1 / 13

Interstellar Scattering of Sgr A*

Interstellar Scattering of Sgr A*. D. C. Backer Astronomy Department & Radio Astronomy Laboratory UC Berkeley. Credit: B 4 , F. Lo, G. Bower, Y. Lithwick, et multi-alia. An Early View on Scatter Broadening. Backer 1978 ApJ , 222 , L9. b. zb/Z. Origins of DCB 1978….

wilsonkristin
Download Presentation

Interstellar Scattering of Sgr A*

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. Interstellar Scattering of Sgr A* D. C. Backer Astronomy Department & Radio Astronomy Laboratory UC Berkeley Credit: B4, F. Lo, G. Bower, Y. Lithwick, et multi-alia Sgr A* 30th Fest -- 2004 March

  2. An Early View on Scatter Broadening Backer 1978 ApJ, 222, L9 b zb/Z Sgr A* 30th Fest -- 2004 March

  3. Origins of DCB 1978… Sgr A* 30th Fest -- 2004 March

  4. Demagnification of Angular Broadening • Scattering angle is property of screen • Observed source apparent size is result of magnification Sgr A* 30th Fest -- 2004 March

  5. 1985 Nature, 315, 124 Sgr A* 30th Fest -- 2004 March

  6. OH Maser Scattering Frail et al. (1994) ApJ427, L43 Sgr A* 30th Fest -- 2004 March

  7. Wide Field Source Scattering Bower et al. (2001) ApJ, 558, L27 Lazio & Cordes (1998) ApJ, 505, 715 Sgr A* 30th Fest -- 2004 March

  8. Summary • Sgr A* has 2:1 image size dependent on lambda2.0 & image shape on baseline2.0 • OH masers within ~0.5o (lat; 65 pc) have similar sizes & ellipticities. • Required scattering measure: few pc cm-6 on scales of 10’s km (from max b & z/Z estimate). Sgr A* 30th Fest -- 2004 March

  9. Location of Scattering Plasma-I • Mezger & Pauls, 1979 IAU Symposium84, p.357 • EI: 300 pc (l); 120 pc (b); 1.4x104 pc cm-6; 7 cm-3 • EII: 130 pc (l); 80 pc (b); 3.1x104 pc cm-6; 16 cm-3 Sgr A* 30th Fest -- 2004 March

  10. X-Ray Emitting Hot Plasma • Koyama et al. (1996) PASJ, 48, 249; Munro et al. (2003) ApJ, 589, 225 -- 8.5’ x 8.5’ (20 pc x 20 pc) • Koyama et al. (1996): 3x10-13 ergs cm-2 s-1 arcmin-2; Mereghetti et al. (1999) 5/3 larger; something like 2-8 keV; point sources 10% Sgr A* 30th Fest -- 2004 March

  11. Bipolar Wind Bland-Hawthorne & Cohen (2003) ApJ, 582, 246 At apex cylindrical shell: Sgr A* 30th Fest -- 2004 March

  12. Location of Scattering Plasma-II Sgr A* 30th Fest -- 2004 March

  13. IPS Survey of Backgrnd QSO/AGN Cohen & Gunderman (1968) ApJ, 145, 165 Sgr A* 30th Fest -- 2004 March

More Related