--------------------------------------------------------- | 10:00 - 10:45 AGN FEEDBACK IN CLUSTERS AND AGN JETS | --------------------------------------------------------- AGN INTERACTIONS AND FEEDBACK IN CLUSTERS OF GALAXIES (Invited Review) Elizabeth Blanton (BU) The majority of cool core clusters contain a radio source at their centers associated with a cluster dominant elliptical galaxy. The cooling gas can feed these central AGN which have outbursts approximately every 10^7 - 10^8 years. The AGN heat the central cluster gas preventing much of it from cooling to temperatures low enough to form stars. This heating can be in the form of buoyantly-rising bubbles inflated by the AGN, rippling sound waves, and shocks. I will review AGN feedback in clusters, giving examples of each of these types of heating mechanisms. -------------------------------- |10:45 Coffee Break and posters| -------------------------------- ----------------------------------------------------------------- | 11:15 - 12:30 AGN FEEDBACK IN CLUSTERS AND AGN JETS - cont. | ----------------------------------------------------------------- THE ROLE OF THERMAL INSTABILITY IN AGN FEEDBACK Paul Nulsen (CfA), David Rafferty (PSU), Brian McNamara (Waterloo), Mark Voit (Michigan), Ken Cavagnolo (Michigan), Megan Donahue (Michigan) Star formation in giant elliptical galaxies at cluster centers is probably limited by AGN feedback, but the feedback process is poorly understood. Star formation and the presence of extended line emitting gas in these systems has been related to the thermal properties of their hot atmospheres. The results point to thermal instability limited by thermal conduction as the source of the star forming and the line emitting gas. They suggest that thermal instability plays a significant role in the feedback cycle. If so, AGN outbursts may be fed by predominantly by cool gas, even in hot atmospheres. THE CURRENT STATE OF THE M87 JET Dan Harris (CfA): We will show the latest results of our Chandra monitoring and give an analysis of variability timescales for the nucleus and knot HST-1. We find an impulsive behavior for the brightening and fading of HST-1. We will also compare the evidences for the site of the excess TeV emission. WHAT ARE JETS MADE OF? CONSTRAINTS FROM TRANSVERSE EXPANSION RATES John Wardle and Jennifer Weston (Brandeis) Some jets exhibit transverse expansion rates that are superluminal, and many expand at a significant fraction of the relativistic sound speed. This requires that the jet fluid is not too much weighed down by protons. This implies either a large value for the lower cutoff in the electron energy distribution, or that many of the positive particles are positrons. THE LOCATIONS OF HIGH-ENERGY FLARES IN BLAZAR JETS Al Marscher (BU) Modeling the physics of relativistic jets requires knowledge of the locations of the emission at different wavebands. This can be accomplished by combining multiwaveband monitoring with VLBI imaging and, where available, polarimetry. I will present recent observational results demonstrating that there are at least two sites of X-ray flares in the jets of the blazars BL Lac and 3C 279. One is the core seen on 43 GHz VLBA images, where a standing shock probably exists, while the other is closer to the central engine. In BL Lac, this upstream region has a helical field, which MHD jet formation theories associate with the acceleration and collimation zone of the jet. CORRELATED MULTIWAVELENGTH POLARIZATION IN A SURVEY OF BLAZARS Francesca D'Arcangelo (BU) In October of 2005 and March of 2006, we observed 19 blazars in a collaborative multiwavelength campaign to determine the polarization characteristics of these objects. Observations were taken in the optical at Steward Observatory and the Crimean Astrophysical Observatory, in the infrared at Lowell Observatory, and at 43 GHz with the VLBA. We determine the values and variability of percentage polarization, electric vector position angle (EVPA), and flux density in each blazar. The characteristics of optical emission are then correlated with emission from the resolved 43 GHz parsec-scale jet, allowing us to establish a spatial location for the optical emission. The values of optical EVPA agree with those in the 43 GHz core for 13 of our 19 objects, and similarity in rapid EVPA variability is observed in a number of objects. We find that the optical/IR emission is cospatial with the stationary core of the VLBA jet for the majority of our blazars. Special focus will be placed on the core of blazar OJ287, which we have modeled as a spine-sheath system with a magnetic field aligned along the axis of the jet. ----------------- | 12.30 - Lunch | ----------------- ------------------------------------------ | 14:00 - 15:15 MULTI-WAVELENGTH SURVEYS | ------------------------------------------ HIGH-RESOLUTION CHANDRA, HST, AND VLA IMAGING AND SPECTROSCOPIC OBSERVATIONS OF RADIO-LOUD SEYFERT GALAXIES Dan Evans (CfA), J. C. Lee, T. J. Turner, R. P. Kraft, S. Bianchi, M. J. Hardcastle, H. L. Marshall, S. C. Gallagher, K. A. Weaver High-resolution Chandra imaging and gratings spectroscopy, combined with with HST and VLA observations, are powerful tools for probing the nuclei and ionized kpc-scale NLRs in Seyfert galaxies. By observing the subclass of "radio-loud Seyferts", we can study the energetics and relationships between the AGN, outflows, and gas, and test models that link outflows with feedback between gas accretion and black-hole growth. Here, we present multiwavelength observations of the nearby Seyfert 2 galaxies NGC 2110 and IC 5063. We discuss the morphological interdependencies of the warm [OIII] gas, hot X-ray gas, and radio outflows, and argue that both collisional ionization and AGN photoionization play important roles in governing the extended circumnuclear environments in these sources. THE SDSS/XMM-NEWTON QUASAR SURVEY AND THE alpha_ox-L_uv CORRELATION Monica Young (BU), Martin Elvis , Guido Risaliti We have cross-correlated the DR5 Sloan Digital Sky Survey (SDSS) quasar selection with the XMM-Newton archive to obtain one of the largest known samples of quasars with both optical and X-ray observations (790 quasars). Of these, 60% (473 quasars) have high enough signal-to-noise to extract X-ray spectral information. We present the preliminary results as we apply this survey to the well-studied anti-correlation between the optical-to-X-ray spectral index (\alpha_{ox}) and the optical luminosity (l_{uv}) found in AGN. This relation has been discussed for over 40 years but a physical cause has yet to be determined, largely because of the complexity of disk-corona models. Many past studies have utilized the 2500 \AA and 2 keV fluxes to calculate \alpha_{ox}, but this choice is historical, and is somewhat arbitrary from a scientific point of view. With a large sample of optical and X-ray spectra, we can investigate how the choice of other frequencies influences the significance, dispersion and slope of the \alpha_{ox}-l_{uv} relation, thereby giving us clues as to the underlying physical processes. This work is funded by NASA grants NNX07AI22G and G06-7102X. SDSS QSOs IN THE ChaMP Paul Green (CfA) et al. We study the spectral energy distributions and evolution of a couple thousand SDSS QSOs that were observed in 323 Chandra images analyzed by the Chandra Multiwavelength Project (ChaMP). We confirm a significant correlation between the ratio of optical/UV to X-ray flux (alphaOX) and optical luminosity, but it is flatter than those previously seen, and poorly fit by a linear relation across the full luminosity range. No correlation is seen for lower luminosity AGN alone. We report significant X-ray spectra hardening towards both higher X-ray luminosity, and for relatively X-ray loud quasars. These trends may represent a relative increase in non-thermal X-ray emission such as that associated with radio loud quasars, and our findings thereby strengthen analogies between Galactic black hole binaries and AGN. HOST GALAXIES, CLUSTERING, AND EVOLUTION OF RADIO, X-RAY, AND IR-SELECTED AGN AT z < 1 Ryan Hickox (CfA) I will present studies of active galactic nuclei and their host galaxies at z < 1 using data from the 9 deg^2 multiwavelength Bootes survey, with redshifts from MMT/AGES. AGN selected in different wavebands (radio, X-ray, infrared) have different host galaxy and clustering properties, and likely represent different modes of supermassive black hole accretion. I discuss the various AGN modes in the context of the cosmological evolution of galaxies and their central black holes. IRAC POWER-LAW AGN Shinae Park (CfA), Giovanni Fazio, Pauline Barmby Mid-infrared detections of AGN are necessary to obtain a more complete and reliable census of the AGN population. Here, we analyze a sample of ~500 candidate AGN in the EGS defined by their power-law SEDs from 3.6-8 um. These sources tend to be luminous and lie at higher redshifts than the general sample. One-third of these are detected by deep Chandra observations, though X-ray stacking analysis suggests significant X-ray emission even among the undetected sources. We expect that many of these sources represent AGN that are X-ray obscured. ---------------------- | 15:30 Poster Break | ---------------------- ---------------------------------- | 16:00 - 16:45 STRUCTURE OF AGN | ---------------------------------- THE NATURE OF AN AGN ACCRETION DISK WITHIN THE CENTRAL PARSEC: STRENGTHENED EVIDENCE FOR SPIRAL STRUCTURE Liz Humpreys (CfA), Reid, Greenhill, Moran, Argon A major issue for understanding the accretion process of AGN is determining the structure of the inner accretion disk. The only way to map the disk at distances < 1 pc from the central supermassive black hole is by using radio interferometric observations of nuclear water masers. In a new study of the nuclear masers of nearby Seyfert 2/LINER NGC 4258, we have imaged a sub-parsec (0.11 -- 0.28 pc) portion of the disk at 18 epochs using VLBI. The observations have enabled a first measurement of the thickness of the maser medium to be 5 micro-as or 0.0002 pc (1sigma). Assuming that this corresponds to the thickness of the accretion disk, hydrostatic equilibrium requires a gas temperature of about 600 K i.e., consistent with the physical conditions required to pump the masers. We confirm that warping of the disk could result in obscuration of the central engine, and that there is a characteristic radial scale of 0.027 pc for maser emission along the disk midline (the diameter perpendicular to the line-of-sight to the black hole) consistent with a model of spiral density waves in the disk. We find a trend in centripetal accelerations of masers in the line-of-sight to the black hole, as a function of disk impact parameter, that is long-lived with respect to the transit time of masers orbiting in front of the black hole. The trend could be due to (i) a spiral arm of mass 10^5 Msolar of pattern speed << Keplerian rotation; (ii) disk geometry and orientation that results in a preferred region for maser emission; or, (iii) eccentricity in maser orbits. A preliminary investigation of case (iii) indicates that maser emission in front of the black hole that arises from a single, eccentric orbit is unlikely to be the cause. WHY ARE SOME QUASARS RADIO LOUD? Rudy Schild (CfA): A combined reverberation-microlensing analysis of radio loud gravitationally lensed Q0957 and radio quiet Q2237 (Einstein Cross) shows an important difference in the internal structures. In the radio loud quasar, the inner edge of the accretion disc is found to lie at 70 R_G which is well outside of the region of the least stable orbit, and also outside of co-rotation. In radio quiet Q2237 the inner edge of the accretion disc is measured to lie just inside of the least stable orbit, approximately 6 R_G, and also well within co-rotation. We infer that the relationship to co-rotation is the principal mechanism determining the quasar spectral state, and that quasars remain fixed in a particular state for hundreds of years without undergoing state switching. It is easy to understand that since the central region is flooded with X-rays, matter must be ionized, and charged particles will respond differently to the magnetic forces encountered inside of co-rotation. The response would be in the sense to reverse the flow of ions, and produce inner secondary flows that quench the lo-hard state electron jet flow. The large empty central region of lo-hard Q0957 suggests magnetic propeller interaction of a strong central dipole field, and the non-standard models describing such structures will be discussed by Dr. Darryl Leiter. OBSERVATIONAL AND THEORETICAL EVIDENCE FOR THE EMERGENCE OF A NEW PARADIGM FOR QUASARS AND AGN Darryl Leiter (NRAO) Unique microlensing observations of quasar Q0957 in a radio loud low hard state and quasar Q2237 in a radio quiet spectral high soft state have permitted a detailed reconstruction of their internal structures emitting radiation (Schild, Leiter, and Robertson; Astron. Journ, vol132, pg140, (2006);Astron. Journ.,vol135, pg947, (2008)). Surprisingly the internal structures, observed within these two quasars in different spectral states, have been found to be similar to the features seen in accretion flows into young stellar objects which contain central compact objects which possess intrinsically anchored magnetic moments. The existence of intrinsic magnetic moments within the central super massive compact objects inside of these two quasars are observationally supported by: a) the fact that the inner accretion disk of the radio loud quasar is observed to be truncated at a very large radius by a very thin hot inner ring surrounding a large empty interior region and, b) the fact that both the radio loud and the radio quiet quasars contain elliptical Elvis outflow structures at radial distances about ten times further out which have very wide opening angles. Hence we conclude that we are seeing the physical effects associated with the presence of intrinsically magnetic, highly redshifted central compact objects in these quasars which cannot be black holes because astrophysical black holes cannot possess observable intrinsic magnetic moments. Instead the central compact objects in these appear to be "Magnetospheric Eternally Collapsing Objects" (MECO) which are permitted in the framework of the Einstein-Maxwell equations when solved within the context of Quantum Electrodynamic plasma physics, (Robertson and Leiter, ApJ, vol565, pg447, (2002); ApJLett, vol596, pg203, (2003); MNRAS, vol350, pg1391, (2004)). MECO can form by the same gravitational collapse process believed to result in black holes but due to internally generated synchrotron radiation pressure, which becomes trapped inside of their photon orbits, they become Eddington limited at very high redshift and are thus prevented from collapsing through their event horizons. Due to the extreme redshifts of the surface radiation emitted from the MECO Eddington limited surface, their intrinsic surface radiations are too faint to be easily detected at astronomical distances. However in quasars we find that MECO can be observationally distinguished from black holes primarily by their ability to exhibit the observable effects of their intrinsic magnetic moments on their quasar accretion disk environments. ------------------------ | 16:45 Refreshments | ------------------------ ----------- | POSTERS | ----------- 1. IR-VARIABLE OBJECTS IN THE IRAC DARK CALIBRATION FIELD Matt Ashby (CfA) Fouesneau, J. Hora, J. Surace, J. Krick, and G. Fazio The Spitzer Space Telescope has devoted 2-3 h of every IRAC instrument campaign to a particularly dark field near the north ecliptic pole since the beginning of the mission in 2003. The IRAC Dark Calibration Field is now the deepest IRAC integration to come out of the Spitzer mission. Furthermore, the unique temporal information (65 epochs so far) provided a means of closely monitoring brightness variations in stars and galaxies from 3 to 9.5 microns. We have photometered all 65 IRAC epochs in all four IRAC bands, generating more than 4 x 10000 light curves covering 1420 days. Based on these light curves we detect roughly 20 variable stars and 100 variable galaxies, and we are now engaged in characterizing these objects. 2. ZOOMING IN ON QSO ACCRETION DISKS THROUGH CHROMATIC MICROLENSING Jeffrey Blackburne (MIT), David Pooley, Paul L. Schechter, & Saul Rappaport Microlensing can serve as a powerful tool to "zoom in" on the structure of AGN. Recently some multiply imaged QSOs have been found to exhibit chromatic variations in their flux ratios, with X-ray ratios conflicting with lens models more than optical ratios. This suggests that the compact X-ray emitting region is strongly microlensed, while the larger size of the UV/optical disk is comparable to the microlens Einstein radius, decreasing the microlensing effect. This is in conflict with the standard thin disk model, which predicts a smaller optical disk. Simulations suggest that there will be strong evolution in the flux ratios of microlensed images within the optical regime. We have undertaken a broadband survey of twelve quadruply lensed QSOs from 0.4 to 2.2 microns, to find this evolution and characterize the size of the disk as a function of wavelength. 3. THE SPECTRAL ENERGY DISTRIBUTIONS OF RED 2MASS AGN Joanna Kuraszkiewicz (CfA) B. J. Wilkes, H. Ghosh, P. Smith, G. Schmidt, D. Hines, R. Cutri, B. Nelson, J. C. McDowell We present infrared(IR) to X--ray spectral energy distributions (SEDs) of 44 red AGN selected from the 2MASS survey on the basis of their red J-K>2 color and later observed by Chandra. Our sample covers objects of varying optical type from Type 1 objects (most have strong FeII and weak [OIII] emission lines resembling optical spectra of BALQSOs or NLS1s), through Type 1.2-1.9, which include highly polarized (3%