Search Publications
The Low-Mass Initial Mass Function in the 30 Doradus Starburst Cluster
Moneti, A.; Brandner, W.; Zinnecker, H. +5 more
We present deep Hubble Space Telescope NICMOS 2 F160W band observations of the central 56'' × 57'' (14 pc × 14.25 pc) region around R136 in the starburst cluster 30 Dor (NGC 2070) located in the Large Magellanic Cloud. Our aim is to derive the stellar initial mass function (IMF) down to ~1 M sun in order to test whether the IMF in a mas…
Confirmation of and Variable Energy Injection by a Near-Relativistic Outflow in APM 08279+5255
Brandt, W. N.; Garmire, G. P.; Chartas, G. +2 more
We present results from multi-epoch spectral analysis of XMM-Newton and Chandra observations of the broad absorption line (BAL) quasar APM 08279+5255. Our analysis shows significant X-ray BALs in all epochs with rest-frame energies lying in the range of ~6.7-18 keV. The X-ray BALs and 0.2-10 keV continuum show significant variability on timescales…
Multiwavelength Observations of a TeV-Flare from W Comae
Pian, E.; Costa, E.; Cucchiara, A. +165 more
We report results from an intensive multiwavelength campaign on the intermediate-frequency-peaked BL Lacertae object W Com (z = 0.102) during a strong outburst of very high energy gamma-ray emission in 2008 June. The very high energy gamma-ray signal was detected by VERITAS on 2008 June 7-8 with a flux F(>200 GeV) =(5.7 ± 0.6) × 10-11
The AzTEC/SMA Interferometric Imaging Survey of Submillimeter-selected High-redshift Galaxies
Wilner, David J.; Yun, Min S.; Fazio, Giovanni G. +14 more
We present results from a continuing interferometric survey of high-redshift submillimeter galaxies (SMGs) with the Submillimeter Array, including high-resolution (beam size ~2 arcsec) imaging of eight additional AzTEC 1.1 mm selected sources in the COSMOS field, for which we obtain six reliable (peak signal-to-noise ratio (S/N) >5 or peak S/N …
Mapping the Dark Matter from UV Light at High Redshift: An Empirical Approach to Understand Galaxy Statistics
Ferguson, Henry C.; Giavalisco, Mauro; Somerville, Rachel S. +5 more
We present a simple formalism to interpret the observations of two galaxy statistics, the UV luminosity function (LF) and two-point correlation functions for star-forming galaxies at z~4, 5, and 6 in the context of Λ cold dark matter cosmology. Both statistics are the result of how star formation takes place in dark matter halos, and thus are used…
Observing Episodic Coronal Heating Events Rooted in Chromospheric Activity
De Pontieu, Bart; McIntosh, Scott W.
We present the results of a multi-wavelength study of episodic plasma injection into the corona of active region (AR) 10942. We exploit long-exposure images of the Hinode and Transition Region and Coronal Explorer spacecraft to study the properties of faint, episodic, "blobs" of plasma that are propelled upward along coronal loops that are rooted …
Red Supergiants in the Andromeda Galaxy (M31)
Massey, Philip; Clayton, Geoffrey C.; Levesque, Emily M. +5 more
Red supergiants (RSGs) are a short-lived stage in the evolution of moderately massive stars (10-25 M sun), and as such their location in the H-R diagram provides an exacting test of stellar evolutionary models. Since massive star evolution is strongly affected by the amount of mass loss a star suffers, and since the mass-loss rates depe…
Evidence for a Pre-Eruptive Twisted Flux Rope Using the Themis Vector Magnetograph
Aulanier, G.; Canou, A.; Amari, T. +3 more
Although there is evidence that twisted structures form during large-scale eruptive events, it is not yet clear whether these exist in the pre-eruptive phase as twisted flux ropes (TFRs) in equilibrium. This question has become a major issue since several theoretical mechanisms can lead to the formation of TFRs. These models consider either the ev…
High-Speed Transition Region and Coronal Upflows in the Quiet Sun
De Pontieu, Bart; McIntosh, Scott W.
We study the line profiles of a range of transition region (TR) emission lines observed in typical quiet-Sun regions. In magnetic network regions, the Si IV 1402 Å, C IV 1548 Å, N V 1238 Å, O VI 1031 Å, and Ne VIII 770 Å spectral lines show significant asymmetry in the blue wing of the emission line profiles. We interpret these high-velocity upflo…
A Quintet of Black Hole Mass Determinations
Filippenko, Alexei V.; Ho, Luis C.; Gebhardt, Karl +11 more
We report five new measurements of central black hole masses based on Space Telescope Imaging Spectrograph and Wide Field Planetary Camera 2 observations with the Hubble Space Telescope (HST) and on axisymmetric, three-integral, Schwarzschild orbit-library kinematic models. We selected a sample of galaxies within a narrow range in velocity dispers…