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New constraints on modified Newtonian dynamics from galaxy clusters
Silk, Joseph; Pointecouteau, Etienne
We revisit the application of modified Newtonian dynamics (MOND) to galaxy clusters. We confront the high-quality X-ray data for eight clusters of galaxies observed by the XMM-Newton satellite with the predictions of MOND. We obtain a ratio of the MOND dynamical mass to the baryonic mass of Mm/Mb= 4.94 +/- 0.50 in the outer p…
Spitzer and Hubble Space Telescope Constraints on the Physical Properties of the z~7 Galaxy Strongly Lensed by A2218
Kneib, J. -P.; Le Floc'h, E.; Dole, H. +10 more
We report the detection of a z~7 galaxy strongly lensed by the massive galaxy cluster A2218 (z=0.175) at 3.6 and 4.5 µm using the Spitzer Space Telescope and at 1.1 µm using the Hubble Space Telescope. The new data indicate a refined photometric redshift in the range of 6.6-6.8 depending on the presence of Lyα emission. The spectral en…
A Study of Edge-On Galaxies with the Hubble Space Telescope Advanced Camera for Surveys. II. Vertical Distribution of the Resolved Stellar Population
de Jong, Roelof S.; Seth, Anil C.; Dalcanton, Julianne J.
We analyze the vertical distribution of the resolved stellar populations in six low-mass (Vmax=67-131 km s-1), edge-on, spiral galaxies observed with the Hubble Space Telescope Advanced Camera for Surveys. In each galaxy we find evidence for an extraplanar stellar component extending up to 15 scale heights (3.5 kpc) above the…
Giant Molecular Clouds in M64
Blitz, L.; Rosolowsky, E.
We investigate the properties of giant molecular clouds (GMCs) in the molecule-rich galaxy M64 (NGC 4826). In M64, the mean surface density of molecular gas is 2N(H2)~1022 cm-2 over a 2 kpc region, equal to the surface densities of individual GMCs in the Milky Way. We observed the J=1-->0 transitions of CO,
Hubble Space Telescope and Ground-based Observations of SN 1993J and SN 1998S: CNO Processing in the Progenitors
Filippenko, Alexei V.; Pun, C. S. J.; Garnavich, Peter +13 more
Ground-based and Hubble Space Telescope observations are presented for SN 1993J and SN 1998S. SN 1998S shows strong, relatively narrow circumstellar emission lines of N III-V and C III-IV, as well as broad lines from the ejecta. Both the broad ultraviolet and optical lines in SN 1998S indicate an expansion velocity of ~7000 km s-1. The …
Narrow Iron Kα Lines in Active Galactic Nuclei: Evolving Populations?
Zhou, Xin-Lin; Wang, Jian-Min
We assemble a sample consisting of 66 active galactic nuclei (AGNs) from the literature and from the XMM-Newton archive in order to investigate the origin of the 6.4 keV narrow iron Kα line (NIKAL). The X-ray Baldwin effect of the NIKAL is confirmed in this sample. We find that the equivalent width (EW) of the NIKAL is more strongly inversely corr…
Magnetic Flux Ropes in the Solar Photosphere: The Vector Magnetic Field under Active Region Filaments
Lites, B. W.
This study is an observational search for evidence of prominence-associated magnetic flux ropes at the photospheric level in plage regions away from sunspots. Although there are a few cases of supposed flux rope geometry in the photosphere of complex sunspot regions (notably ``δ sunspots''), such cases appear to be fairly rare and therefore do not…
Physics of accretion in the millisecond pulsar XTE J1751-305
Gierliński, Marek; Poutanen, Juri
We have undertaken an extensive study of X-ray data from the accreting millisecond pulsar XTE J1751-305 observed by RXTE and XMM-Newton during its 2002 outburst. In all aspects this source is similar to the prototypical millisecond pulsar SAX J1808.4-3658, except for the higher peak luminosity of 13 per cent of Eddington, and the optical depth of …
Reddening, Absorption, and Decline Rate Corrections for a Complete Sample of Type Ia Supernovae Leading to a Fully Corrected Hubble Diagram to v < 30,000 km s-1
Saha, A.; Tammann, G. A.; Reindl, B. +1 more
Photometric (BVI) and redshift data corrected for streaming motions are compiled for 111 ``Branch-normal,'' four 1991T-like, seven 1991bg-like, and two unusual supernovae of Type Ia (SNe Ia). Color excesses E(B-V)host of normal SNe Ia, due to the absorption of the host galaxy, are derived by three independent methods, giving excellent a…
An Infrared Coronagraphic Survey for Substellar Companions
Weinberger, Alycia J.; Schneider, Glenn; Hines, Dean C. +10 more
We have used the F160W filter (1.4-1.8 µm) and the coronagraph on the Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) on the Hubble Space Telescope to survey 45 single stars with a median age of 0.15 Gyr, an average distance of 30 pc, and an average H magnitude of 7 mag. For the median age we were capable of detecting a 30MJ…