Infrared Emission from AGN

Infrared observations of complete samples of active galactic nuclei (AGN) have shown that a substantial fraction of their bolometric luminosity is emitted at wavelengths ~8-1000microns. In radio-loud and Blazar-like objects much of this emission appears to be direct non-thermal synchrotron radiation. However, in the much larger numbers of radio-quiet AGN it is now clear that thermal dust emission is responsible for the bulk of radiation from the near-infrared through submillimeter wavelengths. Luminous infrared-selected AGN are often surrounded by powerful nuclear starbursts, both of which appear to be fueled by enormous supplies of molecular gas and dust funneled into the nuclear region during the strong interaction/merger of gas rich disks. All-sky surveys in the infrared show that luminous infrared AGN are at least as numerous as optically-selected AGN of comparable bolometric luminosity, suggesting that AGN may spend a substantial fraction of their lifetime in a dust-enshrouded phase. The space density of luminous infrared AGN at high redshift may be sufficient to account for much of the X-Ray background, and for a substantial fraction of the far-infrared background as well. These objects plausibly represent a major epoch in the formation of spheroids and massive black holes (MBH).Comment: LaTex, 13 pages with 6 embedded postscript figures. To appear in IAU 194, "Activity in Galaxies and Related Phenomena

New Results from a Near-Infrared Search for Hidden Broad-Line Regions in Ultraluminous Infrared Galaxies

This paper reports the latest results from a near-infrared search for hidden broad-line regions (BLRs: FWHM >~ 2,000 km/s) in ultraluminous infrared galaxies (ULIGs). The new sample contains thirty-nine ULIGs from the 1-Jy sample selected for their lack of BLRs at optical wavelengths. The results from this new study are combined with those from our previous optical and near-infrared surveys to derive the fraction of all ULIGs with optical or near-infrared signs of genuine AGN activity (either a BLR or [Si VI] emission). Comparisons of the dereddened emission-line luminosities of the optical or obscured BLRs detected in the ULIGs of the 1-Jy sample with those of optical quasars indicate that the obscured AGN/quasar in ULIGs is the main source of energy in at least 15 -- 25% of all ULIGs in the 1-Jy sample. This fraction is 30 -- 50% among ULIGs with L_ir > 10^{12.3} L_sun. These results are compatible with those from recent mid-infrared spectroscopic surveys carried out with ISO. (abridged)Comment: 40 pages including 10 figures and 3 tables (Table 3 should be printed in landscape mode

Carbon deposition model for oxygen-hydrocarbon combustion. Task 6: Data analysis and formulation of an empirical model

The formation and deposition of carbon (soot) was studied in the Carbon Deposition Model for Oxygen-Hydrocarbon Combustion Program. An empirical, 1-D model for predicting soot formation and deposition in LO2/hydrocarbon gas generators/preburners was derived. The experimental data required to anchor the model were identified and a test program to obtain the data was defined. In support of the model development, cold flow mixing experiments using a high injection density injector were performed. The purpose of this investigation was to advance the state-of-the-art in LO2/hydrocarbon gas generator design by developing a reliable engineering model of gas generator operation. The model was formulated to account for the influences of fluid dynamics, chemical kinetics, and gas generator hardware design on soot formation and deposition

Phylogenetic and functional analysis of the Cation Diffusion Facilitator (CDF) family: improved signature and prediction of substrate specificity

BACKGROUND The Cation Diffusion Facilitator (CDF) family is a ubiquitous family of heavy metal transporters. Much interest in this family has focused on implications for human health and bioremediation. In this work a broad phylogenetic study has been undertaken which, considered in the context of the functional characteristics of some fully characterised CDF transporters, has aimed at identifying molecular determinants of substrate selectivity and at suggesting metal specificity for newly identified CDF transporters. RESULTS Representative CDF members from all three kingdoms of life (Archaea, Eubacteria, Eukaryotes) were retrieved from genomic databases. Protein sequence alignment has allowed detection of a modified signature that can be used to identify new hypothetical CDF members. Phylogenetic reconstruction has classified the majority of CDF family members into three groups, each containing characterised members that share the same specificity towards the principally-transported metal, i.e. Zn, Fe/Zn or Mn. The metal selectivity of newly identified CDF transporters can be inferred by their position in one of these groups. The function of some conserved amino acids was assessed by site-directed mutagenesis in the poplar Zn2+ transporter PtdMTP1 and compared with similar experiments performed in prokaryotic members. An essential structural role can be assigned to a widely conserved glycine residue, while aspartate and histidine residues, highly conserved in putative transmembrane domains, might be involved in metal transport. The potential role of group-conserved amino acid residues in metal specificity is discussed. CONCLUSION In the present study phylogenetic and functional analyses have allowed the identification of three major substrate-specific CDF groups. The metal selectivity of newly identified CDF transporters can be inferred by their position in one of these groups. The modified signature sequence proposed in this work can be used to identify new hypothetical CDF members

Numerical methods and calculations for droplet flow, heating and ignition

A numerical method was devised and employed to solve a variety of problems related to liquid droplet combustion. The basic transport equations of mass, momentum and energy were formulated in terms of generalized nonorthogonal coordinates, which allows for adaptive griding and arbitrary particle shape. Example problems are solved for internal droplet heating, droplet ignition and high Reynolds number flow over a droplet

Outflows in Infrared-Luminous Starbursts at z < 0.5. II. Analysis and Discussion

We have performed an absorption-line survey of outflowing gas in 78 starburst-dominated, infrared-luminous galaxies. This is the largest study of superwinds at z < 3. Superwinds are found in almost all infrared-luminous galaxies, and changes in detection rate with SFR--winds are found twice as often in ultraluminous infrared galaxies (ULIRGs) as in less-luminous galaxies--reflect different wind geometries. The maximum velocities we measure are 600 km/s, though most of the outflowing gas has lower velocities (100-200 km/s). (One galaxy has velocities exceeding 1000 km/s.) Velocities in LINERs are higher than in HII galaxies, and outflowing ionized gas often has higher velocities than the neutral gas. Wind properties (velocity, mass, momentum, and energy) scale with galaxy properties (SFR, luminosity, and galaxy mass), consistent with ram-pressure driving of the wind. Wind properties increase strongly with increasing galactic mass, contrary to expectation. These correlations flatten at high SFR (> 10-100 M_sun/yr), luminosities, and masses. This saturation is due to a lack of gas remaining in the wind's path, a common neutral gas terminal velocity, and/or a decrease in the efficiency of thermalization of the supernovae energy. It means that mass entrainment efficiency, rather than remaining constant, declines in galaxies with SFR > 10 M_sun/yr and M_K < -24. Half of our sample consists of ULIRGs, which host as much as half of the star formation in the universe at z > 1. The powerful, ubiquitous winds we observe in these galaxies imply that superwinds in massive galaxies at redshifts above unity play an important role in the evolution of galaxies and the intergalactic medium.Comment: 68 pages, 20 figures in AASTeX preprint style; to appear in September issue of ApJS; Figure 17 replaced with correct versio

Unveiling The Sigma-Discrepancy II: Revisiting the Evolution of ULIRGs & The Origin of Quasars

We present the first central velocity dispersions (sigma_o) measured from the 0.85 micron Calcium II Triplet (CaT) for 8 advanced (i.e. single nuclei) local (z < 0.15) Ultraluminous Infrared Galaxies (ULIRGs). First, these measurements are used to test the prediction that the "sigma-Discrepancy," in which the CaT sigma_o is systematically larger than the sigma_o obtained from the 1.6 or 2.3 micron stellar CO band-heads, extends to ULIRG luminosities. Next, we combine the CaT data with rest-frame I-band photometry obtained from archival Hubble Space Telescope data and the Sloan Digital Sky Survey (SDSS) to derive dynamical properties for the 8 ULIRGs. These are then compared to the dynamical properties of 9,255 elliptical galaxies from the SDSS within the same redshift volume and of a relatively nearby (z < 0.4) sample of 53 QSO host galaxies. A comparison is also made between the I-band and H-band dynamical properties of the ULIRGs. We find four key results: 1) the sigma-Discrepancy extends to ULIRG luminosities; 2) at I-band ULIRGs lie on the Fundamental Plane (FP) in a region consistent with the most massive elliptical galaxies and not low-intermediate mass ellipticals as previously reported in the near-infrared; 3) the I-band M/L of ULIRGs are consistent with an old stellar population, while at H-band ULIRGs appear significantly younger and less massive; and 4) we derive an I-band Kormendy Relation from the SDSS ellipticals and demonstrate that ULIRGs and QSO host galaxies are dynamically similar.Comment: Accepted to The Astrophysical Journal. 6 Figures, 5 Tables, 4 Appendices. Version 2 changes: Corrects errors in Table 1 of Appendix C; and now formatted using ApJ emulat

An IRAS High Resolution Image Restoration (HIRES) Atlas of All Interacting Galaxies in the IRAS Revised Bright Galaxy Sample

We present high-resolution (30"-1') 12, 25, 60, and 100 micron images of 106 interacting galaxy systems contained in the IRAS Revised Bright Galaxy Sample (RBGS, Sanders et al. 2003), a complete sample of all galaxies having a 60 micron flux density greater than 5.24 Jy. These systems were selected to have at least two distinguishable galaxies separated by less than three average galactic diameters, and thus we have excluded very widely separated systems and very advanced mergers. The new complete survey has the same properties as the prototype survey of Surace et al. 1993. We find no increased tendency for infrared-bright galaxies to be associated with other infrared bright galaxies among the widely separated pairs studied here. We find small enhancements in far-infrared activity in multiple galaxy systems relative to RBGS non-interacting galaxies with the same blue luminosity distribution. We also find no differences in infrared activity (as measured by infrared color and luminosity) between late and early-type spiral galaxies.Comment: 49 pages, 13 figures. To appear in the Astronomical Journal. Figures have been degraded due to space considerations. A PDF version with higher quality figures is available at http://humu.ipac.caltech.edu/~jason/pubs/surace_hires.pd