Search Publications
Using Megamaser Disks to Probe Black Hole Accretion
Greene, Jenny E.; den Brok, Mark; Peng, Chien Y. +7 more
We examine the alignment between H2O megamaser disks on subparsec scales with circumnuclear disks and bars on <500 pc scales observed with the Hubble Space Telescope (HST)/WFC3. The HST imaging reveals young stars, indicating the presence of gas. The megamaser disks are not well aligned with the circumnuclear bars or disks as traced …
Mapping the differential reddening in globular clusters
Kepler, S. O.; Bonatto, C.; Campos, Fabíola
We build differential-reddening maps for 66 Galactic globular clusters (GCs) with archival Hubble Space Telescope WFC/ACS F606W and F814W photometry. Because of the different GC sizes (characterized by the half-light radius Rh) and distances to the Sun, the WFC/ACS field of view (200 arcsec × 200 arcsec) coverage (Robs) lies …
Jeans instability criterion modified by external tidal field.
Jog, C. J.
The well-known Jeans criterion describes the onset of instabilities in an infinite, homogeneous, self-gravitating medium supported by pressure. Most realistic astrophysical systems, however, are not isolated - instead they are under the influence of an external field such as the tidal field due to a neighbour. Here, we do a linear perturbation ana…
The simultaneous low state spectral energy distribution of 1ES 2344+514 from radio to very high energies
Maraschi, L.; Covino, S.; Antonelli, L. A. +193 more
Context. BL Lacertae objects are variable at all energy bands on time scales down to minutes. To construct and interpret their spectral energy distribution (SED), simultaneous broad-band observations are mandatory. Up to now, the number of objects studied during such campaigns is very limited and biased towards high flux states.
Aims: We pres…
A variation of the fraction of stars that form in bound clusters within M83.
Bastian, N.; Adamo, A.; Silva-Villa, E.
Recent observations, as well as theoretical studies, have suggested that stellar cluster formation may depend on local and global environmental properties. In particular, the fraction of stars that form within long-lived bound clusters (Γ) may depend on environment, with indications that it may be higher in the more extreme environments of high st…
The He II Post-reionization Epoch: HST/COS Observations of the Quasar HS1700+6416
Shull, J. Michael; Syphers, David
The reionization epoch of singly ionized helium (He II) is believed to start at redshifts z ~ 3.5-4 and be nearly complete by z ~= 2.7. We explore the post-reionization epoch with far-ultraviolet spectra of the bright, high-redshift quasar HS1700+6416 taken by the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope, which show strong H…
The Molecular Gas Density in Galaxy Centers and how it Connects to Bulges
Drory, Niv; Fisher, David B.; Bolatto, Alberto +3 more
In this paper we present gas density, star formation rate (SFR), stellar masses, and bulge-disk decompositions for a sample of 60 galaxies. Our sample is the combined sample of the BIMA SONG, CARMA STING, and PdBI NUGA surveys. We study the effect of using CO-to-H2 conversion factors that depend on the CO surface brightness, and also th…
The K-band luminosity functions of super star clusters in luminous infrared galaxies, their slopes and the effects of blending
Kankare, E.; Väisänen, P.; Randriamanakoto, Z. +3 more
Super star clusters (SSCs) are typically found in interacting galaxies and trace an extreme form of star formation. We present a K-band study of SSC candidates in a sample of local luminous infrared galaxies (LIRGs) using two adaptive optics instruments: the Very Large Telescope's Nasmyth Adaptive Optics System-COude Near Infrared CAmera (NACO) an…
HST/WFC3 imaging of protostellar jets in Carina: [Fe II] emission tracing massive jets from intermediate-mass protostars
Smith, Nathan; Reiter, Megan
We present narrow-band Wide Field Camera 3 (WFC3)-UVIS and WFC3-IR images of four externally irradiated protostellar jets in the Carina nebula: HH 666, HH 901, HH 902 and HH 1066. These massive jets are unusual because they are bathed in UV radiation from dozens of nearby O-type stars, but despite the strong incident ionizing radiation, portions o…
Interplanetary Network Localizations of Konus Short Gamma-Ray Bursts
Frontera, F.; Orlandini, M.; Cline, T. +71 more
Between the launch of the Global Geospace Science Wind spacecraft in 1994 November and the end of 2010, the Konus-Wind experiment detected 296 short-duration gamma-ray bursts (including 23 bursts which can be classified as short bursts with extended emission). During this period, the Interplanetary Network (IPN) consisted of up to 11 spacecraft, a…