This paper proposes a simple, empirically derived, unifying structure for the inner regions of quasars. This structure is constructed to explain the broad absorption line regions (BALRs) and the narrow "associated" ultraviolet and X-ray "ionized" absorbers (NALs) and is also found to explain the broad emission line regions (BELRs) and several scattering features, including a substantial fraction of the broad X-ray Fe-K emission line and the biconical extended narrow emission line region (ENLR) structures seen on large kiloparsec scales in Seyfert images. The model proposes that a funnel-shaped thin shell outflow creates all of these features. The wind arises vertically from a narrow range of radii on a disk at BELR velocities. Radiation force then accelerates the flow radially, so that it bends outward to a cone angle of ~60° and has a divergence angle of ~6°, to give a covering factor of ~10%. When the central continuum is viewed from the side, through this wind, narrow high-ionization "associated" ultraviolet absorption lines and the X-ray "ionized absorbers" are seen, as in many low-luminosity active galactic nuclei (AGNs). When viewed end-on, the full range of velocities is seen in absorption with a large total column density, giving rise to the broad absorption line systems seen in a minority of quasars, the BAL QSOs. The wind is both warm (~106 K) and highly ionized. This warm highly ionized medium (WHIM) has a density of ~109 cm-3, putting it in pressure equilibrium with the BELR clouds; the BELR is then a cool phase embedded in the overall outflow, avoiding cloud destruction through shear. The wind has the correct ionization parameter and filling factor for this. The high- and low-ionization zones of the BELR correspond to the cylindrical and conical regions of the wind, since the former is exposed to the full continuum while the latter receives only the continuum filtered by the former. The warm wind is significantly Thomson thick along the radial flow direction, producing the polarized optical continuum found in BALs, but is only partially ionized, creating a broad fluorescent 6.4 keV Fe-K emission line and greater than 10 keV Compton hump. The conical shell outflow can produce a biconical matter-bounded NELR. Luminosity-dependent changes in the structure, reducing the cylindrical part of the flow or increasing the mean angle to the disk axis and decreasing the wind opening angle, may explain the UV and X-ray Baldwin effects and the greater prevalence of obscuration in low-luminosity AGNs.

https://iopscience.iop.org/article/10.1086/317778/pdf

A Structure for Quasars

Spectrophotometric observations at high signal-to-noise ratio were obtained of a complete sample of 348 DA white dwarfs from the Palomar Green (PG) Survey. Fits of observed Balmer lines to synthetic spectra calculated from pure-hydrogen model atmospheres were used to obtain robust values of Teff, log g, masses, radii, and cooling ages. The luminosity function of the sample, weighted by 1/Vmax, was obtained and compared with other determinations. Incompleteness of the sample due to selection by photographic mu - mb color and magnitude limits was found to be a serious problem, and an attempt is made to correct for this. The mass distribution of the white dwarfs is derived, after important corrections for the radii of the white dwarfs in this magnitude-limited survey and for the cooling time scales. This distribution has (1) a "peak" component centered near 0.6 M⊙, (2) a low-mass component centered near 0.4 M⊙, and (3) a high-mass component above about 0.8 M⊙. The formation rate of DA white dwarfs from the PG is estimated to be 0.6 × 10-12 pc-3 yr-1. Of these, 75% are from the peak component, 10% from the low-mass component, and 15% from the high-mass component. The low-mass component requires binary evolution for 100% of the objects, with a degenerate companion likely in the majority of cases. Comparison with predictions from a theoretical study of the white dwarf formation rate for single stars indicates that ≥80% of the high-mass component requires a different origin, presumably mergers of lower mass double degenerate stars. The need for a binary channel may not be as great for the massive, very hot white dwarfs found in the EUV all-sky surveys. In an Appendix, we even suggest that an enhanced density of the massive white dwarfs at lower Galactic latitudes might be due to some of them being the progeny of B stars in Gould's Belt. In order to estimate the recent formation rate of all white dwarfs in the local Galactic disk, corrections for incompleteness of the PG, addition of the DB-DO white dwarfs, and allowance for stars hidden by luminous binary companions had to be applied to enhance the rate. An overall formation rate of white dwarfs recently in the local Galactic disk of (1 ± 0.25) × 10-12 pc-3 yr-1 is obtained. Admittedly, the systematic errors in this estimate are difficult to quantify. Two recent studies of samples of nearby Galactic planetary nebulae lead to estimates around twice as high. Difficulties in reconciling these determinations are discussed.

https://iopscience.iop.org/article/10.1086/425738/pdf

The Formation Rate and Mass and Luminosity Functions of DA White Dwarfs from the Palomar Green Survey

A catalog of 2249 white dwarfs which have been identified spectroscopically is presented complete through 1996 April. This compilation is the fourth edition of the Villanova Catalog of Spectroscopically Identified White Dwarfs. For each degenerate star, the following data entries with references are provided: (1) a catalog coordinate designation or WD number, in order of right ascension; (2) the right ascension and declination for epoch 1950.0; (3) the spectral type based upon the new system; (4) a catalog symbol denoting binary membership; (5) a list of most names known to exist for a given star; (6) proper motion and position angle; (7) broadband UBV photometry, V, B-V, U-B; (8) multichannel spectrophotometry, v(MC), g-r; (9) Stromgren narrowband photometry, y, b-y, u-b; (10) an absolute visual magnitude based upon the best available color-magnitude calibration or trigonometric parallax; (11) the observed radial velocity uncorrected for gravitational redshift or solar motion; and (12) the trigonometric parallax with mean error when available. Notes for unusual or peculiar stars and a coded Reference Key alphabetized by the first author's last name are presented, as well as an expanded table cross-referencing all names to the catalog WD number. An introduction and full descriptions of the entries are provided in the text.

/pdf/a-catalog-of-spectroscopically-identified-white-dwarfs-4n7mqjl4cc.pdf

A Catalog of Spectroscopically Identified White Dwarfs

▪ Abstract Broad emission lines hold fundamental clues about the kinematics and structure of the central regions in AGN. In this article we review the most robust line profile properties and correlations emerging from the best data available. We identify fundamental differences between the profiles of radio-quiet and radio-loud sources as well as differences between the high- and low-ionization lines, especially in the radio-quiet majority of AGN. An Eigenvector 1 correlation space involving FWHM Hβ, W(FeIIopt)/W(Hβ), and the soft X-ray spectral index provides optimal discrimination between all principal AGN types (from narrow-line Seyfert 1 to radio galaxies). Both optical and radio continuum luminosities appear to be uncorrelated with the E1 parameters. We identify two populations of radio-quiet AGN: Population A sources (with FWHM(Hβ) 4000 km s−1, generally strong FeII emission and a soft X-ray excess) show almost no parameter space overlap with radio-loud sources. Population B shows optical properties...

Phenomenology of Broad Emission Lines in Active Galactic Nuclei

Starburst-driven galactic winds are responsible for the transport of mass, in particular metal-enriched gas, and energy out of galaxies and into the intergalactic medium. These outflows directly affect the chemical evolution of galaxies, and heat and enrich the intergalactic and intercluster medium.



Currently, several basic problems preclude quantitative measurements of the impact of galactic winds: the unknown filling factors of, in particular, the soft X-ray-emitting gas prevent accurate measurements of densities, masses and energy content; multiphase temperature distributions of unknown complexity bias X-ray-determined abundances; unknown amounts of energy and mass may reside in hard to observe T∼105 K and T∼107.5 K phases; and the relative balance of thermal versus kinetic energy in galactic winds is not known.



In an effort to address these problems, we perform an extensive hydrodynamical parameter study of starburst-driven galactic winds, motivated by the latest observation data on the best-studied starburst galaxy M82. We study how the wind dynamics, morphology and X-ray emission depend on the ISM distribution of the host galaxy, the starburst star formation history and strength, and the presence and distribution of mass-loading by dense clouds. We also investigate and discuss the influence of finite numerical resolution on the results of these simulations.



We find that the soft X-ray emission from galactic winds comes from low filling factor (η≲2 per cent) gas, which contains only a small fraction (≲10 per cent) of the mass and energy of the wind, irrespective of whether the wind models are strongly mass-loaded or not. X-ray observations of galactic winds do not directly probe the gas that contains the majority of the energy, mass or metal-enriched gas in the outflow.



X-ray emission comes from a complex phase-continuum of gas, covering a wide range of different temperatures and densities. No distinct phases, as are commonly assumed when fitting X-ray spectra, are seen in our models. Estimates of the properties of the hot gas in starburst galaxies based on fitting simple spectral models to existing X-ray spectra should be treated with extreme suspicion.



The majority of the thermal and kinetic energy of these winds is in a volume-filling hot, T∼107 K, component which is extremely difficult to probe observationally because of its low density and hence low emissivity. Most of the total energy is in the kinetic energy of this hot gas, a factor that must be taken into account when attempting to constrain wind energetics observationally. We also find that galactic winds are efficient at transporting large amounts of energy out of the host galaxy, in contrast to their inefficiency at transporting mass out of star-forming galaxies.

/pdf/starburst-driven-galactic-winds-i-energetics-and-intrinsic-x-4l0pmruwnm.pdf

Starburst-driven galactic winds — I. Energetics and intrinsic X-ray emission

Les observations polarimetriques optiques d'un ensemble, complet jusqu'a la magnitude B = 16.2, de 114 quasars du Palomar-Green Bright Quasar Survey sont presentees. La distribution et la variabilite de la polarisation sont analysees.

An Optical Polarization Survey of the Palomar-Green Bright Quasar Sample

The discovery and study of a PG white dwarf which shows strong linear and circular polarization modulated with a rotation period of 3 hr 24 min is reported. The new star, PG 1031 + 234, is more highly magnetic than even Grw +70 deg 8247, with absorption components of hydrogen in its optical and UV spectra corresponding to fields from 200 to more than 500 MG. An asymmetric dependence of polarization on rotational phase shows that the surface field structure on the star is more complex than a simple centered dipole. The basic observational features can be well reproduced by a rotating star containing an oblique centered dipole punctuated near its magnetic equator by a high-field spot containing primarily radial field lines.

The new magnetic white dwarf PG 1031 + 234 - Polarization and field structure at more than 500 milion Gauss

We present spectra of the optical transient (OT) associated with GRB 021004. The spectra show a blue continuum with superposed absorption features and one emission line. We confirm two intervening metal-line systems at z = 1.380 and z = 1.602 and one very strong absorption system at a redshift of z = 2.323. Lyα emission is also seen at this redshift. While the spectrum of the OT overall cannot be simply described with a power law, the spectral index over the range 5500-8850 A is steep, Fν ∝ ν-0.96±0.03. Comparison of spectra from multiple epochs shows a distinct color evolution with the OT becoming redder with time over the first 3 days. This is the first clear example of color change in an OT detected spectroscopically.

The spectroscopic variability of GRB 021004

About 12 hrs of polarimetric data on BL Lacertae obtained on three nights in 1983-1984 are presented, and potential error sources are assessed. Polarimetric variations are continually present and detected on time scales from hours to as short as 30 minutes; a particularly well-defined event is identified and discussed in detail. Variations at frequencies greater than 1/15 minutes are below the measurement errors and therefore must be very weak. The power spectra of variations in both polarization and position angle are dominated by low frequencies and can be roughly characterized by power laws with spectral index three over periods of 15 minutes to three hours. Position-angle variations appear smoother than those of the degree of polarization. 13 references.

The hiss of BL Lacertae

BG cMi est la seule polaire intermediaire connue pour etre magnetique. De nouvelles observations revelent que la dependance en longueur d'onde de sa polarisation circulaire augmente rapidement dans l'IR, de V 1 =−0,25%±0,06% dans le rouge optique, jusqu'a V J =−1,74%±0,26% a 1,25 μm

Steven C. West

Papers

An Optical Polarization Survey of the Palomar-Green Bright Quasar Sample

The new magnetic white dwarf PG 1031 + 234 - Polarization and field structure at more than 500 milion Gauss

The spectroscopic variability of GRB 021004

The hiss of BL Lacertae

The discovery of near-infrared polarized cyclotron emission in the intermediate polar BG Canis Minoris