73 research outputs found
Concurrent Image Processing Executive (CIPE). Volume 1: Design overview
The design and implementation of a Concurrent Image Processing Executive (CIPE), which is intended to become the support system software for a prototype high performance science analysis workstation are described. The target machine for this software is a JPL/Caltech Mark 3fp Hypercube hosted by either a MASSCOMP 5600 or a Sun-3, Sun-4 workstation; however, the design will accommodate other concurrent machines of similar architecture, i.e., local memory, multiple-instruction-multiple-data (MIMD) machines. The CIPE system provides both a multimode user interface and an applications programmer interface, and has been designed around four loosely coupled modules: user interface, host-resident executive, hypercube-resident executive, and application functions. The loose coupling between modules allows modification of a particular module without significantly affecting the other modules in the system. In order to enhance hypercube memory utilization and to allow expansion of image processing capabilities, a specialized program management method, incremental loading, was devised. To minimize data transfer between host and hypercube, a data management method which distributes, redistributes, and tracks data set information was implemented. The data management also allows data sharing among application programs. The CIPE software architecture provides a flexible environment for scientific analysis of complex remote sensing image data, such as planetary data and imaging spectrometry, utilizing state-of-the-art concurrent computation capabilities
Concurrent Image Processing Executive (CIPE)
The design and implementation of a Concurrent Image Processing Executive (CIPE), which is intended to become the support system software for a prototype high performance science analysis workstation are discussed. The target machine for this software is a JPL/Caltech Mark IIIfp Hypercube hosted by either a MASSCOMP 5600 or a Sun-3, Sun-4 workstation; however, the design will accommodate other concurrent machines of similar architecture, i.e., local memory, multiple-instruction-multiple-data (MIMD) machines. The CIPE system provides both a multimode user interface and an applications programmer interface, and has been designed around four loosely coupled modules; (1) user interface, (2) host-resident executive, (3) hypercube-resident executive, and (4) application functions. The loose coupling between modules allows modification of a particular module without significantly affecting the other modules in the system. In order to enhance hypercube memory utilization and to allow expansion of image processing capabilities, a specialized program management method, incremental loading, was devised. To minimize data transfer between host and hypercube a data management method which distributes, redistributes, and tracks data set information was implemented
Concurrent Image Processing Executive (CIPE). Volume 3: User's guide
CIPE (the Concurrent Image Processing Executive) is both an executive which organizes the parameter inputs for hypercube applications and an environment which provides temporary data workspace and simple real-time function definition facilities for image analysis. CIPE provides two types of user interface. The Command Line Interface (CLI) provides a simple command-driven environment allowing interactive function definition and evaluation of algebraic expressions. The menu interface employs a hierarchical screen-oriented menu system where the user is led through a menu tree to any specific application and then given a formatted panel screen for parameter entry. How to initialize the system through the setup function, how to read data into CIPE symbols, how to manipulate and display data through the use of executive functions, and how to run an application in either user interface mode, are described
How Will Astronomy Archives Survive The Data Tsunami?
The field of astronomy is starting to generate more data than can be managed,
served and processed by current techniques. This paper has outlined practices
for developing next-generation tools and techniques for surviving this data
tsunami, including rigorous evaluation of new technologies, partnerships
between astronomers and computer scientists, and training of scientists in
high-end software engineering engineering skills.Comment: 8 pages, 3 figures; ACM Queue. Vol 9, Number 10, October 2011
(http://queue.acm.org/detail.cfm?id=2047483
VLASS tidal disruption events with optical flares I: the sample and a comparison to optically-selected TDEs
In this work, we use the Jansky VLA Sky Survey (VLASS) to compile the first
sample of six radio-selected tidal disruption events (TDEs) with transient
optical counterparts. While we still lack the statistics to do detailed
population studies of radio-selected TDEs, we use these events to suggest
trends in host galaxy and optical light curve properties that may correlate
with the presence of radio emission, and hence can inform optically-selected
TDE radio follow-up campaigns. We find that radio-selected TDEs tend to have
faint and cool optical flares, as well as host galaxies with low SMBH masses.
Our radio-selected TDEs also tend to have more energetic, larger radio emitting
regions than radio-detected, optically-selected TDEs. We consider possible
explanations for these trends, including by invoking super-Eddington accretion
and enhanced circumnuclear media. Finally, we constrain the radio-emitting TDE
rate to be Gpc yr.Comment: 26 pages, 5 tables, 11 figures, submitted to Ap
Astrophysical implications of hypothetical stable TeV-scale black holes
We analyze macroscopic effects of TeV-scale black holes, such as could
possibly be produced at the LHC, in what is regarded as an extremely
hypothetical scenario in which they are stable and, if trapped inside Earth,
begin to accrete matter. We examine a wide variety of TeV-scale gravity
scenarios, basing the resulting accretion models on first-principles, basic,
and well-tested physical laws. These scenarios fall into two classes, depending
on whether accretion could have any macroscopic effect on the Earth at times
shorter than the Sun's natural lifetime. We argue that cases with such effect
at shorter times than the solar lifetime are ruled out, since in these
scenarios black holes produced by cosmic rays impinging on much denser white
dwarfs and neutron stars would then catalyze their decay on timescales
incompatible with their known lifetimes. We also comment on relevant lifetimes
for astronomical objects that capture primordial black holes. In short, this
study finds no basis for concerns that TeV-scale black holes from the LHC could
pose a risk to Earth on time scales shorter than the Earth's natural lifetime.
Indeed, conservative arguments based on detailed calculations and the
best-available scientific knowledge, including solid astronomical data,
conclude, from multiple perspectives, that there is no risk of any significance
whatsoever from such black holes.Comment: Version2: Minor corrections/fixed typos; updated reference
The first systematically identified repeating partial tidal disruption event
Tidal disruption events (TDEs) occur when a star enters the tidal radius of a
supermassive black hole (SMBH). If the star only grazes the tidal radius, a
fraction of the stellar mass will be accreted in a partial TDE (pTDE). The
remainder can continue orbiting and may re-disrupted at pericenter, causing a
repeating pTDE. pTDEs may be as or more common than full TDEs (fTDEs), yet few
are known. In this work, we present the discovery of the first repeating pTDE
from a systematically-selected sample, AT\,2020vdq. AT\,2020vdq was originally
identified as an optically- and radio-flaring TDE. Around years after its
discovery, it rebrightened dramatically and rapidly in the optical. The optical
flare was remarkably fast and luminous compared to previous TDEs. It was
accompanied by extremely broad () optical/UV spectral features and
faint X-ray emission (\,erg\,s), but no new
radio-emitting component. Based on the transient optical/UV spectral features
and the broadband light curve, we show that AT\,2020vdq is a repeating pTDE. We
then use it to constrain TDE models; in particular, we favor a star originally
in a very tight binary system that is tidally broken apart by the Hills
mechanism. We also constrain the repeating pTDE rate to be to
yr galaxy, with uncertainties dominated by the unknown
distribution of pTDE repeat timescales. In the Hills framework, this means the
binary fraction in the galactic nucleus is of the order few percent.Comment: 24 pages, 13 figures, submitted to Ap
An Optically-Discovered Outburst from XTE J1859+226
Using the Zwicky Transient Facility, in 2021 February we identified the first
known outburst of the Black Hole X-ray Transient XTE J1859+226 since its
discovery in 1999. The outburst was visible at X-ray, UV, and optical
wavelengths for less than 20 days, substantially shorter than its 320-day full
outburst in 1999, and the observed peak luminosity was two orders of magnitude
lower. Its peak bolometric luminosity was only erg s,
implying an Eddington fraction of about . The source remained
in the hard spectral state throughout the outburst. From optical spectroscopy
measurements we estimate an outer disk radius of 10 cm. The low observed
X-ray luminosity is not sufficient to irradiate the entire disk, but we observe
a surprising exponential decline in the X-ray lightcurve. These observations
highlight the potential of optical and infrared (O/IR) synoptic surveys to
discover low-luminosity activity from X-ray transients.Comment: 12 pages, 6 figures, accepted for publication in Ap
The Early Ultraviolet Light-Curves of Type II Supernovae and the Radii of Their Progenitor Stars
We present a sample of 34 normal SNe II detected with the Zwicky Transient
Facility, with multi-band UV light-curves starting at days after
explosion, as well as X-ray detections and upper limits. We characterize the
early UV-optical colors and provide prescriptions for empirical host-extinction
corrections. We show that the days UV-optical colors and the blackbody
evolution of the sample are consistent with the predictions of spherical phase
shock-cooling (SC), independently of the presence of `flash ionization"
features. We present a framework for fitting SC models which can reproduce the
parameters of a set of multi-group simulations without a significant bias up to
20% in radius and velocity. Observations of about half of the SNe II in the
sample are well-fit by models with breakout radii cm. The other
half are typically more luminous, with observations from day 1 onward that are
better fit by a model with a large cm breakout radius. However,
these fits predict an early rise during the first day that is too slow. We
suggest these large-breakout events are explosions of stars with an inflated
envelope or a confined CSM with a steep density profile, at which breakout
occurs. Using the X-ray data, we derive constraints on the extended
( cm) CSM density independent of spectral modeling, and find most
SNe II progenitors lose a few years before
explosion. This provides independent evidence the CSM around many SNe II
progenitors is confined. We show that the overall observed breakout radius
distribution is skewed to higher radii due to a luminosity bias. We argue that
the of red supergiants (RSG) explode as SNe II with breakout
radii consistent with the observed distribution of field RSG, with a tail
extending to large radii, likely due to the presence of CSM.Comment: Submitted to ApJ. Comments are welcome at [email protected] or
[email protected]
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