3,997 research outputs found

    Observing the earliest moments of supernovae using strong gravitational lenses

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    We determine the viability of exploiting lensing time delays to observe strongly gravitationally lensed supernovae (gLSNe) from first light. Assuming a plausible discovery strategy, the Legacy Survey of Space and Time (LSST) and the Zwicky Transient Facility (ZTF) will discover ∼\sim 110 and ∼\sim 1 systems per year before the supernova (SN) explosion in the final image respectively. Systems will be identified 11.7−9.3+29.811.7^{+29.8}_{-9.3} days before the final explosion. We then explore the possibility of performing early-time observations for Type IIP and Type Ia SNe in LSST-discovered systems. Using a simulated Type IIP explosion, we predict that the shock breakout in one trailing image per year will peak at ≲\lesssim 24.1 mag (≲\lesssim 23.3) in the BB-band (F218WF218W), however evolving over a timescale of ∼\sim 30 minutes. Using an analytic model of Type Ia companion interaction, we find that in the BB-band we should observe at least one shock cooling emission event per year that peaks at ≲\lesssim 26.3 mag (≲\lesssim 29.6) assuming all Type Ia gLSNe have a 1 M⊙_\odot red giant (main sequence) companion. We perform Bayesian analysis to investigate how well deep observations with 1 hour exposures on the European Extremely Large Telescope would discriminate between Type Ia progenitor populations. We find that if all Type Ia SNe evolved from the double-degenerate channel, then observations of the lack of early blue flux in 10 (50) trailing images would rule out more than 27% (19%) of the population having 1 M⊙_\odot main sequence companions at 95% confidence.Comment: 17 pages, 15 figures (including appendices). Accepted by MNRAS 3rd May 202

    An opportunity to begin again

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    Precise time delays from strongly gravitationally lensed type Ia supernovae with chromatically microlensed images

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    Time delays between the multiple images of strongly gravitationally lensed Type Ia supernovae (glSNe Ia) have the potential to deliver precise cosmological constraints, but the effects of microlensing on time delay extraction have not been studied in detail. Here we quantify the effect of microlensing on the glSN Ia yield of the Large Synoptic Survey Telescope (LSST) and the effect of microlensing on the precision and accuracy of time delays that can be extracted from LSST glSNe Ia. Microlensing has a negligible effect on the LSST glSN Ia yield, but it can be increased by a factor of ∼2 over previous predictions to 930 systems using a novel photometric identification technique based on spectral template fitting. Crucially, the microlensing of glSNe Ia is achromatic until three rest-frame weeks after the explosion, making the early-time color curves microlensing-insensitive time delay indicators. By fitting simulated flux and color observations of microlensed glSNe Ia with their underlying, unlensed spectral templates, we forecast the distribution of absolute time delay error due to microlensing for LSST, which is unbiased at the sub-percent level and peaked at 1% for color curve observations in the achromatic phase, while for light-curve observations it is comparable to state-of-the-art mass modeling uncertainties (4%). About 70% of LSST glSN Ia images should be discovered during the achromatic phase, indicating that microlensing time delay uncertainties can be minimized if prompt multicolor follow-up observations are obtained. Accounting for microlensing, the 1-2 day time delay on the recently discovered glSN Ia iPTF16geu can be measured to 40% precision, limiting its cosmological utility

    Costs of cannabis testing compliance: Assessing mandatory testing in the California cannabis market.

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    Most U.S. states that have regulated and taxed cannabis have imposed some form of mandatory safety testing requirements. In California, the country's largest and oldest legal cannabis market, mandatory testing was first enforced by state regulators in July 2018, and additional mandatory tests were introduced at the end of 2018. All cannabis must be tested and labeled as certified by a state-licensed cannabis testing laboratory before it can be legally marketed in California. Every batch that is sold by licensed retailers must be tested for more than 100 contaminants, including 66 pesticides with tolerance levels lower than the levels allowable for any other agricultural product in California. This paper estimates the costs of compliance with mandatory cannabis testing laws and regulations, using California's testing regime as a case study. We use state government data, data collected from testing laboratories, and data collected from lab equipment suppliers to run a set of Monte Carlo simulations and estimate the cost per pound of compliance with California's new cannabis testing regulations. We find that cost per pound is highly sensitive to average batch size and testing failure rates. We present results under a variety of different assumptions about batch size and failure rates. We also find that under realistic assumptions, the loss of cannabis that must be destroyed if a batch fails testing accounts for a larger share of total testing costs than does the cost of the lab tests. Using our best estimates of average batch size (8 pounds) and failure rate (4%) in the 2019 California market, we estimate testing cost at $136 per pound of dried cannabis flower, or about 10 percent of the reported average wholesale price of legal cannabis in the state. Our findings explain effects of the testing standards on the cost of supplying legal licensed cannabis, in California, other U.S. states, and foreign jurisdictions with similar testing regimes

    Single-object Imaging and Spectroscopy to Enhance Dark Energy Science from LSST

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    Single-object imaging and spectroscopy on telescopes with apertures ranging from ~4 m to 40 m have the potential to greatly enhance the cosmological constraints that can be obtained from LSST. Two major cosmological probes will benefit greatly from LSST follow-up: accurate spectrophotometry for nearby and distant Type Ia supernovae will expand the cosmological distance lever arm by unlocking the constraining power of high-z supernovae; and cosmology with time delays of strongly-lensed supernovae and quasars will require additional high-cadence imaging to supplement LSST, adaptive optics imaging or spectroscopy for accurate lens and source positions, and IFU or slit spectroscopy to measure detailed properties of lens systems. We highlight the scientific impact of these two science drivers, and discuss how additional resources will benefit them. For both science cases, LSST will deliver a large sample of objects over both the wide and deep fields in the LSST survey, but additional data to characterize both individual systems and overall systematics will be key to ensuring robust cosmological inference to high redshifts. Community access to large amounts of natural-seeing imaging on ~2-4 m telescopes, adaptive optics imaging and spectroscopy on 8-40 m telescopes, and high-throughput single-target spectroscopy on 4-40 m telescopes will be necessary for LSST time domain cosmology to reach its full potential. In two companion white papers we present the additional gains for LSST cosmology that will come from deep and from wide-field multi-object spectroscopy.Comment: Submitted to the call for Astro2020 science white paper

    Three Essays on the Objective Function in Economics.

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    This dissertation consists of three largely independent essays. The first finds a significant correlation between the price of crude oil and significant terrorist attacks by groups of Middle Eastern origin against Western nations. In particular, such terrorist attacks are considerably more common after oil prices fall than after they rise. The paper goes on to suggest that a model based on expected utility theory may account for this observation. Agents that are predisposed to comitting terrorist acts – but have not yet done so – may be triggered to act when economic conditions worsen. The second essay shows that the monetary policies of both the Federal Reserve and the European Central Bank tend to be influenced by the degree of dispersion of unemployment rates across regions. This result is very robust, particularly for the United States. However, the two central banks appear to respond differently to this dispersion. That either bank cares about dispersion at all is surprising, as a result similar to certainty equivalence suggests that – at least in the standard cases – the banks should only be concerned with aggregate measures. We propose two alternative theories that seem, respectively, to be consistent with each bank’s policies. The third essay outlines a strictly neoclassical economic approach to studying behavior linked to emotions. The paper suggests that by explicitly including emotions as an argument in the utility function, textbook economics can yield some non-obvious insights into some human behaviors. The essay demonstrates the neoclassical technique in a number of different settings, and finds it to be applicable to a wide variety of behavrioral phenomena. A unifying theme for these papers – and one that is particularly stressed in the third chapter – is that a correct identification of the objective function of economic agents can be vital in trying to explain puzzling phenomena.Ph.D.Public Policy & EconomicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/57701/2/dgoldste_1.pd
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