandra Observa8on - r B ~ 230 pc ( r s ) - P B ~ erg s -1 - M B ~ 0.12 M! yr -1 Di Maqeo et al. 2003, ApJ, 582,133

12 SMA observations

13 SMA observations Taiwan Time for SMA will be opened to EA colleagues from next semester. Due for the proposal will be Feb. 8th

14 SMA images 2014, Jan , May , Feb. 28

15 EVPAs of M87 CORE KNOT A (Contaminated) KNOT B KNOT C P.A. of extend jet

16 EVPAs of M87 CORE KNOT A (Contaminated) KNOT B KNOT C Knot A Knot B Knot C 2014, Feb , May 13 P.A. of extend jet Knot A Knot C Knot B

17 EVPAs of M87 CORE KNOT A (Contaminated) KNOT B KNOT C P.A. of extend jet

18 EVPAs of M87 CORE KNOT A (Contaminated) KNOT B KNOT C Knot A Knot B Knot C Perlman+ P.A. of extend jet

19 Origin of the polarization emission Polarized flux towards core ~ mjy Frac8onal polariza8on towards core ~ 1 2 % Core show the rapid 8me varia8on; shortest 8me sale we detected ~ 6 weeks, corresponds to light crossing 8me of 0.04 pc (~ 60 Rs) MERLIN at 1.7 GHz EVN at 1.7 GHz VLBA at 2.3 GHz VLBA at 5.0 GHz VLBA at 8.4 GHz VLBA at 15 GHz VLBA at 24 GHz VLBA at 43 GHz VLBA at 86 GHz EHT at 230 GHz

20 RM fitting towards M rad m , Jan mon. EVPA [degree] rad m rad m , Jan , Feb mon rad m -2 3 mon. 2014, May 13 λ 2 [mm 2 ]

21 Mean RM and Mass accretion rate Assuming no time variation, <RM> = (-0.2 ± 1.3) 10 5 rad m -2!! RM < rad m -2!! M < M! yr -1 (at 21 r s ) M < M B (at 21 r s ) Humm, SMA would not be sufficient. Let s go to longer wavelength (as λ 2 ) and higher sensi8vity

22 ALMA CY2 & CY3 observations: CY2 obs. Date: Sep, 19, 2015 Freq.: 90.5, Resolu8on: 0.3 arcsec CY3 obs. Date: Nov, 11, 2015 Freq.: 90.5, Resolu8on: 0.06 arcsec ALMA observations

23 ALMA CY2 & CY3 observations: ALMA observations

24 ALMA CY2 observations IPOL QPOL UPOL

25 RM with ALMA Preliminary: Asada et al. in skep8cal

26 Mean RM and Mass accretion rate Assuming no time variation,

27 RM fitting towards M 87 1 BAF / ADAF GADAF 3D MHD sim. Pang et al. 2011, MNRAS, 415, D HD sim. Yuan et al. 2012, ApJ, 761, 130 ADIOS Jet power Ṁ/ṀB CDAF M = M B (at 21 r s ) Pj/ ṀBc Substan8al decrease of the mass accre8on rate. Probably very strong constraint on RIAF!! R/R s

28 Comparison with Jet Power Accre8ng Power :P acc (= Mc 2 ) ~ erg s -1 Li+ 2009, ApJ, 699, 513 Even if 10 % of P acc used for jet, it s smaller than L jet Another possibili8es to support jet power: Jet would be supported by BH spin!!

29 Issues Presenta8on by Monika Moscibrodzka et EHT2016

30 Issues Presenta8on by Monika Moscibrodzka et EHT2016

31 Towards ALMA CY5 observation - Future mm/submm VLBI RM obs. will derive radial profile of accre8on flow together with the direct image of its innermost region. Hada et al. 2016

32 Summary

33 Summary - MM polarimetry is a strong tool to probe accre8on flow - SMA monitoring detected rapid 8me varia8on of EVPA - SMA polarimetry to measure RM associated with AF of M 87 - M is es8mated to be < M! yr -1 with SMA - M is substan8ally decreased, consistent with CDAF/ADIOS - Accre8ng Power may not be enough to support Kine8c Power of Jet. - We need a beqer models - RM studies using mm/submm VLBI will overcome the beam depolariza8on issues