30 research outputs found
Body genres, embodiment and engagement: Second Person in Audio Storytelling
In the article, “Film Bodies: Gender, Genre and Excess” (1991), Linda Williams defines as body genres the film genres that are based on stimulating certain physical reactions in the bodies of spectators. These are fear (horror), sexual arousal (pornography), and tears (melodrama). All three genres share, “an apparent lack of proper aesthetic distance, a sense of over-involvement in sensation and emotion. We feel manipulated,” by them. The bodies of whoever watches these films are involved in an “involuntary mimicry” of the body on the screen. During a talk at the 2016 Third Coast Conference, radio producer Eleanor McDowall inquired about the equivalent of body genres in audio storytelling (radio, podcast, and other forms of audio narratives). What are those sound works that engage the bodies of their listeners, not by merely talking about bodily reactions, but by actually provoking them
The ROSAT Deep Cluster Survey: the X-ray Luminosity Function out to z=0.8
We present the X-ray Luminosity Function (XLF) of the ROSAT Deep Cluster
Survey (RDCS) sample over the redshift range 0.05-0.8. Our results are derived
from a complete flux-limited subsample of 70 galaxy clusters, representing the
brightest half of the total sample, which have been spectroscopically
identified down to the flux limit of 4*10^{-14} erg/cm^2/s (0.5-2.0 keV) and
have been selected via a serendipitous search in ROSAT-PSPC pointed
observations. The redshift baseline is large enough that evolutionary effects
can be studied within the sample. The local XLF (z < 0.25) is found to be in
excellent agreement with previous determinations using the ROSAT All-Sky Survey
data. The XLF at higher redshifts, when combined with the deepest number counts
constructed to date (f>2*10^{-14} arg/cm^2/s), reveal no significant evolution
at least out to z=0.8, over a luminosity range 2*10^{42}-3*10^{44} erg/s in the
[0.5-2 keV] band. These findings extend the study of cluster evolution to the
highest redshifts and the faintest fluxes probed so far in X-ray surveys. They
complement and do not necessarily conflict with those of the Einstein Extended
Medium Sensitivity Survey, leaving the possibility of negative evolution of the
brightest end of the XLF at high redshifts.Comment: 12 pages, 4 figures, LaTeX (aasms4.sty). To appear in ApJ Letter
High energy from space
The following subject areas are covered: (1) important scientific problems for high energy astrophysics (stellar activity, the interstellar medium in galaxies, supernovae and endpoints of stellar evolution, nucleosynthesis, relativistic plasmas and matter under extreme conditions, nature of gamma-bursts, identification of black holes, active nuclei, accretion physics, large-scale structures, intracluster medium, nature of dark matter, and the X- and gamma-ray background); (2) the existing experimental programs (Advanced X-Ray Astrophysics Facility (AXAF), Gamma Ray Observatory (GRO), X-Ray Timing Explorer (XTE), High Energy Transient Experiment (HETE), U.S. participation in foreign missions, and attached Shuttle and Space Station Freedom payloads); (3) major missions for the 1990's; (4) a new program of moderate missions; (5) new opportunities for small missions; (6) technology development issues; and (7) policy issues
The Chandra Deep Field South: the 1 Million Second
We present the main results from our 940 ksec observation of the Chandra Deep
Field South (CDFS), using the source catalog described in an accompanying paper
(Giacconi et al. 2001). We extend the measurement of source number counts to
5.5e-17 erg/cm^2/s in the soft 0.5-2 keV band and 4.5e-16 erg/cm^2/s in the
hard 2-10 keV band. The hard band LogN-LogS shows a significant flattening
(slope~=0.6) below ~1e-14 erg/cm^2/s, leaving at most 10-15% of the X-ray
background (XRB) to be resolved, the main uncertainty lying in the measurement
of the total flux of the XRB. On the other hand, the analysis in the very hard
5-10 keV band reveals a relatively steep LogN-LogS (slope ~=1.3) down to 1e-15
erg/cm^2/s. Together with the evidence of a progressive flattening of the
average X-ray spectrum near the flux limit, this indicates that there is still
a non negligible population of faint hard sources to be discovered at energies
not well probed by Chandra, which possibly contribute to the 30 keV bump in the
spectrum of the XRB. We use optical redshifts and identifications, obtained
with the VLT, for one quarter of the sample to characterize the combined
optical and X-ray properties of the CDFS sample. Different source types are
well separated in a parameter space which includes X-ray luminosity, hardness
ratio and R-K color. Type II objects, while redder on average than the field
population, have colors which are consistent with being hosted by a range of
galaxy types. Type II AGN are mostly found at z<~1, in contrast with
predictions based on AGN population synthesis models, thus suggesting a
revision of their evolutionary parameters.Comment: Accepted by The Astrophysical Journal, 24 pages, 8 figures, 1 color
jpg plate (fig.1
A Classic Type 2 QSO
In the Chandra Deep Field South 1Msec exposure we have found, at redshift
3.700 +- 0.005, the most distant Type 2 AGN ever detected. It is the source
with the hardest X-ray spectrum with redshift z>3. The optical spectrum has no
detected continuum emission to a 3sigma detection limit of ~3 10^{-19}
ergs/s/cm^2/AA and shows narrow lines of Ly_alpha, CIV, NV, HeII, OVI, [OIII],
and CIII]. Their FWHM line widths have a range of ~700-2300 km/s with an
average of approximately ~1500 km/s. The emitting gas is metal rich (Z ~2.5-3
Z_solar). In the X-ray spectrum of 130 counts in the 0.5-7 keV band there is
evidence for intrinsic absorption with N_H > 10^{24} cm^{-2}. An iron K_alpha
line with rest frame energy and equivalent width of ~6.4 keV and ~1 keV,
respectively, in agreement with the obscuration scenario, is detected at a
2sigma level. If confirmed by our forthcoming XMM observations this would be
the highest redshift detection of FeK_alpha. Depending on the assumed cosmology
and the X-ray transfer model, the 2-10 keV rest frame luminosity corrected for
absorption is ~10^{45 +- 0.5} ergs/s, which makes our source a classic example
of the long sought Type 2 QSOs. From standard population synthesis models,
these sources are expected to account for a relevant fraction of the
black-hole-powered QSO distribution at high redshift.Comment: 24 LaTeX pages including 6 postscript figures. Revised version,
accepted by Ap
The X-Ray Derived Cosmological Star Formation History and the Galaxy X-Ray Luminosity Functions in the Chandra Deep Fields North and South
The cosmological star formation rate in the combined Chandra Deep Fields
North and South is derived from our X-Ray Luminosity Function for Galaxies in
these Deep Fields. Mild evolution is seen up to redshift order unity with SFR ~
(1 + z)^{2.7}. This is the first directly observed normal star-forming galaxy
X-ray luminosity function (XLF) at cosmologically interesting redshifts (z>0).
This provides the most direct measure yet of the X-ray derived cosmic
star-formation history of the Universe. We make use of Bayesian statistical
methods to classify the galaxies and the two types of AGN, finding the most
useful discriminators to be the X-ray luminosity, X-ray hardness ratio, and
X-ray to optical flux ratio. There is some residual AGN contamination in the
sample at the bright end of the luminosity function. Incompleteness slightly
flattens the XLF at the faint end of the luminosity function. The XLF has a
lognormal distribution and agrees well with the radio and infrared luminosity
functions. However, the XLF does not agree with the Schechter luminosity
function for the H-alpha LF indicating that additional and different physical
processes may be involved in the establishment of the lognormal form of the
XLF. The agreement of our star formation history points with the other star
formation determinations in different wavebands (IR, Radio, H-alpha) gives an
interesting constraint on the IMF, and X-rays may be measuring directly the
binary star formation history of the Universe. X-ray studies will continue to
be useful for probing the star formation history of the universe by avoiding
problems of obscuration. Star formation may therefore be measured in more
detail by deep surveys with future x-ray missions.Comment: Accepted for publication in ApJ. 19 pages with 10 figures formatted
with emulateapj. Version with B/W only figures available at
http://www.pha.jhu.edu/~ptak/paper