Improved relay optical element for spectroradiometer using cryogenically cooled detector

By coating half of one element in the relay optical system of a spectroradiometer with a very high emissivity paint, the effect of the reflected radiation from the back of the filter wheel is eliminated optically. This causes the detector to view a constant level of radiation, regardless of how the reflectivity of the back of the filter wheel changes

Disentangling the near infrared continuum spectral components of the inner 500 pc of Mrk 573: two-dimensional maps

We present a near infrared study of the spectral components of the continuum in the inner 500$\times$500 pc$^2$ of the nearby Seyfert galaxy Mrk573 using adaptive optics near-infrared integral field spectroscopy with the instrument NIFS of the Gemini North Telescope at a spatial resolution of $\sim$50 pc. We performed spectral synthesis using the {\sc starlight} code and constructed maps for the contributions of different age components of the stellar population: young ($age\leq100$ Myr), young-intermediate ($100<age\leq700$ Myr), intermediate-old ($700$ Myr $2$ Gyr) to the near-IR K-band continuum, as well as their contribution to the total stellar mass. We found that the old stellar population is dominant within the inner 250 pc, while the intermediate age components dominate the continuum at larger distances. A young stellar component contributes up to $\sim$20% within the inner $\sim$70 pc, while hot dust emission and featureless continuum components are also necessary to fit the nuclear spectrum, contributing up to 20% of the K-band flux there. The radial distribution of the different age components in the inner kiloparsec of Mrk573 is similar to those obtained by our group for the Seyfert galaxies Mrk1066, Mrk1157 and NGC1068 in previous works using a similar methodology. Young stellar populations ($\leq$100 Myr) are seen in the inner 200-300 pc for all galaxies contributing with $\ge$20% of the K-band flux, while the near-IR continuum is dominated by the contribution of intermediate-age stars ($t=$100 Myr-2 Gyr) at larger distances. Older stellar populations dominate in the inner 250 pc

Resolved Spectroscopy of the Narrow-Line Region in NGC 1068. I. The Nature of the Continuum Emission

We present the first long-slit spectra of the Seyfert 2 galaxy NGC 1068 obtained by the Space Telescope Imaging Spectrograph (STIS); the spectra cover the wavelength range 1150 - 10,270 Angstroms at a spatial resolution of 0.05 - 0.1 arcsec and a spectral resolving power of 1000. In this first paper, we concentrate on the far-UV to near-IR continuum emission from the continuum ``hot spot'' and surrounding regions extending out to +/- 6 arcsec (+/-432 pc) at a position angle of 202 degrees In addition to the broad emission lines detected by spectropolarimetry, the hot spot shows the ``little blue bump'' in the 2000 - 4000 Ang. range, which is due to Fe II and Balmer continuum emission. The continuum shape of the hot spot is indistinguishable from that of NGC 4151 and other Seyfert 1 galaxies. Thus, the hot spot is reflected emission from the hidden nucleus, due to electron scattering (as opposed to wavelength-dependent dust scattering). The hot spot is ~0.3 arcsec in extent and accounts for 20% of the scattered light in the inner 500 pc. We are able to deconvolve the extended continuum emission in this region into two components: electron-scattered light from the hidden nucleus (which dominates in the UV) and stellar light (which dominates in the optical and near-IR). The scattered light is heavily concentrated towards the hot spot, is stronger in the northeast, and is enhanced in regions of strong narrow-line emission. The stellar component is more extended, concentrated southwest of the hot spot, dominated by an old (> 2 x 10 Gyr) stellar population, and includes a nuclear stellar cluster which is ~200 pc in extent.Comment: 32 pages, Latex, includes 11 figures (postscript), to appear in the Astrophysical Journa

Application of superconducting coils to the NASA prototype magnetic balance

Application of superconducting coils to a general purpose magnetic balance was studied. The most suitable currently available superconducting cable for coils appears to be a bundle of many fine wires which are transposed and are mechanically confined. Sample coils were tested at central fields up to .5 Tesla, slewing rates up to 53 Tesla/ sec and frequencies up to 30 Hz. The ac losses were measured from helium boil-off and were approximately 20% higher than those calculated. Losses were dominated by hysteresis and a model for loss calculation which appears suitable for design purposes is presented along with computer listings. Combinations of two coils were also tested and interaction losses are reported. Two feasible geometries are also presented for prototype magnetic balance using superconductors

A Catalog of MIPSGAL Disk and Ring Sources

We present a catalog of 416 extended, resolved, disk- and ring-like objects as detected in the MIPSGAL 24 micron survey of the Galactic plane. This catalog is the result of a search in the MIPSGAL image data for generally circularly symmetric, extended "bubbles" without prior knowledge or expectation of their physical nature. Most of the objects have no extended counterpart at 8 or 70 micron, with less than 20% detections at each wavelength. For the 54 objects with central point sources, the sources are nearly always seen in all IRAC bands. About 70 objects (16%) have been previously identified, with another 35 listed as IRAS sources. Among the identified objects, those with central sources are mostly listed as emission-line stars, but with other source types including supernova remnants, luminous blue variables, and planetary nebulae. The 57 identified objects (of 362) without central sources are nearly all PNe (~90%).which suggests that a large fraction of the 300+ unidentified objects in this category are also PNe. These identifications suggest that this is primarily a catalog of evolved stars. Also included in the catalog are two filamentary objects that are almost certainly SNRs, and ten unusual compact extended objects discovered in the search. Two of these show remarkable spiral structure at both 8 and 24 micron. These are likely background galaxies previously hidden by the intervening Galactic plane

A Cloudy/Xspec Interface

We discuss new functionality of the spectral simulation code CLOUDY which allows the user to calculate grids with one or more initial parameters varied and formats the predicted spectra in the standard FITS format. These files can then be imported into the x-ray spectral analysis software XSPEC and used as theoretical models for observations. We present and verify a test case. Finally, we consider a few observations and discuss our results.Comment: 13 pages, 1 table, 4 figures, accepted for publication in PAS

Outflows in the Narrow Line Region of Bright Seyfert Galaxies - I: GMOS-IFU Data

We present two-dimensional maps of emission-line fluxes and kinematics, as well as of the stellar kinematics of the central few kpc of five bright nearby Seyfert galaxies -- Mrk\,6, Mrk\,79, Mrk\,348, Mrk\,607 and Mrk\,1058 -- obtained from observations with the Gemini Multi-Object Spectrograph (GMOS) Integral Field Unit (IFU) on the Gemini North Telescope. The data cover the inner 3\farcs5$\times$5\farcs0 -- corresponding to physical scales in the range 0.6$\times$0.9 to 1.5$\times$2.2\,kpc$^2$ -- at a spatial resolution ranging from 110 to 280 pc with a spectral coverage of 4300 -- 7100\,\AA\ and velocity resolution of $\approx$ 90\,km\,s$^{-1}$. The gas excitation is Seyfert like everywhere but show excitation, but show excitation gradients that are correlated with the gas kinematics, reddening and/or the gas density. The gas kinematics show in all cases two components: a rotation one similar to that observed in the stellar velocity field, and an outflow component. In the case of Mrk607, the gas is counter-rotating relative to the stars. Enhanced gas velocity dispersion is observed in association to the outflows according to two patterns: at the locations of the highest outflow velocities along the ionization axis or perpendicularly to it in a strip centered at the nucleus that we attribute to an equatorial outflow. Bipolar outflows are observed in Mrk\,348 and Mrk\,79, while in Mrk\,1058 only the blueshifted part is clearly observed, while in the cases of Mrk\,6 and Mrk\,607 the geometry of the outflow needs further constraints from modeling to be presented in a forthcoming study, where the mass flow rate and powers will also be obtained.Comment: 20 pages, accepted by MNRA

On the Effects of Dissipative Turbulence on the Narrow Emission-Line Ratios in Seyfert Galaxies

We present a photoionization model study of the effects of micro-turbulence and dissipative heating on emission lines for number and column densities, elemental abundances, and ionizations typical for the narrow emission line regions (NLRs) of Seyfert galaxies. Earlier studies of NLR spectra generally found good agreement between the observations and the model predictions for most strong emission lines, such as [O III] $\lambda$5007, [O II] $\lambda$3727, [N II] $\lambda$6583, [Ne III] $\lambda$3869, and the H and He recombination lines. Nevertheless, the strengths of lines from species with ionization potentials greater than that of He$^{+}$(54.4 eV), e.g. N$^{+4}$ and Ne$^{+4}$, were often under-predicted. Among the explanations suggested for these discrepancies were (selectively) enhanced elemental abundances and contributions from shock heated gas. Interestingly, the NLR lines have widths of several 100 km s$^{-1}$, well in excess of the thermal broadening. If this is due to micro-turbulence, and the turbulence dissipates within the emission-line gas, the gas can be heated in excess of that due to photoionization. We show that the combined effects of turbulence and dissipative heating can strongly enhance N V $\lambda$1240 (relative to He II $\lambda$1640), while the heating alone can boost the strength of [Ne V] $\lambda$3426. We suggest that this effect is present in the NLR, particularly within $\sim$ 100 pc of the central engine. Finally, since micro-turbulence would make clouds robust against instabilities generated during acceleration, it is not likely to be a coincidence that the radially outflowing emission-line gas is turbulent.Comment: 29 oages, including 10 figures. Accepted for publication in the Astrophysical Journa

HST Observations and Photoionization Modeling of the LINER Galaxy NGC 1052

We present a study of available Hubble Space Telescope (HST) spectroscopic and imaging observations of the low ionization nuclear emission line region (LINER) galaxy NGC 1052. The WFPC2 imagery clearly differentiates extended nebular Halpha emission from that of the compact core. Faint Object Spectrograph (FOS) observations provide a full set of optical and UV data (1200-6800 Angstroms). These spectral data sample the innermost region (0."86 x 0."86 ~ 82pc x 82pc) and exclude the extended Halpha emission seen in the WFPC2 image. The derived emission line fluxes allow a detailed analysis of the physical conditions within the nucleus. The measured flux ratio for Halpha/Hbeta, F{Halpha}/F{Hbeta}=4.53, indicates substantial intrinsic reddening, E(B-V)=0.42, for the nuclear nebular emission. This is the first finding of a large extinction of the nuclear emission line fluxes in NGC 1052. If the central ionizing continuum is assumed to be attenuated by a comparable amount, then the emission line fluxes can be reproduced well by a simple photoionization model using a central power law continuum source with a spectral index of alpha = -1.2 as deduced from the observed flux distribution. A multi-density, dusty gas gives the best fit to the observed emission line spectrum. Our calculations show that the small contribution from a highly ionized gas observed in NGC 1052 can also be reproduced solely by photoionization modeling. The high gas covering factor determined from our model is consistent with the assumption that our line of sight to the central engine is obscured.Comment: 23 pages, 7 Postscript figures, 1 jpeg figure ; uses aaspp4.sty, 11pt to appear in The Astrophysical Journa