Search Publications
Spectroscopy along Multiple, Lensed Sight Lines through Outflowing Winds in the Quasar SDSS J1029+2623
Gandhi, Poshak; Oguri, Masamune; Misawa, Toru +3 more
We study the origin of absorption features on the blue side of the C IV broad emission line of the large-separation lensed quasar SDSS J1029+2623 at z em ~ 2.197. The quasar images, produced by a foreground cluster of galaxies, have a maximum separation angle of θ ~ 22.''5. The large angular separation suggests that the sight lines to t…
Probing of the Interactions between the Hot Plasmas and Galaxies in Clusters from z = 0.1 to 0.9
Shimasaku, Kazuhiro; Gandhi, Poshak; Makishima, Kazuo +7 more
Based on optical and X-ray data for a sample of 34 relaxed rich clusters of galaxies with redshifts of 0.1-0.9, we studied relative spatial distributions of the two major baryon contents, the cluster galaxies and the hot plasmas. Using multi-band photometric data taken with the UH88 telescope, we determined the integrated (two-dimensional) radial …
An XMM-Newton view of the merging activity in the Centaurus cluster
Fabian, A. C.; Sanders, J. S.; Walker, S. A.
We report the results of XMM-Newton observations of the regions around the core of the Centaurus cluster where evidence for merging activity between the subgroup Cen 45 and the main Centaurus cluster has previously been observed using ASCA and ROSAT data. We confirm the ASCA findings of a temperature excess surrounding Cen 45. We find that this te…
Probing nuclear activity versus star formation at z ∼ 0.8 using near-infrared multi-object spectroscopy
Pérez García, A. M.; Acosta-Pulido, J. A.; Alonso-Herrero, A. +3 more
We present near-infrared (NIR) spectroscopic observations of 28 X-ray and mid-infrared selected sources at a median redshift of z ∼ 0.8 in the Extended Groth Strip (EGS). To date this is the largest compilation of NIR spectra of active galactic nuclei (AGN) at this redshift. The data were obtained using the multi-object spectroscopic mode of the L…
Influences of the interplanetary magnetic field clock angle and cone angle on the field-aligned currents in the magnetotail
Dunlop, M.; Liu, Z. X.; Shi, J. K. +1 more
The influences of the interplanetary magnetic field (IMF) cone angle θ and clock angle ϕ on the field-aligned currents (FACs) at the plasma sheet boundary layers (PSBLs) have been investigated using Cluster Data. The FAC occurrence increases monotonically with IMF cone angle and has two peaks at -90° and +110° clock angle, respectively. The peak a…
The Massive Star Population in M101. I. The Identification and Spatial Distribution of the Visually Luminous Stars
Humphreys, Roberta M.; Grammer, Skyler
An increasing number of non-terminal giant eruptions are being observed by modern supernova and transient surveys. But very little is known about the origin of these giant eruptions and their progenitors, many of which are presumably very massive, evolved stars. Motivated by the small number of progenitors positively associated with these giant er…
A sunward propagating fast wave in the magnetosheath observed after the passage of an interplanetary shock
Pallocchia, G.
The interaction of an interplanetary (IP) shock with the terrestrial magnetosphere causes some noticeable effects on the global scale structure of the magnetosphere itself. One of these effects is given by an earthward motion of the bow shock followed, some minutes later, by a sunward displacement. As demonstrated by past observational studies, in…
Nonlinear Color-Metallicity Relations of Globular Clusters. IV. Testing the Nonlinearity Scenario for Color Bimodality via HST/WFC3 u-band Photometry of M84 (NGC 4374)
Blakeslee, John P.; Sohn, Sangmo T.; Kim, Hak-Sub +4 more
Color distributions of globular clusters (GCs) in most massive galaxies are bimodal. Assuming linear color-to-metallicity conversions, bimodality is viewed as the presence of merely two GC subsystems with distinct metallicities, which serves as a critical backbone of various galaxy formation theories. Recent studies, however, revealed that the col…
Valleys in pit craters on Mars: Characteristics, distribution, and formation mechanisms
Fassett, Caleb I.; Peel, Samantha E.
New observations of central pit craters on Mars reveal that some craters contain prominent interior valley networks that drain into their central pit. In this study, we catalog the distribution of pit craters with associated valleys, and characterize in detail five diverse, well-preserved examples. In some instances, sedimentary deposits we interp…
Probing the evolution of the substructure frequency in galaxy clusters up to z ~ 1
Böhringer, H.; Chon, G.; Weißmann, A.
Context. Galaxy clusters are the last and largest objects to form in the standard hierarchical structure formation scenario through merging of smaller systems. The substructure frequency in the past and present epoch provides excellent means for studying the underlying cosmological model.
Aims: Using X-ray observations, we study the substruct…