scholarly journals A Long-Term Study of Ultraluminous X-ray Sources in NGC 891

Universe ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 18
Author(s):  
Nicholas M. Earley  ◽  
Vikram V. Dwarkadas  ◽  
Victoria Cirillo 
Keyword(s):  
Spiral Galaxy ◽  
Spectral Properties ◽  
Time Window ◽  
Single Model ◽  
Term Study ◽  
X Ray ◽  
Long Term Study ◽  
Individual Source

We perform empirical fits to the Chandraand XMM-Newton spectra of three ultraluminous X-ray sources (ULXs) in the edge-on spiral galaxy NGC 891, monitoring the region over a 17-year time window. One of these sources was visible since the early 1990s with ROSAT and was observed multiple times with Chandra and XMM-Newton. Another was visible since 2011. We build upon prior analyses of these sources by analyzing all available data at all epochs. Where possible Chandra data is used, since its superior spatial resolution allows for more effective isolation of the emission from each individual source, thus providing a better determination of their spectral properties. We also identify a new transient ULX, CXOU J022230.1+421937, which faded from view over the course of a two month period from Nov 2016 to Jan 2017. Modeling of each source at every epoch was conducted using six different models ranging from thermal bremsstrahlung to accretion disk models. Unfortunately, but as is common with many ULXs, no single model yielded a much better fit than the others. The two known sources had unabsorbed luminosities that remained fairly consistent over five or more years. Various possibilities for the new transient ULX are explored.

scholarly journals A long-term study of AGN X-ray variability

2017 ◽  
Vol 599 ◽  
pp. A82 ◽  
Author(s):  
R. Middei ◽  
F. Vagnetti ◽  
S. Bianchi ◽  
F. La Franca ◽  
M. Paolillo ◽  
...  
Keyword(s):  
Term Study ◽  
X Ray ◽  
Long Term Study

scholarly journals A comprehensive long-term study of the radio and X-ray variability of NGC 4051 Paper II

2016 ◽  
Vol 465 (2) ◽  
pp. 1336-1347 ◽  
Author(s):  
S. Jones ◽  
I. McHardy ◽  
T. J. Maccarone
Keyword(s):  
Term Study ◽  
X Ray ◽  
Long Term Study ◽  
Ngc 4051

scholarly journals Multiwavelength Study of the Shapley Concentration

1998 ◽  
Vol 179 ◽  
pp. 342-343
Author(s):  
S. Bardelli ◽  
E. Zucca ◽  
G. Zamorani ◽  
G. Vettolani ◽  
R. Scaramella
Keyword(s):  
Clusters Of Galaxies ◽  
Term Study ◽  
Remarkable Feature ◽  
X Ray ◽  
Hot Gas ◽  
Long Term Study ◽  
Motion Problem ◽  
Peculiar Motion ◽  
East West

The Shapley Concentration is a prominent supercluster in the southern sky. It is interesting not only for its relevance in the peculiar motion problem (it seems to be responsible of ∼ 30% of the acceleration acting on the Local Group of galaxies), but also because it is the most remarkable feature which appears studying the distribution of the Abell-ACO clusters of galaxies: Zucca et al. (1993) found that at every density contrast the Shapley Concentration stands out as the richest supercluster in the sky. In particular, the central part of this supercluster is dominated by a complex containing the three ACO clusters A3556, A3558 and A3562 and the poor cluster SC1329-314, which form a structure elongated ∼ 3° along the East-West direction. We are carrying on a long term study of the Shapley Concentration in order to describe its dynamical state and to determine its mass. The project consists of redshift determinations (with the ESO telescopes at La Silla) for galaxies both in the clusters (Bardelli et al. 1994) and in the inter-cluster field of this supercluster, X-ray observations (ROSAT) of the hot gas in the clusters (Bardelli et al. 1996) and radio observations (ATCA, MOST and VLA, Venturi et al. 1996) of the radiogalaxies.

scholarly journals MORPHODYNAMIC UPSCALING WITH THE MORFAC APPROACH

2011 ◽  
Vol 1 (32) ◽  
pp. 59 ◽  
Author(s):  
Roshanka Ranasinghe ◽  
Cilia Swinkels ◽  
Arjen Luijendijk ◽  
Judith Bosboom ◽  
Dano Roelvink ◽  
...  
Keyword(s):  
A Priori ◽  
Objective Method ◽  
Term Study ◽  
General Validity ◽  
Coastal Evolution ◽  
Long Term Study ◽  
Bed Form ◽  
Initial Results

The Morphological Acceleration Factor (MORFAC) approach for morphodynamic upscaling enables the simulation of long term coastal evolution. However the general validity of the MORFAC concept for coastal applications has not yet been comprehensively investigated. Furthermore, a robust and objective method for the a priori determination of the highest MORFAC that is suitable for a given simulation (i.e. critical MORFAC) does not currently exist. This paper presents some initial results of an ongoing, long-term study that attempts to rigorously and methodically investigate the limitations and strengths of the MORFAC approach. Based on the results of a numerical modelling exercise using the morphodynamic model Delft3D, the main dependencies and sensitivities of the MORFAC approach are investigated. A criterion (based on the CFL condition for bed form migration) for the a priori determination of the critical MORFAC is also proposed.

Preparation And elemental analysis of ancient fibers

1987 ◽  
Vol 45 ◽  
pp. 410-411
Author(s):  
Allen Angel ◽  
Kathryn A. Jakes
Keyword(s):  
Cross Sections ◽  
Physical Structure ◽  
Energy Dispersive ◽  
Archaeological Sites ◽  
X Ray ◽  
Long Term Storage ◽  
Backscattered Electron ◽  
Electron Imaging

Fabrics recovered from archaeological sites often are so badly degraded that fiber identification based on physical morphology is difficult. Although diagenetic changes may be viewed as destructive to factors necessary for the discernment of fiber information, changes occurring during any stage of a fiber's lifetime leave a record within the fiber's chemical and physical structure. These alterations may offer valuable clues to understanding the conditions of the fiber's growth, fiber preparation and fabric processing technology and conditions of burial or long term storage (1).Energy dispersive spectrometry has been reported to be suitable for determination of mordant treatment on historic fibers (2,3) and has been used to characterize metal wrapping of combination yarns (4,5). In this study, a technique is developed which provides fractured cross sections of fibers for x-ray analysis and elemental mapping. In addition, backscattered electron imaging (BSI) and energy dispersive x-ray microanalysis (EDS) are utilized to correlate elements to their distribution in fibers.

Quinapril for Sclerosis Failed in Long-Term Study

2007 ◽  
Vol 38 (6) ◽  
pp. 14
Author(s):  
DAMIAN MCNAMARA
Keyword(s):  
Term Study ◽  
Long Term Study
Sign in / Sign up

Export Citation Format

Share Document