Probing cosmic rays in AGN and Clusters of Galaxies using radio observations

1. Probing cosmic rays in AGN and Clusters of Galaxies using radio observations Nectaria A. B. Gizani1 Manolis Plionis2 • Hellenic Open University, School of Natural Sciences and Tecnhology • 2. Institute of Astronomy & Astrophysics, National Astronomical Observatory of Athens

2. Sample of 70 Abell clusters selected based on their dynamic activity (if cluster → before/after merger event) X-ray, radio, optical data Acceleration – propagation of cosmic rays

3. Radio features observed in many galaxy clusters Diffuse low surface (~μJ/arcsec2 @ 20 cm) radio (synchrotron) emission of relativistic particles spiraling intracluster magnetic fields not associated directly with the galaxies of cluster Halos relics minihalos Halos: large size (~ 1 Mpc), steep spectrum, located @ cluster centre, low/negligible polarization, found usually in clusters with merger events→disrupt cooling flow Relics: large size (~ 1 Mpc), steep spectrum, located @ cluster periphery, found usually in clusters with merger events→disrupt cooling flow, highly polarized Minihalos: steep spectrum, of shorter size (~ 500 kpc), surrounding host AGN of cooling flow cluster, considered due to reacceleration of relic population of relativistic electrons, or proton-proton collision with ICM

4. Type Position Size α Polarization Halo centrally ≥ Mpc ≥ 1 < few % peaked Giant relic Peripheral ~ Mpc ≥ 1 ~10-30 % Mini-halo centrally ≤ 0.5 Mpc ≥ 1.5 < few % peaked Phoenix Peripheral ~100 kpc ≥ 1.5 ~10-30 % AGN relic Close to the few  10 kpc ≥ 1.5 ≤20 % host galaxy Ferrari et al., 2008

5. 3 AGNs from the sample, host galaxies at cluster center

6. 3C 388 radio power P178 MHz = 4.8 1025W Hz-1sr-1 at 178 MHz. relatively small radio source with a total extent of 92 kpc. complex structure: faint halo in the eastern lobe with steep spectrum and high polarization, and a relic of an older jet activity. Similar western lobe low surface brightness structure, luminous jet possible counter-j Flat low frequency spectra Roettiger et al., 1994 VLA, 20 cm z = 0.0908, cD galaxy @ cluster centre FRII

7. Our ROSAT HRIobservations: warm gas confining the lobes Most X-rays seem to come from the centre of the host galaxy with radius 33 kpc. Total extent out to 180 kpc Its luminosity is 51035W in the energy range 0.1−2.4 keV. no~1.5 10-2 cm-3 This component must be the AGN or a cooling flow of the size of the galaxy. The core component is simulated efficiently with a typical β0.53, kT~3 keV. The density of the gas drops with radius as ~r -1.6. However this decrease is not fast enough to allow for a constant expansion velocity of the source. 3C388 at the centre of poor cluster of galaxies with very dense ICM. Einstein Observatory: extended emission and a luminosity of 51036W in the range 0.5−4.5 keV,typical of Abell clusters. ICM confines the lobes Distortion of gas by radio lobes? radio lobes extend further than nucleus of X-ray emission Leahy & Gizani., 2001

8. Multiphase gas with kT~ 3.5 keV (3 keV within radio lobes) β~0.44, rc~ 15 kpc, Lx ~ 2.71035W in the (0.1−10.0)keV, 8.3 10-2 cm-3. Possible sbcluster Chandra map, 35 ks in (0.5-2) keV Kraft et al., 2005

9. Presence of cavities associated with radio lobes, but no shocks in gas, X-ray/radio correlation with jet, hotspots of western side of radio emission

10. optical Hercules A MR = -23.75 z = 0.154 • Very elongated cD galaxy: • double nucleus & tail • radio emission from • dimmer, larger galaxy HST/WFPC2, Baum et al. 1996

11. Environment Kpc-scale (Gizani & Leahy) pc-scale (Gizani & Garrett) VLA + PieTown link (Gizani, Cohen & Kassim) A+B confign 325 MHz, 74 MHz at 5.7  4.8arcsec and 25. × 9.7 arcsec VLA radio data, 1".4 L-band (A+B+C confign) 1665, 1435, 1365 & 1295 MHz X-band (B+C+D confign) 8465 & 8415 MHz C-band (B+C+D confgn) 4873 MHz (archived data) EVN radio data, 18 mas • 1665 MHz • MERLIN data .51 arcsec • 1665 MHz

12. Hercules A radio VLA Gizani & Leahy, 2003 R.A. 16h 48 m 40 s , Dec. +05 ° 04' 36".0, FR1.5 VLA A+B+C 18 cm, 1.4´´

13. Ltot ~ 3.81037 W, (10 MHz — 100 GHz) Ho = 65 km/Mpc s, qo = 0 linear size ~ 194" (540 kpc), width ~ 70" (250 kpc) P178 MHz = 2.3  1027 WHz–1sr–1

15. Collimation of jets

16. Cont map: I-map, 6 cm, 1.4 arcsec contours separated by factors Ö2, 1st at 0.145 mJy/beam Vector magnitude: m B-vectors ^ m-vectors. Projected B-field follows closely edges, jets & ring-like structures in lobes

17. steep spectrum, a@ -1.5, young jets, rings a@ -.7 older lobes a@ -1.5 faint material -2.5 £a£ -1.5 acore» -1.3, steep spectrum, optically thin Snµna, a<0

19. Depoln map DP3.66 , 1.4 ´´; Depoln started in west DPl1l2= ml1/ml2 , where l1>l2 , m = p/I, fractional poln p: polarized intensity, I: total intensity

20. DP186 , 1.4´´ Western side more depolarized than eastern Laing-Garrington effect

21. Polarization

22. 325 MHz, A & B array 5.7  4.8arcsec Hercules A radio VLA+PT link Gizani, Cohen & Kassim, 2005

23. 74 MHz with PT, grey scale Q map 25. × 9.7 arcsec, p.a. 30.95o

24. Hercules A radio EVN 1- Gaussian fit rms» 3.6 ´ 10-4Jy/beam @ 14.6 mJy ~18.2 ´ 7 mas p.a. ~ 139° Tb@ 2 ´ 107 K VLA B+C+D , 3.6 cm, 0.74 asec, rms ~ 11 mJy Gizani & Garrett

25. @ the center of Cluster of Galaxies Abell 0 to 1 X-ray emission: ROSAT PSPC and HRI

26. Total X-ray extent »2.2 Mpc The cooling radius is 90 kpc. The central cooling time is 2–6 Gyrsignificant compared to the Hubble time 15 Gyr the cluster core has a cooling flow. ICM confines lobes HRI, 32 arcsec PSPC, 32 arcsec weak central source (HRI) with size <15 kpc and luminosity 2 × 1036W (0.1–2.4 keV) Gizani & Leahy, 2004

27. Contour map: PSPC + HRI 0.5-2 keV, 32´´, 1stcont 2.94 10-10 Wm-2 sr-1 Lobes confined by thermal pressure of ICM. Little entrainment  lobe energy~particles (more),fields Grey: log- 20cm radio 1.4´´ Lx » 4.81037 W Lx point » 21036 W, size=15 kpc central electron density (away from the central source) : nο ≈ 1.0 × 10-2 cm−3 typical of modest cooling flows.  presence of dense gas in which the radio source is situated. NH=6.21020 cm−2 Gizani & Leahy, 2004 Multiphase gas ROSAT: 0.5 < kT(keV) < 1, NH » 6.21020cm-2Gizani & Leahy, 2004 BeppoSax: 3 £kT (keV) £ 5, Trussoni et al., 2001, ASCA: kT» 4.25 keV, Siebert & Brinkmann, 99

28. Chandra: ICM confines inner jets, presence of cavities not associated with radio lobes and front shock surrounding radio sourcecocoon shock Chandra map in (0.3-7.5)keV, smoothed at 2″ devided by β model Nulsen et al., 2006

29. b-Fit : • @ 0.74, rc@ 121 kpc, no» 1  104m-3 dense environment Gizani & Leahy, 2004

30. RM = k<f>, f(r) = 0.81òr0neB×dlFaraday depth, l: line of sight East:-200 £RM(rad/m2 ) £200 West: RM exceeds ± 500 rad/m2 Points plotted if error RM < 5 rad/m2

31. Combining radio (Faraday rotation) + X-ray data (e- density): extragalactic magnetic field of ICM has central typical value of 3 Bo(μG)  9, and radial dependence B(r)  nm-1 (= Bo nm-1), n is the electron density found from α1~ 0.7, α2~2.0 On tangling scales 4Do(kpc) 35

32. 3C310 HST/WFPC2 0.05´´ Chiaberge et al., 1999 Z =0.054 central kpc emission ~^ radio jet axis, Bright pair, MR@ -23 Martel et al., 1999 linear correlation of optical flux of compact core with radio core

33. 3C310 Van Breugel & Fomalont, 1984 VLA, 21 cm, 4 ´´, • kpc-scale • VLA radio, 18 cm & 6 cm I & Q, U data retrieved from archive L1.4 GHz = 7.8 Jy, P178 MHz~ 3.57 ´ 1025WHz–1 Steep spectrum a = –1.38, FR1.5, linear size 173 kpc

34. VLA, 21 cm, 4 arcs Kpc-jet(s) Core center of western nucleus of bright pair Van Breugel & Fomalont, 1984

35. 21 cm, 4 arcsec ~ 130 mJy Pcore6 cm ~ 7.25 1023 WHz-1

36. pc-scale(Gizani & Garrett) • Global VLBI (4 mas) study of radio core, 18 cm Natural weighted 10 mas ~16.5 mJy » 17´ 5 mas ~ 85o Tb~ 2.5´ 107 K Global VLBI, 18 cm, phase referencing

37. RASS (ROSAT All Sky Survey), 2' | snapshot observations Miller et al., 1999 ICM confines the lobes ? Hardcastle & Worrall, 1999 ROSAT/HRI pointed observations: extended emission, centered on AGN 0.35<β<0.9 40″ < rc < 140″ 3C310 center of Z1500.6+2559, Lx ~ 9.8 1035 W, 1—3 keV, X-ray emissionambiguous, maybe centered on RG afterall, Radio/X-ray interaction?

38. Work in Progress Look for halos/relics in the other sources of sample Her A • Radio jets and galaxy major axis, aligned ! • p.a.=100o and ~ 100o (east-west) • galaxy prolate in shape • West 1994 - model: evidence of formation of cD galaxies and powerful radio sources through highly anisotropic mergers

39. ICM confines the lobes very well Pmin<< Pth B-fields (μG) implied by Inverse Compton arguments Her A 4.3 3C388 3.8 → BIC≈ 3Bme 3C310 3.6

40. Her A 3C 388

41. Also for 3C388: gas pressure in radio lobes >> minimum pressure Possible explanation: Excess pressure due to low energy e- / e+ and/or relativistic protons with B below equipartition. Confirmed by Chandra To retain equipartition (≠ numerical simulnsBIC< Bme)  reconciliation if “invisible” particles (protons, low energy electrons) dominate. From umin→ jet kinetic luminosity in radio-loud AGN is ~ bolometric luminosity of AGN if not >> If jets : primary energy loss mechanism in AGN, ellipticals centered in clusters → much of accretion energy heats cluster gas. Jets have dramatic effect on cluster gas at early epochs

42. Radiative Cooling time (Gyr) Hercules A 6.4 (hot phase) 2 (cool phase) 3C388 ~3.7 Age of Universe ~ 15 Gyrs tcool < tage presence of cooling flow + extended radio emission  seems to be ongoing acceleration mechanism in ICM, but steep spectrum suggests short lifetimes of radiating particles If tcool~10 Gyrs i.e. cooling significant to Hubble time  cooling radius  90 kpc ~ less than core radius ~ 120 kpc

43. Main points 3c348, 3c388, 3c310: Interesting sources No radio halo structures (cooling flow clusters) Do they contain relic sources ? Presence of cavities, not associated with radio lobes for Her A!!, 3C310 can’t tell X-ray + multifrequency radio data can show presence of cavities: targeted radio observations are needed to confirm if central AGN feeds radio lobes. Low frequency radio to study radio outburst episodes