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A Catalog of X-Ray Point Sources in the Abell 133 Region
Shin, Jaejin,Plotkin, Richard. M.,Woo, Jong-Hak,Gallo, Elena,Mulchaey, John S. American Astronomical Society 2018 The Astrophysical journal Supplement series Vol.238 No.2
<P>As an evolutionary phase of galaxies, active galactic nuclei (AGNs) over a large range of redshifts have been utilized for understanding cosmic evolution. In particular, the population and evolution of AGNs have been investigated through the study of the cosmic X-ray background in various fields. As one of the deep fields observed by Chandra, with a total of 2.8 Ms exposures, Abell 133 is a special region for investigating AGNs, providing a testbed for probing the environmental effects on AGN triggers, since cluster environments can be different from field environments. The achieved flux limits of data at the 50%. completeness levels of 6.95 x 10(-16), 1.43 x 10(-16), and 1.57 x 10(-15) erg s(-1) cm(-2) are 0.5-8, 0.5-2, and 2-8 keV. Using the wavdetect and no-source binomial probability (i.e., p < 0.007), we analyze the combined Chandra image, detecting 1617 (in 0.5-8 keV), 1324 (in 0.5-2 keV), and 1028 (in 2-8 keV) X-ray point sources in the Abell 133 region. Here, we present the X-ray point source catalog with the source fluxes, which can be combined with multiwavelength data for future works. We find that the number count distribution of the X-ray point sources is well reproduced with a broken power-law model, while the best-fit model parameters are sensitive to the fitting range of the number count distribution. Finally, we find an excess of number density (a decrease of AGN fraction) at the central region of the cluster, which reflects the effect of dense environments on AGN triggers, a finding similar to those of other studies of galaxy clusters.</P>
AMUSE-FIELD. II. NUCLEATION OF EARLY-TYPE GALAXIES IN THE FIELD VERSUS CLUSTER ENVIRONMENT
Baldassare, Vivienne F.,Gallo, Elena,Miller, Brendan P.,Plotkin, Richard M.,Treu, Tommaso,Valluri, Monica,Woo, Jong-Hak IOP Publishing 2014 The Astrophysical journal Vol.791 No.2
<P>The optical light profiles of nearby early-type galaxies are known to exhibit a smooth transition from nuclear light deficits to nuclear light excesses with decreasing galaxy mass, with as much as 80% of the galaxies with stellar masses below 10(10) M-circle dot hosting a massive nuclear star cluster (NSC). At the same time, while all massive galaxies are thought to harbor nuclear supermassive black holes (SMBHs), observational evidence for SMBHs is slim at the low end of the mass function. Here, we explore the environmental dependence of the nucleation fraction by comparing two homogeneous samples of nearby field versus cluster early-type galaxies with uniform Hubble Space Telescope (HST) coverage. Existing Chandra X-ray Telescope data for both samples yield complementary information on low-level accretion onto nuclear SMBHs. Specifically, we report on dual-band (F475W and F850LP) Advanced Camera for Surveys (ACS) imaging data for 28 out of the 103 field early-type galaxies that compose the AMUSE-Field Chandra survey, and compare our results against the companion HST and Chandra surveys for a sample of 100 Virgo Cluster early-types (ACS Virgo Cluster and AMUSE-Virgo surveys, respectively). We model the two-dimensional light profiles of the field targets to identify and characterize NSCs, and find a field nucleation fraction of 26%(+ 17%)(-11%) (at the 1 sigma level), consistent with the measured Virgo nucleation fraction across a comparable mass distribution (30%(+ 17%)(-12%)). Coupled with the Chandra result that SMBH activity is higher for the field, our findings indicate that, since the last epoch of star formation, the funneling of gas to the nuclear regions has been inhibited more effectively for Virgo galaxies, arguably via ram pressure stripping.</P>
Kang, Ju-Hee,Mollenhauer, Brit,Coffey, Christopher S.,Toledo, Jon B.,Weintraub, Daniel,Galasko, Douglas R.,Irwin, David J.,Van Deerlin, Vivianna,Chen-Plotkin, Alice S.,Caspell-Garcia, Chelsea,Walig&oa Springer-Verlag 2016 Acta neuropathologica Vol.131 No.6
<P>The development of biomarkers to predict the progression of Parkinson's disease (PD) from its earliest stage through its heterogeneous course is critical for research and therapeutic development. The Parkinson's Progression Markers Initiative (PPMI) study is an ongoing international multicenter, prospective study to validate biomarkers in drug-na < ve PD patients and matched healthy controls (HC). We quantified cerebrospinal fluid (CSF) alpha-synuclein (alpha-syn), amyloid-beta1-42 (A beta(1-42)), total tau (t-tau), and tau phosphorylated at Thr181 (p-tau) in 660 PPMI subjects at baseline, and correlated these data with measures of the clinical features of these subjects. We found that CSF alpha-syn, t-tau and p-tau levels, but not A beta(1-42), were significantly lower in PD compared with HC, while the diagnostic value of the individual CSF biomarkers for PD diagnosis was limited due to large overlap. The level of alpha-syn, but not other biomarkers, was significantly lower in PD patients with non-tremor-dominant phenotype compared with tremor-dominant phenotype. In addition, in PD patients the lowest A beta(1-42), or highest t-tau/A beta(1-42) and t-tau/alpha-syn quintile in PD patients were associated with more severe non-motor dysfunction compared with the highest or lowest quintiles, respectively. In a multivariate regression model, lower alpha-syn was significantly associated with worse cognitive test performance. APOE epsilon 4 genotype was associated with lower levels of A beta(1-42), but neither with PD diagnosis nor cognition. Our data suggest that the measurement of CSF biomarkers in early-stage PD patients may relate to disease heterogeneity seen in PD. Longitudinal observations in PPMI subjects are needed to define their prognostic performance.</P>