AGN Winds and Blazar Phenomenology

The launch of {\em Fermi} produced a significant number of AGN detections to allow statistical treatment of their properties. One of the first such systematics was the "Blazar Divide" in FSRQs and BL Lacs according to their gamma-ray spectral index and luminosity. Further data accumulation indicated this separation to be less clear than thought before. An MHD wind model which can model successfully the Seyfert X-ray absorber properties provides the vestiges of an account of the observed blazar classification. We propose to employ this model to model in detail the broad band blazar spectra and their statistical properties in terms of the physical parameters of these MHD winds

AGN Unification, X-Ray Absorbers and Accretion Disk MHD Winds

We present the 2D photoionization structure of the MHD winds of AGN accretion disks. We focus our attention on a specific subset of winds, those with poloidal currents that lead to density profiles n(r) \propto 1/r. We employ the code XSTAR to compute the local ionization balance, emissivities and opacity which are then used in the self-consistent transfer of radiation and ionization of a host of ionic species of a large number of elements over then entire poloidal plane. Particular attention is paid to the Absorption Measure Distribution (AMD), namely their hydrogen-equivalent column of these ions per logarithmic 7 interval, dN_H/dlog ? (? = L/n(r)r(sup 2) is the ionization parameter), which provides a measure of the winds' radial density profiles. For the given density profile, AMD is found to be independent of ?, in good agreement with analyses of Chandra and XMM data, suggesting the specific profile as a fundamental AGN property. Furthermore, the ratio of equatorial to polar column densities of these winds is \simeq 10(exp 4); as such, it is shown they serve as the "torus" necessary for AGN unification with phenomenology consistent with the observations. The same winds are also shown to reproduce the observed columns and velocities of C IV and Fe XXV of SAL QSOs once the proper ionizing spectra and inclination angles are employed

Supernova Bounds on the Dark Photon Using its Electromagnetic Decay

The hypothetical massive dark photon ($\gamma'$) which has kinetic mixing with the SM photon can decay electromagnetically to $e^+e^-$ pairs if its mass $m$ exceeds $2m_e$ and otherwise into three SM photons. These decays yield cosmological and supernovae associated signatures. We briefly discuss these signatures, particularly in connection with the supernova SN1987A and delineate the extra constraints that may then arise on the mass and mixing parameter of the dark photon. In particular, we find that for dark photon mass $m_{\gamma'}$ in the 5-20 MeV range, arguments based on supernova 1987A observations lead to a bound on $\epsilon$ which is about 300 times stronger than the presently existing bounds based on energy loss arguments.Comment: 10 pages, 6 figures, minor typos corrected, version to appear in NP

Dust formation in AGN winds

Infrared observations of active galactic nucleus (AGN) reveal emission from the putative dusty circumnuclear 'torus' invoked by AGN unification, that is heated up by radiation from the central accreting black hole (BH). The strong 9.7 and 18 micron silicate features observed in the AGN spectra both in emission and absorption, further indicate the presence of such dusty environments. We present detailed calculations of the chemistry of silicate dust formation in AGN accretion disk winds. The winds considered herein are magnetohydrodynamic (MHD) winds driven off the entire accretion disk domain that extends from the BH vicinity to the radius of BH influence, of order of 1 to 100 pc depending on the mass of the resident BH. Our results indicate that these winds provide conditions conducive to the formation of significant amounts of dust, especially for objects accreting close to their Eddington limit, making AGN a significant source of dust in the universe, especially for luminous quasars. Our models justify the importance of a r to the power -1 density law in the winds for efficient formation and survival of dust grains. The dust production rate scales linearly with the mass of the central BH and varies as a power law of index between 2 to 2.5 with the dimensionless mass accretion rate. The resultant distribution of the dense dusty gas resembles a toroidal shape, with high column density and optical depths along the equatorial viewing angles, in agreement with the AGN unification picture.Comment: 22 pages, 17 figures (some have subfigures), Accepted for publication in The Astrophysical Journa

The infrared echo of SN2010jl and its implications for shock breakout characteristics

SN 2010jl is a Type IIn core collapse supernova whose radiative output is powered by the interaction of the SN shock wave with its surrounding dense circumstellar medium (CSM). After day ~60, its light curve developed a NIR excess emission from dust. This excess could be a thermal IR echo from pre-existing CSM dust, or emission from newly-formed dust either in the cooling postshock region of the CSM, or in the cooling SN ejecta. Recent analysis has shown that dust formation in the CSM can commence only after day ~380, and has also ruled out newly-formed ejecta dust as the source of the NIR emission. The early (< 380 d) NIR emission can therefore only be attributed to an IR echo. The H-K color temperature of the echo is about 1250 K. The best fitting model requires the presence of about 1.6e-4 Msun of amorphous carbon dust at a distance of 2.2e16 cm from the explosion. The CSM-powered luminosity is preceded by an intense burst of hard radiation generated by the breakout of the SN shock through the stellar surface. The peak burst luminosity seen by the CSM dust is significantly reduced by Thomson scattering in the CSM, but still has the potential of evaporating the dust needed to produce the echo. We show that the survival of the echo-producing dust provides important constraints on the intensity, effective temperature, and duration of the burst.Comment: Accepted for publication in the ApJ, 20 pages, 1 table, and 17 figure

Broad redshifted line as a signature of outflow

We formulate and solve the diffusion problem of line photon propagation in a bulk outflow from a compact object (black hole or neutron star) using a generic assumption regarding the distribution of line photons within the outflow. Thomson scattering of the line photons within the expanding flow leads to a decrease of their energy which is of first order in v/c, where v is the outflow velocity and c is the speed of light. We demonstrate that the emergent line profile is closely related to the time distribution of photons diffusing through the flow (the light curve) and consists of a broad redshifted feature. We analyzed the line profiles for the general case of outflow density distribution. We emphasize that the redshifted lines are intrinsic properties of the powerful outflow that are supposed to be in many compact objects.Comment: 16 pages, 1 black-white figure and 2 color figures; accepted for publication in the Astrophysical Journa

Magnetars as Astrophysical Laboratories of Extreme Quantum Electrodynamics: The Case for a Compton Telescope

A next generation of Compton and pair telescopes that improve MeV-band detection sensitivity by more than a decade beyond current instrumental capabilities will open up new insights into a variety of astrophysical source classes. Among these are magnetars, the most highly magnetic of the neutron star zoo, which will serve as a prime science target for a new mission surveying the MeV window. This paper outlines the core questions pertaining to magnetars that can be addressed by such a technology. These range from global magnetar geometry and population trends, to incisive probes of hard X-ray emission locales, to providing cosmic laboratories for spectral and polarimetric testing of exotic predictions of QED, principally the prediction of the splitting of photons and magnetic pair creation. Such fundamental physics cannot yet be discerned in terrestrial experiments. State of the art modeling of the persistent hard X-ray tail emission in magnetars is presented to outline the case for powerful diagnostics using Compton polarimeters. The case highlights an inter-disciplinary opportunity to seed discovery at the interface between astronomy and physics.Comment: 11 pages, 4 figures, Astro2020 Science White Paper submitted to the National Academies of Science

The Extended Pulsar Magnetosphere

We present the structure of the 3D ideal MHD pulsar magnetosphere to a radius ten times that of the light cylinder, a distance about an order of magnitude larger than any previous such numerical treatment. Its overall structure exhibits a stable, smooth, well-defined undulating current sheet which approaches the kinematic split monopole solution of Bogovalov 1999 only after a careful introduction of diffusivity even in the highest resolution simulations. It also exhibits an intriguing spiral region at the crossing of two zero charge surfaces on the current sheet, which shows a destabilizing behavior more prominent in higher resolution simulations. We discuss the possibility that this region is physically (and not numerically) unstable. Finally, we present the spiral pulsar antenna radiation pattern.Comment: 6 pages, 3 figures, accepted in MNRA