SwePub - search: WFRF:(Fransson Peter)

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1.	Wang, Xiaofeng, et al. (author) Evidence for type ia supernova diversity from ultraviolet observations with the hubble space telescope 2012 In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 749:2, s. 126- Journal article (peer-reviewed)abstract We present ultraviolet (UV) spectroscopy and photometry of four Type Ia supernovae (SNe 2004dt, 2004ef, 2005M, and 2005cf) obtained with the UV prism of the Advanced Camera for Surveys on the Hubble Space Telescope. This data set provides unique spectral time series down to 2000 angstrom. Significant diversity is seen in the near-maximum-light spectra (similar to 2000-3500 angstrom) for this small sample. The corresponding photometric data, together with archival data from Swift Ultraviolet/Optical Telescope observations, provide further evidence of increased dispersion in the UV emission with respect to the optical. The peak luminositiesmeasured in the uvw1/F250W filter are found to correlate with the B-band light-curve shape parameter Delta m(15)(B), but with much larger scatter relative to the correlation in the broadband B band (e.g., similar to 0.4 mag versus similar to 0.2 mag for those with 0.8 mag < Delta m(15)(B) < 1.7 mag). SN 2004dt is found as an outlier of this correlation (at > 3 sigma), being brighter than normal SNe Ia such as SN 2005cf by similar to 0.9 mag and similar to 2.0 mag in the uvw1/F250W and uvm2/F220W filters, respectively. We show that different progenitor metallicity or line-expansion velocities alone cannot explain such a large discrepancy. Viewing-angle effects, such as due to an asymmetric explosion, may have a significant influence on the flux emitted in the UV region. Detailed modeling is needed to disentangle and quantify the above effects.
2.	Clocchiatti, Alejandro, et al. (author) Late-time HST photometry of SN1994I : Hints of positron annihilation energy deposition 2008 In: Publications of the Astronomical Society of the Pacific. - : IOP Publishing. - 0004-6280 .- 1538-3873. ; 120:865, s. 290-300 Journal article (peer-reviewed)abstract We present multicolor Hubble Space Telescope ( HST) WFPC2 broadband observations of the Type Ic SN 1994I obtained similar to 280 d after maximum light. We measure the brightness of the SN and, relying on the detailed spectroscopic database of SN 1994I, we transform the ground-based photometry obtained at early times to the HST photometric system, deriving light curves for the WFPC2 F439W, F555W, F675W, and F814W passbands that extend from 7 days before to 280 days after maximum. We use the multicolor photometry to build a quasi-bolometric light curve of SN 1994I, and compare it with similarly constructed light curves of other supernovae. In doing so, we propose and test a scaling in energy and time that allows for a more meaningful comparison of the exponential tails of different events. Through comparison with models, we find that the late-time light curve of SN 1994I is consistent with that of spherically symmetric ejecta in homologous expansion, for which the ability to trap the gamma-rays produced by the radioactive decay of Co-56 diminishes roughly as the inverse of time squared. We also find that by the time of the HST photometry, the light curve was significantly energized by the annihilation of positrons.
3.	France, Kevin, et al. (author) HST-COS Observations of Hydrogen, Helium, Carbon, and Nitrogen Emission from the SN 1987A Reverse Shock 2011 In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 743:2, s. 186- Journal article (peer-reviewed)abstract We present the most sensitive ultraviolet observations of Supernova 1987A to date. Imaging spectroscopy from the Hubble Space Telescope-Cosmic Origins Spectrograph shows many narrow (Δv ~ 300 km s-1) emission lines from the circumstellar ring, broad (Δv ~ 10-20 × 103 km s-1) emission lines from the reverse shock, and ultraviolet continuum emission. The high signal-to-noise ratio (>40 per resolution element) broad Lyα emission is excited by soft X-ray and EUV heating of mostly neutral gas in the circumstellar ring and outer supernova debris. The ultraviolet continuum at λ > 1350 Å can be explained by H I two-photon (2s 2 S 1/2-1s 2 S 1/2) emission from the same region. We confirm our earlier, tentative detection of N V λ1240 emission from the reverse shock and present the first detections of broad He II λ1640, C IV λ1550, and N IV] λ1486 emission lines from the reverse shock. The helium abundance in the high-velocity material is He/H = 0.14 ± 0.06. The N V/Hα line ratio requires partial ion-electron equilibration (Te /Tp ≈ 0.14-0.35). We find that the N/C abundance ratio in the gas crossing the reverse shock is significantly higher than that in the circumstellar ring, a result that may be attributed to chemical stratification in the outer envelope of the supernova progenitor. The N/C abundance may have been stratified prior to the ring expulsion, or this result may indicate continued CNO processing in the progenitor subsequent to the expulsion of the circumstellar ring. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.
4.	France, Kevin, et al. (author) MAPPING HIGH-VELOCITY H alpha AND Ly alpha EMISSION FROM SUPERNOVA 1987A 2015 In: Astrophysical Journal Letters. - 2041-8205 .- 2041-8213. ; 801:1 Journal article (peer-reviewed)abstract We present new Hubble Space Telescope images of high-velocity H alpha and Ly alpha emission in the outer debris of SN 1987 A. The Ha images are dominated by emission from hydrogen atoms crossing the reverse shock (RS). For the first time we observe emission from the RS surface well above and below the equatorial. ring (ER), suggesting a bipolar or conical structure perpendicular to the ring plane. Using the H alpha imaging, we measure the mass flux of hydrogen atoms crossing the RS front, in the velocity intervals (-7500 < V-obs < -2800 km s(-1)) and (1000 < V-obs < 7500 km s(-1)), (M)(H) over dot = 1.2 x 10(-3) M-circle dot yr(-1). We also present the first Ly alpha imaging of the whole remnant and new Chandra X-ray observations. Comparing the spatial distribution of the Ly alpha and X-ray emission, we observe that the majority of the high-velocity Ly alpha emission originates interior to the ER. The observed Ly alpha/H alpha photon ratio, < R(L alpha/H alpha)> approximate to 17, is significantly higher than the theoretically predicted ratio of approximate to 5 for neutral atoms crossing the RS front. We attribute this excess to Ly alpha emission produced by X-ray heating of the outer debris. The spatial orientation of the Ly alpha and X-ray emission suggests that X-ray heating of the outer debris is the dominant Ly alpha production mechanism in SN 1987 A at this phase in its evolution.
5.	France, Kevin, et al. (author) MAPPING high-velocity Hα and Lyα emission from supernova 1987A 2015 In: Astrophysical Journal Letters. - 2041-8205 .- 2041-8213. ; 801:1 Journal article (peer-reviewed)abstract We present new Hubble Space Telescope images of high-velocity H alpha and Ly alpha emission in the outer debris of SN 1987 A. The Ha images are dominated by emission from hydrogen atoms crossing the reverse shock (RS). For the first time we observe emission from the RS surface well above and below the equatorial. ring (ER), suggesting a bipolar or conical structure perpendicular to the ring plane. Using the H alpha imaging, we measure the mass flux of hydrogen atoms crossing the RS front, in the velocity intervals (-7500 < V-obs < -2800 km s(-1)) and (1000 < V-obs < 7500 km s(-1)), (M)(H) over dot = 1.2 x 10(-3) M-circle dot yr(-1). We also present the first Ly alpha imaging of the whole remnant and new Chandra X-ray observations. Comparing the spatial distribution of the Ly alpha and X-ray emission, we observe that the majority of the high-velocity Ly alpha emission originates interior to the ER. The observed Ly alpha/H alpha photon ratio, < R(L alpha/H alpha)> approximate to 17, is significantly higher than the theoretically predicted ratio of approximate to 5 for neutral atoms crossing the RS front. We attribute this excess to Ly alpha emission produced by X-ray heating of the outer debris. The spatial orientation of the Ly alpha and X-ray emission suggests that X-ray heating of the outer debris is the dominant Ly alpha production mechanism in SN 1987 A at this phase in its evolution.
6.	France, Kevin, et al. (author) Observing Supernova 1987A with the Refurbished Hubble Space Telescope 2010 In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 329:5999, s. 1624-1627 Journal article (peer-reviewed)abstract Observations with the Hubble Space Telescope (HST), conducted since 1990, now offer an unprecedented glimpse into fast astrophysical shocks in the young remnant of supernova 1987A. Comparing observations taken in 2010 with the use of the refurbished instruments on HST with data taken in 2004, just before the Space Telescope Imaging Spectrograph failed, we find that the Ly alpha and H alpha lines from shock emission continue to brighten, whereas their maximum velocities continue to decrease. We observe broad, blueshifted Ly alpha, which we attribute to resonant scattering of photons emitted from hot spots on the equatorial ring. We also detect N v lambda lambda 1239, 1243 angstrom line emission, but only to the red of Ly alpha. The profiles of the N v lines differ markedly from that of H alpha, suggesting that the N4+ ions are scattered and accelerated by turbulent electromagnetic fields that isotropize the ions in the collisionless shock.
7.	Fransson, Claes, et al. (author) Hubble Space Telescope and Ground-based Observations of SN 1993J and SN 1998S : CNO Processing in the Progenitors 2005 In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 622, s. 991-1007 Journal article (peer-reviewed)abstract Ground-based and Hubble Space Telescope observations are presented for SN 1993J and SN 1998S. SN 1998S shows strong, relatively narrow circumstellar emission lines of N III-V and C III-IV, as well as broad lines from the ejecta. Both the broad ultraviolet and optical lines in SN 1998S indicate an expansion velocity of ~7000 km s-1. The broad emission components of Lyα and Mg II are strongly asymmetrical after day 72 past the explosion and differ in shape from Hα. Different models based on dust extinction from dust in the ejecta or shock region, in combination with Hα from a circumstellar torus, are discussed. It is concluded, however, that the double-peaked line profiles are more likely to arise as a result of optical depth effects in the narrow, cool, dense shell behind the reverse shock than in a torus-like region. The ultraviolet lines of SN 1993J are broad, with a boxlike shape, coming from the ejecta and a cool, dense shell. The shapes of the lines are well fitted by a shell with inner velocity ~7000 km s-1 and outer velocity ~10,000 km s-1. For both SN 1993J and SN 1998S a strong nitrogen enrichment is found, with N/C~12.4 in SN 1993J and N/C~6.0 in SN 1998S. From a compilation of all supernovae with determined CNO ratios, we discuss the implications of these observations for the structure of the progenitors of Type II supernovae. Based in part on observations obtained with the Hubble Space Telescope, which is operated by AURA, Inc., under NASA contract NAS 5-26555.
8.	Fransson, Claes, et al. (author) THE DESTRUCTION OF THE CIRCUMSTELLAR RING OF SN 1987A 2015 In: Astrophysical Journal Letters. - 2041-8205 .- 2041-8213. ; 806:1 Journal article (peer-reviewed)abstract We present imaging and spectroscopic observations with Hubble Space Telescope and Very Large Telescope of the ring of SN 1987A from 1994 to 2014. After an almost exponential increase of the shocked emission from the hotspots up to day similar to 8000 (similar to 2009), both this and the unshocked emission are now fading. From the radial positions of the hotspots we see an acceleration of these up to 500-1000 km s(-1), consistent with the highest spectroscopic shock velocities from the radiative shocks. In the most recent observations (2013 and 2014), we find several new hotspots outside the inner ring, excited by either X-rays from the shocks or by direct shock interaction. All of these observations indicate that the interaction with the supernova ejecta is now gradually dissolving the hotspots. We predict, based on the observed decay, that the inner ring will be destroyed by similar to 2025.
9.	Graves, Genevieve J. M., et al. (author) Limits from the Hubble Space Telescope on a Point Source in SN 1987A 2005 In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 629, s. 944-959 Journal article (peer-reviewed)abstract We observed supernova 1987A (SN 1987A) with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST) in 1999 September and again with the Advanced Camera for Surveys (ACS) on the HST in 2003 November. Our spectral observations cover ultraviolet (UV) and optical wavelengths from 1140 to 10266 Å, and our imaging observations cover UV and optical wavelengths from 2900 to 9650 Å. No point source is observed in the remnant. We obtain a limiting flux of Fopt<=1.6×10-14 ergs s-1 cm-2 in the wavelength range 2900-9650 Å for any continuum emitter at the center of the supernova remnant (SNR). This corresponds to an intrinsic luminosity of Lopt<=5×1033 ergs s-1. It is likely that the SNR contains opaque dust that absorbs UV and optical emission, resulting in an attenuation of ~35% due to dust absorption in the SNR. Correcting for this level of dust absorption would increase our upper limit on the luminosity of a continuum source by a factor of 1.54. Taking into account dust absorption in the remnant, we find a limit of Lopt<=8×1033 ergs s-1. We compare this upper bound with empirical evidence from point sources in other supernova remnants and with theoretical models for possible compact sources. We show that any survivor of a possible binary system must be no more luminous than an F6 main-sequence star. Bright young pulsars such as Kes 75 or the Crab pulsar are excluded by optical and X-ray limits on SN 1987A. Other nonplerionic X-ray point sources have luminosities similar to the limits on a point source in SN 1987A; RCW 103 and Cas A are slightly brighter than the limits on SN 1987A, while Pup A is slightly fainter. Of the young pulsars known to be associated with SNRs, those with ages <=5000 yr are all too bright in X-rays to be compatible with the limits on SN 1987A. Examining theoretical models for accretion onto a compact object, we find that spherical accretion onto a neutron star is firmly ruled out and that spherical accretion onto a black hole is possible only if there is a larger amount of dust absorption in the remnant than predicted. In the case of thin-disk accretion, our flux limit requires a small disk, no larger than 1010 cm, with an accretion rate no more than 0.3 times the Eddington accretion rate. Possible ways to hide a surviving compact object include the removal of all surrounding material at early times by a photon-driven wind, a small accretion disk, or very high levels of dust absorption in the remnant. It will not be easy to improve substantially on our optical-UV limit for a point source in SN 1987A, although we can hope that a better understanding of the thermal infrared emission will provide a more complete picture of the possible energy sources at the center of SN 1987A.
10.	Heng, Kevin, et al. (author) Evolution of the Reverse Shock Emission from SNR 1987A 2006 In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 644, s. 959-970 Journal article (peer-reviewed)abstract We present new (2004 July) G750L and G140L Space Telescope Imaging Spectrograph (STIS) data of the Hα and Lyα emission from supernova remnant (SNR) 1987A. With the aid of earlier data, from 1997 October to 2002 October, we track the local evolution of Lyα emission and both the local and global evolution of Hα emission. The most recent observations allow us to directly compare the Hα and Lyα emission from the same slit position and at the same epoch. Consequently, we find clear evidence that, unlike Hα, Lyα is reflected from the debris by resonant scattering. In addition to emission that we can clearly attribute to the surface of the reverse shock, we also measure comparable emission, in both Hα and Lyα, that appears to emerge from supernova debris interior to the surface. New observations taken through slits positioned slightly eastward and westward of a central slit show a departure from cylindrical symmetry in the Hα surface emission. Using a combination of old and new observations, we construct a light curve of the total Hα flux, F, from the reverse shock, which has increased by a factor of ~4 over about 8 yr. However, due to large systematic uncertainties, we are unable to discern between the two limiting behaviors of the flux: F~t (self-similar expansion) and F~t5 (halting of the reverse shock). Such a determination is important for constraining the rate of hydrogen atoms crossing the shock, which is relevant to the question of whether the reverse shock emission will vanish in <~7 yr. Future deep, low- or moderate-resolution spectra are essential for accomplishing this task.
11.	Kotak, Rubina, et al. (author) Spitzer Measurements of Atomic and Molecular Abundances in the Type IIP SN 2005af 2006 In: The Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 651:2, s. L117-L120 Journal article (peer-reviewed)abstract We present results based on mid-infrared (3.6-30 μm) observations with the Spitzer Space Telescope of the nearby Type IIP supernova 2005af. We report the first ever detection of the SiO molecule in a Type IIP supernova. Together with the detection of the CO fundamental, this is an exciting finding as it may signal the onset of dust condensation in the ejecta. From a wealth of fine-structure lines we provide abundance estimates for stable Ni, Ar, and Ne that, via spectral synthesis, may be used to constrain nucleosynthesis models.
12.	Michael, Eli, et al. (author) Hubble Space Telescope Observations of High-Velocity Lyα and Hα Emission from Supernova Remnant 1987A : The Structure and Development of the Reverse Shock 2003 In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 593, s. 809-830 Journal article (peer-reviewed)abstract We present two-dimensional line profiles of high-velocity (~+/-12,000 km s-1) Lyα and Hα emission from supernova remnant 1987A obtained with the Space Telescope Imaging Spectrograph between 1997 September and 2001 September (days 3869-5327 after the explosion). This emission comes from hydrogen in the debris that is excited and ionized as it passes through the remnant's reverse shock. We use these profiles to measure the geometry and development of the reverse-shock surface. The observed emission is confined within ~+/-30° about the remnant's equatorial plane. At the equator, the reverse shock has a radius of ~75% of the distance to the equatorial ring. We detect marginal differences (6%+/-3%) between the location of the reverse-shock front in the northeast and southwest parts of the remnant. The radius of the reverse shock surface increases for latitudes above the equator, a geometry consistent with a model in which the supernova debris expands into a bipolar nebula. Assuming that the outer supernova debris has a power-law density distribution, we can infer from the reverse-shock emission light curve an expansion rate (in the northeast part of the remnant) of 3700+/-900kms-1, consistent with the expansion velocities determined from observations in radio (Manchester et al.) and X-ray (Park et al.; Michael et al.) wavelengths. However, our most recent observation (at day 5327) suggests that the rate of increase of mass flux across the northeast sector of the reverse shock has accelerated, perhaps because of deceleration of the reverse shock caused by the arrival of a reflected shock created when the blast wave struck the inner ring. Resonant scattering within the supernova debris causes Lyα photons created at the reverse shock to be directed preferentially outward, resulting in a factor of ~5 difference in the observed brightness of the reverse shock in Lyα between the near and far sides of the remnant. Accounting for this effect, we compare the observed reverse-shock Lyα and Hα fluxes to infer the amount of interstellar extinction by dust as E(B-V)=0.17+/-0.01 mag. We also notice extinction by dust in the equatorial ring with E(B-V)~0.02-0.08 mag, which implies dust-to-gas ratios similar to that of the LMC. Since Hα photons are optically thin to scattering, the observed asymmetry in brightness of Hα from the near and far sides of the remnant represents a real asymmetry in the mass flux through the reverse shock of ~30%. We discuss future observational strategies that will permit us to further investigate the reverse-shock dynamics and resonant scattering of the Lyα line and to constrain better the extinction by dust within and in front of the remnant.
13.	Alp, Dennis, et al. (author) The 30 Year Search for the Compact Object in SN 1987A 2018 In: Astrophysical Journal. - : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 864:2 Journal article (peer-reviewed)abstract Despite more than 30 years of searching, the compact object in Supernova (SN) 1987A has not yet been detected. We present new limits on the compact object in SN 1987A using millimeter, near-infrared, optical, ultraviolet, and X-ray observations from ALMA, VLT, HST, and Chandra. The limits are approximately 0.1 mJy (0.1 x 10(-26) erg s(-1) cm(-2) Hz(-1)) at 213 GHz, 1 L-circle dot (6 x 10(-29) erg s(-1) cm(-2) Hz(-1)) in the optical if our line of sight is free of ejecta dust, and 10(36) erg s(-1) (2 x 10(-30) erg s(-1) cm(-2) Hz(-1) ) in 2-10 keV X-rays. Our X-ray limits are an order of magnitude less constraining than previous limits because we use a more realistic ejecta absorption model based on three-dimensional neutrino-driven SN explosion models. The allowed bolometric luminosity of the compact object is 22 L-circle dot if our line of sight is free of ejecta dust, or 138L(circle dot) if dust-obscured. Depending on assumptions, these values limit the effective temperature of a neutron star (NS) to <4-8 MK and do not exclude models, which typically are in the range 3-4 MK. For the simplest accretion model, the accretion rate for an efficiency 77 is limited to <10(-11) eta(-1) M-circle dot yr(-1), which excludes most predictions. For pulsar activity modeled by a rotating magnetic dipole in vacuum, the limit on the magnetic field strength (B) for a given spin period (P) is B less than or similar to 10(14) P-2 G s(-2), which firmly excludes pulsars comparable to the Crab. By combining information about radiation reprocessing and geometry, we infer that the compact object is a dust-obscured thermally emitting NS, which may appear as a region of higher-temperature ejecta dust emission.
14.	Elfgren, Christina, et al. (author) fMRI activity in the medial temporal lobe during famous face processing 2006 In: NeuroImage. - : Elsevier BV. - 1095-9572 .- 1053-8119. ; 30:2, s. 609-616 Journal article (peer-reviewed)abstract The current event-related fMRI study examined the relative involvement of different parts of the medial temporal lobe (MTL), particularly the contribution of hippocampus and perirhinal cortex, in either intentional or incidental recognition of famous faces in contrast to unfamiliar faces. Our intention was to further explore the controversial contribution of MTL in the processing of semantic memory tasks. Subjects viewed a sequence of famous and unfamiliar faces. Two tasks were used encouraging attention to either fame or gender. In the fame task, the subjects were requested to identify the person when seeing his/her face and also to try to generate the name of this person. In the gender task, the subjects were asked to conduct a judgement of a person's gender when seeing his/her face. The visual processing was hence directed to gender and thereby expected to diminish attention to semantic information leading only to a “passive” registration of famous and non-familiar faces. Recognition of famous faces, in both contrasts, produced significant activations in the MTL. First, during the intentional recognition (the person identification task) increased activity was observed in the anterolateral part of left hippocampus, in proximity to amygdala. Second, during the incidental recognition of famous faces (the gender classification task), there was increased activity in the left posterior MTL with focus in the perirhinal cortex. Our results suggest that the hippocampus may be centrally involved in the intentional retrieval of semantic memories while the perirhinal cortex is associated with the incidental recognition of semantic information.
15.	Fransson, Claes, et al. (author) Late spectral evolution of the ejecta and reverse shock in SN 1987a 2013 In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 768:1, s. 88- Journal article (peer-reviewed)abstract We present observations with the Very Large Telescope and Hubble Space Telescope (HST) of the broad emission lines from the inner ejecta and reverse shock of SN 1987A from 1999 February until 2012 January (days 4381-9100 after explosion). We detect broad lines from H alpha, H beta, Mg I], Na I, [O I], [Ca II], and a feature at similar to 9220 angstrom. We identify the latter line with Mg II lambda lambda 9218, 9244, which is most likely pumped by Ly alpha fluorescence. H alpha and H beta both have a centrally peaked component extending to similar to 4500 km s(-1) and a very broad component extending to greater than or similar to 11,000 km s(-1), while the other lines have only the central component. The low-velocity component comes from unshocked ejecta, heated mainly by X-rays from the circumstellar environment, whereas the very broad component comes from faster ejecta passing through the reverse shock, created by the collision with the circumstellar ring. The flux in H alpha from the reverse shock has increased by a factor of four to six from 2000 to 2007. After that there is a tendency of flattening of the light curve, similar to what may be seen in the optical lines from the shocked ring. The core component seen in H alpha, [Ca II], and Mg II has experienced a similar increase, which is consistent with that found from HST photometry. The energy deposition of the external X-rays is calculated using explosion models for SN 1987A and we predict that the outer parts of the unshocked ejecta will continue to brighten because of this. The external X-ray illumination also explains the edge-brightened morphology of the ejecta seen in the HST images. We finally discuss evidence for dust in the ejecta from line asymmetries.
16.	Gröningsson, Per, et al. (author) Time evolution of the line emission from the inner circumstellar ring of SN 1987A and its hot spots 2008 In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 492:2, s. 481-491 Journal article (peer-reviewed)abstract We present seven epochs between October 1999 and November 2007 of high resolution VLT/UVES echelle spectra of the ejecta-ring collision of SN 1987A. The fluxes of most of the narrow lines from the unshocked gas decreased by a factor of 2-3 during this period, consistent with the decay from the initial ionization by the shock break-out. However, [O III] in particular shows an increase up to day ~6800. This agrees with radiative shock models where the pre-shocked gas is heated by the soft X-rays from the shock. The evolution of the [O III] line ratio shows a decreasing temperature of the unshocked ring gas, consistent with a transition from a hot, low density component which was heated by the initial flash ionization to the lower temperature in the pre-ionized gas ahead of the shocks. The line emission from the shocked gas increases rapidly as the shock sweeps up more gas. We find that the neutral and high ionization lines follow the evolution of the Balmer lines roughly, while the intermediate ionization lines evolve less rapidly. Up to day ~6800, the optical light curves have a similar evolution to that of the soft X-rays. The break between day 6500 and day 7000 for [O III] and [Ne III] is likely due to recombination to lower ionization levels. Nevertheless, the evolution of the [Fe XIV] line, as well as the lines from the lowest ionization stages, continue to follow that of the soft X-rays, as expected. There is a clear difference in the line profiles between the low and intermediate ionization lines, and those from the coronal lines at the earlier epochs. This shows that these lines arise from regions with different physical conditions, with at least a fraction of the coronal lines coming from adiabatic shocks. At later epochs the line widths of the low ionization lines, however, increase and approach those of the high ionization lines of [ Fe X-XIV] . The H line profile can be traced up to ~500 km s-1 at the latest epoch. This is consistent with the cooling time of shocks propagating into a density of (1-4) 104 cm-3. This means that these shocks are among the highest velocity radiative shocks observed.
17.	Kivimäki, Mika, et al. (author) Associations of job strain and lifestyle risk factors with risk of coronary artery disease : a meta-analysis of individual participant data 2013 In: CMJA. Canadian Medical Association Journal. Onlineutg. Med tittel. - : CMA Joule Inc.. - 0820-3946 .- 1488-2329. ; 185:9, s. 763-769 Journal article (peer-reviewed)abstract Background: It is unclear whether a healthy lifestyle mitigates the adverse effects of job strain on coronary artery disease. We examined the associations of job strain and lifestyle risk factors with the risk of coronary artery disease.Methods: We pooled individual-level data from 7 cohort studies comprising 102 128 men and women who were free of existing coronary artery disease at baseline (1985–2000). Questionnaires were used to measure job strain (yes v. no) and 4 lifestyle risk factors: current smoking, physical inactivity, heavy drinking and obesity. We grouped participants into 3 lifestyle categories: healthy (no lifestyle risk factors), moderately unhealthy (1 risk factor) and unhealthy (2–4 risk factors). The primary outcome was incident coronary artery disease (defined as first nonfatal myocardial infarction or cardiac-related death).Results: There were 1086 incident events in 743 948 person-years at risk during a mean follow-up of 7.3 years. The risk of coronary artery disease among people who had an unhealthy lifestyle compared with those who had a healthy lifestyle (hazard ratio [HR] 2.55, 95% confidence interval [CI] 2.18–2.98; population attributable risk 26.4%) was higher than the risk among participants who had job strain compared with those who had no job strain (HR 1.25, 95% CI 1.06–1.47; population attributable risk 3.8%). The 10-year incidence of coronary artery disease among participants with job strain and a healthy lifestyle (14.7 per 1000) was 53% lower than the incidence among those with job strain and an unhealthy lifestyle (31.2 per 1000).Interpretation: The risk of coronary artery disease was highest among participants who reported job strain and an unhealthy lifestyle; those with job strain and a healthy lifestyle had half the rate of disease. A healthy lifestyle may substantially reduce disease risk among people with job strain.
18.	Madsen, Ida E.H., et al. (author) Study protocol for examining job strain as a risk factor for severe unipolar depression in an individual participant meta-analysis of 14 European cohorts 2014 In: F1000 Research. - : F1000 Research Ltd. - 2046-1402. ; 2 Journal article (peer-reviewed)abstract Background: Previous studies have shown that gainfully employed individuals with high work demands and low control at work (denoted "job strain") are at increased risk of common mental disorders, including depression. Most existing studies have, however, measured depression using self-rated symptom scales that do not necessarily correspond to clinically diagnosed depression. In addition, a meta-analysis from 2008 indicated publication bias in the field.Methods: This study protocol describes the planned design and analyses of an individual participant data meta-analysis, to examine whether job strain is associated with an increased risk of clinically diagnosed unipolar depression based on hospital treatment registers. The study will be based on data from approximately 120,000 individuals who participated in 14 studies on work environment and health in 4 European countries. The self-reported working conditions data will be merged with national registers on psychiatric hospital treatment, primarily hospital admissions. Study-specific risk estimates for the association between job strain and depression will be calculated using Cox regressions. The study-specific risk estimates will be pooled using random effects meta-analysis.Discussion: The planned analyses will help clarify whether job strain is associated with an increased risk of clinically diagnosed unipolar depression. As the analysis is based on pre-planned study protocols and an individual participant data meta-analysis, the pooled risk estimates will not be influenced by selective reporting and publication bias. However, the results of the planned study may only pertain to severe cases of unipolar depression, because of the outcome measure applied.
19.	Mannfolk, Peter, et al. (author) Can resting-state functional MRI serve as a complement to task-based mapping of sensorimotor function? A test-retest reliability study in healthy volunteers. 2011 In: Journal of Magnetic Resonance Imaging. - : Wiley. - 1522-2586 .- 1053-1807. ; 34, s. 511-517 Journal article (peer-reviewed)abstract PURPOSE: To investigate if resting-state functional MRI (fMRI) reliably can serve as a complement to task-based fMRI for presurgical mapping of the sensorimotor cortex. MATERIALS AND METHODS: Functional data were obtained in 10 healthy volunteers using a 3 Tesla MRI system. Each subject performed five bilateral finger tapping experiments interleaved with five resting-state experiments. Following preprocessing, data from eight volunteers were further analyzed with the general linear model (finger tapping data) and independent component analysis (rest data). Test-retest reliability estimates (hit rate and false alarm rate) for resting-state fMRI activation of the sensorimotor network were compared with the reliability estimates for task-evoked activation of the sensorimotor cortex. The reliability estimates constituted a receiver operating characteristics curve from which the area under the curve (AUC) was calculated. Statistical testing was performed to compare the two groups with respect to reliability. RESULTS: The AUC was generally higher for the task experiments, although median AUC was not significantly different on a group level. Also, the two groups showed comparable levels of within-group variance. CONCLUSION: Test-retest reliability was comparable between resting-state measurements and task-based fMRI, suggesting that presurgical mapping of functional networks can be a supplement to task-based fMRI in cases where patient status excludes task-based fMRI. J. Magn. Reson. Imaging 2011;. © 2011 Wiley-Liss, Inc.
20.	Marion, G. H., et al. (author) TYPE IIb SUPERNOVA SN 2011dh : SPECTRA AND PHOTOMETRY FROM THE ULTRAVIOLET TO THE NEAR-INFRARED 2014 In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 781:2, s. 69- Journal article (peer-reviewed)abstract We report spectroscopic and photometric observations of the Type IIb SN 201 ldh obtained between 4 and 34 days after the estimated date of explosion (May 31.5 UT). The data cover a wide wavelength range from 2000 angstrom in the ultraviolet (UV) to 2.4 mu m in the near-infrared (NIR). Optical spectra provide line profiles and velocity measurements of H I, He I, Call, and Fe It that trace the composition and kinematics of the supernova (SN). NIR spectra show that helium is present in the atmosphere as early as 11 days after the explosion. A UV spectrum obtained with the Space Telescope Imaging Spectrograph reveals that the UV flux for SN 2011dh is low compared to other SN IIb. Modeling the spectrum with SYNOW suggests that the UV deficit is due to line blanketing from TinH and Co II. The HI and He I velocities in SN 2011dh are separated by about 4000 km s(-1) at all phases. A velocity gap is consistent with models for a preexplosion structure in which a hydrogen-rich shell surrounds the progenitor. We estimate that the H shell of SN 2011dh is approximate to 8 times less massive than the shell of SN 1993J and approximate to 3 times more massive than the shell of SN 2008ax. Light curves (LCs) for 12 passbands are presented: UVW2, UVM2, UVW1, U, u', B, V, r', i', J, H, and Ks. In the B band, SN 2011dh reached peak brightness of 13.17 mag at 20.0 +/- 0.5 after the explosion. The maximum bolometric luminosity of 1.8 +/- 0.2 x 10(42) erg s(-1) occurred approximate to 22 days after the explosion. NIR emission provides more than 30% of the total bolometric flux at the beginning of our observations, and the NIR contribution increases to nearly 50% of the total by day 34. The UV produces 16% of the total flux on day 4, 5% on day 9, and 1% on day 34. We compare the bolometric LCs of SN 2011dh, SN 2008ax, and SN 1993J. The LC are very different for the first 12 days after the explosions, but all three SN IIb display similar peak luminosities, times of peak, decline rates, and colors after maximum. This suggests that the progenitors of these SN IIb may have had similar compositions and masses, but they exploded inside hydrogen shells that have a wide range of masses. SN 2011dh was well observed, and a likely progenitor star has been identified in preexplosion images. The detailed observations presented here will help evaluate theoretical models for this SN and lead to a better understanding of SN IIb.
21.	Marklund, Petter, et al. (author) Sustained and transient neural modulations in prefrontal cortex related to declarative long-term memory, working memory, and attention. 2007 In: Cortex. - 0010-9452. ; 43:1, s. 22-37 Journal article (peer-reviewed)abstract Common activations in prefrontal cortex (PFC) during episodic and semantic long-term memory (LTM) tasks have been hypothesized to reflect functional overlap in terms of working memory (WM) and cognitive control. To evaluate a WM account of LTM-general activations, the present study took into consideration that cognitive task performance depends on the dynamic operation of multiple component processes, some of which are stimulus-synchronous and transient in nature; and some that are engaged throughout a task in a sustained fashion. PFC and WM may be implicated in both of these temporally independent components. To elucidate these possibilities we employed mixed blocked/event-related functional magnetic resonance imaging (fMRI) procedures to assess the extent to which sustained or transient activation patterns overlapped across tasks indexing episodic and semantic LTM, attention (ATT), and WM. Within PFC, ventrolateral and medial areas exhibited sustained activity across all tasks, whereas more anterior regions including right frontopolar cortex were commonly engaged in sustained processing during the three memory tasks. These findings do not support a WM account of sustained frontal responses during LTM tasks, but instead suggest that the pattern that was common to all tasks reflects general attentional set/vigilance, and that the shared WM-LTM pattern mediates control processes related to upholding task set. Transient responses during the three memory tasks were assessed relative to ATT to isolate item-specific mnemonic processes and were found to be largely distinct from sustained effects. Task-specific effects were observed for each memory task. In addition, a common item response for all memory tasks involved left dorsolateral PFC (DLPFC). The latter response might be seen as reflecting WM processes during LTM retrieval. Thus, our findings suggest that a WM account of shared PFC recruitment in LTM tasks holds for common transient item-related responses rather than sustained state-related responses that are better seen as reflecting more general attentional/control processes.
22.	Mattila, Seppo, et al. (author) Abundances and Density Structure of the Inner Circumstellar Ring Around SN 1987A 2010 In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 717:2, s. 1140-1156 Journal article (peer-reviewed)abstract We present optical spectroscopic data of the inner circumstellar ring around supernova (SN) 1987A from the Anglo-Australian Telescope and the Very Large Telescope (VLT) between ~1400 and ~5000 days post-explosion. We also assembled the available optical and near-infrared line fluxes from the literature between ~300 and ~2000 days. These line light curves were fitted with a photoionization model to determine the density structure and the elemental abundances for the inner ring. We found densities ranging from 1 × 103 to 3 × 104 atoms cm-3 and a total mass of the ionized gas of ~5.8 × 10-2 M sun within the inner ring. Abundances inferred from the optical and near-infrared data were also complemented with estimates of Lundqvist & Fransson based on ultraviolet lines. This way we found an He/H ratio (by number of atoms) of 0.17 ± 0.06 which is roughly 30% lower than previously estimated and twice the solar and the Large Magellanic Cloud (LMC) value. We found an N/O ratio of 1.5 ± 0.7, and the total (C+N+O)/(H+He) abundance about 1.6 times its LMC value or roughly 0.6 times the most recent solar value. An iron abundance of 0.20 ± 0.11 times solar was found which is within the range of the estimates for the LMC. We also present late time (~5000-7500 days) line light curves of [O III], [Ne III], [Ne IV], [Ar III], [Ar IV], and [Fe VII] from observations with the VLT. We compared these with model fluxes and found that an additional 102 atoms cm-3 component was required to explain the data of the highest ionization lines. Such low-density gas is expected in the H II-region interior to the inner ring which likely extends also to larger radii at higher latitudes (out of the ring plane). At epochs later than ~5000 days, our models underproduce the emission of most of these lines as expected due to the contribution from the interaction of the SN ejecta with the ring.
23.	Mattila, Seppo, et al. (author) Adaptive Optics Discovery of Supernova 2004ip in the Nuclear Regions of the Luminous Infrared Galaxy IRAS 18293-3413 2007 In: The Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 659:1, s. L9-L12 Journal article (peer-reviewed)abstract We report a supernova discovery in Ks-band images from the NAOS CONICA adaptive optics (AO) system on the ESO Very Large Telescope. The images were obtained as part of a near-infrared search for highly obscured supernovae in the nuclear regions of luminous and ultraluminous infrared galaxies. SN 2004ip is located within a circumnuclear starburst at 1.4" (or 500 pc) projected distance from the K-band nucleus of the luminous infrared galaxy IRAS 18293-3413. The supernova luminosity and light curve are consistent with a core-collapse event suffering from a host galaxy extinction of up to about 40 mag in the V band, which is as expected for a circumnuclear starburst environment. This is the first supernova to be discovered making use of AO correction and demonstrates the potential of the current 8 m-class telescopes equipped with AO in discovering supernovae from the innermost nuclear regions of luminous and ultraluminous infrared galaxies.
24.	Mattila, Seppo, et al. (author) Supernova 2004ip in IRAS 18293-3413 = Psn K0409-001 2007 Other publication (other academic/artistic)
25.	Nilsson, Peter, et al. (author) Structural typing of systemic amyloidoses by luminescent-conjugated polymer spectroscopy. 2010 In: The American journal of pathology. - : Elsevier BV. - 1525-2191 .- 0002-9440. ; 176:2, s. 563-574 Journal article (peer-reviewed)abstract Most systemic amyloidoses are progressive and lethal, and their therapy depends on the identification of the offending proteins. Here we report that luminescent-conjugated thiophene polymers (LCP) sensitively detect amyloid deposits. The heterodisperse polythiophene acetic acid derivatives, polythiophene acetic acid (PTAA) and trimeric PTAA, emitted yellow-red fluorescence on binding to amyloid deposits, whereas chemically homogeneous pentameric formic thiophene acetic acid emitted green-yellow fluorescence. The geometry of LCPs modulates the spectral composition of the emitted light, thereby reporting ligand-induced steric changes. Accordingly, a screen of PTAA-stained amyloid deposits in histological tissue arrays revealed striking spectral differences between specimens. Blinded cluster assignments of spectral profiles of tissue samples from 108 tissue samples derived from 96 patients identified three nonoverlapping classes, which were found to match AA, AL, and ATTR immunotyping. We conclude that LCP spectroscopy is a sensitive and powerful tool for identifying and characterizing amyloid deposits.

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