Silke Britzen's research while affiliated with Max Planck Institute for Radio Astronomy and other places
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Publications (99)
In a companion paper, we present the first spatially resolved polarized image of Sagittarius A* on event horizon scales, captured using the Event Horizon Telescope, a global very long baseline interferometric array operating at a wavelength of 1.3 mm. Here we interpret this image using both simple analytic models and numerical general relativistic...
The Event Horizon Telescope observed the horizon-scale synchrotron emission region around the Galactic center supermassive black hole, Sagittarius A* (Sgr A*), in 2017. These observations revealed a bright, thick ring morphology with a diameter of 51.8 ± 2.3 μ as and modest azimuthal brightness asymmetry, consistent with the expected appearance of...
Analyzing single-dish and very long baseline interferometry radio, as well as Fermi Large Area Telescope γ -ray observations, we explained the three major flares in the γ -ray light curve of FSRQ J1048+7143 with the spin–orbit precession of the dominant mass black hole in a supermassive black hole binary system. Here, we report on the detection of...
The Event Horizon Telescope (EHT) observed in 2017 the supermassive black hole at the center of the Milky Way, Sagittarius A* (Sgr A*), at a frequency of 228.1 GHz ($\lambda$=1.3 mm). The fundamental physics tests that even a single pulsar orbiting Sgr A* would enable motivate searching for pulsars in EHT datasets. The high observing frequency mean...
The combined study of the flaring of Active Galactic Nuclei (AGN) at radio wavelengths and pc-scale jet kinematics with Very Long Baseline Interferometry (VLBI) has led to the view that i) the observed flares are associated with ejections of synchrotron blobs from the core, and ii) most of the flaring would follow a one-to-one correlation with the...
The combined study of the flaring of active galactic nuclei (AGNs) at radio wavelengths and parsec-scale jet kinematics with Very Long Baseline Interferometry has led to the view that (i) the observed flares are associated with ejections of synchrotron blobs from the core, and (ii) most of the flaring follows a one-to-one correlation with the eject...
BL Lac objects detected at TeV energies preferentially belong to the subclass called 'high-frequency-peaked' BL Lacs (HBLs). Parsec-scale radio jets in these TeV-HBLs often show dominant, slow moving radio knots that are at most mildly superluminal. We report the first systematic campaign to characterise the Intra-Night Optical Variability (INOV) o...
The nearby radio galaxy M87 is a prime target for studying black hole accretion and jet formation1,2. Event Horizon Telescope observations of M87 in 2017, at a wavelength of 1.3 mm, revealed a ring-like structure, which was interpreted as gravitationally lensed emission around a central black hole³. Here we report images of M87 obtained in 2018, at...
The nearby radio galaxy M87 is a prime target for studying black hole accretion and jet formation^{1,2}. Event Horizon Telescope observations of M87 in 2017, at a wavelength of 1.3 mm, revealed a ring-like structure, which was interpreted as gravitationally lensed emission around a central black hole^3. Here we report images of M87 obtained in 2018...
Interpretation of resolved polarized images of black holes by the Event Horizon Telescope (EHT) requires predictions of the polarized emission observable by an Earth-based instrument for a particular model of the black hole accretion system. Such predictions are generated by general relativistic radiative transfer (GRRT) codes, which integrate the...
Mrk 501 is one of the most prominent TeV-emitting blazars and belongs to the class of high synchrotron peaked (HSP) blazars. The Doppler factors derived from the jet kinematics are much too low to provide sufficient beaming for the detected high-energy emission (the so-called Lorentz factor crisis). This BL Lac object is also a prime example of a m...
We draw a multimessenger picture of J1048+7143, a flat-spectrum radio quasar known to show quasiperiodic oscillations in the γ -ray regime. We generate the adaptively binned Fermi Large Area Telescope light curve of this source above 168 MeV to find three major γ -ray flares of the source, such that each of the three flares consists of two sharp su...
We draw the multimessenger picture of J1048+7143, a flat-spectrum radio quasar known to show quasi-periodic oscillations in the $\gamma$-ray regime. We generate the adaptively-binned Fermi Large Area Telescope light curve of this source above 168 MeV to find three major $\gamma$-ray flares of the source, such that all three flares consist of two-tw...
The blazar J1924–2914 is a primary Event Horizon Telescope (EHT) calibrator for the Galactic center's black hole Sagittarius A*. Here we present the first total and linearly polarized intensity images of this source obtained with the unprecedented 20 μas resolution of the EHT. J1924–2914 is a very compact flat-spectrum radio source with strong opti...
We report measurements of the gravitationally lensed secondary image—the first in an infinite series of so-called “photon rings”—around the supermassive black hole M87* via simultaneous modeling and imaging of the 2017 Event Horizon Telescope (EHT) observations. The inferred ring size remains constant across the seven days of the 2017 EHT observing...
The ongoing monitoring of the Galactic center and Sgr A*, the central supermassive black hole, produces surprising and unexpected findings. This goes hand in hand with the technical evolution of ground- and space-based telescopes and instruments, but also with the progression of image filter techniques such as the Lucy–Richardson algorithm. As we c...
We present the first very long baseline interferometric (VLBI) observations of the blazar OJ 287 carried out jointly with the Global Millimeter VLBI Array (GMVA) and the phased Atacama Large Millimeter/submillimeter Array (ALMA) at 3.5 mm on 2017 April 2. The participation of phased ALMA has not only improved the GMVA north–south resolution by a fa...
The Event Horizon Telescope (EHT) observed the compact radio source, Sagittarius A* (Sgr A*), in the Galactic Center on 2017 April 5–11 in the 1.3 mm wavelength band. At the same time, interferometric array data from the Atacama Large Millimeter/submillimeter Array and the Submillimeter Array were collected, providing Sgr A* light curves simultaneo...
Recent developments in very long baseline interferometry (VLBI) have made it possible for the Event Horizon Telescope (EHT) to resolve the innermost accretion flows of the largest supermassive black holes on the sky. The sparse nature of the EHT's (u, v)-coverage presents a challenge when attempting to resolve highly time-variable sources. We demon...
We present a framework for characterizing the spatiotemporal power spectrum of the variability expected from the horizon-scale emission structure around supermassive black holes, and we apply this framework to a library of general relativistic magnetohydrodynamic (GRMHD) simulations and associated general relativistic ray-traced images relevant for...
In this paper we quantify the temporal variability and image morphology of the horizon-scale emission from Sgr A*, as observed by the EHT in 2017 April at a wavelength of 1.3 mm. We find that the Sgr A* data exhibit variability that exceeds what can be explained by the uncertainties in the data or by the effects of interstellar scattering. The magn...
Astrophysical black holes are expected to be described by the Kerr metric. This is the only stationary, vacuum, axisymmetric metric, without electromagnetic charge, that satisfies Einstein's equations and does not have pathologies outside of the event horizon. We present new constraints on potential deviations from the Kerr prediction based on 2017...
The extraordinary physical resolution afforded by the Event Horizon Telescope has opened a window onto the astrophysical phenomena unfolding on horizon scales in two known black holes, M87* and Sgr A*. However, with this leap in resolution has come a new set of practical complications. Sgr A* exhibits intraday variability that violates the assumpti...
We present the first very-long-baseline interferometric (VLBI) observations of the blazar OJ287 carried out jointly with the Global Millimeter VLBI Array (GMVA) and the phased Atacama Large Millimeter/submillimeter Array (ALMA) at 3.5 mm on April 2, 2017. Participation of phased-ALMA not only has improved the GMVA north-south resolution by a factor...
In this paper we provide a first physical interpretation for the Event Horizon Telescope's (EHT) 2017 observations of Sgr A*. Our main approach is to compare resolved EHT data at 230 GHz and unresolved non-EHT observations from radio to X-ray wavelengths to predictions from a library of models based on time-dependent general relativistic magnetohyd...
We present the first event-horizon-scale images and spatiotemporal analysis of Sgr A* taken with the Event Horizon Telescope in 2017 April at a wavelength of 1.3 mm. Imaging of Sgr A* has been conducted through surveys over a wide range of imaging assumptions using the classical CLEAN algorithm, regularized maximum likelihood methods, and a Bayesia...
In this paper we provide a first physical interpretation for the Event Horizon Telescope's (EHT) 2017 observations of Sgr A*. Our main approach is to compare resolved EHT data at 230 GHz and unresolved non-EHT observations from radio to X-ray wavelengths to predictions from a library of models based on time-dependent general relativistic magnetohyd...
We present the first Event Horizon Telescope (EHT) observations of Sagittarius A* (Sgr A*), the Galactic center source associated with a supermassive black hole. These observations were conducted in 2017 using a global interferometric array of eight telescopes operating at a wavelength of λ = 1.3 mm. The EHT data resolve a compact emission region w...
We present Event Horizon Telescope (EHT) 1.3 mm measurements of the radio source located at the position of the supermassive black hole Sagittarius A* (Sgr A*), collected during the 2017 April 5–11 campaign. The observations were carried out with eight facilities at six locations across the globe. Novel calibration methods are employed to account f...
The black hole images obtained with the Event Horizon Telescope (EHT) are expected to be variable at the dynamical timescale near their horizons. For the black hole at the center of the M87 galaxy, this timescale (5–61 days) is comparable to the 6 day extent of the 2017 EHT observations. Closure phases along baseline triangles are robust interferom...
Very-long-baseline interferometry (VLBI) observations of active galactic nuclei at millimeter wavelengths have the power to reveal the launching and initial collimation region of extragalactic radio jets, down to $10-100$ gravitational radii ($r_g=GM/c^2$) scales in nearby sources. Centaurus A is the closest radio-loud source to Earth. It bridges t...
The black-hole images obtained with the Event Horizon Telescope (EHT) are expected to be variable at the dynamical timescale near their horizons. For the black hole at the center of the M87 galaxy, this timescale (5-61 days) is comparable to the 6-day extent of the 2017 EHT observations. Closure phases along baseline triangles are robust interferom...
Very-long-baseline interferometry (VLBI) observations of active galactic nuclei at millimetre wavelengths have the power to reveal the launching and initial collimation region of extragalactic radio jets, down to 10–100 gravitational radii ( r g ≡ G M / c ² ) scales in nearby sources ¹ . Centaurus A is the closest radio-loud source to Earth ² . It...
Our understanding of strong gravity near supermassive compact objects has recently improved thanks to the measurements made by the Event Horizon Telescope (EHT). We use here the M87* shadow size to infer constraints on the physical charges of a large variety of nonrotating or rotating black holes. For example, we show that the quality of the measur...
Our understanding of strong gravity near supermassive compact objects has recently improved thanks to the measurements made by the Event Horizon Telescope (EHT). We use here the M87* shadow size to infer constraints on the physical charges of a large variety of nonrotating or rotating black holes. For example, we show that the quality of the measur...
Synchrotron radiation from hot gas near a black hole results in a polarized image. The image polarization is determined by effects including the orientation of the magnetic field in the emitting region, relativistic motion of the gas, strong gravitational lensing by the black hole, and parallel transport in the curved spacetime. We explore these ef...
In 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting supermassive black hole of mass ~6.5 × 10⁹ M_⊙. The EHTC also partnered with several international facilit...
We present the results from a full polarization study carried out with the Atacama Large Millimeter/submillimeter Array (ALMA) during the first Very Long Baseline Interferometry (VLBI) campaign, which was conducted in 2017 April in the λ3 mm and λ1.3 mm bands, in concert with the Global mm-VLBI Array (GMVA) and the Event Horizon Telescope (EHT), re...
In 2017 April, the Event Horizon Telescope (EHT) observed the near-horizon region around the supermassive black hole at the core of the M87 galaxy. These 1.3 mm wavelength observations revealed a compact asymmetric ring-like source morphology. This structure originates from synchrotron emission produced by relativistic plasma located in the immedia...
Event Horizon Telescope (EHT) observations at 230 GHz have now imaged polarized emission around the supermassive black hole in M87 on event-horizon scales. This polarized synchrotron radiation probes the structure of magnetic fields and the plasma properties near the black hole. Here we compare the resolved polarization structure observed by the EH...
On 2019/07/30.86853 UT, IceCube detected a high-energy astrophysical neutrino candidate. The Flat Spectrum Radio Quasar PKS 1502+106 is located within the 50 percent uncertainty region of the event. Our analysis of 15 GHz Very Long Baseline Array (VLBA) and astrometric 8 GHz VLBA data, in a time span prior and after the IceCube event, reveals evide...
The 2017 Event Horizon Telescope (EHT) observations of the central source in M87 have led to the first measurement of the size of a black-hole shadow. This observation offers a new and clean gravitational test of the black-hole metric in the strong-field regime. We show analytically that spacetimes that deviate from the Kerr metric but satisfy weak...
The 2017 Event Horizon Telescope (EHT) observations of the central source in M87 have led to the first measurement of the size of a black-hole shadow. This observation offers a new and clean gravitational test of the black-hole metric in the strong-field regime. We show analytically that spacetimes that deviate from the Kerr metric but satisfy weak...
The Event Horizon Telescope (EHT) has recently delivered the first resolved images of M87*, the supermassive black hole in the center of the M87 galaxy. These images were produced using 230 GHz observations performed in 2017 April. Additional observations are required to investigate the persistence of the primary image feature—a ring with azimuthal...
3C 279 is an archetypal blazar with a prominent radio jet that show broadband flux density variability across the entire electromagnetic spectrum. We use an ultra-high angular resolution technique – global Very Long Baseline Interferometry (VLBI) at 1.3 mm (230 GHz) – to resolve the innermost jet of 3C 279 in order to study its fine-scale morpholog...
The Event Horizon Telescope (EHT) Collaboration has recently produced the first resolved images of the central supermassive black hole in the giant elliptical galaxy M87. Here we report on tests of the consistency and accuracy of the general relativistic radiative transfer codes used within the collaboration to model M87* and Sgr A*. We compare and...
The Event Horizon Telescope (EHT) provides the unprecedented ability to directly resolve the structure and dynamics of black hole emission regions on scales smaller than their horizons. This has the potential to critically probe the mechanisms by which black holes accrete and launch outflows, and the structure of supermassive black hole spacetimes....
Recently, near-infrared [email protected] observations at 2.2 μm announced the detection of three bright "flares"in the vicinity of the Galactic center supermassive black hole (SMBH) that exhibited orbital motion at a distance of about 6-11 gravitational radii from an ∼4 × 106 M o˙ black hole. There are indications of the presence of a large-scale,...
Recently, near-infrared GRAVIY@ESO observations at $2.2\,\mu{\rm m}$ have announced the detection of three bright "flares" in the vicinity of the Galactic center black hole that exhibited orbital motion at the radius about $6 - 11$ gravitational radii of $4.14\times 10^6\, M_{\odot}$ black hole. There are indications of the presence of a large-scal...
For about 500 intermediate-redshift sources ($0.04<z<0.4$), whose radio flux densities at $1.4\,{\rm GHz}$ are larger than 10 mJy, we performed additional observations at 4.85 GHz and 10.45 GHz using 100-m Effelsberg telescope. Our radio-optical galaxies are located preferentially in the Composite and AGN spectral classes in the narrow line optical...
Context . The empirical relations between supermassive black holes and their host spheroids point towards the crucial role of galactic nuclei in affecting the properties of their hosts. A detailed understanding of how the activity of a galactic nucleus regulates the growth of its host is still missing.
Aims . To understand the activity and the type...
In this contribution, we summarize our results concerning the observational constraints on the electric charge associated with the Galactic centre black hole – Sgr A*. According to the no-hair theorem, every astrophysical black hole, including supermassive black holes, is characterized by at most three classical, externally observable parameters –...
3C 84 (NGC 1275, Perseus A) is a bright radio source at the center of an ongoing merger, where HST observations show two colliding spiral galaxies. 3C 84 holds promise to improve our understanding about how of the activity of active galactic nuclei, the formation of supermassive binary black holes, feedback processes, and galaxy collisions are inte...
A detailed understanding of how the activity of a galactic nucleus regulates the growth of its host is still missing. To understand the activity and the types of accretion of supermassive black holes in different hosts, it is essential to study radio-optical properties of a large sample of extragalactic sources. In particular, we aim at studying th...
We present the calibration and reduction of Event Horizon Telescope (EHT) 1.3 mm radio wavelength observations of the supermassive black hole candidate at the center of the radio galaxy M87 and the quasar 3C 279, taken during the 2017 April 5-11 observing campaign. These global very long baseline interferometric observations include for the first t...
We present measurements of the properties of the central radio source in M87 using Event Horizon Telescope data obtained during the 2017 campaign. We develop and fit geometric crescent models (asymmetric rings with interior brightness depressions) using two independent sampling algorithms that consider distinct representations of the visibility dat...
The Event Horizon Telescope (EHT) has mapped the central compact radio source of the elliptical galaxy M87 at 1.3 mm with unprecedented angular resolution. Here we consider the physical implications of the asymmetric ring seen in the 2017 EHT data. To this end, we construct a large library of models based on general relativistic magnetohydrodynamic...
We present the first Event Horizon Telescope (EHT) images of M87, using observations from April 2017 at 1.3 mm wavelength. These images show a prominent ring with a diameter of ∼40 μas, consistent with the size and shape of the lensed photon orbit encircling the "shadow" of a supermassive black hole. The ring is persistent across four observing nig...
2019. The American Astronomical Society.. When surrounded by a transparent emission region, black holes are expected to reveal a dark shadow caused by gravitational light bending and photon capture at the event horizon. To image and study this phenomenon, we have assembled the Event Horizon Telescope, a global very long baseline interferometry arra...
In this contribution, we summarize our results concerning the observational constraints on the electric charge associated with the Galactic centre black hole - Sgr A*. According to the no-hair theorem, every astrophysical black hole, including supermassive black holes, is characterized by at most three classical, externally observable parameters -...
The Galactic centre supermassive black hole (SMBH), in sharp contrast with its complex environment, is characterized by only three classical parameters -- mass, spin, and electric charge. Its charge is poorly constrained. It is, however, usually assumed to be zero because of neutralization due to the presence of plasma. We revisit the question of t...
We re-analyzed OJ287 in 120 Very Long Baseline Array (VLBA, MOJAVE) observations (at 15 GHz) covering the time span between Apr. 1995 and Apr. 2017. We find that the radio jet motion over the sky is consistent with a precessing and nutating jet source. The variability of the radio flux-density can be explained by Doppler beaming due to a change in...
To date, PMN J2134-0419 (at a redshift z=4.33) is the second most distant quasar known with a milliarcsecond-scale morphology permitting direct estimates of the jet proper motion. Based on two-epoch observations, we constrained its radio jet proper motion using the very long baseline interferometry (VLBI) technique. The observations were conducted...
We review observational aspects of the active galactic nuclei and their jets in connection with the detection of high-energy neutrinos by the Antarctic IceCube Neutrino Observatory. We propose that a reoriented jet generated by the spin-flipping supermassive black hole in a binary merger is likely the source of such high-energy neutrinos. Hence the...
The Dusty S-cluster Object (DSO/G2) orbiting the supermassive black hole (Sgr A*) in the Galactic centre has been monitored in both near-infrared continuum and line emission. There has been a dispute about the character and the compactness of the object: interpreting it as either a gas cloud or a dust-enshrouded star. A recent analysis of polarimet...
The compact and, with about 4.3+-0.3 million solar masses, very massive object located at the center of the Milky Way is currently the very best candidate for a supermassive black hole (SMBH) in our immediate vicinity. If SgrA* is indeed a SMBH it will, in projection onto the sky, have the largest event horizon and will certainly be the first and m...
Zusammenfassung
Einsteins Allgemeine Relativitätstheorie ist auch hundert Jahre nach ihrer Veröffentlichung die beste Gravitationstheorie. Neuerdings konnte sie sogar im Grenzbereich starker Gravitation bestätigt werden, wurden doch Gravitationswellen verschmelzender Schwarzer Löcher direkt gemessen. Allerdings bleiben Quanteneffekte in Einsteins M...
Schwarze Löcher gehören zu den faszinierendsten und ohnehin attraktivsten astrophysikalischen Phänomenen. In den Zentren von Galaxien sind sie verantwortlich für die Emission von Strahlung und für Jets. Nach der Entdeckung von Gravitationswellen von zwei verschmelzenden Schwarzen Löchern steht als nächstes großes Ziel die direkte Beobachtung des Sc...
Black Holes are probably the most elusive solutions of Einstein’s theory of General Relativity. Despite numerous observations of the direct galactic environment and indirect influence of astrophysical black holes (e.g. jets, variable emission across the wavelength spectrum, feedback processes, etc.)—a direct proof of their existence is still lackin...
We report serendipitous detections of line emission with ALMA in band 3, 6, and 7 in the central parsec of the Galactic center at an up to now highest resolution (<0.7″). Among the highlights are the very first and highly resolved images of sub-mm molecular emission of CS, H ¹³ CO ⁺ , HC 3 N, SiO, SO, C 2 H, and CH 3 OH in the immediate vicinity (~...
We report serendipitous detections of line emission with the Atacama Large Millimeter/submillimeter Array (ALMA) in band 3, 6, and 7 in the central parsec down to within 1" around Sgr A* at an up to now highest resolution (<0.5") view of the Galactic Center (GC) in the sub-millimeter (sub-mm) domain. From the 100 GHz continuum and the H39\alpha emi...
We aim to unveil the most massive central cluster black holes in the
universe. We present a new search strategy which is based on a black hole mass
gain sensitive 'calorimeter' and which links the innermost stellar density
profile of a galaxy to the adiabatic growth of its central SMBH. In a first
step we convert observationally inferred feedback p...
We are pleased to present the proceedings from the Astronomy at High Angular Resolution 2011: The central kiloparsec in galactic nuclei conference. The conference took place in the Physikzentrum of the Deutsche Physikalische Gesellschaft (DPG), Bad Honnef, Germany, from 28 August to 2 September 2011. It was the second conference of this kind, follo...
Recent VLBI studies of the morphology and kinematics of individual BL Lac
objects (S5 1803+784, PKS 0735+178, etc.) have revealed a new paradigm for the
pc-scale jet kinematics of these sources. Unlike the apparent superluminal
outward motions usually observed in blazars, most, if not all, jet components
in these sources appear to be stationary wit...
Context. The recent release of the First Fermi-LAT Source Catalog solidified the predominant association of extragalactic γ-ray emitters to active galaxies, in particular blazars. A tight connection between AGN jet kinematics and γ-ray properties has been argued for, attributing the energetic emission from active galaxies to their highly relativist...
The quasar B0605-085 (OH 010) shows a hint for probable periodical variability in the radio total flux-density light curves. We study the possible periodicity of B0605-085 in the total flux-density, spectra and opacity changes in order to compare it with jet kinematics on parsec scales. We have analyzed archival total flux-density variability at te...
In the context of the evolution of large structures in the Universe, it is unclear whether active galaxies are a phase which each galaxy undergoes, and what is the importance of the evolution of black holes in their centers. Binary black hole (BBH) systems could play a key role in our understanding of the above question. We investigate the Caltech-...
Citations
... This phenomenon halts the accretion process temporarily. A strong and ordered magnetic field is observed in Sgr A * in the recent polarimetric observation results [64,65]. MAD is currently the most favored one. ...
... This phenomenon halts the accretion process temporarily. A strong and ordered magnetic field is observed in Sgr A * in the recent polarimetric observation results [64,65]. MAD is currently the most favored one. ...
... Periodicities in AGN can usually be explained by a number of model families, relying on single (e.g., Lai 2003) or binary black holes (e.g., Roos et al. 1993;Bon et al. 2012;Kun et al. 2018;Jaiswal et al. 2019;Kun et al. 2020;Britzen et al. 2023;Kun et al. 2023), on the accretion disk (Bardeen & Petterson 1975;Caproni et al. 2006), or instabilities within the jet (e.g., Hardee et al. 1994;Perucho et al. 2006). Application of these models depends on the complexity of the observed behavior: while models relying on, e.g., single black holes or the precession of an accretion disk can usually explain a stable period, for cases when the time duration between flares changes, inclusions are needed. ...
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... One of the key predictions of general-relativistic (GR) MHD simulations is that the black hole spin must play a key role in powering relativistic jets, while the poloidal magnetic field loops are brought twisted by the frame-dragging effect (McKinney et al. 2012;Blandford et al. 2019). These jets are directly observed in about 10% of active galaxies, and one of the most prominent cases is that in M87* galaxy (Lu et al. 2023). A powerful jet is obtained when the magnetic flux on horizon overcomes the gravitational expulsion (Komissarov & McKinney 2007). ...
Reference: Broad band spectral modeling of M87 nucleus
... Recent observations of the kinematics of the parsec-scale jet in Mrk 501 have revealed a fascinating phenomenon, i.e., the outer portion of the jet exhibits a significant drift perpendicular to the inner jet, resulting in a gradual straightening of the jet over time. Additionally, based on the radio observation, Britzen et al. [39] suggests the presence of a spine-sheath structure within the jet. To provide a specific explanation for the existence of the spine-layer structure, we employ a Gaussian component to represent the layer jet and investigate its flux variations. ...
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... In Kun et al. (2022b), we analyzed and modeled the Fermi Large Area Telescope (LAT) light curve of the blazar J1048 +7143, and concluded that the multiwavelength behavior of this source is compatible with the spin-orbit precession of an SMBBH (Gergely & Biermann 2009) in the heart of the galaxy. This active galactic nucleus (AGN) indeed belongs to a group of blazars that reveal precession-induced variability (see Britzen et al. 2023, and references therein). ...
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... [37,38] The ongoing study of compact objects continues to propel our comprehension of gravity, quantum mechanics, and cosmology. The gravitational waves detected by the LIGO and Virgo collaboration [39], along with the observations conducted by ETH on the M87 galaxy and the Milky Way [40][41][42][43][44][45][46][47][48], furnish robust evidence for the existence of black holes. However, current observational data does not confirm the internal structure of these black holes. ...
... While extensive VLBI observations of blazars at millimeter wavelengths, required to test this picture, are still missing, a few recent results of such observations may be explained within the frameworks of the standing-shock model of the core [34,35]. When a jet is viewed at an angle larger than ∼ 20 • , a similar source is observed as a radio galaxy, and the beaming of the relativistic part of the jet is greatly reduced. ...
Reference: Neutrino production in blazar radio cores
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... In recent years, the horizon-scale photographs of supermassive black holes within the millimeter wave band have been viewed with great anticipation for exploring black hole physics [2][3][4]. It is believed that the observed bright rings are due to the so-called photon ring formed by multi-level images caused by the strong gravitational lensing effect [5][6][7][8][9]. However, since the observations are sensitive to the astronomical environments around black holes, the extent to which the currently photographed bright rings are correlated with the photon rings is still a controversial topic [10][11][12][13]. ...
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... The effects of the solar mass outweigh the effects of the angular momentum, as anticipated. However, the data may be used to investigate how planets and stars move in the vicinity of a revolving supermassive black hole [35,[42][43][44][45]. In addition, one can also use the results for pulsar planets [46][47][48], where the relativistic effects due to the rotation of the central body are more noticeable with respect to our solar system. ...
Reference: Adiabatic theory in Kerr spacetimes
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