A5083220430- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Stellar, planetary, and galactic studies
- Pulsars and Gravitational Waves Research
- Radio Astronomy Observations and Technology
- Particle Accelerators and Free-Electron Lasers
- Adaptive optics and wavefront sensing
- Solar and Space Plasma Dynamics
- X-ray Spectroscopy and Fluorescence Analysis
- Geophysics and Gravity Measurements
- Scientific Measurement and Uncertainty Evaluation
- Cosmology and Gravitation Theories
- Advanced X-ray Imaging Techniques
- Astrophysics and Star Formation Studies
- Mechanics and Biomechanics Studies
- Relativity and Gravitational Theory
- Black Holes and Theoretical Physics
- Reservoir Engineering and Simulation Methods
- Gyrotron and Vacuum Electronics Research
- Atomic and Molecular Physics
- Scientific Research and Discoveries
Max Planck Institute for Radio Astronomy
2015-2024
National Astronomical Observatories
2014-2024
Chinese Academy of Sciences
2017-2024
Drexel University
2023
Max Planck Society
2009-2020
Centro de Astrobiología
2019
University of Maryland, College Park
2018
Tokyo Institute of Technology
2018
California Institute of Technology
2018
University of Crete
2018
After the All-Sky Automated Survey for SuperNovae (ASAS-SN) discovered a significant brightening of inner region NGC 2617, we began ~70 day photometric and spectroscopic monitoring campaign from X-ray through near-infrared (NIR) wavelengths. We report that 2617 went dramatic outburst, during which its flux increased by over an order magnitude followed increase optical/ultraviolet (UV) continuum almost magnitude. classified as Seyfert 1.8 galaxy in 2003, is now 1 due to appearance broad...
Abstract The Einstein Probe (EP) is an interdisciplinary mission of time-domain and X-ray astronomy. Equipped with a wide-field lobster-eye focusing imager, EP will discover cosmic transients monitor the variability known sources in 0.5–4 keV, at combination detecting sensitivity cadence that not accessible to previous current monitoring missions. can perform quick characterisation or outbursts Wolter-I telescope onboard. In this paper, science objectives are presented. expected enlarge...
Context. It has been demonstrated that active galactic nuclei are powered by gas accretion onto supermassive black holes located at their centres. The paradigm the of inactive galaxies also occupied was predicted long ago theory. In past decade, this conjecture confirmed discovery giant-amplitude, non-recurrent X-ray flares from such and explained in terms outburst radiation stars tidally disrupted a dormant hole those galaxies.
The narrow-line Seyfert 1 Galaxy 1H 0707−495 went into a low state from 2010 December to 2011 February, discovered by monitoring campaign using the X-Ray Telescope on Swift satellite. We triggered 100 ks XMM–Newton observation of source in January, revealing have dropped factor 10 soft band, below keV, and 2 at 5 compared with long 2008. sharp spectral drop usually seen around 7 keV now extends lower energies, 6 our frame. spectrum is well fitted relativistically blurred reflection similar...
We present 3-50 keV NuSTAR observations of the AGN Mrk 335 in a very low flux state. The spectrum is dominated by strong features at energies iron line 5-7 and Compton hump from 10-30 keV. source variable during observation, with variability concentrated energies, which suggesting either relativistic reflection or absorption scenario. In this work we focus on interpretation, making use new models that self consistently calculate fraction, blurring angle-dependent for different coronal...
Context. Since July 2014, the Gaia mission has been engaged in a high-spatial-resolution, time-resolved, precise, accurate astrometric, and photometric survey of entire sky. Aims. We present Science Alerts project, which operation since 1 June 2016. describe system developed to enable discovery publication transient events as seen by . Methods. outline data handling, timings, performances, we detection algorithms filtering procedures needed manage high false alarm rate. identify two classes...
In recent years, indirect evidence has emerged suggesting that many nearby nonactive galaxies harbor quiescent supermassive black holes. Knowledge of the frequency occurrence holes, their masses and spins, is broad relevance for studying hole growth galaxy active galactic nuclei formation evolution. It been suggested an unavoidable consequence existence best diagnostic presence in galaxies, would be occasional tidal disruption stars captured by These events manifest themselves form luminous...
We report on the deepest X-ray observation of narrow-line Seyfert 1 galaxy Mrk 335 in low-flux state obtained with Suzaku. The data are compared to a 2006 high-flux Suzaku when source was ∼10 times brighter. Describing two flux levels self-consistently partial covering models would require extreme circumstances, as be subject negligible absorption during bright and 95 per cent near Compton-thick material dim. Blurred reflection from an accretion disc around nearly maximum spinning black hole...
We present the detection of compact radio structures 14 radio-loud narrow-line Seyfert 1 (NLS1) galaxies from Very Long Baseline Array (VLBA) observations at 5 GHz performed in 2013. While 50% sources our sample show a core only, remaining exhibit core-jet structure. The measured brightness temperatures cores range 108.4 to 1011.4 K with median value 1010.1 K, indicating that emission is non-thermal jets, and that, likely, most are not strongly beamed, thus implying low jet speed these NLS1...
We studied the radio emission from four radio-loud and gamma-ray-loud narrow-line Seyfert 1 galaxies. The goal was to investigate whether a relativistic jet is operating at source, quantify its characteristics. relied on most systematic monitoring of such system in cm mm bands which conducted with Effelsberg 100 m IRAM 30 telescopes covers longest time-baselines frequencies date. extract variability parameters compute brightness temperatures Doppler factors. powers were computed light curves...
In the canonical model for tidal disruption events (TDEs), stellar debris circularizes quickly to form an accretion disc of size about twice orbital pericentre star. Most TDEs and candidates discovered in optical/ultraviolet have broad optical emission lines with complex diverse profiles puzzling origin. Liu et al. recently developed a relativistic elliptical constant eccentricity radius well reproduced double-peaked line TDE candidate PTF09djl large extremely eccentric disc. this paper, we...
We present radio observations of the tidal disruption event candidate (TDE) XMMSL1 J0740$-$85 spanning 592 to 875 d post X-ray discovery. detect emission that fades from an initial peak flux density at 1.6 GHz $1.19\pm 0.06$ mJy $0.65\pm suggesting association with TDE. This makes $d=75$ Mpc nearest TDE detected date and only fifth overall. The observed luminosity rules out a powerful relativistic jet like seen in Swift J1644+57. Instead we infer equipartition analysis most likely arises...
The project MOMO (Multiwavelength Observations and Modelling of OJ 287) was set up to test predictions binary supermassive black hole (SMBH) scenarios understand disk-jet physics the blazar 287. After a correction, precessing (PB) SMBH model predicted next main outburst 287 in 2022 October, no longer July, making well observable testable. We have densely covered this period our ongoing multi-frequency radio, optical, UV, X-ray monitoring. not detected. Instead, at low optical-UV emission...
Abstract We present the first results from a 100-day Swift, NICER, and ground-based X-ray–UV–optical reverberation mapping campaign of Narrow-line Seyfert 1 Mrk 335, when it was in an unprecedented low X-ray flux state. Despite dramatic suppression variability, we still observe UV–optical lags as expected disk reverberation. Moreover, are consistent with archival observations luminosity >10 times higher. Interestingly, both low- high-flux states reveal that 6–11 longer than thin disk....
Recent XMM-Newton observations of the high-redshift, lensed, broad absorption line (BAL) quasi-stellar object APM 08279+5255, one most luminous objects in universe, allowed detection a high column density absorber (NH ≈ 1023 cm-2) form K-shell edge significantly ionized iron (Fe XV-Fe XVIII) and corresponding lower energy absorption. Our findings confirm basic prediction phenomenological geometry models for BAL outflow can constrain size absorbing region. The Fe/O abundance material is...
The galaxy SDSSJ095209.56+214313.3 (SDSSJ0952+2143 hereafter) showed remarkable emission-line and continuum properties strong variability first reported in 2008 (Paper I). spectral low-energy are the consequence of a powerful high-energy flare which was itself not observed directly. Here we report follow-up optical, near-infrared (NIR), mid-infrared (MIR), X-ray observations SDSSJ0952+2143. We discuss outburst scenarios terms stellar tidal disruption by supermassive black hole, peculiar an...
Monitoring of the narrow line Seyfert 1 galaxy Markarian 335 (Mrk 335) with Swift satellite discovered an X-ray flare beginning 2014 August 29. At peak, 0.5-5keV count rate had increased from that in low flux state by a factor 10. A target opportunity observation was triggered NuSTAR, catching decline on September 20. We present joint analysis and NuSTAR observations to understand cause this flare. The spectrum shows increase directly observed continuum softening photon index 2.49...
Abstract We present simultaneous XMM–Newton and NuSTAR observations of the repeat changing-look AGN NGC 1566, which dramatically increased in brightness IR to X-ray bands 2018. The broad-band spectrum was taken at peak outburst is typical Seyfert 1 AGN. shows a soft excess, Compton hump, warm absorption reflection, ruling out tidal disruption as cause demonstrating that ‘standard’ accretion disk can develop very rapidly. high-resolution grating reveals has launched ∼500 km s−1 outflow,...
We report the detection of high-amplitude X-ray flaring AGN HE 1136-2304, which is accompanied by a strong increase in flux broad Balmer lines, changing its Seyfert type from almost 2 1993 down to 1.5 2014. 1136-2304 was detected XMM–Newton slew survey at >10 times it had ROSAT all-sky survey, and confirmed with Swift follow-up after increasing factor ∼30. Optical spectroscopy SALT shows that has changed 1.95 galaxy, greatly increased line emission an blue continuum >4. The spectra NuSTAR...
ABSTRACT We report detection of a very bright X-ray–UV–optical outburst OJ 287 in 2020 April–June, the second brightest since beginning our Swift multiyear monitoring late 2015. It is shown that predominantly powered by jet emission. Optical–UV–X-rays are closely correlated, and low-energy part XMM–Newton spectrum displays an exceptionally soft emission component consistent with synchrotron origin. A much harder X-ray power-law (Γx = 2.4, still relatively steep when compared to expectations...
Abstract Based on our dedicated Swift monitoring program, MOMO, OJ 287 is one of the best-monitored blazars in X-ray–UV–optical regime. Here, we report results from accompanying, dense, multifrequency (1.4–44 GHz) radio between 2015 and 2022 covering a broad range activity states. Fermi γ -ray observations were added. We characterize flux spectral variability detail, including discrete correlation function other analyses, discuss its connection with multiwavelength emission. Deep fades...