M. Tornikoski
A5025529036- Astrophysics and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Neutrino Physics Research
- Dark Matter and Cosmic Phenomena
- Galaxies: Formation, Evolution, Phenomena
- Astronomical Observations and Instrumentation
- Solar and Space Plasma Dynamics
- Particle Accelerators and Free-Electron Lasers
- Astronomy and Astrophysical Research
- Gyrotron and Vacuum Electronics Research
- Geophysics and Gravity Measurements
- Particle accelerators and beam dynamics
- GNSS positioning and interference
- Ionosphere and magnetosphere dynamics
- Calibration and Measurement Techniques
- Stellar, planetary, and galactic studies
- Particle Detector Development and Performance
- Pulsars and Gravitational Waves Research
- Computational Physics and Python Applications
- Cosmology and Gravitation Theories
- Particle physics theoretical and experimental studies
- Radio Wave Propagation Studies
- Superconducting and THz Device Technology
Aalto University
2015-2024
Saha Institute of Nuclear Physics
2021
Gran Sasso Science Institute
2021
University of Rijeka
2021
Max Planck Institute for Physics
2021
Bureau Veritas (France)
2009-2020
Metsähallitus (Finland)
2004-2015
St Petersburg University
2010
University of Turku
2009
University of Michigan
2009
We present results from monitoring the multi-waveband flux, linear polarization, and parsec-scale structure of quasar PKS 1510-089, concentrating on eight major gamma-ray flares that occurred during interval 2009.0-2009.5. The peaks were essentially simultaneous with maxima at optical wavelengths, although flux ratio two wavebands varied by an order magnitude. polarization vector rotated 720 degrees a 5-day period encompassing six these flares. This culminated in very bright, roughly 1 day,...
<i>Aims. <i/>We have calculated variability Doppler boosting factors, Lorentz and viewing angles for a large sample of sources by using total flux density observations at 22 37 GHz VLBI data.<i>Methods. decomposed the curves into exponential flares determined brightness temperatures fastest flares. By assuming same intrinsic temperature each source, we factors 87 sources. In addition used new apparent jet speed data to calculate 67 sources.<i>Results. find that all quasars in our are...
We analyze the parsec-scale jet kinematics from 2007 June to 2018 December of a sample $\gamma$-ray bright blazars monitored roughly monthly with Very Long Baseline Array at 43 GHz under VLBA-BU-BLAZAR program. implement novel piece-wise linear fitting method derive 521 distinct emission knots total 3705 intensity images in 22 quasars, 13 BL Lacertae objects, and 3 radio galaxies. Apparent speeds these components range $0.01c$ $78c$, 18.6\% (other than "core") are quasi-stationary. One-fifth...
Over 13600 continuum observations of extragalactic sources are presented. These 157 at 22, 37 and 87 GHz more than doubles the millimeter these sources. The data between 1990.5 1995.5, combined with our earlier published they form a 15 year database.
The blazar 3C 279, one of the brightest identified extragalactic objects in γ-ray sky, underwent a large (factor ~10 amplitude) flare γ-rays toward end 3 week pointing by Compton Gamma Ray Observatory (CGRO), 1996 January-February. peak represents highest intensity ever recorded for this object. During high state, extremely rapid variability was seen, including an increase factor 2.6 ~8 hr, which strengthens case relativistic beaming. Coordinated multifrequency observations were carried out...
We analyze the behavior of parsec-scale jet quasar 3C 454.3 during pronounced flaring in 2005–2008. Three major disturbances propagated down along different trajectories with Lorentz factors Γ > 10. The show a clear connection millimeter-wave outbursts, 2005 May/June, 2007 July, and December. High-amplitude optical events R-band light curve precede peaks outbursts by 15–50 days. Each outburst is accompanied an increase X-ray activity. associate propagation superluminal knots derive location...
We combine time-dependent multi-waveband flux and linear polarization observations with sub-milliarcsecond-scale polarimetric images at lambda=7mm of the BL Lacertae-type blazar OJ287 to locate gamma-ray emission in prominent flares jet source >14pc from central engine. demonstrate a highly significant correlation between strongest millimeter-wave through Monte-Carlo simulations. The two reported peaks occurred near beginning major mm-wave outbursts, each which is associated maximum...
We have conducted a multiwavelength survey of 42 radio loud narrow-1ine Seyfert 1 galaxies (RLNLS1s), selected by searching among all the known sources this type and omitting those with steep spectra. analyse data from frequencies to X-rays, supplement these information available online catalogues literature in order cover full electromagnetic spectrum. This is largest for source. detected 90% X-rays found 17% at γ rays. Extreme variability high energies was also found, down timescales as...
We present time-resolved broad-band observations of the quasar 3C 279 obtained from multi-wavelength campaigns conducted during first two years Fermi Gamma-ray Space Telescope mission. While investigating previously reported gamma-ray/optical flare accompanied by a change in optical polarization, we found that emission appears delayed with respect to gamma-ray about 10 days. X-ray reveal pair `isolated' flares separated ~90 days, only weak counterparts. The spectral structure measured...
We analyze the multifrequency behavior of quasar 3C 454.3 during three prominent \gamma-ray outbursts: 2009 Autumn, 2010 Spring, and Autumn. The data reveal a repeating pattern, including triple flare structure, in properties each outburst, which implies similar mechanism(s) location for all events. multi-frequency indicates that lower frequency events are co-spatial with outbursts, although emission varies on shortest timescales. determine variability from UV to IR wavelengths an outburst...
We present simultaneous Planck, Swift, Fermi, and ground-based data for 105 blazars belonging to three samples with flux limits in the soft X-ray, hard gamma-ray bands. Our unique set has allowed us demonstrate that selection method strongly influences results, producing biases cannot be ignored. Almost all BL Lac objects have been detected by Fermi-LAT, whereas ~40% of flat-spectrum radio quasars (FSRQs) radio, X-ray selected are still below detection limit even after integrating 27 months...
We analyze the parsec-scale jet kinematics from 2007 June to 2013 January of a sample $\gamma$-ray bright blazars monitored roughly monthly with Very Long Baseline Array at 43~GHz. In total 1929 images, we measure apparent speeds 252 emission knots in 21 quasars, 12 BL~Lacertae objects (BLLacs), and 3 radio galaxies, ranging 0.02$c$ 78$c$; 21\% are quasi-stationary. Approximately 1/3 moving execute non-ballistic motions, quasars exhibiting acceleration along within 5~pc (projected) core,...
We present observations of a major outburst at centimeter, millimeter, optical, X-ray, and γ-ray wavelengths the BL Lacertae object AO 0235+164. analyze timing multi-waveband variations in flux linear polarization, as well changes Very Long Baseline Array images λ = 7 mm with ∼0.15 milliarcsec resolution. The association events different wavebands is confirmed high statistical significance by probability arguments Monte Carlo simulations. A series sharp peaks optical pronounced maximum...
Identifying the most likely sources for high-energy neutrino emission has been one of main topics in astrophysics ever since first observation neutrinos by IceCube Neutrino Observatory. Active galactic nuclei with relativistic jets, also known as blazars, have considered to be candidates because their ability accelerate particles high energies. We study connection between radio and events using data from Owens Valley Radio Observatory (OVRO) Mets\"ahovi blazar monitoring programs. identify...
Abstract Most large galaxies host supermassive black holes in their nuclei and are subject to mergers, which can produce a hole binary (SMBHB), hence periodic signatures due orbital motion. We report unique radio flux density variations the blazar PKS 2131−021, strongly suggest an SMBHB with separation of ∼0.001–0.01 pc. Our 45.1 yr light curve shows two epochs strong sinusoidal variation same period phase within ≲2% ∼10%, respectively, straddling 20 when this was absent. simulated curves...
We have collected a large amount of multifrequency data for objects in the Metsähovi Radio Observatory BL Lacertae sample and computed their spectral energy distributions (SED) log ν – representation. This is first time SEDs Lacs been studied with over 300 objects. The synchrotron components were fitted parabolic function to determine peak frequency, . checked dependence between luminosities at several frequency bands test blazar sequence scenario, which states that source luminosity depends...
Of the blazars detected by EGRET in GeV γ-rays, 3C 279 is not only best observed but also one of monitored at lower frequencies. We have assembled 11 spectra, from GHz radio through time intervals observations. Although some data appeared previous publications, most are new, including taken during high states early 1999 and 2000. All spectra show substantial γ-ray contribution to total luminosity object; a state, dominates over that all other frequencies factor more than 10. There no clear...
The radio quasar 3C 454.3 underwent an exceptional optical outburst lasting more than 1 year and culminating in spring 2005. maximum brightness detected was R = 12.0, which represents the most luminous state thus far observed (M_B ~ -31.4). In order to follow emission behaviour of source detail, a large multiwavelength campaign organized by Whole Earth Blazar Telescope (WEBT). Continuous optical, near-IR monitoring performed several bands. ToO pointings Chandra INTEGRAL satellites provided...
Aims. Since the CGRO operation in 1991–2000, one of primary unresolved questions about blazar γ-ray emission has been its possible correlation with low-energy (in particular optical) emission. To help answer this problem, Whole Earth Blazar Telescope (WEBT) consortium organized GLAST-AGILE Support Program (GASP) to provide optical-to-radio monitoring data be compared detections by AGILE and GLAST satellites. This new WEBT project started early September 2007, just before a strong detection...
Aims. We present an update of the 3C 273's database hosted by ISDC, completed with data from radio to gamma-ray observations over last 10 years. use this large set study multiwavelength properties quasar, especially focussing on its variability behaviour.
We present the results of extensive multi-frequency monitoring radio galaxy 3C 111 between 2004 and 2010 at X-ray (2.4--10 keV), optical (R band), (14.5, 37, 230 GHz) wave bands, as well multi-epoch imaging with Very Long Baseline Array (VLBA) 43 GHz. Over six years observation, significant dips in light curve are followed by ejections bright superluminal knots VLBA images. This shows a clear connection radiative state near black hole, where X-rays produced, events jet. The continuum flux Fe...
We report on the detection of a very rapid TeV gamma-ray flare from BL Lacertae 2011 June 28 with Very Energetic Radiation Imaging Telescope Array System (VERITAS). The flaring activity was observed during 34.6-minute exposure, when integral flux above 200 GeV reached $(3.4\pm0.6) \times 10^{-6} \;\text{photons}\;\text{m}^{-2}\text{s}^{-1}$, roughly 125% Crab Nebula measured by VERITAS. light curve indicates that observations missed rising phase but covered significant portion decaying...
We present the results of extensive multi-frequency monitoring radio galaxy 3C 120 between 2002 and 2007 at X-ray, optical, wave bands, as well imaging with Very Long Baseline Array (VLBA). Over 5 yr observation, significant dips in X-ray light curve are followed by ejections bright superluminal knots VLBA images. Consistent this, flux 37 GHz anti-correlated leading variations. This implies that, this galaxy, radiative state accretion disk plus corona system, where X-rays produced, has a...