1 / 14

AGN ( Quazars & Blazars ) EBL (CMB & CIB) Pre- Majic 2

AGN ( Quazars & Blazars ) EBL (CMB & CIB) Pre- Majic 2. By: Yousef Pezeshkian. Table of Contents. AGN: Active Galactic Nuclei EBL: Extragalactic Background Light CIB: Cosmic Infra-red Background Attenuation of γ-rays at TeV energies by CIB. AGN: Active Galactic Nuclei.

neena
Download Presentation

AGN ( Quazars & Blazars ) EBL (CMB & CIB) Pre- Majic 2

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. AGN (Quazars & Blazars)EBL (CMB & CIB)Pre-Majic 2 By: Yousef Pezeshkian

  2. Table of Contents • AGN: Active Galactic Nuclei • EBL: Extragalactic Background Light • CIB: Cosmic Infra-red Background • Attenuation of γ-rays at TeV energies by CIB

  3. AGN: Active Galactic Nuclei • From normal galaxies to Radio galaxies (1940: radio astronomy→ Radio Galaxies → Active galaxies) • 1960: discovery of 2 source of Radio waves: 3C 273, 3C 48 (Source number 273 in the third Cambridge Catalogue of radio sources) • Unusual properties: They were like stars, Unknown lines in their spectrum → Quasar: Quasi-stellar radio sources • 1963: Unknown lines are H lines with great red-shifts • 1970: Blazars and BL Lac objects • Until 2000: More than 10,000 quasars have been discovered, more than 90% were not source of radio waves

  4. Quasar 3C 273 as imaged by the Hubble Space Telescope's Advanced Camera for Surveys Quasar 3C273 is in the center of the image, and its jet, which may measure 150000 light-years in length, is visible

  5. Radio map of the quasar 3C 48 made from VLBA 1.4-GHz observations, made by uploader. Cross indicates core, arrow shows 0.5 arcsec

  6. AGN: Active Galactic Nuclei • 3 AGN types: • Quazar • Blazar → BL Lac objects • Seyfert (Carl Keenan Seyfert, 1943)

  7. EBL: Extragalactic Background Light • The EBL is usually divided into six wavelength ranges: • CGB: Cosmic gamma-ray background • CXB: Cosmic X-ray background • CUVOB: Cosmic ultra-violet and optical background • CIB:  Cosmic infrared background • CMB: Cosmic microwave background • CRB: Cosmic radio background

  8. CMB: Cosmic microwave background Recognition that the brightness of the night sky is an important astronomical datum dates back at least to Olbers (1826; see Harrison 1990 for an historical review). Most radiant backgrounds shown in Figure other than the CMB are causally connected The discovery of the cosmic microwave background (Penzias & Wilson 1965) CMB: The fossil blackbody radiation from the Big Bang

  9. CIB:  Cosmic infrared background Formation of structure in the universe One of the outstanding challenges in modern cosmology

  10. CIB:  The observational evidence • Direct measurements of this radiation • provided by NASA’s Cosmic Background Explorer (COBE) satellite • additional evidence coming from the Japanese Infrared Telescope in Space (IRTS) • Indirect evidence • Intergalactic attenuation of γ-rays at TeV energies

  11. Attenuation of TeV γ-rays by CIB

  12. Attenuation of TeV γ-rays by CIB For a given Eγ the opticaldepth is proportional to the number density of background photons. • Requirements for determination of the CIB from γ-ray observations: • (1) knowledge of the intrinsic spectrum of the γ-ray source • (2) knowledge of the spectral shape of the CIB • (3) the assumption that the attenuation takes place in the intergalactic medium by the CIB instead of in the source itself or its immediate vicinity

More Related