| 1. |
- Galbany, L., et al.
(författare)
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PISCO: The PMAS/PPak Integral-field Supernova Hosts Compilation
- 2018
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Ingår i: Astrophysical Journal. - : IOP PUBLISHING LTD. - 0004-637X .- 1538-4357. ; 855:2
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Tidskriftsartikel (refereegranskat)abstract
- We present the PMAS/PPak Integral-field Supernova hosts COmpilation (PISCO), which comprises integral field spectroscopy (IFS) of 232 supernova (SN) host galaxies that hosted 272 SNe, observed over several semesters with the 3.5 m telescope at the Calar Alto Observatory (CAHA). PISCO is the largest collection of SN host galaxies observed with wide-field IFS, totaling 466,347 individual spectra covering a typical spatial resolution of similar to 380 pc. Focused studies regarding specific SN Ia-related topics will be published elsewhere; this paper aims to present the properties of the SN environments, using stellar population (SP) synthesis, and the gas-phase interstellar medium, providing additional results separating stripped-envelope SNe into their subtypes. With 11,270 H ii regions detected in all galaxies, we present for the first time a statistical analysis of H ii regions, which puts H ii regions that have hosted SNe in context with all other star-forming clumps within their galaxies. SNe Ic are associated with environments that are more metal-rich and have higher EW(H alpha) and higher star formation rate within their host galaxies than the mean of all H ii regions detected within each host. This in contrast to SNe IIb, which occur in environments that are very different compared to other core-collapse SNe types. We find two clear components of young and old SPs at SNe IIn locations. We find that SNe II fast decliners tend to explode at locations where the Sigma(SFR) is more intense. Finally, we outline how a future dedicated IFS survey of galaxies in parallel to an untargeted SN search would overcome the biases in current environmental studies.
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| 2. |
- Pearson Johansson, Joel, et al.
(författare)
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Near-infrared Supernova Ia Distances : Host Galaxy Extinction and Mass-step Corrections Revisited
- 2021
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Ingår i: Astrophysical Journal. - : IOP Publishing Ltd. - 0004-637X .- 1538-4357. ; 923:2
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Tidskriftsartikel (refereegranskat)abstract
- We present optical and near-infrared (NIR, Y-, J-, H-band) observations of 42 Type Ia supernovae (SNe Ia) discovered by the untargeted intermediate Palomar Transient Factory survey. This new data set covers a broad range of redshifts and host galaxy stellar masses, compared to previous SN Ia efforts in the NIR. We construct a sample, using also literature data at optical and NIR wavelengths, to examine claimed correlations between the host stellar masses and the Hubble diagram residuals. The SN magnitudes are corrected for host galaxy extinction using either a global total-to-selective extinction ratio, R-V = 2.0, for all SNe, or a best-fit R-V for each SN individually. Unlike previous studies that were based on a narrower range in host stellar mass, we do not find evidence for a "mass step," between the color- and stretch-corrected peak J and H magnitudes for galaxies below and above log(M-*/M-circle dot) = 10. However, the mass step remains significant (3 sigma) at optical wavelengths (g, r, i) when using a global R-V, but vanishes when each SN is corrected using their individual best-fit R-V. Our study confirms the benefits of the NIR SN Ia distance estimates, as these are largely exempted from the empirical corrections dominating the systematic uncertainties in the optical.
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| 3. |
- Dieckmann, Mark E, 1969-, et al.
(författare)
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Particle-in-cell simulation of a strong double layer in a nonrelativistic plasma flow : Electron acceleration to ultrarelativistic speeds
- 2009
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 694:1, s. 154-164
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Tidskriftsartikel (refereegranskat)abstract
- Two charge- and current-neutral plasma beams are modeled with a one-dimensional particle-in-cell simulation. The beams are uniform and unbounded. The relative speed between both beams is 0.4c. One beam is composed of electrons and protons, and the other of protons and negatively charged oxygen (dust). All species have the temperature 9.1 keV. A Buneman instability develops between the electrons of the first beam and the protons of the second beam. The wave traps the electrons, which form plasmons. The plasmons couple energy into the ion acousticwaves, which trap the protons of the second beam. Astructure similar to a proton phase-space hole develops, which grows through its interaction with the oxygen and the heated electrons into a rarefaction pulse. This pulse drives a double layer, which accelerates a beam of electrons to about 50 MeV, which is comparable to the proton kinetic energy. The proton distribution eventually evolves into an electrostatic shock. Beams of charged particles moving at such speeds may occur in the foreshock of supernova remnant (SNR) shocks. This double layer is thus potentially relevant for the electron acceleration (injection) into the diffusive shock acceleration by SNR shocks.
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| 4. |
- Schad, A., et al.
(författare)
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A UNIFIED APPROACH TO THE HELIOSEISMIC INVERSION PROBLEM OF THE SOLAR MERIDIONAL FLOW FROM GLOBAL OSCILLATIONS
- 2011
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Ingår i: Astrophysical Journal. - : University of Chicago Press. - 0004-637X .- 1538-4357. ; 734:2, s. 97-
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Tidskriftsartikel (refereegranskat)abstract
- Measurements from tracers and local helioseismology indicate the existence of a meridional flow in the Sun with strength in the order of 15 m s(-1) near the solar surface. Different attempts were made to obtain information on the flow profile at depths up to 20 Mm below the solar surface. We propose a method using global helioseismic Doppler measurements with the prospect of inferring the meridional flow profile at greater depths. Our approach is based on the perturbation of the p-mode eigenfunctions of a solar model due to the presence of a flow. The distortion of the oscillation eigenfunctions is manifested in the mixing of p-modes, which may be measured from global solar oscillation time series. As a new helioseismic measurement quantity, we propose amplitude ratios between oscillations in the Fourier domain. We relate this quantity to the meridional flow and unify the concepts presented here for an inversion procedure to infer the meridional flow from global solar oscillations.
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| 5. |
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| 6. |
- Dieckmann, Mark E, 1969-, et al.
(författare)
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The formation of a relativistic partially electromagnetic planar plasma shock
- 2008
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 675:1, s. 586-595
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Tidskriftsartikel (refereegranskat)abstract
- Relativistically colliding plasma is modeled by particle-in-cell simulations in one and two spatial dimensions, with an ion-to-electron mass ratio of 400 and a temperature of 100 keV. The energy of an initial quasi-parallel magnetic field is 1% of the plasma kinetic energy. Energy dissipation by a growing wave pulse of mixed polarity, probably an oblique whistler wave, and different densities of the colliding plasma slabs result in the formation of an energetic electromagnetic structure within milliseconds. The structure, which develops for an initial collision speed of 0.9c, accelerates electrons to Lorentz factors of several hundred. A downstream region forms, separating the forward and reverse shocks. In this region, the plasma approaches an energy equipartition between electrons, ions, and the magnetic field. The electron energy spectrum resembles a power law at high energies, with an exponent close to −2.7, or . The magnetic field reflects upstream ions, which form a beam and drag the electrons along to preserve the plasma quasineutrality. The forward and reverse shocks are asymmetric due to the unequal slab densities. The forward shock may be representative for the internal shocks of gamma-ray bursts.
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