bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observation of a U-like shaped velocity evolution of plasma expansion during a high-power diode operation
Authors: Cai Dan , Liu Lie , Ju Jinchuan , Zhao Xuelong , Qiu Yongfeng 
Published: July 2014

AbstractThe diode closure velocity has been investigated in pulsed high-power diodes operating with the mode of space-charge-limed bipolar flow. A combination of time-resolved electrical and optical diagnostics has been employed to study the basic phenomenon of the temporal and spatial evolutions of the diode plasmas. The results from the two diagnostics were compared. Since anode plasma rapidly expands, the diode closure speedvdincreases in the end of the current pulse. The diode closure speedvdcan be divided into three stages with a U-like whole shape. The obtained results can be used in various applications, for instance, the high-power microwave sources, electron-beam plasma heating, and material treating.
NONORTHOGONAL GEOMETRIC REALIZATIONS OF COXETER GROUPS
Authors: FU XIANG 
Published: July 2014

AbstractWe define in an axiomatic fashion aCoxeter datumfor an arbitrary Coxeter group$\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}W$. This Coxeter datum will specify a pair of reflection representations of$W$in two vector spaces linked only by a bilinear pairing without any integrality or nondegeneracy requirements. These representations are not required to be embeddings of$W$in the orthogonal group of any vector space, and they give rise to a pair of inter-related root systems generalizing the classical root systems of Coxeter groups. We obtain comparison results between these nonorthogonal root systems and the classical root systems. Further, we study the equivalent of the Tits cone in these nonorthogonal representations.
RACISM, MORALISM, AND SOCIAL CRITICISM1
Authors: Shelby Tommie 
Published: July 2014

AbstractThrough a critical engagement with Lawrence Blum’s theory of racism, I defend a “social criticism” model for the philosophical study of racism. This model relies on empirical analyses of social and psychological phenomena but goes beyond this to include the assessment of the warrant of widely held beliefs and the normative evaluation of attitudes, actions, institutions, and social arrangements. I argue that we should give political philosophy theoretical primacy over moral philosophy in normative analyses of racism. I also show how conceptualizing racism as an ideology gives us a unified account of racism and helps us to see what is truly troubling about racism, both in the past and today.
Photoionization, line emission diagnostics
Authors: Kewley Lisa 
Published: July 2014

AbstractPhotoionization models for AGN, including Seyfert and LINERs are discussed. These photoionization models can be used to derive emission-line diagnostics for AGN that can determine the properties of the AGN and surrounding ISM, including the relative AGN contribution to the EUV radiation field, the hardness of the AGN radiation field, the ionization state of the gas, and the metallicity of the narrow-line region. It is shown how the AGN emission-line diagnostics are expected to change with redshift. Finally, latest application of these models by the author to wide integral field spectroscopy to separate starburst and AGN contributions in composite galaxies are presented.
Revised activity types for Markarian galaxies
Authors: Mickaelian A. M. , Abrahamyan H. V. , Harutyunyan G. S. , Paronyan G. M. 
Published: July 2014

AbstractThe sample of Markarian galaxies consists of 1515 UV-excess galaxies containing many active galaxies, both AGN and Starburst (SB). Several catalogs of Markarian galaxies have been published; however activity types are based on old spectroscopic data. The SDSS spectroscopy and some other recent spectral observations allow classify or re-classify many of Markarian galaxies, altogether we have retrieved and studied 779 SDSS and 300 other spectra. Out of 779 SDSS spectra, we have classified 533 HII, 31 Composites, 12 LINERs, 4 S2.0, 5 S1.9, 8 S1.8, 5 NLS1.5, 11 S1.5, 8 NLS1.2, 21 S1.2, 4 NLS1, 4 S1.0, 2 QSO, 11 AGN (without an exact class), 52 Em (HII or AGN), 65 Abs, and 3 Stars. On the other hand, the galaxies are being classified depending on the fact in which wavelength range they have been observed and studied. E.g. some Sy2 type galaxies turn to be Sy1 when classified in IR. Many hidden AGN (in X-ray and IR) appear to be normal galaxies in optical range. So for better understanding, IR spectra are necessary as well.
A Massive Sample of Radio Spectral Indices for AGN in the JVLA FIRST Survey
Authors: Becker Bob 
Published: July 2014

AbstractThe final 800 sq. deg of sky covered by FIRST was observed with the new, improved JVLA. The data were split between two bandpasses at 1335 and 1730 MHz and included all four Stokes parameters, thus allowing both spectral and polarimetric results. The lower frequency bandpass data were considered part of FIRST and are available through the FIRST website (http://sundog.stsci.edu/). Here we present the higher frequency bandpass data as pertain to AGN. Foremost, we present spectral index results for the 5000 quasars with spectroscopic redshifts and the 50,000 quasars with photometric redshifts that fall in the survey area. The spectral indices are analyzed as a function of redshift and optical properties both for quasars detected above the 1 mJy limit and, via image stacking, for quasars at flux densities down to 10 mJy.
LOFAR and Radio Loud AGN
Authors: Williams Wendy L. , Röttgering Huub , van Weeren Reinout 
Published: July 2014

AbstractAt very low frequencies, the new pan-European radio telescope, LOFAR, is opening the last unexplored window of the electromagnetic spectrum for astrophysical studies. LOFAR will deeply survey the northern sky from ~ 10 up to 240 MHz. In this contribution we briefly describe some of the capabilities of LOFAR and the surveys planned to study fundamental issues related to the formation and evolution of galaxies and clusters of galaxies. We describe some of the challenges of low frequency observations with LOFAR and our progress in overcoming them. Further, we present some recent results from the ongoing imaging commissioning efforts. In the second part we discuss our studies of Low Excitation and High Excitation Radio Galaxies in the Boötes field and how LOFAR Surveys will help in studying their evolution.
The Australia Telescope Large Area Survey: Measuring the AGN contribution to galaxies over cosmic time
Authors: Chow Kate 
Published: July 2014

AbstractThe Australia Telescope Large Area Survey (ATLAS) is the widest deep radio survey ever attempted, covering ~7deg2 across its two fields, the Chandra Deep Field South (CDFS) and the European Large Area ISO Survey South 1 Region (ELAIS-S1). ATLAS has extensive multiwavelength data, including optical, infrared and X-ray, to complement its ~15μJy rms 1.4 GHz radio data. At these faint radio flux densities, the proportion of AGN to star-forming galaxies (SFGs) is high, and there are likely many composite objects, which have both an AGN and ongoing star formation. In ATLAS, we estimate that the number of AGN is approximately 50%, and this proportion will change with decreasing flux density. To understand the relationship between the AGN and the host galaxy, we need to measure the contribution of the AGN to the total luminosity, and determine how this varies with the evolutionary stage of the galaxy. Here I present results exploring the AGN contribution to galaxies over cosmic time, through the use of different multiwavelength discriminants.
AGN in the Atacama Cosmology Telescope Survey Data
Authors: Gralla Megan , Marriage T. ,   ACT Collaboration
Published: July 2014

AbstractThe Atacama Cosmology Telescope (ACT) is a six-meter telescope in the Atacama Desert that observes simultaneously in frequency bands centered at 150, 220 and 270 GHz. ACT has surveyed an area of approximately 450 square degrees in the south (−55 deg) and approximately 500 square degrees along the equator. Most of the sources detected by ACT are blazars. I will present source counts and spectral indices as well as multi-wavelength properties determined by matching with external datasets. In addition to studying sources detected in the survey, we have used the ACT data to statistically study the millimeter properties of radio sources selected from low frequency (1.4 GHz) surveys.
Radio Properties of AGN
Authors: Abrahamyan Hayk V. , Mickaelian Areg M. 
Published: July 2014

AbstractTo study the radio properties of AGN, we cross-correlate and investigate Veron-Cetty & Veron catalog of QSOs and Active Galaxies (v.13, 2010) with a number of radio catalogs: NVSS, FIRST, GB6, 87GB, SUMSS, WISH, WENSS, and 7C. This catalog contains 168,940 objects with positional accuracy of mostly 1 arcsec, though many positions have larger errors. We use new cross-correlation software based on accuracy of each object independently. In this software we take into account errors for each source and take identifications with errors within 3 sigma. Altogether, we find ~16,000 AGN having radio detection in any of the listed catalogs. Using all data from radio catalogs, we derive a homogeneous sample of radio AGN. The sample allows accomplish several tasks, including study of the distribution of radio sources by activity types, differences in physical properties of radio-loud and radio-quiet AGN, luminosity functions for various types of radio AGN, study of the q parameter by AGN types and its evolution, etc.
Multi-frequency, multi-epoch VLBI observations of the M87 jet
Authors: Hada Kazuhiro , Giroletti Marcello , Giovannini Gabriele , Doi Akihiro , Kino Motoki , Nagai Hiroshi , Honma Mareki , Kawaguchi Noriyuki 
Published: July 2014

AbstractWe present some of preliminary results obtained by our dense monitoring project of the M87 jet with VERA 22 and 43 GHz starting from October 2010. The aims of this monitor are to clarify the detailed physical properties of the M87 jet base near the black hole, including the connection to γ-ray productions, jet kinematics and nuclear opacity. We detected a remarkable increase of the radio flux from the jet base of M87 during an elevated very-high-energy γ-ray activity occurred in the early 2012, suggesting that the γ-ray is produced in the immediate vicinity of the central black hole.
Activity types for X-ray candidate AGN from SDSS
Authors: Paronyan Gurgen M. , Harutyunyan Gohar S. , Mickaelian Areg M. 
Published: July 2014

AbstractThe Joint Catalogue of Hamburg ROSAT Sources (HRC/BHRC) is the result of merging of HRC and BHRC catalogs built on the basis of optical identifications of ROSAT BSC and ROSAT FSC. Altogether, 8132 sources are present. Based on this catalogue, we have compiled a sample of ROSAT AGN, including candidate ones. In this paper we classify candidate AGN (those that previously had not been spectroscopically classified) by their activity type. The sample contains 955 objects with count rate of photons CR>0.04 ct/s in the area with galactic latitudes |b|>30 and declinations δ>0, however only 217 objects have SDSS DR10 spectra. The classification led to the following results: 95 AGN, 71 absorption-line galaxies, 42 stars, and 9 unclassified objects.
AGN surveys to study galaxy evolution along cosmic times
Authors: Spinoglio Luigi 
Published: July 2014

AbstractVarious observational techniques have been used to survey galaxies and AGN, from X-rays to radio frequencies, both photometric and spectroscopic. I will review these techniques aimed at the study of galaxy evolution and of the role of AGNs and star formation as the two main energy production mechanisms. I will then present as a new observational approach the far-IR spectroscopic surveys that could be done with planned astronomical facilities of the next future, such as SPICA from the space and CCAT from the ground.
Multi-Wavelength AGN from Ground and Space, from Far-IR to High-Energy
Authors: Stern Daniel 
Published: July 2014

AbstractI will discuss multi-wavelength AGN studies, with a focus on mid-IR and radio selected obscured AGN. Obscured AGN, which are robustly identified across the full sky by WISE, are the dominant AGN population. I will discuss several aspects of the mid-IR obscured AGN population, ranging from detailed studies of extreme sources, the so-called WISE ultraluminous ‘hot dust-obscured galaxy’ or ‘hot DOG’ sample, as well as more general studies comparing obscured and unobscured AGN identified in wide-area surveys.
The Multiwavelength AGN Population and the X-ray Background
Authors: Treister Ezequiel , Urry Claudia M. , Schawinski Kevin , Simmons Brooke D. , Natarajan Priyamvada , Volonteri Marta 
Published: July 2014

AbstractIn order to fully understand galaxy formation we need to know when in the cosmic history are supermassive black holes (SMBHs) growing more intensively, in what type of galaxies this growth is happening and what fraction of these sources are invisible at most wavelengths due to obscuration. Active Galactic Nuclei (AGN) population synthesis models that can explain the spectral shape and intensity of the cosmic X-ray background (CXRB) indicate that most of the SMBH growth occurs in moderate-luminosity (LX~ 1044 erg/s) sources (Seyfert-type AGN), at z~ 0.5−1 and in heavily obscured but Compton-thin, NH~ 1023cm−2, systems. However, this is not the complete history, as a large fraction of black hole growth does not emit significantly in X-rays either due to obscuration, intrinsic low luminosities or large distances. The integrated intensity at high energies indicates that a significant fraction of the total black hole growth, 22%, occurs in heavily-obscured systems that are not individually detected in even the deepest X-ray observations. We further investigate the AGN triggering mechanism as a function of bolometric luminosity, finding evidence for a strong connection between significant black hole growth events and major galaxy mergers from z~ 0 to z~ 3, while less spectacular but longer accretion episodes are most likely due to other (stochastic) processes. AGN activity triggered by major galaxies is responsible for ~60% of the total black hole growth. Finally, we constrain the total accreted mass density in supermassive black holes at z > 6, inferred via the upper limit derived from the integrated X-ray emission from a sample of photometrically selected galaxy candidates. We estimate an accreted mass density <1000 M⊙Mpc−3 at z~ 6, significantly lower than the previous predictions from some existing models of early black hole growth and earlier prior observations.
Red QSOs in the MBH-M∗ plane
Authors: Bongiorno Angela 
Published: July 2014

AbstractWe present new results on the the MBH-M∗ relation of X-ray obscured, red QSOs at high redshift (1.2<z<2.6). The sample is made of 21 red QSOs, nine of them are new sources for which near-infrared spectra have been obtained with SINFONI and XShooter observations at ESO VLT, and show a broad Hα component. The rest of the sample (12 sources) is made of sources taken from the literature with similar properties. From the broad Hα line we have computed the BH masses through the virial formula while stellar masses have been obtained through multi-component SED fitting.We find that red QSOs preferentially lie on the local relation up to z ~ 2.6 with the most massive objects mainly located above it. We also studied the evolution of these sources on the MBH-M∗ plane compared to a sample of optically blue type–1 QSOs and we find that obscured red QSOs show a constant MBH/M∗ ratio consistent/slightly higher than the local one but lower than what has been found for blue QSOs. These sources may represent the intermediate phase (blow-out phase) between the major-merger induced starbursts which appear as ULIRGs and SMGs and the optical type–1 blue QSOs which are revealed once the dust and nuclear gas is cleared up.
Identifying the Most Luminous QSOs in the Universe from Multiwavelength Sky Surveys
Authors: Kimball Amy , Condon J. , Lonsdale C. , Lacy M. 
Published: July 2014

AbstractI have combined data from sky surveys in the UV to the mid-IR, along with radio and X-ray data, to identify the most luminous QSOs in the Universe. The primary sky surveys were the Sloan Digital Sky Survey (SDSS) 7th Data Release QSO Catalog, which provides unambiguous broad-line QSO classification and robust redshifts, and the Wide-field Infrared Survey Explorer (WISE) mid-IR catalog, because a large percentage of QSO bolometric luminous emerges in the IR. Out of the 100,000 SDSS/WISE QSOs, we find 140 (< 0.2%) with bolometric luminosity greater than 2×1014Lo, with redshifts ranging from about 1.7 to 5. The most luminous QSO found has Lbol ≈7×1014Lo. Merger-based galaxy evolution models predict that the host galaxies of such sources at peak QSO luminosity are undergoing a short-lived phase of extreme AGN feedback and massive star-formation activity after a major merger. Upcoming sub-mm observations with the new Atacama Large Millimeter/Sub-millimeter Array (ALMA), for a subset of the sample, will soon reveal crucial host galaxy properties of this unique sample.
A study of optical/IR selected AGNs with SDSS and WISE
Authors: Shao Li 
Published: July 2014

AbstractWe analyze a sample of 30,000 nearby obscured AGNs with SDSS and WISE. We use a “pair-matching” technique to subtract the host 4.6μm contribution, with the aid of SDSS data. By combining Seyferts with local SDSS quasars, we show that the [Oiii] and the intrinsic AGN 4.6μm luminosities correlate roughly linearly over 4 orders of magnitude, despite of large scatter. We also compare the partition functions of the total integrated 4.6μm and [Oiii] line luminosities from Seyferts and IR-bright LINERs, as function of a variety of host galaxy properties. The result suggests the optical and the IR selected AGNs represent the same galaxy population. We further study the environment of the AGNs, finding a link between the IR nuclear emission and the galaxy interaction.
Ultraviolet Line-Continuum properties of Seyfert 1 galaxies and quasars
Authors: Doddamani Vijayakumar H. , Vedavathi P. 
Published: July 2014

AbstractActive galaxies are most luminous objects in the universe whose spectra are characterized by both permitted and forbidden emission line features. The spectra of Seyfert 1 galaxies and quasars contain strong and broad emission lines of wide ranging ionization potentials. The velocity widths of the lines range from a minimum of ≈ 500 km/s for narrow lines to a maximum of 20,000 km/sec for broad lines. The UV spectra of the active galaxies contain strong and broad emission lines such as Lyα, NV, SiIV, OIV], CIV, CIII] and MgII lines. The widths of the broad lines are attributed to the differential doppler shifts of the emission lines due to the bulk motions of individual clumpy gas clouds in the BLR region. We have anlysed UV spectra of Seyfert 1 galaxies and quasars from IUE satellite archival database to understand the nature of dependence of the emission line properties with the underlying UV continuum. We have undertaken line luminosity correlation studies for Lyα and CIV lines with their underlying UV continuum luminosity at 1125Å, 1425Å & 1625Å. The IUE archival spectra have been reduced for galactic reddening using the E(B-V) and NHI values published continuum luminosity has been observed at 1125Å, 1425Å & 1625Å. The Lyα line line has exhibited strongest linear correlation wavelengths while CIV line has shown at 1425Å and 2625Å wavelengths. These results are empirically consistent with the predictions of the general multi-component photo-ionization models suggesting that the central strong UV continuum has been reprocessed by the clumpy gas clouds of the broad emission region (BLR). A detailed account of the data reduction, UV flux measurement and the significance of line-luminosity correlations are discussed in this paper.
Investigation of Distant Quasars
Authors: Hovhannisyan Martik , Andreasyan R. , Paronyan G. , Abrahamyan H. 
Published: July 2014

AbstractTo study physical and morphological characteristics of distant quasars we carry out radio-optical investigation of 30 quasars from the Cambridge 7C catalogue second area (0.097 square radians). All these objects have angular sizes less than 1 arcsec on 102 MHz images. Average values of absolute magnitudes and spectral indices have been calculated for them (M = −26.51 ± 0.25, a = 0.66±0.25). It was shown that 60% of compact radio sources from the FIRST catalogue (1400 MHz) are candidates of distant quasars.
Size Measurements of the Quasar X-Ray Continuum Emission Region by Analysis of Microlensing in Chandra Imagery
Authors: MacLeod Chelsea L. , Morgan Christopher W. 
Published: July 2014

AbstractMicrolensing offers a unique way to constrain the physical extent of different emission regions in a lensed quasar, putting to test various accretion and continuum emission models. We perform a microlensing analysis using six Chandra observations (spanning six years) of the lensed quasar SDSS 0924+0219 (redshift zs=1.52), in which X-ray microlensing variability is detected with high confidence. The system exhibits pronounced microlensing variability in the X-rays compared to the optical, indicating a comparatively small extent of r1/2<3.8×104 cm (95% confidence) for the X-ray continuum emitting region, near the inner edge of the accretion disk.
Clustering and Halo Occupation Distribution of Active Galactic Nuclei
Authors: Miyaji Takamitsu , Krumpe M. , Coil A. , Aceves H. , Husemann B. 
Published: July 2014

AbstractWe present the results of our series of studies on correlation function and halo occupation distribution of AGNs utilizing data the ROSAT All-Sky Survey (RASS) and the Sloan Digital Sky Survey (SDSS) in the redshift range of 0.07<z<0.36. In order to improve the signal-to-noise ratio, we take cross-correlation approach, where cross-correlation functions (CCF) between AGNs and much more numerous AGNs are analyzed. The calculated CCFs are analyzed using the Halo Occupation Distribution (HOD) model, where the CCFs are divided into the term contributed by the AGN-galaxy pairs that reside in one dark matter halo (DMH), (the 1-halo term) and those from two different DMHs (the 2-halo term). The 2-halo term is the indicator of the bias parameter, which is a function of the typical mass of the DMHs in which AGNs reside. The combination of the 1-halo and 2-halo terms gives, not only the typical DMH mass, but also how the AGNs are distributed among the DMHs as a function of mass separately for those at the center of the DMHs and satellites. The main results are as follows: (1) the range of typical mass of the DMHs in various sub-samples of AGNs log (MDMH/h−1MΘ) ~ 12.4–13.4, (2) we found a dependence of the AGN bias parameter on the X-ray luminosity of AGNs, while the optical luminosity dependence is not significant probably due to smaller dynamic range in luminosity for the optically-selected sample, and (3) the growth of the number of AGNs per DMH (N (MDMH)) with MDMH is shallow, or even may be flat, contrary to that of the galaxy population in general, which grows with MDMH proportionally, suggesting a suppression of AGN triggering in denser environment. In order to investigate the origin of the X-ray luminosity dependence, we are also investigating the dependence of clustering on the black hole mass and the Eddington ratio, we also present the results of this investigation.
Dependence of equivalent width of quasar emission lines on UV-optical spectral index
Authors: Torbaniuk Olena , Ivashchenko Ganna 
Published: July 2014

AbstractUsing 192 composite spectra stacked from subsamples of individual SDSS quasar spectra binned in spectral index, αλ, and logarithm of monochromatic luminosity at 1450 Å, log l1450, and modelling separate spectral ranges with superposition of emission lines it was found that: there is a dependence of emission line equivalent width (EW) on αλ (correlation or anti-correlation) for some lines, mostly for those lines for which the Baldwin effect is detected, while for the lines for which the Baldwin effect is not observed any αλ-dependence was found.