16442176
The origin and physical mechanism of the ensemble Baldwin effect
We have conducted a systematic investigation of the origin and underlying physics of the line--line and line--continuum correlations of AGNs, particularly the Baldwin effect. Based on the homogeneous sample of Seyfert 1s and QSOs in the SDSS DR4, we find the origin of all the emission-line regularities is Eddington ratio (L/Ledd). The essential physics is that L/Ledd regulates the distributions of the properties (particularly column density) of the clouds bound in the line-emitting region.
118478408
COEXISTENCE OF GRAVITATIONALLY-BOUND AND RADIATION-DRIVEN C IV EMISSION LINE REGIONS IN ACTIVE GALACTIC NUCLEI
There are mutually contradictory views in the literature of the kinematics and structure of high-ionization line (e. g., C IV) emitting regions in active galactic nuclei (AGNs). Two kinds of broad emission line region (BELR) models have been proposed, outflow and gravitationally-bound BELR, which are supported, respectively, by blueshift of the C IV line and reverberation mapping observations. To reconcile these two apparently different models, we present a detailed comparison study between the C IV and Mg II lines using a sample of AGNs selected from the Sloan Digital Sky Survey. We find that the kinematics of the C IV region is different from that of Mg II, which is thought to be controlled by gravity. A strong correlation is found between the blueshift and asymmetry of the C IV profile and the Eddington ratio. This provides strong observational support for the postulation that the outflow is driven by radiation pressure. In particular, we find robust evidence that the C IV line region is largely dominated by outflow at high Eddington ratios, while it is primarily gravitationally-bounded at low Eddington ratios. Our results indicate that these two emitting regions coexist in most AGNs. The emission strength from these two gases varies smoothly with Eddington ratio in opposite ways. This explanation naturally reconciles the apparently contradictory views proposed in previous studies. Finally, candidate models are discussed which can account for both the enhancement of outflow emission and suppression of normal BEL in AGNs with high Eddington ratios.
119290451
The Prevalence of Narrow Optical Fe II Emission Lines in Type 1 Active Galactic Nuclei
From detailed spectral analysis of a large sample of low-redshift active galactic nuclei (AGNs) selected from the Sloan Digital Sky Survey, we demonstrate-statistically for the first time-that narrow optical Fe II emission lines, both permitted and forbidden, are prevalent in type 1 AGNs. Remarkably, these optical lines are completely absent in type 2 AGNs, across a wide luminosity range, from Seyfert 2 galaxies to type 2 quasars. We suggest that the narrow Fe II-emitting gas is confined to a disk-like geometry in the innermost regions of the narrow-line region on physical scales smaller than the obscuring torus.
915469
Optical identification of radio-loud active galactic nuclei in the ROSAT-Green-Bank sample with SDSS spectroscopy
Results of extended and refined optical identification of 181 radio/X-ray sources in the RASS-Green Bank (RGB) catalog are presented (Brinkmann et al. 1997) which have been spectroscopically observed in the Sloan Digital Sky Survey (SDSS) DR5. The SDSS spectra of the optical counterparts are modeled in a careful and self-consistent way by incorporating the host galaxy's starlight. Optical emission line parameters are presented, which are derived accurately and reliably, along with the radio 1.4-5 GHz spectral indices estimated using (non-simultaneous) archival data. For 72 sources, the identifications are presented for the first time. It is confirmed that the majority of strong radio/X-ray emitters are radio-loud active galactic nuclei (AGNs), particularly blazars. Taking advantage of the high spectral quality and resolution and our refined spectral modeling, we are able to disentangle narrow line radio galaxies (NLRGs), as vaguely termed in most previous identification work, into Seyfert II galaxies and LINERs (low-ionization nuclear emission regions), based on the standard emission line diagnostics. The NLRGs in the RGB sample, mostly belonging to 'weak line radio galaxies', are found to have optical spectra consistent predominantly with LINERs, and only a small fraction with Seyfert II galaxies. A small number of LINERs have radio power as high as 10(23)-10(26) W Hz(-1) at 5 GHz, being among the strongest radio emitting LINERs known so far. Two sources are identified with radio-loud narrow line Seyfert I galaxies (NLS1s), a class of rare objects. The presence is also confirmed of flat-spectrum radio quasars whose radio-optical-X-ray effective spectral indices are similar to those of High-energy peaked BL Lacs (HBLs), as suggested by Padovani et al., although it is still a debate as to whether this is the case for their actual spectral energy distributions.
118506676
CO observation of SNR IC 443
We present our 12CO and 13CO mapping observations of SNR IC 443 interacting with molecular clouds. It is the first large-scale high-resolution 13CO mapping observation in the surrounding region. The morphologies of IC 443 in 12CO and 13CO are compared with the optical, infrared, Spitzer far-infrared, X-ray, and neutral atomic gas (HI). We also make comparison and analysis in the kinematics, using the date-cubes of 12CO, 13CO and HI, to help distinguish the complicated gas motions in the shocked regions. Based on the work of Wang & Scoville (1992), we present a new model to explain the coexistence of multiple shocks with different speeds in a pc-scale region at the central clump B. We test this new model by analyzing the HI and CO distribution in both velocity and space domain. We also establish the relationship between the dissociation rate of shocked molecular gas and the shock velocity in this region. Finally, we derive the optical depth of 12CO with the 13CO spectra in clump B, and discuss the validity of the assumption of optically thin emission for the shocked 12CO.
119237398
Study of double parton scattering using W + 2-jet events in proton-proton collisions at $ \sqrt{s} $ = 7 TeV
A bstractDouble parton scattering is investigated in proton-proton collisions at $ \sqrt{s} $ = 7 TeV where the final state includes a W boson, which decays into a muon and a neutrino, and two jets. The data sample corresponds to an integrated luminosity of 5 fb−1, collected with the CMS detector at the LHC. Observables sensitive to double parton scattering are investigated after being corrected for detector effects and selection efficiencies. The fraction of W + 2-jet events due to double parton scattering is measured to be 0.055 ± 0.002 (stat.) ± 0.014 (syst.). The effective cross section, σeff, characterizing the effective transverse area of hard partonic interactions in collisions between protons is measured to be 20.7 ± 0.8(stat.) ± 6.6(syst.)mb.

5761866
Intrinsic Constraints on Very High Energy Emission in Gamma-Ray-loud Blazars
Photons with very high energy (VHE) up to TeV emitted from active galactic nuclei (AGNs) provide some invaluable information on the origin of gamma-ray emission. Although 66 blazars have been detected by EGRET, only three low-redshift X-ray-selected BL Lac objects (Mrk 421, Mrk 501, and 1ES 2344+514) are conclusive TeV emitters (PKS 2155-304 is a potential TeV emitter), since VHE photons may be absorbed by cosmological background infrared photons (external absorption). Based on the "mirror" effect of clouds in the broad-line region, we argue that there is an intrinsic mechanism for the deficiency of TeV emission in blazars. Employing the observable quantities, we derive the pair production optical depth tau(gamma gamma)(epsilon(obs)) due to the interaction of VHE photons with the reflected synchrotron photons by electron Thomson scattering in the broad-line region. This sets stronger constraints on very high energy emission, and provides a sensitive upper limit on the Doppler factor of the relativistic bulk motion. It has been suggested that the intrinsic absorption be distinguished from the external by the observation on variation of the multiwavelength continuum.
16201574
The Hot Disk Corona and Magnetic Turbulence in Radio-quiet Active Galactic Nuclei: Observational Constraints
We compile a sample consisting of 56 radio-quiet active galactic nuclei so as to investigate the statistical properties of the hot corona in accretion disks from ASCA observations. The black hole masses in the sample are estimated via several popular methods, and the bolometric luminosities from the multiwavelength continuum. This allows us to estimate the Eddington ratio (E = L-bol/L-Edd) so that the undergoing physical processes can be tested via hard X-ray data. We use the least- squares method of multivariate regression and find a strong correlation between F-X = L2-10 keV/L-bol and E as F-X proportional to E-064. This indicates that the release of gravitational energy in the hot corona is controlled by the Eddington ratio. On the other hand, the correlation between the hard X- ray spectral index (Gamma) and E depends critically on the types of objects: Gamma is nearly constant (Gamma proportional to E-0) in broad- line Seyfert 1 galaxies, whereas Gamma proportional to log E-0.18 in narrow- line Seyfert 1 galaxies, although this is not very significant. We can set constraints on the forms of the magnetic stress tensor on the condition that F-X is proportional to the fraction f of gravitational energy dissipated in the hot corona and that f is proportional to the magnetic energy density in the disk. We find that the shear stress tensor is favored by the correlation in the present sample, t. P where P-gas is the gas pressure.
118604314
ACCRETION DISKS IN ACTIVE GALACTIC NUCLEI: GAS SUPPLY DRIVEN BY STAR FORMATION
Self-gravitating accretion disks collapse to star-forming (SF) regions extending to the inner edge of the dusty torus in active galactic nuclei (AGNs). A full set of equations including feedback of star formation is given to describe the dynamics of the regions. We explore the role of supernova explosions (SNexp), which act to excite turbulent viscosity, in the transportation of angular momentum in the regions within 1 pc scale. We find that accretion disks with typical rates in AGNs can be driven by SNexp in the regions and metals are produced spontaneously. The present model predicts a metallicity-luminosity relationship consistent with that observed in AGNs. As relics of SF regions, a ring (or belt) consisting of old stars remains for every episode of supermassive black hole activity. We suggest that multiple stellar rings with random directions interact and form a nuclear star cluster after episodes driven by star formation.