5 research outputs found
Suzaku and XMM-Newton Observations of the Fornax cluster: Temperature and Metallicity Distribution
Suzaku observed a central region and five offset regions within 0.2 r180 in
the Fornax cluster, a nearby poor cluster, and XMM-Newton mapped the cluster
with 15 pointings out to 0.3 r180. The distributions of O, Mg, Si, S, and Fe in
the intracluster medium (ICM) were studied with Suzaku, and those of Fe and
temperature were studied with XMM. The temperature of the ICM gradually
decreases with radius from 1.3 keV at 0.04 r180 to 1 keV at 0.2-0.3 r180. If
the new solar abundances of Lodders et al. (2003) and a single-temperature
plasma model are adopted, O, Mg, Si, S, and Fe show similar abundances: 0.4-0.6
solar within 0.02-0.2 r180. This Fe abundance is similar to those at 0.1-0.2
r180 in rich clusters and other groups of galaxies. At 0.2-0.3 r180, the Fe
abundance becomes 0.2-0.3 solar. A two-temperature plasma model yields ICM
abundances that are higher by a factor of 1.2-1.5, but gives similar abundance
ratios among O, Mg, Si, S, and Fe. The northern region has a lower ICM
temperature and higher brightness and Fe abundance, whereas the southern region
has a higher ICM temperature and lower brightness and Fe abundance. These
results indicate that the cD galaxy may have traveled from the north because of
recent dynamical evolution. The cumulative oxygen- and iron-mass-to-light
ratios within 0.3 r180 are more than an order of magnitude lower than those of
rich clusters and some relaxed groups of galaxies. Past dynamical evolution
might have hindered the strong concentration of hot gas in the Fornax cluster's
central region. Scatter in the IMLR and similarity in the element abundances in
the ICM of groups and clusters of galaxies indicate early metal synthesis.Comment: 15 pages, 13 figures, accepted for publication in PAS
Ocular Tilt Reaction in Compensated Vestibular Schwannoma
Almost a century ago, Brain (1) initially described vestibular schwannoma as a cause of utricular dysfunction. The resultant syndrome of ocular torsion, skew deviation, and tilt of subjective visual vertical (SVV) with/without head tilt was later termed ocular tilt reaction (OTR) (2). The patient in Brain's article (quoted from Cushing's monograph (3)) had a large tumor causing increased intracranial pressure with displacement of the cerebellum and brainstem. A subsequent study also showed that ipsiversive SVV tilts were found in patients with large cerebellopontine angle tumors and marked compression of neighboring structures (4). We describe a patient with a vestibular schwannoma who exhibited ipsiversive OTR as the sole clinical finding and discuss a potential mechanism for a peripheral origin of OTR