Studies on the molluscan and fish hosts of the "salmon poisoning" fluke, Nanophyetus salmincola (Chapin)

This study¹ was undertaken: (1) to obtain information on the distribution of the snail, Oxytrema silicula, in three coastal rivers in Oregon, and the seasonal incidence of infection in these snails and in snails from an inland stream, with the cercariae of the trematode, Nanophyetus salinincola; (2) to follow cercarial development in the snail under natural and experimental conditi is; (3) to determine the species of animals naturally infected with the metacercariae and those susceptible to experimental infection; and (4) to follow development of the metacercariae in the fish hosts. The snail was found widely distributed in the Alsea, Siletz, and Yaquina Rivers both in fresh and brackish water, Salinities in the brackish water areas were as. high as 11.2 parts per thousand. Large snails were observed in all rivers during each season of the year. The incidence of infection with N. salmincola was highest in snails with aperture diameters from 10 to 1.3 mm, and varied from 27 percent in snails from the Alsea River to 29 percent in snails from the Siletz, and Yaquina Rivers. Thirty-five percent of snails from Oak Creek, a stream near Corvallis, were found infected with cercariae of N. salmincola. There was no apparent change in the intensity of infection in the snails during the study period. Immature, but not mature, cercariae of N. salmincola were found in snails during the months of December through March. Identity of these cercariae as N. salmincola was shown by holding infected snails at room temperature for 15 days. At the end of this time 90 percent of the snails infected with N. salmincola contained mature cercariae. Mature cercariae were noted in snails during the months of April through November. The kidneys from 116 of 152 ocean-caught coho salmon, Oncorhynchus kisutch, and from 11 of 1.5 ocean-caught chinook salmon, O. tshawytscha, were found infected with 1 to 2400 metacercariae of N. salmincola. A dog fed two of these kidneys developed "salmon poisoning" disease. These results demonstrated for the first time that salinity was without any "cleansing" effect on either the trematode or the etiologic agent, though this effect was previously believed to occur. The fishes Cottus perplexus, Lampetra richardsoni, L. tridentata, and Richardsonius balteatus, and the Pacific giant salamander, Dicamptodon ensatus, all from western Oregon streams, were found naturally infected with the metacerariae of N. saimincola. This is the first report of natural infections in an animal other than a fish and in nonsalmonid fishes. Fourteen species of fishes were experimentally infected: Salmo gairdneri, S. salar, S. trutta, Salvelinus fontinalis, S. namaycush, L. richardsoni, C. perplexus, Carassius auratus, R. balteatus, Catostomus macrocheilus, Lepomis macrochirus, Gasterosteus a. aculeatus, G. a. microcephalus, and Gambusia affinis. This extends the number of salmonid and nonsalmonid fishes susceptible to experimental infection. Cysts from all five of the naturally infected animals and from 12 of the 14 experimentally infected fishes were given to hamsters by stomach tube. The identification of the parasites as N. salmincola was confirmed by recovery of adult flukes from the hamsters in all instances. except one (probably because of low dosage). Metacercariae from 1 to 106 days old from the experimentally infected fishes, and from naturally infected animals were studied. The stylet was absent in rnetacerariae approximately 50 days and older. The excretory bladder was always filled with round granules in metacercaniae 15 days and older. The diameter of the cyst and thickness of the cyst wall increased with age of the parasite

Unbiased Cosmological Parameter Estimation from Emission Line Surveys with Interlopers

The galaxy catalogs generated from low-resolution emission line surveys often contain both foreground and background interlopers due to line misidentification, which can bias the cosmological parameter estimation. In this paper, we present a method for correcting the interloper bias by using the joint-analysis of auto- and cross-power spectra of the main and the interloper samples. In particular, we can measure the interloper fractions from the cross-correlation between the interlopers and survey galaxies, because the true cross-correlation must be negligibly small. The estimated interloper fractions, in turn, remove the interloper bias in the cosmological parameter estimation. For example, in the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) low-redshift ($z<0.5$) [O II] $\lambda3727${\AA} emitters contaminate high-redshift ($1.9<z<3.5$) Lyman-$\alpha$ line emitters. We demonstrate that the joint-analysis method yields a high signal-to-noise ratio measurement of the interloper fractions while only marginally increasing the uncertainties in the cosmological parameters relative to the case without interlopers. We also show the same is true for the high-latitude spectroscopic survey of Wide-Field Infrared Survey Telescope (WFIRST) mission where contamination occurs between the Balmer-$\alpha$ line emitters at lower redshifts ($1.1<z<1.9$) and Oxygen ([O III] $\lambda5007${\AA}) line emitters at higher redshifts ($1.7<z<2.8$).Comment: 36 pages, 26 figure

A Stellar Dynamical Measurement of the Black Hole Mass in the Maser Galaxy NGC 4258

We determine the mass of the black hole at the center of the spiral galaxy NGC 4258 by constructing axisymmetric dynamical models of the galaxy. These models are constrained by high spatial resolution imaging and long-slit spectroscopy of the nuclear region obtained with the {\em Hubble Space Telescope}, complemented by ground-based observations extending to larger radii. Our best mass estimate is \MBH = (3.3 \pm 0.2) \times 10^7 \MSun for a distance of 7.28 Mpc (statistical errors only). This is within 15% of (3.82\pm 0.01) \times 10^7 \MSun, the mass determined from the kinematics of water masers (rescaled to the same distance) assuming they are in Keplerian rotation in a warped disk. The construction of accurate dynamical models of NGC 4258 is somewhat compromised by an unresolved active nucleus and color gradients, the latter caused by variations in the stellar population and/or obscuring dust. These problems are not present in the $\sim 30$ other black hole mass determinations from stellar dynamics that have been published by us and other groups; thus, the relatively close agreement between the stellar dynamical mass and the maser mass in NGC 4258 enhances our confidence in the black hole masses determined in other galaxies from stellar dynamics using similar methods and data of comparable quality.Comment: 58 pages, submitted to ApJ. Some figures excluded due to size. The entire paper is at http://www.noao.edu/noao/staff/lauer/nuker_papers.htm

The Black Hole Mass and Extreme Orbital Structure in NGC1399

The largest galaxies, and in particular central galaxies in clusters, offer unique insight into understanding the mechanism for the growth of nuclear black holes. We present Hubble Space Telescope kinematics for NGC1399, the central galaxy in Fornax. We find the best-fit model contains a black hole of 5.1 +-0.7 x 10^8 Msun (at a distance of 21.1 Mpc), a factor of over 2 below the correlation of black hole mass and velocity dispersion. We also find a dramatic signature for central tangential anisotropy. The velocity profiles on adjacent sides 0.5" away from the nucleus show strong bimodality, and the central spectrum shows a large drop in the dispersion. Both of these observations point to an orbital distribution that is tangentially biased. The best-fit orbital model suggests a ratio of the tangential to radial internal velocity dispersions of three. This ratio is the largest seen in any galaxy to date and will provide an important measure for the mode by which the central black hole has grown.Comment: 9 pages, accepted for publication in the Astrophysical Journa

Dwarf Galaxy Dark Matter Density Profiles Inferred from Stellar and Gas Kinematics

We present new constraints on the density profiles of dark matter (DM) halos in seven nearby dwarf galaxies from measurements of their integrated stellar light and gas kinematics. The gas kinematics of low mass galaxies frequently suggest that they contain constant density DM cores, while N-body simulations instead predict a cuspy profile. We present a data set of high resolution integral field spectroscopy on seven galaxies and measure the stellar and gas kinematics simultaneously. Using Jeans modeling on our full sample, we examine whether gas kinematics in general produce shallower density profiles than are derived from the stars. Although 2/7 galaxies show some localized differences in their rotation curves between the two tracers, estimates of the central logarithmic slope of the DM density profile, gamma, are generally robust. The mean and standard deviation of the logarithmic slope for the population are gamma=0.67+/-0.10 when measured in the stars and gamma=0.58+/-0.24 when measured in the gas. We also find that the halos are not under concentrated at the radii of half their maximum velocities. Finally, we search for correlations of the DM density profile with stellar velocity anisotropy and other baryonic properties. Two popular mechanisms to explain cored DM halos are an exotic DM component or feedback models that strongly couple the energy of supernovae into repeatedly driving out gas and dynamically heating the DM halos. We investigate correlations that may eventually be used to test models. We do not find a secondary parameter that strongly correlates with the central DM density slope, but we do find some weak correlations. Determining the importance of these correlations will require further model developments and larger observational samples. (Abridged)Comment: 29 pages, 18 figures, 10 tables, accepted for publication in Ap

The VIRUS-P Exploration of Nearby Galaxies (VENGA): Survey Design and First Results

VENGA is a large-scale extragalactic IFU survey, which maps the bulges, bars and large parts of the outer disks of 32 nearby normal spiral galaxies. The targets are chosen to span a wide range in Hubble types, star formation activities, morphologies, and inclinations, at the same time of having vast available multi-wavelength coverage from the far-UV to the mid-IR, and available CO and 21cm mapping. The VENGA dataset will provide 2D maps of the SFR, stellar and gas kinematics, chemical abundances, ISM density and ionization states, dust extinction and stellar populations for these 32 galaxies. The uniqueness of the VIRUS-P large field of view permits these large-scale mappings to be performed. VENGA will allow us to correlate all these important quantities throughout the different environments present in galactic disks, allowing the conduction of a large number of studies in star formation, structure assembly, galactic feedback and ISM in galaxies.Comment: 7 pages, 3 figures, proceedings of the "Third Biennial Frank N. Bash Symposium, New Horizons in Astronomy" held in Austin, TX, Oct. 2009. To be published in the Astronomical Society of the Pacific Conference Series, eds. L. Stanford, L. Hao, Y. Mao, J. Gree

The Relationship Between Black Hole Mass and Velocity Dispersion in Seyfert 1 Galaxies

Black hole masses in active galactic nuclei (AGN) are difficult to measure using conventional dynamical methods, but can be determined using the technique of reverberation mapping. However, it is important to verify that the results of these different methods are equivalent. This can be done indirectly, using scaling relations between the black hole and the host galaxy spheroid. For this purpose, we have obtained new measurements of the bulge stellar velocity dispersion, sigma, in Seyfert 1 galaxies. These are used in conjunction with the M_bh -- sigma relation to validate nuclear black hole masses, M_bh, in active galaxies determined through reverberation mapping. We find that Seyfert galaxies follow the same M_bh -- sigma relation as non-active galaxies, indicating that reverberation mapping measurements of M_bh are consistent with those obtained using other methods. We also reconsider the relationship between bulge absolute magnitude, M_bulge, and black hole mass. We find that Seyfert galaxies are offset from non-active galaxies, but that the deviation can be entirely understood as a difference in bulge luminosity, not black hole mass; Seyfert hosts are brighter than normal galaxies for a given value of their velocity dispersion, perhaps as a result of younger stellar populations.Comment: 12 pages, 8 figures, accepted for publication in the Astrophysical Journa