1 / 17

Radio Galaxies Part 5

Radio Galaxies Part 5. What is the life of a radio galaxy? - do we know which one are the newly-born radiogalaxies? - what do we need to start a radio galaxy? (or how do you make a black-hole active?) - how many lives has a radio galaxy?. Unified schemes

pahana
Download Presentation

Radio Galaxies Part 5

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Radio Galaxies Part 5

  2. What is the life of a radio galaxy? - do we know which one are the newly-born radiogalaxies? - what do we need to start a radio galaxy? (or how do you make a black-hole active?) - how many lives has a radio galaxy? • Unified schemes are all AGNs really different?

  3. “Compact Steep Spectrum” Radio Galaxies • small radio sources (<1kpc) with steep spectral index: really small (no shortened by projection effects!) • Morphologically similar to kpc-Mpc double-sided radio galaxies (i.e. they have mini-lobes and/or jets on scales 1pc – 1kpc). • The centre of activity, the “core” has an inverted radio spectrum and does not dominate the radio emission at cm wavelengths They are considered to be newly-born radio galaxies

  4. 0710+439 0108+388 1031+567 OQ 208 1843+356 2021+614 2352+495 1943+546 4C31.04 The cast 0035+227 1245+676

  5. Detection of Expansion in young radio sources • The first upper limits on the rate of hotspot separation showed that their velocities were subrelativistic. Velocities can now be measured in more than one frequencies. Cores are detectable at higher frequencies. • Long temporal coverage over 5-20 years enable the detections of ''slow” proper motions.

  6. -1 Source z Size (pc) Velocity( h c) Age Reference Detections Polatidis et al 2002 (1998-2001)[2] 0035+227 0.096 21.8 0.12 ± 0.06 567 Owsianik et al (1982-2000) [5] 0108+388 0.669 22.7 0.18 ± 0.01 403 Giroletti et al 2003(1995-2000)[2] 4C31.04 0.0592 70.1 0.39 ± 0.06 550 Owsianik et al (1980-2000) [8] 0710+439 0.518 87.7 0.30 ± 0.02 932 Taylor et al 2000 (1995-1999)[2] 1031+567 0.4597 109 0.19 ± 0.07 1836 Marecki et al (1989-2001)[5] 1245+676 0.1071 9.6 0.16 ± 0.01 190 Stanghellini (1993-2002) [5] OQ208 0.0766 7 0.10 ± 0.03 224 Polatidis et al (1993-2002)[3] 1843+356 0.763 22.6 0.25 ± 0.02 285 Polatidis et al (1993-2002) [4] 1943+456 0.263 107 0.26 ± 0.04 1306 Tschager et al 2000 (1982-1998) [3] 2021+614 0.227 16.1 0.14 ± 0.02 368 Polatidis et al (1983-2000) [6] 2352+495 0.238 117 0.12 ± 0.03 3003 Limits Tzioumis et al 1998 [5+] 1934-638 0.183 83.2 < 0.05 Taylor & Vermeulen 1997 [2] 1946+708 0.101 39.4 < 0.100 Tingay [3] 1718-649 0.00142 2 < 0.07 yrs Expansion Velocities -1 c They are really young!

  7. What do we need to start a radio galaxy? (or how do you make a black-hole active?) • Supermassive BH seem to be common among big • early-type galaxies: but only a minority are active. • They need fuel! • Interactions/merger can bring gas to the • central regions to feed the monster! Possibility: the AGN-phase (including the radio activity) is only a “short” period in the life of a galaxy. Possibly, every galaxy goes through it. However, no clear evidence from the observations of gas fueling the BH

  8. Can we define an evolutionary sequence? AGN phase : >109 yr • Age of the radio emission: • ~ 107 yrs • Age of the merger: • ~ 109 yrs few x 108 yr The age of the merger derived (to first order) from the HI delay between the two! long-lived HI structures

  9. Recurrent activity Mpc-scale kpc-scale

  10. Unified Schemes

  11. Unified Schemes for AGNs • Diversity in the characteristics of some AGNs can be explained by orientation effects combined with the presence (at least in some cases) of a torus that obscures the central regions (for some orientations) • Parameters that can be used as orientation • indicators: • - Radio jet: superluminal motions, ratio between flux of main and • counter jet • Presence of broad optical lines • - Core dominance (or fractional radio core strength) • (radio core flux/extended flux)

  12. Powerful radio galaxies core dominated lobe dominated broad line narrow line • characteristics that are not orientation depended should be similar between powerful radio galaxies and quasars

  13. Different types of AGNs: a summary Optical Emission Line Properties Decreasing angle to line of sight

  14. More complicated for lower-power radio galaxies - no thick torus? - FRI do not show broad lines but BL Lacs do

  15. Different types of AGNs: a summary Optical Emission Line Properties Decreasing angle to line of sight

More Related