2,684 research outputs found
Hawai‘i Supernova Flows: A Peculiar Velocity Survey Using Over a Thousand Supernovae in the Near-Infrared
No full textPh.D
Discovering and Exploring Extreme Black Holes and their Environments in the Transient Universe
No full textSupermassive black holes (SMBHs) at the centers of galaxies are some of the most luminous objects in the universe when feeding on surrounding material. This occurs when the SMBH is continuously accreting, called an active galactic nuclei (AGN). Or, a star can wander too close to the SMBH and becomes destroyed by the tidal forces, called a tidal disruption event (TDE), and the SMBH feeds on the stellar debris. The current landscape of astrophysics is rich with missions and telescopes ideal for exploring the transient universe, including AGNs and TDEs. Surveys, which image the entire night sky on various timescales ranging from minutes to days, provide crucial data to discover and characterize these nuclear transients. After developing a large sample of highly variable AGN observed by the ASAS-SN survey, I discovered a new, unique nuclear transient that undergoes periodic flares called ASASSN-14ko. One flare in 2014 was mistakenly classified as a supernova and the periodic behavior went undetected until my discovery. ASASSN-14ko is located within AGN ESO 253-G003 with optical flares present in the ASAS-SN light curve since 2014, and after modeling the peak times I find their timings are well-modeled with a period of 115.2 +1.3 -1.2 days and period derivative of -0.0026 +/- 0.0006. I organized, led, carried out, and analyzed data in an intensive multi-wavelength observing campaign to understand this unique object, and obtained X-ray, UV, and optical photometry and spectroscopy with numerous space- and ground-based facilities since 2020. All flares are characterized by a concurrent brightening in the UV and optical. The X-ray luminosities consistently decrease and the spectra become harder during the UV/optical rise but apparently without changes in absorption. The flares' photometric and spectroscopic signatures evolve rapidly. With the current suite of data, ASASSN-14ko is observationally consistent with a repeating partial tidal disruption event. This is the only such object ever discovered that has strongly periodic flares across X-ray, UV, and optical wavelengths, and provides a new laboratory to model TDEs and refine their theoretical frameworks.Ph.D
Messy eaters: A diversity of supermassive black hole accretion behaviors revealed by nuclear transients
No full textPh.D
The Golden Era of Transient Astronomy
No full textAstronomy has seen a massive increase in the discovery and classification of astrophysical transients, which are fleeting celestial events such as supernovae, flaring black holes, and tidal disruption events. The proliferation of sky surveys has produced an unprecedented data deluge, transforming how the astronomical community approaches research in the digital era. I have worked on various types of transients and how they shape their environment, or vice versa. The first 4 chapters discuss unique transients which provided special insight into the physical mechanisms governing their formation and evolution. Next, I take an in-depth look at how and why white dwarf stars explode as Type Ia supernovae. Finally, I present an overview of the Spectroscopic Classification of Transients (SCAT) survey. SCAT is a spectrophotometric transient survey designed to study the myriad of transient phenomena discovered by photometric sky surveys. I conclude by summarizing the current status of the survey, describing the data reduction pipeline, and highlighting preliminary results.Ph.D
Public worship and practical theology in the work of Benjamin Keach (1640-1704)
No full textThe late seventeenth century was a critical and fruitful period
for the Particular Baptists of England. Severely persecuted following
the Restoration, toleration in 1689 brought its own perils.
Particular Baptists were fortunate in having several strong leaders,
especially the London trio of Hanserd Knollys, William Kiffin, and
Benjamin Keach. Such a small and severely persecuted group as the
Baptists could afford little time for academic pursuits, thus of
necessity most of their theology was practical in nature.
Benjamin Keach (1640-1704) was the most outstanding practical
theologian among the English Particular Baptists of the late
seventeenth century. This dissertation is a study of Keach, in
particular his writings on public worship and practical theology.
Although Keach was a prolific author, he has been almost completely
neglected by scholars.
After a biographical sketch of Keach, this study considers his
writings on public worship and practical theology. In the area of
worship, Keach made two outstanding contributions: First, he was the
most vocal apologist for Baptist views on Baptism of his period.
Secondly, and more importantly, his hymn writing and defense of hymn
singing broke new ground, not just for Baptists, but for English
Protestantism, in general. In addition to his contributions in these
areas, he also dealt with the laying on of hands and the sabbath day
worship controversy.
Keach's contributions to practical theology fall into two main
groups: his writings that concern religious education and those that
deal with polity. In addition to these, Keach's vigorous advocacy of
a high Calvinist soteriology are also considered under the rubric of
practical theology. Keach's most important (although not his most
positive) contribution in this area were his soteriological writings.
Although well within the bounds of orthodoxy, some of the tendencies
in Keach's soteriology were taken up by the following generation of
Baptist leaders and developed into a stultifying hyper-Calvinism that
handicapped Baptist evangelism and missions.
In the conclusion, Keach's contributions to a theory of practical
theology are considered
Letter to Benjamin Clark Cutler from Benjamin Stevens
No full textLetter dated April 14, 1863 to Assistant Adjutant General, Captain Benjamin Clark Cutler, Santa Fe, from First Lieutenant Benjamin Stevens, Fort Wingate, New Mexico, recommending John Murphy and Martin Quintana, in the First New Mexico Volunteers, for military promotion to Second Lieutenant. Letter also signed by First Lieutenant J. L. Barbey, joint author. Civil War. HL introduction page overlaid by document. Letter in English, handwritten, 1pp/fr
Some new thoughts founded upon new principles, concerning a threefold motion of the earth. [electronic resource] : The rectification of the Kallender. The flowing and ebbing of the sea. The nature of the magnet. The variation of the compass. The cause of sea currents, and trade winds. The various motions of all the clestial orbs. The finding out the true place of the moon. And facilitating the discovery of the longitude. Not before thought of, or not offer'd to the World in this Manner. Most Humbly propos'd, and offer'd to the Consideration of the Learned and Ingenious, as Subjects of further Contemplation and Improvement. But in a more particular Manner to the Honourable, the Learned, and Ingenious Gentlemen of the Royal Society. By B. H. J.
No full textB. H. J. = Benjamin Habakkuk Jackson.Electronic reproduction.English Short Title Catalog,Reproduction of original from British Library
Substrate specificity of [alpha]-proteobacterial N-end rule adaptors
No full textThesis: Ph. D., Massachusetts Institute of Technology, Department of Biology, 2016.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis. "June 2016." In title on title page [alpha] appears as lower case Greek letters.Includes bibliographical references (pages 103-118).by Benjamin J. Stein.Ph. D
Comparing Optical Variability of Type 1 and Type 2 AGN from the BAT 9 Month Sample Using ASAS-SN and TESS Surveys
No full textWe present an optical variability analysis and comparison of the samples of Seyfert 1 (Sy1) and Seyfert 2 (Sy2) galaxies, selected from the Swift 9 month BAT catalog, using the light curves from Transiting Exoplanet Survey Satellite (TESS) and All-Sky Automated Survey for SuperNovae (ASAS-SN). We measured the normalized excess variance of TESS and ASAS-SN light curves for each target and performed a Kolmogorov–Smirnov test between the two samples, where our results showed significant differences. This is consistent with predictions from the unification model, where Seyfert 2s are obscured by the larger scale dust torus and their variability is suppressed. This variability difference is independent of the luminosity, Eddington ratio, or black hole mass, further supporting geometrical unification models. We searched the dependence of the normalized excess variance of Sy1s on absolute magnitudes, Eddington ratio, and black hole mass, where our results are consistent with relations found in the literature. Finally, a small subsample of changing-look (CL) active galactic nuclei (AGNs) that transitioned during the time frame of the ASAS-SN light curves, with their variability amplitudes changing according to the classification, have larger variability as type 1s and smaller as 2s. The change of variability amplitudes can be used to better pinpoint when the type transition occurred. The consistency trend of the variability amplitude differences between Sy1s and Sy2s and between CL AGNs in 1 or 2 stages suggests that variability can be a key factor in shedding light on the CL AGN or the dichotomy between Sy1 or Sy2 populations
Authorship in Burroughs\u27s Red Night Trilogy and Bowles\u27s Translation of Moroccan Storytellers
No full textIn his article Authorship in Burroughs\u27s Red Night Trilogy and Bowles\u27s Translation of Moroccan Storytellers Benjamin J. Heal discusses Paul Bowles\u27s and William S. Burroughs\u27s varying interrogation of the constructed nature of authorship. In his study Heal focuses on the publication history of Burroughs\u27s Cities of the Red Night (1981), which was written with considerable collaborative influence and Bowles\u27s translation of illiterate Moroccan storytellers, where his influence over the production and editing of the texts is blurred as are the roles of author and translator. Through an examination of Bowles\u27s and Burroughs\u27s authorship strategies in parallel with an explication of the poststructuralist authorship theories of Barthes and Foucault, Heal presents an analysis of the extent of Bowles\u27s and Burroughs\u27s critique of the Western construction of authorship
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