User responses to CPA reports on forecasts; Technical Research Report 2

https://egrove.olemiss.edu/aicpa_news/1272/thumbnail.jp

A spiral-like disk of ionized gas in IC 1459: Signature of a merging collision

The authors report the discovery of a large (15 kpc diameter) H alpha + (NII) emission-line disk in the elliptical galaxy IC 1459, showing weak spiral structure. The line flux peaks strongly at the nucleus and is more concentrated than the stellar continuum. The major axis of the disk of ionized gas coincides with that of the stellar body of the galaxy. The mass of the ionized gas is estimated to be approx. 1 times 10 (exp 5) solar mass, less than 1 percent of the total mass of gas present in IC 1459. The total gas mass of 4 times 10(exp 7) solar mass has been estimated from the dust mass derived from a broad-band color index image and the Infrared Astronomy Satellite (IRAS) data. The authors speculate that the presence of dust and gas in IC 1459 is a signature of a merger event

Electronic structure, magnetism and superconductivity of MgCNi3_{3}

The electronic structure of the newly discovered superconducting perovskite MgCNi$_3$ is calculated using the LMTO and KKR methods. The states near the Fermi energy are found to be dominated by Ni-d. The Stoner factor is low while the electron-phonon coupling constant is estimated to be about 0.7, which suggests that the material is a conventional type of superconductor where T$_C$ is not affected by magnetic interactions. However, the proximity of the Fermi energy to a large peak in the density of states in conjunction with the reported non-stoichiometry of the compound, has consequences for the stability of the results.Comment: 3 pages, 4 figure

Recent results and perspectives on cosmic backgrounds from radio to far-infrared

© 2019 World Scientific Publishing Company. Cosmological and astrophysical surveys from radio to far-infrared, in both temperature and polarization, offer a unique view of the universe properties and of the formation and evolution of its structures. The last release, close to be finalized, of the Planck mission results sets the scene for cosmological models and parameters, while the comparison with other types of data sets raises the issue of possible tensions about some parameters, first of all the Hubble constant. At the same time, on the extragalactic side, Planck carried out the deepest systematic all-sky survey of SZ galaxy clusters and detected thousands of dusty galaxies and many hundreds of extragalactic radio sources, also allowing us to investigate many specific topics, including molecular hydrogen clouds in galactic halos. The exploitation of future generation of CMB missions and the next radio facilities will allow us to deeply investigate several topics in cosmology and astrophysics, from the existence of primordial gravitational waves to the energy releases in the primeval plasma, from the dawn ages and the epoch of reionization to the formation and evolution of early galaxies and clusters, while a wide set of open astrophysical problems can be studied with future IR missions

Recent results and perspectives on cosmic backgrounds from radio to far-infrared

© 2019 World Scientific Publishing Company. Cosmological and astrophysical surveys from radio to far-infrared, in both temperature and polarization, offer a unique view of the universe properties and of the formation and evolution of its structures. The last release, close to be finalized, of the Planck mission results sets the scene for cosmological models and parameters, while the comparison with other types of data sets raises the issue of possible tensions about some parameters, first of all the Hubble constant. At the same time, on the extragalactic side, Planck carried out the deepest systematic all-sky survey of SZ galaxy clusters and detected thousands of dusty galaxies and many hundreds of extragalactic radio sources, also allowing us to investigate many specific topics, including molecular hydrogen clouds in galactic halos. The exploitation of future generation of CMB missions and the next radio facilities will allow us to deeply investigate several topics in cosmology and astrophysics, from the existence of primordial gravitational waves to the energy releases in the primeval plasma, from the dawn ages and the epoch of reionization to the formation and evolution of early galaxies and clusters, while a wide set of open astrophysical problems can be studied with future IR missions

On the Nature of the NGC 1275 System

Sub-arcsecond images, taken in B, R, and H-Alpha filters, and area spectroscopy obtained with the WIYN 3.5-m telescope provide the basis for an investigation of the unusual structures in the stellar body and ionized gas in and around the Perseus cluster central galaxy, NGC 1275. Our H-Alpha filter is tuned to gas at the velocity of NGC 1275, revealing complex, probably unresolved, small-scale features in the extended ionized gas, located up to 50/h kpc from NGC 1275. The mean H-Alpha surface brightness varies little along the outer filaments; this, together with the complex excitation state demonstrated by spectra, imply that the filaments are likely to be tubes, or ribbons, of gas. The morphology, location and inferred physical parameters of the gas in the filaments are consistent with a model whereby the filaments form through compression of the intracluster gas by relativistic plasma emitted from the active nucleus of NGC 1275. Imaging spectroscopy with the Densepak fiber array on WIYN suggests partial rotational support of the inner component of low velocity ionized gas. We confirm and extend evidence for features in the stellar body of NGC 1275, and identify outer stellar regions containing very blue, probably very young, star clusters. We interpret these as evidence for recent accretion of a gas-rich system, with subsequent star formation. We suggest that two main processes, which may be causally connected, are responsible for the rich phenomenology of the NGC 1275 system -- NGC 1275 experienced a recent merger/interaction with a group of gas-rich galaxies, and recent outflows from its AGN have compressed the intracluster gas, and perhaps the gas in the infalling galaxies, to produce a complex web of filaments. (Abridged)Comment: AJ, accepted; a recommended full resolution version is available at http://www.astro.wisc.edu/~chris/pera.p

WFPC2 Observations of the Cooling Flow Elliptical in Abell 1795

We present WFPC2 images of the core of the cooling flow cD galaxy in Abell 1795. An irregular, asymmetric dust lane extends 7 \h75 kpc in projection to the north-northwest. The dust shares the morphology observed in the H$\alpha$ and excess UV emission. We see both diffuse and knotty blue emission around the dust lane, especially at the ends. The dust and emission features lie on the edge of the radio lobes, suggesting star formation induced by the radio source or the deflection of the radio jets off of pre-existing dust and gas. We measure an apparent R$_V$ significantly less than 3.1, implying that the extinction law is not Galactic in the dust lane, or the presence of line emission which is proportional to the extinction. The dust mass is at least 2$\times10^{5} h_{75}^{-2}$ M\solar\ and is more likely to be 6.5$\times10^{5} h_{75}^{-2}$ M\solar.Comment: 14 pages, LaTeX, Figure 4 included, Postscript Figs. 1-3 available at ftp://astro.nmsu.edu/pub/JASON/A1795/, accepted for publication in ApJ Letter

The Spectrum of Integrated Millimeter Flux of the Magellanic Clouds and 30-Doradus from TopHat and DIRBE Data

We present measurements of the integrated flux relative to the local background of the Large and Small Magellanic Clouds and the region 30-Doradus (the Tarantula Nebula) in the LMC in four frequency bands centered at 245, 400, 460, and 630 GHz, based on observations made with the TopHat telescope. We combine these observations with the corresponding measurements for the DIRBE bands 8, 9, and 10 to cover the frequency range 245 - 3000 GHz (100 - 1220 micrometers) for these objects. We present spectra for all three objects and fit these spectra to a single-component greybody emission model and report best-fit dust temperatures, optical depths, and emissivity power-law indices, and we compare these results with other measurements in these regions and elsewhere. Using published dust grain opacities, we estimate the mass of the measured dust component in the three regions.Comment: 41 pages, 4 figures. Accepted for publication in Astrophysical Journa

Tunneling spectroscopy in the magnetic superconductor TmNi2B2C

We present new measurements about the tunneling conductance in the borocarbide superconductor TmNi$_2$B$_2$C. The results show a very good agreement with weak coupling BCS theory, without any lifetime broadening parameter, over the whole sample surface. We detect no particular change of the tunneling spectroscopy below 1.5K, when both the antiferromagnetic (AF) phase and the superconducting order coexist.Comment: Submitted to Phys. Rev. B, Rapid Communication