230 GHz VLBI OBSERVATIONS OF M87: EVENT‐HORIZON‐SCALE STRUCTURE DURING AN ENHANCED VERY‐HIGH‐ENERGY $\gamma $‐RAY STATE IN 2012

Akiyama, Kazunori; Lu, R.-S.; Fish, Vincent L.; Doeleman, Sheperd S.; Broderick, Avery E.; Dexter, Jason; Hada, Kazuhiro; Kino, Motoki; Nagai, Hiroshi; Honma, Mareki; Johnson, Michael D.; Algaba, Juan Carlos; Asada, Keiichi; Brinkerink, Christiaan D.; Blundell, R.; Bower, Geoffrey C.; Cappallo, R. J.; Crew, G. B.; Dexter, Matt; Dzib, S. A.; Freund, R.; Friberg, Per; Gurwell, M. A.; Ho, P. T. P.; Inoue, Makoto; Krichbaum, T. P.; Loinard, Laurent; MacMahon, David H. E.; Marrone, Daniel P.; Moran, J. M.; Nakamura, Masanori; Nagar, Neil M.; Ortiz-León, Gisela N.; Plambeck, R. L.; Pradel, Nicolas; Primiani, Rurik A.; Rogers, A. E. E.; Roy, A. L.; Soohoo, Jason; Leon-Tavares, J.; Tilanus, R. P. J.; Titus, Michael S.; Wagner, Jan; Weintroub, Jonathan; Yamaguchi, Paul; Young, Ken; Zensus, J. A.; Ziurys, L. M.

doi:10.1088/0004-637x/807/2/150

Cited by 110 publications

(119 citation statements)

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“…Beyond those associated with stellar processes (e.g., Herbig 1960;Crowther 2007;Humphreys & Davidson 1994;Woosley & Bloom 2006), some of the most energetic outflows are linked to supermassive black holes (SMBHs) during the accretion phase. Such outflows have been observed in different phases of the interstellar medium (ISM): hot plasma (radio jets; Akiyama et al 2015), ionized gas (e.g., Konigl & Kartje 1994;Murray et al 1995;Crenshaw et al 2003), and molecular gas (e.g., Cicone et al 2014), although the connection of the latter to active galactic nuclei (AGNs) is still under debate. Galaxy-wide star formation or compact starburst regions are alternative drivers of such outflows (e.g., Chevalier & Clegg 1985;Veilleux et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Unraveling the Complex Structure of Agn-Driven Outflows. I. Kinematics and Sizes

Karouzos

Woo

Bae

2016

ApJ

106

156

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Outflows driven by active galactic nuclei (AGNs) are often invoked as agents of the long-sought AGN feedback. Yet, characterizing and quantifying the impact on their host galaxies has been challenging. We present Gemini Multi-Object Spectrograph integral field unit data of six local (z 0.1 < ) and luminous (L 10In the first of a series of papers, we investigate the kinematics and constrain the size of the outflows. The ionized gas kinematics can be described as a superposition of a gravitational component that follows the stellar motion and an outflow-driven component that shows large velocity (up to 600 km s −1 ) and large velocity dispersion (up to 800 km s −1 ). Using the spatially resolved measurements of the gas, we kinematically measure the size of the outflow, which is found to be between 1.3 and 2.1 kpc. Owingto the lack of a detailed kinematic analysis, previous outflow studies likely overestimate their size by up to more than a factor of two, depending on how the size is estimated and whether the [O III] or Hα emission line is used. The relatively small size of the outflows for all six of our objects casts doubts on their potency as a mechanism for negative AGN feedback.

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Section: Introductionmentioning

confidence: 99%

Unraveling the Complex Structure of Agn-Driven Outflows. I. Kinematics and Sizes

Karouzos

Woo

Bae

2016

ApJ

106

156

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“…The recent advent of the Event Horizon Telescope (EHT) has allowed observational studies of this jet on a scale of several Schwarzschild radii (R s ) [4,5]. The EHT is quite promising to image the shadow of the central black hole and the jet launching within the inner part of the accretion disk.…”

Section: Introductionmentioning

confidence: 99%

The Structure and Propagation of the Misaligned Jet M87

Hada

2016

Galaxies

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Due to its proximity, M87 is a prime target for next-generation high-resolution VLBI at short millimeter wavelengths, by which the jet launching region and the black hole shadow are expected to be resolved and imaged sometime soon. Along with this situation, high-quality VLBI imaging and monitoring at lower frequencies play an important role in complementing the high-frequency data. Here, we present our recent and ongoing observational studies of the M87 jet on pc-to-subpc scales based on ultra-deep VLBI imaging programs at 86 GHz and 15 GHz. The high-dynamic-range images have allowed us to obtain some remarkably improved views on this jet. We also introduce the KVN and VERA Array (KaVA), a new regularly-operating VLBI network in East Asia, which is quite suitable for studying the structure and propagation of relativistic jets. Some early results from our pilot study for M87-including the detection of superluminal motions near the jet base-implying an efficient magnetic-to-kinetic conversion at these scales, are reported.

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“…Starting in 2007, observations using this array confirmed the existence of eventhorizon-scale structures in Sgr A* [4], detected similarly compact emission at the heart of M87 [5], and revealed ordered and time-variable magnetic fields at the event horizon of Sgr A* [6]. It is this combination of angular resolution and the ability of short millimetre wavelengths to penetrate the accretion flow that provides access to the black hole boundary.…”

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confidence: 74%

“…Starting in 2007, observations using this array confirmed the existence of eventhorizon-scale structures in Sgr A* [4], detected similarly compact emission at the heart of M87 [5], and…”

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confidence: 93%

Seeing the unseeable

Doeleman

2017

Nat Astron

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The Event Horizon Telescope, an Earth-sized interferometer, aims to capture an image of a black hole's event horizon to test the theory of general relativity and probe accretion processes.Black holes are the most mysterious objects predicted by Einstein's theory of general relativity. Yet, despite compelling evidence for their existence, no black hole has been imaged with event-horizon-scale resolution. Supermassive black holes in particular convert the gravitational energy of infalling material into powerful outflows and luminous nuclei that redistribute matter and energy on galactic scales. Horizon-scale access to these central engines of galactic nuclei would enable the most detailed studies of black hole accretion and the formation of relativistic jets, while also providing new tests for the existence of black holes and the validity of general relativity at the boundary of a black hole.The Event Horizon Telescope (EHT) is an international project specifically designed to capture the first image of a black hole and to time-resolve the dynamics of the associated accretion flow on orbital timescales. To do this, our team links a network of millimetre and submillimetre wavelength observatories around the globe to form an Earth-sized very long baseline interferometry (VLBI) array with the required resolving power and sensitivity. Over the past decade, the EHT has built up the necessary infrastructure by deploying hydrogen maser atomic frequency standards and purpose-built ultrahigh data rate VLBI instrumentation to sites in Chile, Hawaii, Mexico, the South Pole, Arizona and Spain. For the first time this spring, the Atacama Large Millimeter/submillimeter Array (ALMA) facility in Chile joined the array with all of its antennas phased together, operating as a single VLBI station and boosting EHT sensitivity by a factor of ten. Inclusion of ALMA enables the EHT to detect sources within the atmospheric coherence time of several seconds. When observing at 1.3 mm wavelength, the longest baselines in less than 25 microarcseconds.This resolution is well matched to the two supermassive black holes with the largest apparent event horizons on the sky. Sagittarius A* (Sgr A*), the four million solar mass black hole at the centre of the Milky Way, has a Schwarzschild radius that subtends 10 microarcseconds, and Messier 87 (M87) hosts an approximately six billion solar mass black hole in Virgo A that has a similar angular size. However, extreme light bending near the event horizon forms a 'silhouette' feature bounded by the edge-brightened photon orbit, which is magnified to a size of ~50 microarcseconds. For these sources, observing this silhouette at its expected size would confirm that all the estimated mass is contained within the photon orbit -an extraordinary strengthening of the case for black holes and confirmation of general relativity. The EHT will also search for periodic signals in the VLBI data that correspond to orbits of inhomogeneities in the accretion flow, which are sensitively dependent on black hole spin.Th...

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230 GHz VLBI OBSERVATIONS OF M87: EVENT‐HORIZON‐SCALE STRUCTURE DURING AN ENHANCED VERY‐HIGH‐ENERGY $\gamma $‐RAY STATE IN 2012

Cited by 110 publications

References 91 publications

Unraveling the Complex Structure of Agn-Driven Outflows. I. Kinematics and Sizes

Unraveling the Complex Structure of Agn-Driven Outflows. I. Kinematics and Sizes

The Structure and Propagation of the Misaligned Jet M87

Seeing the unseeable

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