M87 in context: the radio gamma-ray connection in misaligned AGNs

Transcription

1 M87 in context: the radio gamma-ray connection in misaligned AGNs M. Giroletti and F. D'Ammando on behalf of the Fermi-LAT collaboration, and C. Casadio, P. Grandi, K. Hada M87 Workshop: Towards the 100th Anniversary of the Discovery of Cosmic Jets Taipei, Taiwan, May 27, 2016

2 Part 1 The context: Fermi-LAT misaligned AGNs 2

3 A history of misaligned AGNs and gamma-ray satellites Possible detections: 1970 s, COS-B: 3C s, EGRET: Cen A, 3C111, NGC6251 AGILE: 3C 84 Topics of interest: emission region/mechanism: jet base, kpc jets, lobes, contribution to extragalactic diffuse gamma-ray background LAT, Large Area Telescope on board Fermi, launched in June MeV GeV photon energies 2.4 steradian field of view operated in scanning mode, views entire sky every 3 hrs provides uniform sensitivity over whole sky in ~day time scale, ideal for MWL studies of single sources all sky survey and population studies 3

4 Fermi catalogs four main catalogs: 0FGL/1FGL/2FGL/3FGL, 3mo/11mo/2yr/4yr, 205/1451/1873/3033 sources each one accompanied by an AGN catalog: LBAS, 1LAC, 2LAC, 3LAC 4 E>10 GeV

5 Fermi AGN demographics 3FGL: 3033 sources, 1010 not associated (Acero et al. 2015) 3LAC: 1563/2192 high galactic latitude are AGN (Ackermann et al. 2015) grand total of 1773 gamma-ray AGN including duplicate associations and low latitude affiliations 98% are blazar, or blazar candidates In clean sample of 1444 sources FSRQ: 414 (28%) BLL: 604 (42%) BCU 402 (29%) other 24 (2%) Only a few unidentified sources remain at high fluxes BCU 28% other 2% BLL 42% FSRQ 29% Gamma-ray sources continue to be associated with radio loud objects Vast majority of associated sources are blazars and non blazar sources are typically misaligned blazars (MAGN), or very blazar-like sources (RL NLS1)

6 Fermi misaligned AGNs demographics Growing population since EGRET about 20 in 3LAC not always easy to confirm neighboring confusing sources no evidence of spatial extension variability present in very few cases In 3LAC (clean) 11 (10) FR1 3 (2) FR2 8 (4) SSRQ broad range of luminosity, photon index, variability n MAGN EGRET LBAS 1LAC Abdo10b 6 2LAC 3LAC

7 3LAC MAGN list bold = clean sources: b >10 o, no other candidate counterpart = source also in 2FHL sample (E>50 GeV) Name type F100 Γ z Name type F100 Γ z NGC1218 FR C221 SSRQ na IC 310 FR1/BLL C 264 FR NGC1275 FR PKS SSRQ C FR1/BLL M87 FR TXS SSRQ C SSRQ C111 FR Cen Acore FR Pictor A FR C 286 SSRQ/CSS PKS FR1/BLL Cen B FR C 189 FR C 303 FR C+39.23B CSS NGC 6251 FR C207 SSRQ C 380 SSRQ/CSS NB F100 = photon flux in units of 10-8 ph cm -2 s -1 7

8 some Fermi MAGN radio images 3C 84 3C 264 M 87 3C 303 Atlas of DRAGNs Pic A NGC 6251 Cen A 8

9 FR1 vs FR2 FR1s tend to be more local, steady, with soft spectra but M87 and 3C84 have Γ~2.0 FR2s are more distant and luminous, detected sporadically, more variable and FSRQ-like In 3C and MS4 catalogs, LAT detects preferentially sources with highest core dominance Abdo et al. (2010) Grandi et al. (2012) 9

10 Two extreme opposites Cen A (Abdo et al. 2010) so far only case of lobe emission detected in γ rays IC/CMB mechanism core also detected lowest luminosity AGN core detected by LAT 3C 120 formally not in any AGN LAT catalog episodic activity detected, followed by ejection of VLBI knot (Tanaka+2015, Casadio+2015) 10

11 other interesting gamma-ray ~MAGN (D Ammando et al. 2015) viewing angle 6 o -15 o z=0.056 debated classification, extended steep spectrum emission HST-1 like structure?! MBH~1Msun, dl~240 Mpc MilliArc seconds MilliArc seconds 11

12 Part 2 M87: Fermi-LAT, VHE & VLBI 12

13 M87 at MeV/GeV gamma rays First detected in 3-month source list at flux consistent with EGRET sensitivity First dedicated analysis (Abdo et al. 2009) detection and flux confirmed photon index connecting smoothly with VHE low state no variability SED consistent with 1-z SSC Later analyses around 2010 and 2012 VHE enhanced states (Abramowski et al. 2012, Hada, MG, D Ammando, et al. 2014) confirm flux and photon index modest hints of variability 13

14 Fermi-VLBI results during 2012 elevated VHE status (Hada, MG, D Ammando et al. 2014, ApJ) ~70% increase in VERA GHz radio core no increase in EVN 5 GHz core/hst-1 time lag of radio l.c. provides 0.2c estimate for new component ejection velocity Fermi values to usual levels, but possible drop in flux after VHE decrease 14

15 Harris et al Let s take one step back HST-1 superluminal motion suggests significant Doppler beaming major optical, X-ray, and radio flux density flare occurring around 2005 VHE activity Core VHE variability shows very short time scales, suggesting very compact region radio flux density increase simultaneous to 2008 VHE event ] -1 s 20 VHE instruments VERITAS MAGIC H.E.S.S cm s -2 cm [10 ] A Φ VHE [10 0 VHE Φ 29 Jan 05 Feb 12 Feb Time 0 4 B Acciari et al [kev/s] Φ X-ray 2 Chandra (2-10 kev) knot HST-1 nucleus VLBA (43 GHz) nucleus (r = 1.2 mas) peak flux density jet w/o nucleus ( mas) C Φ radio [Jy] Apr Jul Oct Jan Apr 2008 Time

16 The EVN core+hst-1 monitoring European VLBI Network M87 monitoring project 5 GHz, not EHT but best compromise for sensitivity, angular resolution, dynamic range, on both core and HST-1 carried our in real time (e-evn) 0.8 core 1.8 Jy/bm HST-1 total flux ~20 mjy inner jet ~250 mas long 16

17 The EVN 5 GHz jet from 0 to ~1arcsec core stationary component helix? northern limb brightening? HST-1 individual superluminal knots HST-1 stationary feature 900 mas ~ 70 pc Asada & Nakamura (2012) Asada et al. (2014) EVN 1.6 GHz 17

18 Abramowski et al see Hada et al. (ApJL, 2012)??

19 1. Proper motions of HST-1 VLBA 1.7GHz EVN 5GHz Significant proper motions (>80 mas) over 5 years Main features (in the downstream) are clearly moving with ~4c: Γ=4-6, δ=1.5-4

20 2. Change of P.A. P.A. of the main emission region gradually rotates from -70 (parallel to the inner jet axis) to -90 ~-100 (more horizontal) helical path? From width: BHST1~2.3 mg (slightly in excess of synchrotron cooling time from X-rays, Harris+06)

21 3. Structural variations VHE flare A new upstream component emerged in mid 2010 (near the VHE flare) Moving at a similar superluminal speed A weak slower feature

22 Directed by Kazuhiro Hada

23 Latest epochs switched back to 1.6 GHz due to decreasing flux density slowed down cadence to account for larger beam new component ejection caught nonetheless! ejected in early 2014, (6.3±0.5)c apparent speed but still too few to explain *all* the inferred VHE flares (cfr Wagner talk) 23

24 Take home notes Fermi has provided an order of magnitude increase in the number of gamma-ray detected M-AGNs from 3(?) to >20 with a wide variety of properties M87 is one of the 5 brightest Fermi M-AGN regularly detected at ~2x10-8 ph cm -2 s -1 and Γ=2.05 no significant variability detected Radio monitoring results superluminal component ejection continues to occur ~regularly in HST-1 lots of structure in inner part of the jet 24

25 References Abdo, A. A., et al. 2009, ApJ, 707, 55 Abdo, A. A., et al. 2010a, Science, 328, 725 Abdo, A. A., et al. 2010b, ApJ, 720, 912 Abramowski, A., et al. 2012, ApJ, 746, 151 Acero, F., et al. 2015, ApJS, 218, 23 Acciari, V. A., et al. 2009, Science, 325, 444 Ackermann, M., et al. 2015, ApJ, 810, 14 Asada, K., & Nakamura, M. 2012, ApJ, 745, L28 Asada, K., et al. 2014, ApJ, 781, L2 Baldi, R. D., et al. 2015, A&A, 576, A38 Casadio, C., et al. 2015, ApJ, 808, 162 D'Ammando, F., et al. 2015, MNRAS, 450, 3975 Finke, J. D., et al. 2008, ApJ, 686, Giroletti, M., et al. 2012, A&A, 538, L10 Grandi, P., et al. 2012, arxiv, arxiv: Grandi, P., et al. 2016, MNRAS, 457, 2 Hada, K., et al. 2014, ApJ, 788, 165 Hada, K., et al. 2012, ApJ, 760, 52 Harris, D. E., et al. 2006, ApJ, 640, 211 Harris, D. E., et al. 2009, ApJ, 699, 305 Tanaka, Y. T., et al. 2015, ApJ, 799, L18 25

26 Extra material 26

27 Abstract M87 is one of over a dozen misaligned AGNs revealed by Fermi Large Area Telescope in gamma-rays above E>100 MeV. In this paper, I will first provide a census of the misaligned AGN counts, discussing their observational and physical properties (FR type, luminosity, variability, origin of gamma-ray emission, etc.) in comparison with other gamma-ray AGNs, typically blazars. I will then focus mainly on M87, which we have monitored with VLBI for the last seven years using the EVN, VLBA, and VERA. I will present a study on the core and HST-1 light curves, and the kinematics within HST-1, with a focus on the ejection of new superluminal components, and a comparison with the Fermi light curve. 27

28 other interesting gamma-ray ~MAGN Tol (Grandi, Capetti, Baldi 2016) FSRQ in 3LAC, but LEG spectrum L>1 GeV ~ erg s 1 Γ = 2.78±0.14 no extended radio emission, yet core luminosity of 2x10 39 erg s -1 could be FR0 (Baldi, Capetti & Giovannini, 2015) 28

29 M87 1-z SSC parameters quantity θ value 10 o Γ 2.3 δ 3.9 γ γbreak 4x10 3 p1, p2 1.6, 3.6 r 1.4 x10 16 cm B 55 mg Pj 7 x erg s -1 model by Finke et al. (2008) Abdo et al. (2009) 29