15380121
A Puzzling X-Ray Source Found in the Chandra Deep Field-South
In this Letter, we report the detection of an extremely strong X-ray emission line in the 940 ks Chandra ACIS-I spectrum of CXOCDFS J033225.3-274219. The source was identified as a type 1 active galactic nucleus at a redshift of z = 1.617, with a 2.0-10.0 keV rest-frame X-ray luminosity of ~1044 ergs s-1. The emission line was detected at 6.2 keV, with an equivalent width (EW) of 4.4 keV; both quantities refer to the observed frame. In the rest frame, the line is at 16.2 keV with an EW of 11.5 keV. An X-ray emission line at a similar energy (~17 keV, in the rest frame) in PKS 2149-306 was discovered before using ASCA data. We reject the possibility that the line is due to a statistical or instrumental artifact. The line is most likely due to blueshifted Fe K emission from an relativistic outflow, probably an inner X-ray jet, with velocities of the order of ~0.6c-0.7c. Other possible explanations are also discussed.
119360994
The 172 ks Chandra Exposure of the LALA Bootes Field: X-Ray Source Catalog
We present an analysis of a deep, 172 ks Chandra observation of the Large Area Lyman Alpha survey (LALA) Bootes field, obtained with the Advanced CCD Imaging Spectrometer (ACIS-I) on board the Chandra X-Ray Observatory. This is one of the deepest Chandra images of the extragalactic sky; only the 2 Ms Chandra Deep Field North (CDF-N) and 1 Ms Chandra Deep Field South (CDF-S) are substantially deeper. In this paper we present the X-ray source catalog obtained from this image, along with an analysis of source counts and optical identifications. The X-ray image is composed of two individual observations obtained in 2002 and reaches 0.5–2.0 and 2.0–10.0 keV flux limits of 1.5 × 10-16 and 1.0 × 10-15 ergs cm-2 s-1, respectively, for point sources near the aim point. A total of 168 X-ray sources were detected: 160 in the 0.5–7.0 keV band, 132 in the 0.5–2.0 keV band, and 111 in the 2.0–7.0 keV band. The X-ray source counts were derived and compared with those from other Chandra deep surveys; the hard X-ray source density of the LALA Bootes field is 33% higher than that of CDF-S at the flux level of 2.0 × 10-15 ergs cm-2 s-1, confirming the field-to-field variances of the hard-band source counts reported by previous studies. The deep exposure resolves 72% of the 2.0–10.0 keV X-ray background. Our primary optical data are R-band imaging from the NOAO Deep Wide-Field Survey (NDWFS), with a limiting magnitude of R = 25.7 (Vega, 3 σ, and 4'' diameter aperture). We have found optical counterparts for 152 of the 168 Chandra sources (90%); 144 of these are detected in the R-band image, and eight have optical counterparts in other bands (either BW, V, I, or z'). Among the R-band nondetected sources, not more than 11 of them can possibly be at z > 5, based on the hardness ratios of their X-ray emission and nondetections in bluer bands (BW, V). The majority (~76%) of the X-ray sources are found to have log(fX/fR) within 0.0 ± 1; these are believed to be AGNs. Most of the X-ray–faint/optically bright sources [log(fX/fR) 1.0], which are harder in X-ray and are probably obscured AGNs.
121240830
Relation between Starlight and Nebular Emission Lines of Star-Forming Galaxies
We present an exercise that intends to establish a relationship between the strength of nebular emission lines and optical stellar features in the spectrum of a galaxy. After accurately subtracting the stellar continuum and the underlying stellar absorption, we made reliable measurements of the emission lines of all the galaxies in the Sloan Digital Sky Survey Data Release 2 (SDSS DR2). More than 4000 star-forming galaxies with high S/N ratio of both the stellar spectrum and the emission lines are selected. These galaxy spectra are fitted with the 10 PCs of Yip et al., after all the emission line regions have been filtered out. We find that the flux of hydrogen Balmer emission lines, H α and H β can be well recovered from the PCs, while the metal lines are not well reproduced. The fluxes of H α and H β measured from the PC-reconstructed spectra and from the observed spectra agree well with an rms scatter of only ~0.1 dex. This result suggests that, with moderate spectral resolution and S/N ratio, the optical stellar spectrum of a galaxy can serve as an indicator of star formation rate.
16103411
Partially obscured quasars in the Sloan Digital Sky Survey Early Data Release
We have compiled a sample of 21 low redshift (z . 0.3), luminous active galactic nuclei (AGN) with large Balmer decrements (Hα/Hβ > 7) using the galaxy and QSO catalogs of the Sloan Digital Sky Survey Early Data Release. Using this sample we attempt to determine the fraction of quasars with large internal absorption. We find that these AGN have Strong [O III] λ5007 and broad Hα emission, and that starlight dominates the spectra in the blue band, suggesting that these objects are heavily reddened. Their narrow emission line ratios are similar to those of Seyfert 2 galaxies, yet the average [O III] λ5007 emission is ∼10 times more luminous. Applying the empirical relation between the optical continuum and the Balmer line luminosity for blue quasars, we find that the intrinsic luminosities of these 21 objects are in the range for quasars. We propose that they are obscured, intermediate type quasars analogous to type 1.8 and 1.9 Seyfert galaxies. The ratio of these optically selected, intermediate type quasars to type 1 quasars are found to be around 1, similar to that for local Seyfert galaxies. Preliminary study indicates that most of these quasars are hosted in early type galaxies. Subject headings: galaxies: active — quasars: general — galaxies: nuclei
119329374
Polarization of Quasars: Rotated and Funnel-shaped Outflow
Polarization is a useful probe to investigate the geometries and dynamics of outflow in BAL QSOs. We perform a Monte-Carlo simulation to calculate the polarization produced by resonant and electron scattering in BALR. We find: 1)A rotated and funnel-shaped outflow is preferred to explain many observed polarization features. 2)The resonant scattering can contribute a significant part of NV emission line in some QSOs.
13062064
Polar outflows in six broad absorption line quasars
Using radio observations by FIRST and NVSS, we build a sample of 151 radio-variable quasars selected from the Sloan Digital Sky Survey Data Release 3 (SDSS DR3). Six (and probably another two) of these objects are classified as broad absorption line (BAL) quasars and show radio flux variations of a few tens of percent within 1.5-5 yr. Such large amplitudes of variations imply brightness temperatures much higher than the inverse Compton limits (10(12) K) in all these BAL quasars, suggesting the presence of relativistic jets beaming toward the observer. The angles between the outflow and the jet are constrained to be less than similar to 20 degrees. Such BAL quasars with polar outflows are beyond the simple unification models of BAL and non-BAL quasars, which hypothesize BAL quasars as otherwise normal quasars seen nearly edge-on.
119266124
A DEEP CHANDRA ACIS STUDY OF NGC 4151. I. THE X-RAY MORPHOLOGY OF THE 3 kpc DIAMETER CIRCUM-NUCLEAR REGION AND RELATION TO THE COLD INTERSTELLAR MEDIUM
We report on the imaging analysis of ~200 ks sub-arcsecond resolution Chandra Advanced CCD Imaging Spectrometer (ACIS-S) observations of the nearby Seyfert 1 galaxy NGC 4151. Bright, structured soft X-ray emission is observed to extend from 30 pc to 1.3 kpc in the southwest from the nucleus, much farther than seen in earlier X-ray studies. The terminus of the northeastern X-ray emission is spatially coincident with a CO gas lane, where the outflow likely encounters dense gas in the host galactic disk. X-ray emission is also detected outside the boundaries of the ionization cone, which indicates that the gas there is not completely shielded from the nuclear continuum, as would be the case for a molecular torus collimating the bicone. In the central r < 200 pc region, the subpixel processing of the ACIS data recovers the morphological details on scales of <30 pc (<05) first discovered in Chandra High Resolution Camera images. The X-ray emission is more absorbed toward the boundaries of the ionization cone, as well as perpendicular to the bicone along the direction of a putative torus in NGC 4151. The innermost region where X-ray emission shows the highest hardness ratio is spatially coincident with the near-infrared-resolved H2 emission and dusty spirals we find in an Hubble Space Telescope V – H color image. The agreement between the observed H2 line flux and the value predicted from X-ray-irradiated molecular cloud models supports photo-excitation by X-rays from the active nucleus as the origin of the H2 line, although contribution from UV fluorescence or collisional excitation cannot be ruled out with current data. The discrepancy between the mass of cold molecular gas inferred from recent CO and near-infrared H2 observations may be explained by the anomalous CO abundance in this X-ray-dominated region. The total H2 mass derived from the X-ray observation agrees with the recent measurement by Storchi-Bergmann et al.
11113279
Dynamical electroweak breaking and latticized extra dimensions
Using gauge invariant effective Lagrangians in 1+3 dimensions describing the Standard Model in 1+4 dimensions, we explore dynamical electroweak symmetry breaking. The Top Quark Seesaw model arises naturally, as well as the full CKM structure. We include a discussion of effects of warping, and indicate how other dynamical schemes may also be realized.
119307857
Determination of the Topology Skeleton of Magnetic Fields in a Solar Active Region
Magnetic topology has been a key to the understanding of magnetic energy release mechanism. Based on observed vector magnetograms, we have determined the three-dimensional (3D) topology skeleton of the magnetic fields in the active region NOAA 10720. The skeleton consists of six 3D magnetic nulls and a network of corresponding spines, fans, and null-null lines. For the first time, we have identified a spiral magnetic null in Sun's corona. The magnetic lines of force twisted around the spine of the null, forming a `magnetic wreath' with excess of free magnetic energy and resembling observed brightening structures at extra-ultraviolet (EUV) wavebands. We found clear evidence of topology eruptions which are referred to as catastrophic changes of topology skeleton associated with a coronal mass ejection (CME) and an explosive X-ray flare. These results shed new lights on the structural complexity and its role in explosive magnetic activity. The concept of flux rope has been widely used in modelling explosive magnetic activity, although their observational identity is rather obscure or, at least, lacking of necessary details up to date. We suggest that the magnetic wreath associated with the 3D spiral null is likely an important class of the physical entity of flux ropes.
106635092
Fabrication Studies for a Cylindrical DDS Structure at 90 GHz
A natural extension of work on the next generation of high power RF sources and accelerating cavities for Linear Colliders implies cylindrical, damped, detuned structures for millimeter wavelengths. Commercial availability of WR-10 waveguides and other components in the 75-110 GHz range provides a practical goal. Fabrication methods are surveyed, compared and, in some cases, tested to determine whether they can provide the imposed tolerances. Different techniques and tolerances are compared to previous methods at longer wavelengths. The higher gradients and corresponding surface fields indicate that a better understanding of the surface physics is required as well as how the different fabrication steps influence those surface characteristics that impact the final operation. We consider existing systems at SLAC and elsewhere as a function of frequency to determine what is desirable to measure and control for all phases of the fabrication, testing, conditioning and use of these systems. For example, the importance of crystal structure to the different steps is discussed. The preferred method allows a variety of design alternatives to be pursued simultaneously and extends to shorter wavelengths as well as provides possibilities for embedded test and control elements.
119645806
Chandra X-Ray Sources in the LALA Cetus Field*
The 174 ks Chandra Advanced CCD Imaging Spectrometer exposure of the Large Area Lyman Alpha Survey (LALA) Cetus field is the second of the two deep Chandra images on LALA fields. In this paper we present the Chandra X-ray sources detected in the Cetus field, along with an analysis of X-ray source counts, stacked X-ray spectrum, and optical identifications. A total of 188 X-ray sources were detected: 174 in the 0.5-7.0 keV band, 154 in the 0.5-2.0 keV band, and 113 in the 2.0-7.0 keV band. The X-ray source counts were derived and compared with LALA field (172 ks exposure). Interestingly, we find consistent hard-band X-ray source density, but (36 ± 12)% higher soft-band X-ray source density in Cetus field. The weighted stacked spectrum of the detected X-ray sources can be fitted by a power law with photon index Γ = 1.55. Based on the weighted stacked spectrum, we find that the resolved fraction of the X-ray background drops from (72 ± 1)% at 0.5-1.0 keV to (63 ± 4)% at 6.0-8.0 keV. The unresolved spectrum can be fitted by a power law over the range 0.5-7 keV, with a photon index Γ = 1.22. We also present optical counterparts for 154 of the X-ray sources, down to a limiting magnitude of r' = 25.9 (Vega), using a deep r'-band image obtained with the MMT.