1. Extragalactic Jets: Theory and Observation from Radio to Gamma Ray 21-24 May 2007, Girdwood, AK Jet Properties and Evolution in Small and Intermediate Scale Objects Marcello Giroletti INAF Istituto di Radioastronomia Bologna

2. my outline objects spanning the size range from ~10's of parsecs to a few kiloparsecs. −CSO (Compact Symmetric Objects) population −LPC (Low Power Compact) sources. nature of small radio sources: −spectrum −kinematics −age distribution nature of their jets −orientation −motion, polarization final evolution of the CSO and LPC population

3. basic facts Different arrays reveal similar basic structures on very different angular and linear scales Cygnus A, Carilli, VLA 5 GHz 4C31.04, Giroletti, VLBA 5 GHz

4. large vs. small sources there's a continuum of sizes in radio sources: −ok, sources are born small and then grow up! actually, there's far more small sources than expected by counts of large ones −not all small looking sources are physically small unified models, blazars −not all small sources go all the way to Mpc scale frustration, short-lived activity Kunert-Bajraszewska, Marecki 06 −luminosity decreases while size increases Begelman 96, Alexander 00, Snellen 00, Tinti&De Zotti 06

5. the smallest radio sources Compact Symmetric Objects −<1 kpc −doubles/triples −low polarization −high HI absorption −convex radio spectrum useful for selection Log Frequency Log Flux density self-abs. opt. thin radiation losses

6. LS vs. turnover Smallest sources have highest turnover frequency: −Compact Steep Spectrum sources −GHz Peaked Spectrum −High Frequency Peakers blazar contamination (see Orienti's talk) O'Dea 1998, Dallacasa+ 2004 LS 10 kpc 10 pc 10 GHz 100 MHz peak GPS CSS HFP

7. age estimates: kinematics (1) Measure  s over  t for the hot spot separation Get mean advance velocity v sep =  s/  t Derive 0-order estimate of source age: − t kin =LS/v sep if v sep ~ 0.3c, z=0.05, −  s=0.1 mas per year −need VLBI, long intervals, high frequency

8. age estimates: kinematics (2) Looking in small sources for the youngest radio galaxies −HS advance first detected by Owsianik et al. 1998 −more successful results in several sources: Polatidis&Conway 03 Giroletti+ 04 Gugliucci+ 05... −HS advance velocity ~0.1-0.3 c −bias in selection? 2352+398, Owsianik+ 4C31.04, Giroletti+

9. age estimates: spectral (1) N(E)=N 0 E -  dE/dt = -bH 2 E 2 Q(t)=NE -  S( )=  -  if < *  -(  +0.5) if > * * =10 9 x t -2 x H -3 (GHz, yr, mG) multifrequency observations constrain *, and allow us to derive t spec

10. age estimates: spectral (2) t spec ~10 3 -10 4 yr −Murgia+99, Orienti+07 consistent with kinetics: −but care about assumptions... equipartition no reacceleration synchrotron losses only −...and observations integrated spectrum matched u,v coverage 1323+321

11. jets in CSO for their nature and our selection criteria, CSOs tend to lie in the plane of the sky −we select on the basis of symmetry −little difference between approaching and receding sides −sources on the plane of the sky −if jets are relativistic, then they are debeamed

12. jets in CSO jets are not easy to study in CSOs −orientation (debeaming) −resolution but some are detected −interesting properties... −...related to interaction with medium 2352+495

13. jets in CSO −jet-head interacts with dense ISM bending −4C31.04: Giroletti+03 −0528+514 (CSS quasar): Mantovani+02 HS advance velocity not highly relativistic −dentist drill

14. jets in CSO some components in the jet have higher velocity and polarization (Gugliucci+07) −J1826+1831: strongest polarization (9%) in a confirmed CSO −RM unexpectedly low (as low as -180 rad m -2 ) B field below equipartition? jet closer to on-axis than other CSOs? −J1915+6548 has jet components both polarized and (weakly) superluminal

15. from CSOs to LPCs on a few kpc scales, we find sources that could be evolved CSOs we name them Low Power Compact sources −their radio power is below 10 24 -10 25 W Hz -1 −their linear size is a few kpcs (compact in low frequency surveys - 3C, B2) −they do have active jets −they are more frequently edge dimmed (few hot spots)

16. lpc: from “blobs” to jets at low resolution, sources are compact, core dominated VLBA and high freq. VLA observations reveal rich substructures, including jets, resembling FRI and FRII on 10-1000 times smaller scales. VLBA 1.6 GHz VLA 22 GHz VLA 8.4 GHz

17. lpc jets: ngc4278 P 5 GHz ~ 10 22 W Hz -1, typical for LLAGNs VLBA two-sided pc scale jet 2-epochs study (Giroletti+04): −max v jet = 0.1 c −1.2 <  < 1.7 −2 <  < 3 1 pc10 3 R S

18. lpc timescales: 0648+27 VLA 8 GHz: symmetric double VLA 22 GHz: resolved with compact core, no HS! VLBA, phase-ref 1.6 GHz: detection, exact position, 3  pc scale jet importance of multi-res and broadband obs (Emonts+06, Giroletti+05) −radio: spectral age <1 Myr −neutral hydrogen (H I): major merger 1.5 Gyr ago −optical spectroscopy: starburst activity 0.3 Gyr

19. jets in LPCs LPCs reveal rich, complex structures at high resolution −lobes, hot spots, fed by jets jets typically <1 kpc long structure is often two-sided radio power typical of FR Is, motion studies (eg NGC 4278) suggest mildly relativistic regimes −  ~ 0.9 seem unable to form large kpc scale lobes − LS/t spec << c

20. cso, lpc, and then? 1.large scale FRI/II 2.intermittent activity large scale emission around pc scale CSO (see poster #35) 3.premature end of activity faders (Kunert-Bajraszewska+06) difficult to find, br goes down very rapidly after injection stops - survives better in dense media (Murgia+05) a candidate: 1855+37 (Giroletti+05)

21. 1855+37: a jet turning off? 1855+37 −significant extended emission at low frequency −source not detected at >8.4 GHz no more fresh electrons in the lobes −core much weaker than expected (even with strong debeaming) at 5 GHz nuclear activity might be going off −the sources is in cluster

22. final remarks CSOs are the targets to look for jets first steps however, they are difficult to study (debeaming) and strongly affected by interaction with dense medium LPCs have more evolved jets, probably unable to form kpc scale lobes some of them could even be switched off

23. Radio spectra One more piece of information… little contamination from core B eq ~ 10 2  G T syn ~ 10 5 -10 6 yr v adv, syn << c −consistent with slow/ceased advance in the external medium