The GRB-SLSN Connection: mis-aligned magnetars, weak jet emergence, and observational signatures

Multiple observational lines of evidence support a connection between hydrogen-poor superluminous supernovae (SLSNe) and long duration gamma-ray bursts (GRBs). Both events require a powerful central energy source, usually attributed to a millisecond magnetar or an accreting black hole. The GRB-SLSN link raises several theoretical questions: What distinguishes the engines responsible for these different phenomena? Can a single engine power both a GRB and a luminous SN in the same event? We propose a new unifying model for magnetar thermalization and jet formation: misalignment between the rotation (${\bf \Omega}$) and magnetic dipole (${\bf \mu}$) axes thermalizes a fraction of the spindown power by reconnection in the striped equatorial wind, providing a guaranteed source of "thermal" emission to power the supernova. The remaining un-thermalized power energizes a relativistic jet. In this picture, the GRB-SLSN dichotomy is directly linked to ${\bf \Omega \cdot \mu}$. We extend earlier work to show that even weak relativistic jets of luminosity $\sim10^{46}$ erg s$^{-1}$ can escape the expanding SN ejecta hours after the explosion, implying that escaping relativistic jets may accompany many SLSNe. We calculate the observational signature of these jets. We show that they may produce transient UV cocoon emission lasting a few hours when the jet breaks out of the ejecta surface. A longer-lived optical/UV signal may originate from a mildly-relativistic wind driven from the interface between the jet and the ejecta walls. This provides a new explanation for the secondary early-time maximum observed in some SLSNe light curves, such as LSQ14bdq. This scenario also predicts a population of GRB from on-axis jets with extremely long durations, potentially similar to the population of "jetted tidal disruption events", in coincidence with a small subset of SLSNe.Comment: 17 pages, 7 figures, submitted to MNRA

GNSS Signal Authentication via Power and Distortion Monitoring

We propose a simple low-cost technique that enables civil Global Positioning System (GPS) receivers and other civil global navigation satellite system (GNSS) receivers to reliably detect carry-off spoofing and jamming. The technique, which we call the Power-Distortion detector, classifies received signals as interference-free, multipath-afflicted, spoofed, or jammed according to observations of received power and correlatio n function distortion. It does not depend on external hardware or a network connection and can be readily implemented on many receivers via a firmware update. Crucially, the detector can with high probability distinguish low-power spoofing from ordinary multipath. In testing against over 25 high-quality empirical data sets yielding over 900,000 separate detection tests, the detector correctly alarms on all malicious spoofing or jamming attack s while maintaining a <0.5% single-channel false alarm rate.Aerospace Engineering and Engineering Mechanic

Congress’s Commissioners: Former Hill Staffers at the S.E.C. and Other Independent Regulatory Commissions

The expression “personnel is policy” has become a truism in Washington. Yet our understanding of how the political branches use appointments to project influence into the administrative state is incomplete. This Article leverages data on almost one-thousand commissioners serving on eleven major independent regulatory commissions to chart, for the first time, Congress’s growing practice of placing former legislative-branch personnel onto these entities. We then theorize that this phenomenon is rooted in fundamental changes in American politics in recent decades— and, in turn, that it has deeply affected administrative law and separation of- powers dynamics. Over the past several decades, the number of commissioners with prior service as a lawmaker or congressional staffer increased almost fourfold. Paradoxically, this sea change occurred during a period in which, according to conventional wisdom, Congress’s influence over administration declined. We contend that, faced with a set of worsening pathologies in Congress, lawmakers turned to appointments to influence policy making. At the same time, congressional atrophy and an increasingly rocky confirmation process combined to make executive posts more attractive to Hill staffers than to others

Optometric trends in sports vision: Knowledge, utilization, and practitioner role expansion potential in 1994

Background: The optometric discipline of sports vision is a relatively young and actively growing area which has spurred the interest of optometrists and sports organizations at all levels of athletics. Methods: 473 optometrists were surveyed and compared to a similar survey sent to 100 optometrists in 1980, 1983, and the same 473 in 1987-88. Also, 290 college and 108 professional teams were surveyed. Results: Optometrists felt there were more opportunities available in sports vision. Contact lenses are preferred over spectacles for most general sports, and optometrists usually consider the specific visual demands of the athlete when providing services. Vision therapy was reported to be used in nearly half the practices surveyed. College and professional team results suggest a broader acceptance and utilization of sports vision services. Conclusions: Since the establishment of the American Optometric Association Sports Vision Section (AOA-SVS) seventeen years ago, advances have been made in utilization and acceptance worldwide. The results of this survey, however, show that there. is still an unmet need for vision care and screening services at both the collegiate and professional levels

Dynamics of baryon ejection in magnetar giant flares: implications for radio afterglows, r-process nucleosynthesis, and fast radio bursts

We explore the impact of a magnetar giant flare (GF) on the neutron star (NS) crust, and the associated baryon mass ejection. We consider that sudden magnetic energy dissipation creates a thin high-pressure shell above a portion of the NS surface, which drives a relativistic shockwave into the crust, heating a fraction of these layers sufficiently to become unbound along directions unconfined by the magnetic field. We explore this process using spherically-symmetric relativistic hydrodynamical simulations. For an initial shell pressure $P_{\rm GF}$ we find the total unbound ejecta mass roughly obeys the relation $M_{\rm{ej}}\sim4-9\times10^{24}\:\rm{g}\:(P_{\rm GF}/10^{30}\:\rm{ergs}\:\rm{cm}^{-3})^{1.43}$. For $P_{\rm{GF}}\sim10^{30}-10^{31}\:\rm{ergs}\:\rm{cm}^{-3}$ corresponding to the dissipation of a magnetic field of strength $\sim10^{15.5}-10^{16}\:\rm{G}$, we find $M_{\rm{ej}}\sim10^{25}-10^{26}\:\rm{g}$ with asymptotic velocities $v_{\rm{ej}}/c\sim0.3-0.6$ compatible with the ejecta properties inferred from the afterglow of the December 2004 GF from SGR 1806-20. Because the flare excavates crustal material to a depth characterized by an electron fraction $Y_e\approx0.40-0.46$, and is ejected with high entropy and rapid expansion timescale, the conditions are met for heavy element $r$-process nucleosynthesis via the alpha-rich freeze-out mechanism. Given an energetic GF rate of roughly once per century in the Milky Way, we find that magnetar GFs could be an appreciable heavy $r$-process source that tracks star formation. We predict that GFs are accompanied by short $\sim$minutes long, luminous $\sim10^{39}\:\rm{ergs}\:\rm{s}^{-1}$ optical transients powered by $r$-process decay ("nova brevis"), akin to scaled-down kilonovae. Our findings also have implications for the synchrotron nebulae surrounding some repeating fast radio burst sources.Comment: 24 pages, 12 figures, 2 tables. v2: matches the accepted version in MNRAS (only minor edits were made). Videos showing our Fiducial simulation are available at https://dx.doi.org/10.5281/zenodo.10593900 and at https://www.youtube.com/playlist?list=PLtfS1xXqUmtC2A48QhRvGXxbeMK1vkNn

Two Suns in The Sky: Stellar Multiplicity in Exoplanet Systems

We present results of a reconnaissance for stellar companions to all 131 radial-velocity-detected candidate extrasolar planetary systems known as of July 1, 2005. CPM companions were investigated using the multi-epoch DSS images, and confirmed by matching the trigonometric parallax distances of the primaries to companion distances estimated photometrically. We also attempt to confirm or refute companions listed in the Washington Double Star Catalog, the Catalogs of Nearby Stars, in Hipparcos results, and in Duquennoy & Mayor (1991). Our findings indicate that a lower limit of 30 (23%) of the 131 exoplanet systems have stellar companions. We report new stellar companions to HD 38529 and HD 188015, and a new candidate companion to HD 169830. We confirm many previously reported stellar companions, including six stars in five systems that are recognized for the first time as companions to exoplanet hosts. We have found evidence that 20 entries in the Washington Double Star Catalog are not gravitationally bound companions. At least three, and possibly five, of the exoplanet systems reside in triple star systems. Three exoplanet systems have potentially close-in stellar companions ~ 20 AU away from the primary. Finally, two of the exoplanet systems contain white dwarf companions. This comprehensive assessment of exoplanet systems indicates that solar systems are found in a variety of stellar multiplicity environments - singles, binaries, and triples; and that planets survive the post-main-sequence evolution of companion stars.Comment: 52 pages, 7 figures, Accepted for publication in Ap

Pressure broadening and frequency shift of the D-1 and D-2 lines of Rb and K in the presence of He-3 and N-2

We report the results of a study of the pressure broadening and resonant frequency shift of the absorption profiles of the D-1 and D-2 lines of Rb and K in the presence of He-3 and N-2 gases over a range of number densities. We have also examined the temperature dependence of the broadening and shift over a range of approximately 340 to 400 K. We compare our results for the broadening and shift coefficients for Rb D-1 and D-2 to current values and present coefficients for K D-1 and D-2. DOI:10.1103/PhysRevA.87.03251