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

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

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

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  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

  14. Collimation of jets

  15. 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

  16. 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

  17. 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

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

  19. Polarization

  20. 325 MHz, A & B array 5.7  4.8arcsec Hercules A radio VLA+PT link Gizani, Cohen & Kassim, 2005

  21. 74 MHz with PT, grey scale Q map 25. × 9.7 arcsec, p.a. 30.95o

  22. 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

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

  24. 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

  25. 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

  26. 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

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

  28. 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

  29. 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

  30. 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

  31. 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

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

  33. 21 cm, 4 arcsec ~ 130 mJy Pcore6 cm ~ 7.25 1023 WHz-1

  34. 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

  35. 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?

  36. 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

  37. 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

  38. Her A 3C 388

  39. 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

  40. 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

  41. 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

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