We present very early UV to optical photometric and spectroscopic observations of the peculiar Type IIn supernova (SN) 2011ht in UGC 5460. The UV observations of the rise to peak are only the second ...ever recorded for a Type IIn SN and are by far the most complete. The optical spectra are dominated by strong, Balmer emission with narrow peaks (FWHM ~ 600 km s super(-1)), very broad asymmetric wings (FWHM ~ 4200 km s super(-1)), and blueshifted absorption (~300 km s super(-1)) superposed on a strong blue continuum. The UV spectra are dominated by Fe II, MgII, Si II, and Si III absorption lines broadened by ~1500 km s super(-1). Merged X-ray observations reveal a L sub(0.2-10) = (1.0 + or - 0.2) x 10 super(39) erg s super(-1). Some properties of SN 2011ht are similar to SN impostors, while others are comparable to Type IIn SNe. Early spectra showed features typical of luminous blue variables at maximum and during giant eruptions.
We present the first results from a detailed analysis of photometric and spectrophotometric data on the narrow-line Seyfert 1 (NLS1) galaxy Mrk 335, collected over a 120 day span in the fall of 2010. ...From these data we measure the lag in the He II lambda4686 broad emission line relative to the optical continuum to be 2.7 + or - 0.6 days and the lag in the Hbetalambda4861 broad emission line to be 13.9 + or - 0.9 days. Combined with the line width, the He II lag yields a black hole mass M sub(BH) = (2.6 + or - 0.8) x 10 super(7) M sub(sm circle in circle). This measurement is consistent with measurements made using the Hbetalambda4861 line, suggesting that the He II emission originates in the same structure as Hbeta, but at a much smaller radius. This constitutes the first robust lag measurement for a high-ionization line in an NLS1 galaxy and supports a scenario in which the He II emission originates from gas in virial motion rather than outflow.
In this paper, we present ground-based and Swift photometric and spectroscopic observations of the candidate tidal disruption event (TDE) ASASSN-14li, found at the centre of PGC 043234 (d ≃ 90 Mpc) ...by the All-Sky Automated Survey for SuperNovae (ASAS-SN). The source had a peak bolometric luminosity of L ≃ 1044 erg s-1 and a total integrated energy of E ≃ 7 × 1050 erg radiated over the ~6 months of observations presented. The UV/optical emission of the source is well fitted by a blackbody with roughly constant temperature of T ~ 35 000 K, while the luminosity declines by roughly a factor of 16 over this time. The optical/UV luminosity decline is broadly consistent with an exponential decline, L∝e-t/t0, with t0 ≃ 60 d. ASASSN-14li also exhibits soft X-ray emission comparable in luminosity to the optical and UV emission but declining at a slower rate, and the X-ray emission now dominates. Spectra of the source show broad Balmer and helium lines in emission as well as strong blue continuum emission at all epochs. Finally, we use the discoveries of ASASSN-14li and ASASSN-14ae to estimate the TDE rate implied by ASAS-SN, finding an average rate of r ≃ 4.1 × 10-5 yr-1 per galaxy with a 90 per cent confidence interval of (2.2–17.0) × 10-5 yr-1 per galaxy. ASAS-SN found roughly 1 TDE for every 70 Type Ia supernovae in 2014, a rate that is much higher than that of other surveys.
We present velocity-resolved reverberation results for five active galactic nuclei. We recovered velocity-delay maps using the maximum entropy method for four objects: Mrk 335, Mrk 1501, 3C 120, and ...PG 2130+099. For the fifth, Mrk 6, we were only able to measure mean time delays in different velocity bins of the H beta emission line. The four velocity-delay maps show unique dynamical signatures for each object. For 3C 120, the Balmer lines show kinematic signatures consistent with both an inclined disk and infalling gas, but the He II lambda4686 emission line is suggestive only of inflow. The Balmer lines in Mrk 335, Mrk 1501, and PG 2130+099 show signs of infalling gas, but the He II emission in Mrk 335 is consistent with an inclined disk. We also see tentative evidence of combined virial motion and infalling gas from the velocity-binned analysis of Mrk 6. The maps for 3C 120 and Mrk 335 are two of the most clearly defined velocity-delay maps to date. These maps constitute a large increase in the number of objects for which we have resolved velocity-delay maps and provide evidence supporting the reliability of reverberation-based black hole mass measurements.
We present the results from a detailed analysis of photometric and spectrophotometric data on five Seyfert 1 galaxies observed as a part of a recent reverberation mapping program. The data were ...collected at several observatories over a 140 day span beginning in 2010 August and ending in 2011 January. We obtained high sampling-rate light curves for Mrk 335, Mrk 1501, 3C 120, Mrk 6, and PG 2130+099, from which we have measured the time lag between variations in the 5100 Angstrom continuum and the H beta broad emission line. We then used these measurements to calculate the mass of the supermassive black hole at the center of each of these galaxies. Our new measurements substantially improve previous measurements of M sub(BH) and the size of the broad line-emitting region for four sources and add a measurement for one new object. Our new measurements are consistent with photoionization physics regulating the location of the broad line region in active galactic nuclei.
A model of AW UMa Paczyński, B.; Sienkiewicz, R.; Szczygieł, D. M.
Monthly notices of the Royal Astronomical Society,
07/2007, Letnik:
378, Številka:
3
Journal Article
.
Substantial experimental and theoretical efforts worldwide are devoted to explore the phase diagram of strongly interacting matter. At LHC and top RHIC energies, QCD matter is studied at very high ...temperatures and nearly vanishing net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was created at experiments at RHIC and LHC. The transition from the QGP back to the hadron gas is found to be a smooth cross over. For larger net-baryon densities and lower temperatures, it is expected that the QCD phase diagram exhibits a rich structure, such as a first-order phase transition between hadronic and partonic matter which terminates in a critical point, or exotic phases like quarkyonic matter. The discovery of these landmarks would be a breakthrough in our understanding of the strong interaction and is therefore in the focus of various high-energy heavy-ion research programs. The Compressed Baryonic Matter (CBM) experiment at FAIR will play a unique role in the exploration of the QCD phase diagram in the region of high net-baryon densities, because it is designed to run at unprecedented interaction rates. High-rate operation is the key prerequisite for high-precision measurements of multi-differential observables and of rare diagnostic probes which are sensitive to the dense phase of the nuclear fireball. The goal of the CBM experiment at SIS100 (
s
N
N
=
2.7--4.9 GeV) is to discover fundamental properties of QCD matter: the phase structure at large baryon-chemical potentials (
μ
B
>
500
MeV), effects of chiral symmetry, and the equation of state at high density as it is expected to occur in the core of neutron stars. In this article, we review the motivation for and the physics programme of CBM, including activities before the start of data taking in 2024, in the context of the worldwide efforts to explore high-density QCD matter.
•The Ca4Nb2O9–xNd2O3 pseudobinary samples were synthesized by the high-temperature solid state method.•The limited solid solution with formula (Ca4Nb2)1-xNd2xO9–6x was found to exist in this system ...between 0 ≤ x ≤ 0.40.•The structural phase transition of (Ca4Nb2)1-xNd2xO9–6x occurs with an increase in the content of Nd2O3 in the Ca4Nb2O9–Nd2O3 system as indicated by spectroscopic studies.
The Ca4Nb2O9–xNd2O3 (where x = 0.1–1.0) pseudobinary samples were synthesized by the high-temperature solid state method. Optical properties of Nd3+ ions in this oxide system were studied and related to the structural phase transition dependent on the Nd2O3 oxide content. Structural and optical properties are discussed based on ATR IR, dielectric, diffuse reflectance and emission spectra measurements. The spectroscopic studies show a structural phase transition occurring for x = 0.5 and for which the initial limited solid solution transforms to the diphasic form of Ca2NdNbO6 and Nd2O3.
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