Testing diagnostics of nuclear activity and star formation in galaxies at z > 1

We present some of the first science data with the new Keck/MOSFIRE instrument to test the effectiveness of different AGN/SF diagnostics at z ~ 1.5. MOSFIRE spectra were obtained in three H-band multi-slit masks in the GOODS-S field, resulting in 2 hr exposures of 36 emission-line galaxies. We compare X-ray data with the traditional emission-line ratio diagnostics and the alternative mass-excitation and color-excitation diagrams, combining new MOSFIRE infrared data with previous HST/WFC3 infrared spectra (from the 3D-HST survey) and multiwavelength photometry. We demonstrate that a high [O III]/Hβ ratio is insufficient as an active galactic nucleus (AGN) indicator at z > 1. For the four X-ray-detected galaxies, the classic diagnostics ([O III]/Hβ versus [N II]/Hα and [S II]/Hα) remain consistent with X-ray AGN/SF classification. The X-ray data also suggest that "composite" galaxies (with intermediate AGN/SF classification) host bona fide AGNs. Nearly ~2/3 of the z ~ 1.5 emission-line galaxies have nuclear activity detected by either X-rays or the classic diagnostics. Compared to the X-ray and line ratio classifications, the mass-excitation method remains effective at z > 1, but we show that the color-excitation method requires a new calibration to successfully identify AGNs at these redshifts.

Polymer Fluid Dynamics: Continuum and Molecular Appoaches

To solve problems in polymer fluid dynamics, one needs the equation of continuity, motion, and energy. The last two equations contain the stress tensor and the heat-flux vector for the material. There are two ways to formulate the stress tensor: (1) one can write a continuum expression for the stress tensor in terms of kinematic tensors, or (2) one can select a molecular model that represents the polymer molecule, and then develop an expression for the stress tensor from kinetic theory. The advantage of the kinetic theory approach is that one gets information about the relation between the molecular structure of the polymers and the rheological properties. In this review, we restrict the discussion primarily to the simplest stress tensor expressions or “constitutive equations” containing from two to four adjustable parameters, although we do indicate how these formulations may be extended to give more complicated expressions. We also explore how these simplest expressions are recovered as special cases of a more general framework, the Oldroyd 8-constant model. The virtue of studying the simplest models is that we can discover some general notions as to which types of empiricisms or which types of molecular models seem to be worth investigating further. We also explore equivalences between continuum and molecular approaches. We restrict the discussion to several types of simple flows, such as shearing flows and extensional flows. These are the flows that are of greatest importance in industrial operations. Furthermore, if these simple flows cannot be well described by continuum or molecular models, then it is not necessary to lavish time and energy to apply them to more complex flow problems.

The differential evolution of hot- and cold-dust in galaxies in the last 7.5 GYR

Tese de mestrado em Física, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2016

An Agricultural continuum : a descriptive study of the farmworker population and the settling-out process : based on information collected under Contract no. HEW-OS-72-217.

"Jointly funded by the Department of Health, Education & Welfare and the Office of Economic Opportunity."

A new continuum model for traffic flow. Final report.

Transportation Department, Office of University Research, Washington, D.C.

A new continuum model for traffic flow /

"Final report under contract DOT-RD-82018."

Rural-urban continuum codes for metro and nonmetro counties /

"April 1990"--P. iii.

The ALMACA continuum of services : alcohol and drug abuse in the workplace.

Shipping list no.: 87-243-P.

The complex broad-band X-ray spectra of Seyfert galaxies /

Cover: Laboratory for High Energy Astrophysics.

Training continuum for civil service employees : a guide to training and professional development.

Shipping list no.: 2004-0121-P.

ATCA HI observations of the peculiar galaxy IC 2554

ATCA H I and radio continuum observations of the peculiar southern galaxy IC 2554 and its surroundings reveal typical signatures of an interacting galaxy group. We detected a large H I cloud between IC 2554 and the elliptical galaxy NGC 3136B. The gas dynamics in IC 2554 itself, which is sometimes described as a colliding pair, are surprisingly regular, whereas NGC 3136B was not detected. The H I cloud, which emerges from IC 2554 as a large arc-shaped plume, has a size of similar to30 kpc, larger than that of IC 2554. The total H I mass of the IC 2554 system is similar to2 x 10(9) M., one-third of which resides in the H I cloud. It is possible that tidal interaction between IC 2554 and NGC 3136B caused this spectacular H I cloud, but the possibility of IC 2554 being a merger remnant is also discussed. We also detected H I gas in the nearby galaxies ESO 092-G009 and RKK 1959 and an associated H I cloud, ATCA J1006-6710. Together they have an H I mass of similar to4.6 x 10(8) M-.. Another new H I source, ATCA J1007-6659, with an H I mass of only similar to2.2 x 10(7) M. was detected roughly between IC 2554 and ESO 092-G009 and corresponds to a face-on low surface brightness dwarf galaxy. Star formation is evident only in the galaxy IC 2554 with a rate of similar to4 M. yr(-1).

Galaxy threshing and the origin of ultra-compact dwarf galaxies in the Fornax cluster

A recent all-object spectroscopic survey centred on the Fornax cluster of galaxies has discovered a population of subluminous and extremely compact members, called 'ultra-compact dwarf' (UCD) galaxies. In order to clarify the origin of these objects, we have used self-consistent numerical simulations to study the dynamical evolution a nucleated dwarf galaxy would undergo if orbiting the centre of the Fornax cluster and suffering from its strong tidal gravitational field. We find that the outer stellar components of a nucleated dwarf are removed by the strong tidal field of the cluster, whereas the nucleus manages to survive as a result of its initially compact nature. The developed naked nucleus is found to have physical properties (e. g. size and mass) similar to those observed for UCDs. We also find that although this formation process does not have a strong dependence on the initial total luminosity of the nucleated dwarf, it does depend on the radial density profile of the dark halo in the sense that UCDs are less likely to be formed from dwarfs embedded in dark matter haloes with central 'cuspy' density profiles. Our simulations also suggest that very massive and compact stellar systems can be rapidly and efficiently formed in the central regions of dwarfs through the merging of smaller star clusters. We provide some theoretical predictions on the total number and radial number density profile of UCDs in a cluster and their dependencies on cluster masses.

The surface brightness and colour-magnitude relations for Fornax cluster galaxies

We present BVI photometry of 190 galaxies in the central 4 x 3 deg(2) region of the Fornax cluster observed with the Michigan Curtis Schmidt Telescope. Results from the Fornax Cluster Spectroscopic Survey (FCSS) and the Flair-II Fornax Surveys have been used to confirm the membership status of galaxies in the Fornax Cluster Catalogue (FCC). In our catalogue of 213 member galaxies, 92 (43 per cent) have confirmed radial velocities. In this paper, we investigate the surface brightness-magnitude relation for Fornax cluster galaxies. Particular attention is given to the sample of cluster dwarfs and the newly discovered ultracompact dwarf galaxies (UCDs) from the FCSS. We examine the reliability of the surface brightness-magnitude relation as a method for determining cluster membership and find that at surface brightnesses fainter than 22 mag arcsec(-2), it fails in its ability to distinguish between cluster members and barely resolved background galaxies. Cluster members exhibit a strong surface brightness-magnitude relation. Both elliptical (E) galaxies and dwarf elliptical (dE) galaxies increase in surface brightness as luminosity decreases. The UCDs lie off the locus of the relation. B-V and V-I colours are determined for a sample of 113 cluster galaxies and the colour-magnitude relation is explored for each morphological type. The UCDs lie off the locus of the colour-magnitude relation. Their mean V - I colours (similar to1.09) are similar to those of globular clusters associated with NGC 1399. The location of the UCDs on both surface brightness and colour-magnitude plots supports the 'galaxy threshing' model for infalling nucleated dwarf elliptical (dE, N) galaxies.

The 1000 brightest hipass galaxies: The H I mass function and Omega(H I)

We present a new, accurate measurement of the H I mass function of galaxies from the HIPASS Bright Galaxy Catalog, a sample of 1000 galaxies with the highest H I peak flux densities in the southern (delta