Radiative interaction between the relativistic jet and optically thick envelope in tidal disruption events

Reverberation observations have uncovered an Fe K{\alpha} fluorescence line in the tidal disruption event (TDE) Swift J1644+57 (Kara et al. 2016). The discovery paper used the lag spectrum to argue that the X-ray continuum source was located very close to the blackhole (~30 gravitational radii) and moved sub-relativistically. We reanalyze the lag spectrum, pointing out that dilution effects cause it to indicate a geometric scale an order of magnitude larger than previously inferred. If the X-ray continuum is produced by a relativistic jet, as suggested by rapid variability, high luminosity and hard spectrum, this larger scale predicts an Fe ionization state consistent with efficient K{\alpha} production. Moreover, the momentum of the jet radiation impinging on the surrounding accretion flow on this larger scale accelerates a layer of gas to speeds ~0.1-0.2c, consistent with the blueshifted line profile. Implications of our results on the global picture of jetted TDEs are discussed. A power-law {\gamma}/X-ray spectrum may be produced by external UV-optical photons being repetitively inverse-Compton scattered by cold electrons in the jet, although our model for the K{\alpha} reverberation does not depend on the jet radiation mechanism (magnetic reconnection in a Poynting jet is still a viable mechanism). The non-relativistic wind driven by jet radiation may explain the late-time radio rebrightening in Swift J1644+57. This energy injection may also cause the thermal UV-optical emission from jetted TDEs to be systematically brighter than in non-jetted ones.Comment: 13 pages, 3 figures, MNRAS accepte

Mercury in Florida Bay fish: spatial distribution of elevated concentrations and possible linkages to Everglades restoration

Health advisories are now posted in northern Florida Bay, adjacent to the Everglades, warning of high mercury concentrations in some species of gamefish. Highest concentrations of mercury in both forage fish and gamefish have been measured in the northeastern corner of Florida Bay, adjacent to the dominant freshwater inflows from the Everglades. Thirty percent of spotted seatrout (Cynoscion nebulosus Cuvier, 1830) analyzed exceeded Florida’s no consumption level of 1.5 μg g−1 mercury in this area. We hypothesized that freshwater draining the Everglades served as the major source of methylmercury entering the food web supporting gamefish. A lack of correlation between mercury concentrations and salinity did not support this hypothesis, although enhanced bioavailability of methylmercury is possible as freshwater is diluted with estuarine water. Stable isotopes of carbon, nitrogen, and sulfur were measured in fish to elucidate the shared pathways of methylmercury and nutrient elements through the food web. These data support a benthic source of both methylmercury and nutrient elements to gamefish within the eastern bay, as opposed to a dominant watershed source. Ecological characteristics of the eastern bay, including active redox cycling in near-surface sediments without excessive sulfide production are hypothesized to promote methylmercury formation and bioaccumulation in the benthos. Methylmercury may then accumulate in gamefish through a food web supported by benthic microalgae, detritus, pink shrimp (Farfantepenaeus duorarum Burkenroad, 1939), and other epibenthic feeders. Uncertainty remains as to the relative importance of watershed imports of methylmercury from the Everglades and in situ production in the bay, an uncertainty that needs resolution if the effects of Everglades restoration on mercury levels in fish are to be modeled and managed

Man-computer role in space navigation and guidance Final report

Man computer roles and hardware requirements for navigation and guidance in deep space manned mission

Living With Other Gods: My Mom, My Dad, My Grandmother, and Me

In lieu of an abstract, below is the essay\u27s first paragraph. The notion of “living with other gods” applies to my family. Living with other gods means that people with different beliefs live with one-another peacefully. When applying this notion to my family, one can relate it best to the religious relations that are between my father and me and that are of between my mother and grandmother. My name is Timothy Crumley; I’m 14 years of age, I’m in the 9th grade, and I attend a collage-prep school called The Harley School. My father seems to have no belief in God and this is seen many times when he talks to me about something important: An example would be when he talks about life or where we as humans have come from: there is no mention of God. My mother, however, is different. When talking about where humans came from with her, God is mentioned, but so is science. My grandmother, being from a “conservative Christian” generation, is open minded about science but, when asked or talked with about how life began or where humans came from, mostly only Adam and/or Eve are mentioned. Talking about how life started is only an example, but it is a significant one. As one can see, these three people in my life have different ways of looking at where life came from, so one can easily figure that they must have different views of where life is going