Transient jet formation and state transitions from large-scale magnetic reconnection in black hole accretion discs

Magnetically arrested accretion discs (MADs), where the magnetic pressure in the inner disc is dynamically important, provide an alternative mechanism for regulating accretion to what is commonly assumed in black hole systems. We show that a global magnetic field inversion in the MAD state can destroy the jet, significantly increase the accretion rate, and move the effective inner disc edge in to the marginally stable orbit. Reconnection of the MAD field in the inner radii launches a new type of transient outflow containing hot plasma generated by magnetic dissipation. This transient outflow can be as powerful as the steady magnetically-dominated Blandford-Znajek jet in the MAD state. The field inversion qualitatively describes many of the observational features associated with the high luminosity hard to soft state transition in black hole X-ray binaries: the jet line, the transient ballistic jet, and the drop in rms variability. These results demonstrate that the magnetic field configuration can influence the accretion state directly, and hence the magnetic field structure is an important second parameter in explaining observations of accreting black holes across the mass and luminosity scales.Comment: 5 pages, 3 figures, submitted to MNRAS Letter

DC Conductivities from Non-Relativistic Scaling Geometries with Momentum Dissipation

We consider a gravitational theory with two Maxwell fields, a dilatonic scalar and spatially dependent axions. Black brane solutions to this theory are Lifshitz-like and violate hyperscaling. Working with electrically charged solutions, we calculate analytically the holographic DC conductivities when both gauge fields are allowed to fluctuate. We discuss some of the subtleties associated with relating the horizon to the boundary data, focusing on the role of Lifshitz asymptotics and the presence of multiple gauge fields. The axionic scalars lead to momentum dissipation in the dual holographic theory. Finally, we examine the behavior of the DC conductivities as a function of temperature, and comment on the cases in which one can obtain a linear resistivity.Comment: 32 pages, 3 figures. Figures and references added. Discussion modifie

What is the Hidden Depolarization Mechanism in Low Luminosity AGN?

Millimeter wavelength polarimetry of accreting black hole systems can provide a tomographic probe of the accretion flow on a wide range of linear scales. We searched for linear polarization in two low luminosity active galactic nuclei (LLAGN), M81 and M84, using the Combined Array for Millimeter Astronomy (CARMA) and the Submillimeter Array (SMA). We find upper limits of $\sim 1 - 2\%$ averaging over the full bandwidth and with a rotation measure (RM) synthesis technique. These low polarization fractions, along with similar low values for LLAGN M87 and 3C84, suggest that LLAGN have qualitatively different polarization properties than radio-loud sources and Sgr A*. If the sources are intrinsically polarized and then depolarized by Faraday rotation then we place lower limits on the RM of a few times $10^7\, {\rm rad\, m^{-2}}$ for the full bandwidth case and $\sim 10^9\, {\rm rad\, m^{-2}}$ for the RM synthesis analysis. These limits are inconsistent with or marginally consistent with expected accretion flow properties. Alternatively, the sources may be depolarized by cold electrons within a few Schwarzschild radii from the black hole, as suggested by numerical models.Comment: Accepted for publication in ApJ

The Power of Jets: New Clues from Radio Circular Polarization and X-rays

Jets are ubiquitous in accreting black holes. Often ignored, they may be a major contributor to the emitted spectral energy distribution for sub-Eddington black holes. For example, recent observations of radio-to-X-ray correlations and broad band spectra of X-ray binaries in the low/hard state can be explained by a significant synchrotron contribution from jets also to their IR-to-X-ray spectrum as proposed by Markoff, Falcke, Fender 2001. This model can also explain state-transitions from low/hard to high/soft states. Relativistic beaming of the jet X-ray emission could lead to the appearance of seemingly Super-Eddington X-rays sources in other galaxies. We show that a simple population synthesis model of X-ray binaries with relativistic beaming can well explain the currently found distribution of off-nucleus X-ray point sources in nearby galaxies. Specifically we suggest that the so-called ultra-luminous X-ray sources (ULXs, also IXOs) could well be relativistically beamed microblazars. The same model that can be used to explain X-ray binaries also fits Low-Luminosity AGN (LLAGN) and especially Sgr A* in the Galactic Center. The recent detection of significant circular polarization in AGN radio cores, ranging from bright quasars down to low-luminosity AGN like M81*, Sgr A* and even X-ray binaries, now places additional new constraints on the matter contents of such jets. The emerging picture are powerful jets with a mix of hot and cold matter, a net magnetic flux, and a stable magnetic north pole.Comment: to appear in: ``Lighthouses of the Universe'', Springer Verlag, ESO Astrophysics Symposia, Eds: R.Sunyaev, M.Gilfanov, E.Churazov, LaTex, 8 pages, 5 figures, also available at http://www.mpifr-bonn.mpg.de/staff/hfalcke/publications.html#lighthouse

How to hide large scale outflows: size constraints on the jets of Sgr A*

Despite significant strides made towards understanding accretion, outflow, and emission processes in the Galactic Center supermassive black hole Sagittarius A*, the presence of jets has neither been rejected nor proven. We investigate here whether the combined spectral and morphological properties of the source at radio through near infrared wavelengths are consistent with the predictions for inhomogeneous jets. In particular, we construct images of jets at a wavelength of 7mm based on models that are consistent with the spectrum of Sgr A*. We then compare these models through closure quantities with data obtained from the Very Long Baseline Array at 7mm. We find that the best-fit jet models give comparable or better fits than best-fit Gaussian models for the intrinsic source found in previous analyses. The best fitting jet models are bipolar, are highly inclined to the line of sight ($\theta \ge$ 75 degrees), may favor a position angle on the sky of 105 degrees, and have compact bases with sizes of a few gravitational radii.Comment: 12 pages, 14 figures, submitted to MNRA

Technical report on the enhancement of Millennium Cohort Study data with linked electronic health records; derivation of consent weights

This document applies to the preparation of a Standard Operating Procedure (SOP) for the Wellcome Trust Data Linkage Project regarding the definition of consent weights for linkage to electronic health records between routinely collected data and data from the Millennium Cohort Study (MCS)

Infrared interferometry to spatially and spectrally resolve jets in X-ray binaries

Infrared interferometry is a new frontier for precision ground based observing, with new instrumentation achieving milliarcsecond (mas) spatial resolutions for faint sources, along with astrometry on the order of 10 microarcseconds. This technique has already led to breakthroughs in the observations of the supermassive black hole at the Galactic centre and its orbiting stars, AGN, and exo-planets, and can be employed for studying X-ray binaries (XRBs), microquasars in particular. Beyond constraining the orbital parameters of the system using the centroid wobble and spatially resolving jet discrete ejections on mas scales, we also propose a novel method to discern between the various components contributing to the infrared bands: accretion disk, jets and companion star. We demonstrate that the GRAVITY instrument on the Very Large Telescope Interferometer (VLTI) should be able to detect a centroid shift in a number of sources, opening a new avenue of exploration for the myriad of transients expected to be discovered in the coming decade of radio all-sky surveys. We also present the first proof-of-concept GRAVITY observation of a low-mass X-ray binary transient, MAXI J1820+070, to search for extended jets on mas scales. We place the tightest constraints yet via direct imaging on the size of the infrared emitting region of the compact jet in a hard state XRB.Comment: 12 Pages, 3 figures, accepted for publication in MNRA

Deiksis Waktu dalam Drama Cleopatra Na Onnatachi Karya Ooishi Shizuka

Sera, Deassa Chintia. 2014. Deiksis Waktu Dalam Drama Cleopatra na Onnatachi Karya Ooishi Shizuka. Program Studi Sastra Jepang, Universitas Brawijaya. Pembimbing: (I) Dra. Ismi Prihandari, M.Hum. (II) Sri Aju Indrowaty, M.Pd. Kata Kunci: Deiksis Waktu, Referen, Referensi, Drama Bahasa digunakan sebagai alat untuk saling berkomunikasi antar individu atau kelompok. Ilmu yang mempelajari bahasa disebut linguistik, salah satu cabang linguistik adalah pragmatik. Dalam penelitian ini, penulis mengambil obyek kajian pragmatik yaitu, deiksis waktu dan menjawab dua rumusan masalah yaitu (1) Apa saja bentuk deiksis waktu dalam drama Cleopatra na Onnatachi? (2) Bagaimanakah jenis referensi pada deiksis waktu dalam drama Cleopatra na Onnatachi? Penelitian ini adalah penelitian deskriptif kualitatif. Sumber data yang digunakan adalah deiksis waktu yang terdapat dalam drama Cleopatra na Onnatachi Karya Ooishi Shizuka. Analisis yang digunakan adalah dengan melakukan klasifikasi terhadap keterangan waktu, tabulasi dan analisis data. Dari kasil analisis pada penelitian ini ditemukan 64 kata deiksis waktu yang terdiri dari 47 kata deiksis waktu bentuk Perubahan ruang, seperti今日 (きょう/kyou/hari ini) dan 昔 (むかし/mukashi/dahulu). 17 kata deiksis waktu bentuk Perubahan waktu, seperti 日 (にち/nichi/hari), 今 (いま/ima/sekarang). Kata deiksis waktu yang telah terkumpul tersebut mengandung 19 kata referensi eksofora, yaitu今日 (きょう/kyou/hari ini), 昔 (むかし/mukashi/dahulu), 頃 (ころ/koro/ketika) dan今 (いま/ima/sekarang). 19 kata referensi katafora, seperti今晩 (こんばん/konban/malam hari) dan 将来 (しょうらい/shourai/masa depan). 26 kata referensi anafora, seperti日 (にち/nichi/hari), 時 (とき/toki/saat) dan後 (あと/ato/setelah). Penelitan serupa dapat dilakukan menggunakan jenis deiksis yang sama atau menggunakan jenis deiksis yang lain, misalnya jenis deiksis persona, deiksis ruang, dll. Selain itu, menggunakan obyek penelitian yang belum pernah digunakan agar hasilnya dapat lebih variatif, misalnya komik, novel, siaran berita dalam bahasa Jepang

Using functional data analysis to understand daily activity levels and patterns in primary school-aged children: Cross-sectional analysis of a UK-wide study

Temporal characterisation of physical activity in children is require df oreffectivs strategie sto increase physical activity(PA)

Radio and Millimeter Monitoring of Sgr A*: Spectrum, Variability, and Constraints on the G2 Encounter

We report new observations with the Very Large Array, Atacama Large Millimeter Array, and Submillimeter Array at frequencies from 1.0 to 355 GHz of the Galactic Center black hole, Sagittarius A*. These observations were conducted between October 2012 and November 2014. While we see variability over the whole spectrum with an amplitude as large as a factor of 2 at millimeter wavelengths, we find no evidence for a change in the mean flux density or spectrum of Sgr A* that can be attributed to interaction with the G2 source. The absence of a bow shock at low frequencies is consistent with a cross-sectional area for G2 that is less than $2 \times 10^{29}$ cm$^2$. This result fits with several model predictions including a magnetically arrested cloud, a pressure-confined stellar wind, and a stellar photosphere of a binary merger. There is no evidence for enhanced accretion onto the black hole driving greater jet and/or accretion flow emission. Finally, we measure the millimeter wavelength spectral index of Sgr A* to be flat; combined with previous measurements, this suggests that there is no spectral break between 230 and 690 GHz. The emission region is thus likely in a transition between optically thick and thin at these frequencies and requires a mix of lepton distributions with varying temperatures consistent with stratification.Comment: Accepted for publication in Ap