NGC 4261 NGC 4261 is an elliptical galaxy located behind the Virgo Cluster in the W-cloud.  The active galactic nucleus (AGN) contains a 400 million solar mass supermassive black hole (SMBH)  with a 800 light-year-wide spiral-shaped disk of dust fueling it.  Deep 5 GHz image of the nearby radio galaxy produced by combining multi-configuration data from the Very Large Array. The nucleus at the center is believe to harbor a supermassive black hole. The jets extending east-west fuel the large lobes of radio emission seen clearly in the high quality image. Credit: Teddy Cheung
Say some stuff here... About various properties
ATOM (HESS optical telescope), RXTE Rossi X-Ray Timing Explorer (RXTE) : , Swift Ssc synchrotron self compton SED of PKS 2155–304. The red butterfly is the Fermi spectrum restricted to the MJD 54704–54715 period, while the black butterfly covers MJD 54682–54743. As a cross check of the fit robustness, the differential flux was estimated in eight limited energy bins by a power-law fit (black circles) and are found to be consistent within 1σ of the global fit, including a clear spectral break at ~1 GeV. The gray points are archival NED data, and the two gray butterflies are EGRET measurements. The solid line is a one-zone SSC model. The dashed and the dot-dashed lines are the same model without electrons above γ 1 and γ 2 , respectively. The VHE part is absorbed with the P 0.45 extragalactic background model described in Aharonian et al. ( 2006a ).
Furthermore, the lack of a significant impact on the shape of the SSC component when those electrons are removed indicates that Klein–Nishina effects suppress any significant contribution by those electrons to the emission at ∼TeV energies. These features of this calculation allow that there need not be a correlation between the X-ray and VHE fluxes; and in fact, this is what is observed. In contrast with the 2006 July flare, we do not find any evidence of flux correlation between the X-ray and HESS bands with a Pearson’s r of 0.12 ± 0.1 between these bands.
Hubble pretty pictures, one on left composite with xray and radio One on the right shows feedback from filaments
First detected as gamma ray source 2008 by fermi-lat
veron-cetty and veron catalogue of A
Minos jitter between gps clocks fermilab to soudan 700km
Active Galactic Nuclei <ul><li>Objects that emit significant amounts of radiation from non-thermal sources </li></ul><ul><li>(i.e. not stars or dust or thermal gas). </li></ul><ul><li>AGN Zoo: </li></ul><ul><li>Seyfert Galaxies </li></ul><ul><li>Radio Galaxies </li></ul><ul><ul><li>FR1 </li></ul></ul><ul><ul><li>FR2 </li></ul></ul><ul><li>Quasars </li></ul><ul><li>Blazars </li></ul>
Basic Emission Mechanisms <ul><li>Radio –synchrotron of electrons in the jet </li></ul><ul><li>Infrared – thermal emission from the torus </li></ul><ul><li>Optical – thermal emission from the disk </li></ul><ul><li>X-ray-gamma – Inverse Compton </li></ul>
What causes the jets? <ul><li>Enormous number of jet models </li></ul><ul><li>Current most promising ideas extract energy from the accretion flow via magnetic fields </li></ul><ul><ul><li>Extract energy and angular momentum though magnetic field anchored in the disk </li></ul></ul><ul><ul><li>Extract spin energy of the black hole through magnetic fields threading its horizon </li></ul></ul>
Why are AGNs interesting? <ul><li>Some of the most spectacular objects in our universe </li></ul><ul><li>Black holes could be test beds for quantum gravity </li></ul><ul><li>Source of the high-energy cosmic rays? </li></ul><ul><li>Important for structure formation? </li></ul>
Observing AGN over 13 orders of magnitude in energy <ul><li>Blazar PKS 2155-304 </li></ul>GeV TeV X-ray optical HESS and Fermi, ApJ Letters, 696, L150 (2009) EGRET Fermi
Variability of NGC1275 Brown & Adams, Mon. Not. R. Astron. Soc. (2011)
OPERA results <ul><li>Wait till MINOS says something? Not until 2013+ </li></ul><ul><li>The IceCube collaboration is currently investigating the potential of our data to constrain the velocity of neutrinos at TeV energies… </li></ul>