920 research outputs found
Descriptive Phenomenological Analysis of Influences to Death Anxiety
There are two certainties in life: we are born, and we will die. Everything in between birth and death is our life. This truth leads many individuals to existential questions: What is the meaning of life? How do we become satisfied with life, knowing that death is impending? Does awareness of death motivate how we live? Death anxiety is a well-studied subject; well over 500 studies provide information on who is the most fearful of death among a variety of groups (women versus men, religious verses secular, youth verses elderly, et cetera). These studies also use presuppositions to explain fear of death, such as, elder individuals have less fear of death due to life experience, a practical reason that makes sense and is likely true. My study looks beyond practical reasoning. I used descriptive phenomenological research to explore the subjective experiences of six individuals, to look beyond presuppositions and examine personal reasoning, and explore whether there were commonalities among their experiences. This study found ten (10) commonalities within the subjective experience of each participant that influenced each person’s fear of death. In the whole these commonalities describe the structure of a phenomenon, experiences that alter the fear of death and influences actions taken in life. The commonalities are loss, selfishness, worry about the process of dying, helplessness over what cannot be controlled, common daily fears, meaning-making that is embedded in general reasoning, reports of self-protection, pleasure-seeking drives, struggles with internal and external values, and a feeling of relief that is found in those who have lost a loved one to chronic illness. This study provides an enhanced understanding of how individuals process death anxiety. This dissertation is available in open access at AURA, http://aura.antioch.edu/ and Ohio Link ETD Center, https://etd.ohiolink.edu/etd
A Chandra Observation of the Diffuse Emission in the Face-on Spiral NGC 6946
This paper describes the {\it Chandra} observation of the diffuse emission in
the face-on spiral NGC 6946. Overlaid on optical and H images, the
diffuse emission follows the spiral structure of the galaxy. An overlay on a 6
cm polarized radio intensity map confirms the phase offset of the polarized
emission. We then extract and fit the spectrum of the unresolved emission with
several spectral models. All model fits show a consistent continuum thermal
temperature with a mean value of 0.250.03 keV. Additional degrees of
freedom are required to obtain a good fit and any of several models satisfy
that need; one model uses a second continuum component with a temperature of
0.700.10 keV. An abundance measure of 3 for Si differs
from the solar value at the 90% confidence level; the net diffuse spectrum
shows the line lies above the instrumental Si feature. For Fe, the abundance
measure of 0.670.13 is significant at 99%. Multiple gaussians also provide
a good fit. Two of the fitted gaussians capture the O VII and O VIII emission;
the fitted emission is consistent with an {\it XMM-Newton} RGS spectrum of
diffuse gas in M81. The ratio of the two lines is 0.6-0.7 and suggests the
possibility of non-equilibrium ionization conditions exist in the ISM of NGC
6946. An extrapolation of the point source luminosity distribution shows the
diffuse component is not the sum of unresolved point sources; their
contribution is at most 25%.Comment: accepted for ApJ; 16 pages; 12 figs; to meet Archive size limits,
most converted to jpe
Dissecting the spiral galaxy M83: mid-infrared emission and comparison with other tracers of star formation
We present a detailed mid-infrared study of the nearby, face-on spiral galaxy
M83 based on ISOCAM data. M83 is a unique case study, since a wide variety of
MIR broad-band filters as well as spectra, covering the wavelength range of 4
to 18\mu m, were observed and are presented here. Emission maxima trace the
nuclear and bulge area, star-formation regions at the end of the bar, as well
as the inner spiral arms. The fainter outer spiral arms and interarm regions
are also evident in the MIR map. Spectral imaging of the central 3'x3' (4 kpc x
4 kpc) field allows us to investigate five regions of different environments.
The various MIR components (very small grains, polycyclic aromatic hydrocarbon
(PAH) molecules, ionic lines) are analyzed for different regions throughout the
galaxy. In the total 4\mu m to 18\mu m wavelength range, the PAHs dominate the
luminosity, contributing between 60% in the nuclear and bulge regions and 90%
in the less active, interarm regions. Throughout the galaxy, the underlying
continuum emission from the small grains is always a smaller contribution in
the total MIR wavelength regime, peaking in the nuclear and bulge components.
The implications of using broad-band filters only to characterize the
mid-infrared emission of galaxies, a commonly used ISOCAM observation mode, are
discussed. We present the first quantitative analysis of new H-alpha and 6cm
VLA+Effelsberg radio continuum maps of M83. The distribution of the MIR
emission is compared with that of the CO, HI, R band, H-alpha and 6cm radio. A
striking correlation is found between the intensities in the two mid-infrared
filter bands and the 6cm radio continuum. To explain the tight
mid-infrared-radio correlation we propose the anchoring of magnetic field lines
in the photoionized shells of gas clouds.Comment: 22 pages, 15 figures. Accepted for publication in A&
Hot gas and magnetic arms of NGC 6946 : indications for reconnection heating?
Context. The grand-design face-on spiral galaxy NGC 6946 is remarkable because of its high star formation activity, the massive northern spiral arm, and the magnetic arms, which are observed in polarized radio synchrotron emission and are located between the optical arms and possibly are magnetic reconnection regions. Aims. We used electron densities and temperatures in star-forming (active) and less active regions and compared them to findings from the analysis of the radio data to study the energy budget of NGC 6946. The hot gas above the magnetic arms between the optical arms might suggest gas heating by reconnection. We also study the population of point sources in NGC 6946, including the origin of the puzzling ultra-luminous emission complex MF16. Methods. X-ray observations of NGC 6946 performed with XMM-Newton were used to study the emission from X-ray point sources and diffuse hot gas, including the magnetic arms and the halo. Spectral fitting of the diffuse X-ray emission allowed us to derive temperatures of the hot gas. With assumptions about the emission volume, this allowed us to estimate gas densities, masses, and cooling times. Results. To explain the X-ray emission from the spiral arms of NGC 6946 two-temperature plasma models are needed to account for the disk and halo emission. The interarm regions show only one thermal component. We observe that the temperature of the hot gas in and above the magnetic arm regions increases slightly when compared to the average temperatures in the areas in and above the spiral arms. For the southwestern part of the disk, which is depolarized in the radio range by Faraday rotation, we find more efficient mixing of disk and halo gas. Conclusions. We propose magnetic reconnection in the magnetic arm regions of NGC 6946 as the possible cause of the additional heating of the gas and ordering of the magnetic fields. In the southwestern part of the galactic disk we observed indications of a possible faster outflow of the hot gas. A very hot gas within the MF 16 nebula possibly suggests shock heating by a supernova explosion
A Catalog of Candidate Intermediate-luminosity X-ray Objects
ROSAT, and now Chandra, X-ray images allow studies of extranuclear X-ray
point sources in galaxies other than our own. X-ray observations of normal
galaxies with ROSAT and Chandra have revealed that off-nuclear, compact,
Intermediate-luminosity (Lx[2-10 keV] >= 1e39 erg/s) X-ray Objects (IXOs,
a.k.a. ULXs [Ultraluminous X-ray sources]) are quite common. Here we present a
catalog and finding charts for 87 IXOs in 54 galaxies, derived from all of the
ROSAT HRI imaging data for galaxies with cz <= 5000 km/s from the Third
Reference Catalog of Bright Galaxies (RC3). We have defined the cutoff Lx for
IXOs so that it is well above the Eddington luminosity of a 1.4 Msun black hole
(10^38.3 erg/s), so as not to confuse IXOs with ``normal'' black hole X-ray
binaries. This catalog is intended to provide a baseline for follow-up work
with Chandra and XMM, and with space- and ground-based survey work at
wavelengths other than X-ray. We demonstrate that elliptical galaxies with IXOs
have a larger number of IXOs per galaxy than non-elliptical galaxies with IXOs,
and note that they are not likely to be merely high-mass X-ray binaries with
beamed X-ray emission, as may be the case for IXOs in starburst galaxies.
Approximately half of the IXOs with multiple observations show X-ray
variability, and many (19) of the IXOs have faint optical counterparts in DSS
optical B-band images. Follow-up observations of these objects should be
helpful in identifying their nature.Comment: 29 pages, ApJS, accepted (catalog v2.0) (full resolution version of
paper and future releases of catalog at http://www.xassist.org/ixocat_hri
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