Search Publications
An Energetic AGN Outburst Powered by a Rapidly Spinning Supermassive Black Hole or an Accreting Ultramassive Black Hole
Kirkpatrick, C. C.; McNamara, B. R.; Nulsen, P. E. J. +4 more
Powering the 1062 erg nuclear outburst in the MS0735.6+7421 cluster central galaxy by accretion with a 10% mass-to-energy conversion efficiency implies that its putative supermassive black hole (SMBH) grew by ~6 × 108 M sun over the past 100 Myr. Guided by data at several wavelengths, we place upper limits on the a…
The Implications of a High Cosmic-Ray Ionization Rate in Diffuse Interstellar Clouds
Indriolo, Nick; Fields, Brian D.; McCall, Benjamin J.
Diffuse interstellar clouds show large abundances of H+ 3 which can only be maintained by a high ionization rate of H2. Cosmic rays are the dominant ionization mechanism in this environment, so the large ionization rate implies a high cosmic-ray flux, and a large amount of energy residing in cosmic rays. In this pa…
The Chemical Abundances of Tycho G in Supernova Remnant 1572
Filippenko, Alexei V.; Foley, Ryan J.; Simon, Joshua D. +3 more
We present an analysis of the chemical abundances of the star Tycho G in the direction of the remnant of supernova (SN) 1572, based on Keck high-resolution optical spectra. The stellar parameters of this star are found to be those of a G-type subgiant with T eff = 5900 ± 100 K, log(g/cms2) = 3.85 ± 0.30 dex, and [Fe/H] = -0.0…
MOIRCS Deep Survey. IV. Evolution of Galaxy Stellar Mass Function Back to z ~ 3
Ouchi, M.; Uchimoto, Y. K.; Yamada, T. +11 more
We use very deep near-infrared (NIR) imaging data obtained in MOIRCS Deep Survey (MODS) to investigate the evolution of the galaxy stellar mass function back to z ~ 3. The MODS data reach J = 24.2, H = 23.1, and K = 23.1 (5σ, Vega magnitude) over 103 arcmin2 (wide) and J = 25.1, H = 23.7, and K = 24.1 over 28 arcmin2 (deep) i…
Excitation of Kink Waves Due to Small-Scale Magnetic Reconnection in the Chromosphere?
He, Jiansen; Tian, Hui; Marsch, Eckart +1 more
The kink wave, which has often been observed in coronal loops, is considered as a possibly important energy source contributing to coronal heating. However, its generation has not yet been observed. Here, we report the first observation of kink-wave excitation caused by magnetic reconnection as inferred from Solar Optical Telescope measurements ma…
Measuring the Spin of GRS 1915+105 with Relativistic Disk Reflection
Fabian, A. C.; Miller, J. M.; Homan, J. +5 more
GRS 1915+105 harbors one of the most massive known stellar black holes in the Galaxy. In 2007 May, we observed GRS 1915+105 for ~117 ks in the low/hard state using Suzaku. We collected and analyzed the data with the Hard X-ray Detector/Positive Intrinsic Negative and X-ray Spectrometer cameras spanning the energy range from 2.3 to 55 keV. Fits to …
The Presence of Two Distinct Red Giant Branches in the Globular Cluster NGC 1851
Joo, Seok-Joo; Han, Sang-Il; Kim, Hak-Sub +4 more
There is a growing body of evidence for the presence of multiple stellar populations in some globular clusters, including NGC 1851. For most of these peculiar globular clusters, however, the evidence for the multiple red giant branches (RGBs) having different heavy elemental abundances as observed in ω Centauri is hitherto lacking, although spread…
Hinode Observation of the Magnetic Fields in a Sunspot Light Bridge Accompanied by Long-Lasting Chromospheric Plasma Ejections
Tsuneta, Saku; Shimizu, Toshifumi; Lites, Bruce W. +7 more
We present high-resolution magnetic field measurements of a sunspot light bridge (LB) that produced chromospheric plasma ejections intermittently and recurrently for more than 1 day. The observations were carried out with the Hinode Solar Optical Telescope on 2007 April 29 and 30. The spectro-polarimeter reveals obliquely oriented magnetic fields …
The Environments of High-Redshift Quasi-Stellar Objects
Panagia, N.; Stiavelli, Massimo; Djorgovski, S. G. +9 more
We present a sample of i 775-dropout candidates identified in five Hubble Advanced Camera for Surveys (ACS) fields centered on Sloan Digital Sky Survey quasi-stellar objects (QSOs) at redshift z ~ 6. Our fields are as deep as the GOODS ACS images, which are used as a reference field sample. We find them to be overdense in two fields, un…
The Largest Gravitational Lens: MACS J0717.5+3745 (z = 0.546)
Broadhurst, Tom; Zitrin, Adi; Rephaeli, Yoel +1 more
We identify 13 sets of multiply-lensed galaxies around MACS J0717.5+3745 (z = 0.546), outlining a very large tangential critical curve of major axis ~2farcm8, filling the field of the Hubble Space Telescope/Advanced Camera for Surveys. The equivalent circular Einstein radius is θ e = 55'' ± 3'' (at an estimated source redshift of z