Search Publications
Witnessing the Formation of a Brightest Cluster Galaxy in a Nearby X-ray Cluster
Raychaudhury, Somak; Mulchaey, John S.; Ponman, Trevor J. +3 more
The central dominant galaxies in galaxy clusters constitute the most massive and luminous galaxies in the universe. Despite this, the formation of these brightest cluster galaxies (BCGs) and the impact of this on the surrounding cluster environment remain poorly understood. Here we present multiwavelength observations of the nearby poor X-ray clus…
Ultraviolet-bright Stellar Populations and Their Evolutionary Implications in the Collapsed-core Cluster M15
Anderson, Jay; Cool, Adrienne M.; Serenelli, Aldo M. +4 more
We performed deep photometry of the central region of the Galactic globular cluster M15 from archival Hubble Space Telescope data taken on the High Resolution Channel and Solar Blind Channel of the Advanced Camera for Surveys. Our data set consists of images in far-UV (FUV140; F140LP), near-UV (NUV220; F220W), and blue (B
Side Magnetic Reconnections Induced by Coronal Mass Ejections: Observations and Simulations
Poedts, S.; Bemporad, A.; Landini, F. +2 more
Over the last few years coronagraphic and spectroscopic observations have demonstrated that small-scale eruptions, such as "jets," "narrow coronal mass ejections (CMEs)," "mini CMEs," "streamer puffs," "streamer detachments," and others, occur ubiquitously on the Sun. Nevertheless, the origin of small-scale eruptive events and how these are interr…
The Faint End of the Galaxy Luminosity Function in A1689: A Steep Red Faint End Upturn at z = 0.18
De Propris, Roberto; Bañados, Eduardo; West, Michael J. +1 more
We present a deep and wide I luminosity function (LF) for galaxies in A1689 (z = 0.183) from a mosaic of Hubble Space Telescope WFPC2 images covering 10' on the side. The main result of this work is the detection of a steep upturn in the dwarf galaxy LF, with α ~ -2. The dwarf-to-giant ratio appears to increase outward, but this is because giant g…
The Complex X-ray Spectrum of the Sefyert 1.5 Source NGC 6860
Mushotzky, Richard; Winter, Lisa M.
The X-ray spectrum of the Seyfert 1.5 source NGC 6860 is among the most complex of the sources detected in the Swift Burst Alert Telescope all-sky survey. A short XMM-Newton follow-up observation of the source revealed a flat spectrum both above and below 2 keV. To uncover the complexity of the source, in this paper we analyze both a 40 ks Suzaku …
The Formation of a Magnetic Channel by the Emergence of Current-carrying Magnetic Fields
Jing, Ju; Wang, Haimin; Chae, Jongchul +2 more
A magnetic channel—a series of polarity reversals separating elongated flux threads with opposite polarities—may be a manifestation of a highly non-potential magnetic configuration in active regions. To understand its formation, we have carried out a detailed analysis of the magnetic channel in AR 10930 using data taken by the Solar Optical Telesc…
Observational Evidence of Unwinding and Chirality Changing in Penumbral Filaments by Hinode
Zhang, Hongqi; Liu, Yu; Su, Jiangtao +3 more
In this paper, we present a very important and quite controversial observational property of penumbral filaments that may exhibit twisting motions and change their chirality. Using high-resolution observations from the Solar Optical Telescope on board Hinode, we study the unwinding and twisting motions in the penumbral filaments of active region N…
AKARI Near-infrared Spectroscopy of SDSS-selected Blue Early-type Galaxies
Matsuhara, Hideo; Lee, Myung Gyoon; Lee, Jong Chul +2 more
A near-infrared (NIR; 2.5-4.5 µm) spectroscopic survey of Sloan Digital Sky Survey (SDSS)-selected blue early-type galaxies (BEGs) has been conducted using the AKARI. The NIR spectra of 36 BEGs are secured, which are well balanced in their star formation (SF)/Seyfert/LINER-type composition. For high signal-to-noise ratio, we stack the BEG sp…
Measuring Dark Matter Ellipticity of A901/902 Using Particle-based Lensing
Heymans, Catherine; Goldberg, David M.; Morandi, Andrea +1 more
We present a non-parametric measure of the ellipticity and the alignment of the dark matter halos in the A901/902 supercluster. This supercluster is a system of four separate peaks in a 0fdg5 × 0fdg5 field of view. We map the mass distribution of each individual peak using an improved version of Particle-Based Lensing (PBL) and measure the ellipti…
Properties of a Polar Coronal Hole During the Solar Minimum in 2007
Hahn, M.; Savin, D. W.; Landi, E. +2 more
We report measurements of a polar coronal hole during the recent solar minimum using the Extreme Ultraviolet Imaging Spectrometer on Hinode. Five observations are analyzed that span the polar coronal hole from the central meridian to the boundary with the quiet-Sun corona. We study the observations above the solar limb in the height range of 1.03-…