A5060126668- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- Astrophysical Phenomena and Observations
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- Atmospheric and Environmental Gas Dynamics
- Astrophysics and Star Formation Studies
- Galaxies: Formation, Evolution, Phenomena
- Non-Destructive Testing Techniques
- Nuclear Physics and Applications
- Superconducting Materials and Applications
- Geophysics and Gravity Measurements
- SAS software applications and methods
- Radio Astronomy Observations and Technology
- Neutrino Physics Research
- Adaptive optics and wavefront sensing
- Electrical Fault Detection and Protection
- Solar and Space Plasma Dynamics
- Liver Disease Diagnosis and Treatment
- Distributed and Parallel Computing Systems
- Calibration and Measurement Techniques
- Photovoltaic System Optimization Techniques
University of Turku
2017-2025
LIP - Laboratory of Instrumentation and Experimental Particle Physics
2024
South African Radio Astronomy Observatory
2024
Astronomical Observatory
2024
Cerro Tololo Inter-American Observatory
2024
Queen's University Belfast
2010-2020
Vaisala (Finland)
2018
University of South Florida
2013
Philadelphia University
2013
RELX Group (United States)
2013
We present optical light curves, redshifts, and classifications for 365 spectroscopically confirmed Type Ia supernovae (SNe Ia) discovered by the Pan-STARRS1 (PS1) Medium Deep Survey. detail improvements to PS1 SN photometry, astrometry calibration that reduce systematic uncertainties in distances. combine subset of 279 ($0.03 < z 0.68$) with useful distance estimates from SDSS, SNLS, various low-z HST samples form largest combined sample consisting a total 1048 ranging $0.01 2.3$, which we...
Pan-STARRS1 has carried out a set of distinct synoptic imaging sky surveys including the $3π$ Steradian Survey and Medium Deep in 5 bands ($grizy_{P1}$). The mean 5$σ$ point source limiting sensitivities stacked 3$π$ $grizy_{P1}$ are (23.3, 23.2, 23.1, 22.3, 21.4) respectively. upper bound on systematic uncertainty photometric calibration across is 7-12 millimag depending bandpass. astrometric using Gaia frame comes from comparison results with Gaia: standard deviation median residuals ($...
We report extensive observational data for five of the lowest redshift Super-Luminous Type Ic Supernovae (SL-SNe Ic) discovered to date, namely PTF10hgi, SN2011ke, PTF11rks, SN2011kf and SN2012il. Photometric imaging transients at +50 +230 days after peak combined with host galaxy subtraction reveals a luminous tail phase four these SL-SNe. A high resolution, optical near infrared spectrum from xshooter provides detection broad He I $\lambda$10830 emission line in (+50d) SN2012il, revealing...
We report the results of a three-year-long dedicated monitoring campaign restless luminous blue variable (LBV) in NGC 7259. The object, named SN 2009ip, was observed photometrically and spectroscopically optical near-infrared domains. monitored number erupting episodes past few years, increased density our observations during eruptive episodes. In this paper, we present full historical data set from 2009 to 2012 with multi-wavelength dense coverage two high-luminosity events between August...
We present griz light curves of 146 spectroscopically confirmed Type Ia Supernovae ($0.03 < z <0.65$) discovered during the first 1.5 years Pan-STARRS1 Medium Deep Survey. The natural photometric system is determined by a combination on-site measurements instrument response function and observations spectrophotometric standard stars. find that systematic uncertainties in are currently 1.2\% without accounting for uncertainty HST Calspec definition AB system. A Hubble diagram constructed with...
The Public European Southern Observatory Spectroscopic Survey of Transient Objects (PESSTO) began as a public spectroscopic survey in April 2012. We describe the data reduction strategy and products which are publicly available through ESO archive Data Release 1 (SSDR1). PESSTO uses New Technology Telescope with EFOSC2 SOFI to provide optical NIR spectroscopy imaging. target supernovae transients brighter than 20.5mag for classification. Science targets then selected follow-up based on...
The photometric and spectroscopic properties of 26 well observed Type Ia Supernovae (SNeIa) were analyzed with the aim to explore SNIa diversity. sample includes (Branch-)normal SNe as extreme events like 1991T 1991bg, while truly peculiar SNIa, SN2000cx SN2002cx are not included in our . A statistical treatment reveals existence three different groups. first group (FAINT) consists faint SNeIa similar SN1991bg, low expansion velocities rapid evolution SiII velocity. second ``normal'' SNeIa,...
Recent searches by unbiased, wide-field surveys have uncovered a group of extremely luminous optical transients. The initial discoveries SN 2005ap the Texas Supernova Search and SCP-06F6 in deep Hubble pencil beam survey were followed Palomar Transient Factory confirmation host redshifts for other similar transients share common properties high luminosities (peak magnitudes ∼−21 to −23), blue colors, lack H or He spectral features. physical mechanism that produces luminosity is uncertain,...
We present mid-infrared (MIR) observations of the Type II-plateau supernova (SN) 2004et, obtained with Spitzer Space Telescope between 64 and 1406 days past explosion. Late-time optical spectra are also presented. For period 300–795 explosion, we argue that spectral energy distribution (SED) SN 2004et comprises (1) a hot component due to emission from optically thick gas, as well free–bound radiation; (2) warm newly formed, radioactively heated dust in ejecta; (3) cold an IR echo...
A set of hydrodynamical models based on stellar evolutionary progenitors is used to study the nature SN 2011dh. Our modeling suggests that a large progenitor star ---with R ~200 Rsun---, needed reproduce early light curve This consistent with suggestion yellow super-giant detected at location in deep pre-explosion images star. From main peak bolometric and expansion velocities we constrain mass ejecta be ~2 Msun, explosion energy E= 6-10 x 10^50 erg, 56Ni approximately 0.06 Msun. The was...
Aims.We present a study of the optical and near-infrared (NIR) properties Type Ia Supernova (SN Ia) 2003du.
Context. We investigate two stripped-envelope supernovae (SNe) discovered in the nearby galaxy NGC 5806 by (intermediate) Palomar Transient Factory [(i)PTF]. These SNe, designated PTF12os/SN 2012P and iPTF13bvn, exploded within ~520 days of one another at a similar distance from host-galaxy center. classify PTF12os as Type IIb SN based on our spectral sequence; iPTF13bvn has previously been classified Ib having likely progenitor with zero age main sequence (ZAMS) mass below ~17 M⊙. Because...
We present the detection of putative progenitor Type IIb SN 2011dh in archival pre-explosion Hubble Space Telescope images. Using post-explosion Adaptive Optics imaging with Gemini NIRI+ALTAIR, position supernova (SN) images was determined to within 23 mas. The candidate is consistent an F8 supergiant star (logL/L☉ = 4.92 ± 0.20 and Teff 6000 280 K). Through comparison stellar evolution tracks, this corresponds a single at end core C-burning initial mass MZAMS 13 3 M☉. possibility source...
We present nebular-phase optical and near-infrared spectroscopy of the Type IIP supernova SN 2012aw combined with non-local thermodynamic equilibrium radiative transfer calculations applied to ejecta from stellar evolution/explosion models. Our spectral synthesis models generally show good agreement a MZAMS = 15 M⊙ progenitor star. The emission lines oxygen, sodium, magnesium are all consistent nucleosynthesis in 14–18 range. also demonstrate how evolution oxygen cooling [O i] λ5577, λ6300,...
We present comprehensive photometric and spectroscopic observations of the faint transient SN 2008S discovered in NGC 6946. exhibited slow evolution almost no spectral variability during first nine months, implying a high density CS medium. The light curve is similar shape to that 1998S 1979C, although significantly fainter at maximum light. Our quasi-bolometric lightcurve extends 300 days shows tail phase decay rate consistent with ^{56}Co. propose this evidence for an explosion formation...
We present optical spectra and light curves for three hydrogen-poor superluminous supernovae followed by the Public ESO Spectroscopic Survey of Transient Objects (PESSTO). Time series spectroscopy from a few days after maximum to 100 d later shows them be fairly typical this class, with dominated Ca ii, Mg Fe Si which evolve slowly over most post-peak photospheric phase. determine bolometric apply simple fitting tools, based on diffusion energy input magnetar spin-down, 56Ni decay, collision...
Tidal disruption events (TDEs) are transient flares produced when a star is ripped apart by the gravitational field of supermassive black hole (SMBH). We have observed source in western nucleus merging galaxy pair Arp 299 that radiated >1.5x10^52 erg infrared and radio, but was not luminous at optical or X-ray wavelengths. interpret this as TDE with much its emission re-radiated wavelengths dust. Efficient reprocessing dense gas dust may explain difference between theoretical predictions...
We present optical and near-infrared (NIR) photometry spectroscopy of the Type IIb supernova (SN) 2011dh for first 100 days. complement our extensive dataset with SWIFT ultra-violet (UV) Spitzer mid-infrared (MIR) data to build a UV MIR bolometric lightcurve using both photometric spectroscopic data. Hydrodynamical modelling SN based on this have been presented in Bersten (2012). find that absorption minimum hydrogen lines is never seen below ~11000 km/s but approaches value as get weaker....
We probe the systematic uncertainties from 113 Type Ia supernovae (SNIa) in Pan-STARRS1 (PS1) sample along with 197 SN a combination of low-redshift surveys. The companion paper by Rest et al. (2013) describes photometric measurements and cosmological inferences PS1 sample. largest uncertainty stems calibration low-z samples. increase observed Calspec standards 7 to 10 used define system. SDSS-II systems are compared discrepancies up ~0.02 mag recovered. find proper way treat intrinsic...
We present ultraviolet, optical and near-infrared observations of the interacting transient SN 2009ip, covering period from start outburst in 2012 October until end observing season. The reached a peak magnitude MV = −17.7 mag, with total integrated luminosity 1.9 × 1049 erg over August–December. light curve fades rapidly, dropping by 4.5 mag V-band 100 d. spectra are dominated narrow emission lines broad electron scattering wings, signalling dense circumstellar environment, together...
Hypervelocity stars (HVS) travel with velocities so high, that they exceed the escape velocity of Galaxy. Several acceleration mechanisms have been discussed. Only one HVS (US 708, 2) is a compact helium star. Here we present spectroscopic and kinematic analysis US\,708. Travelling $\sim1200\,{\rm km\,s^{-1}}$, it fastest unbound star in our In reconstructing its trajectory, Galactic center becomes very unlikely as an origin, which hardly consistent most favored ejection mechanism for other...