118455588
The lick AGN monitoring project: Reverberation mapping of optical hydrogen and helium recombination lines
We have recently completed a 64-night spectroscopic monitoring campaign at the Lick Observatory 3 m Shane telescope with the aim of measuring the masses of the black holes in 12 nearby (z < 0.05) Seyfert 1 galaxies with expected masses in the range ~106-107 M ☉ and also the well-studied nearby active galactic nucleus (AGN) NGC 5548. Nine of the objects in the sample (including NGC 5548) showed optical variability of sufficient strength during the monitoring campaign to allow for a time lag to be measured between the continuum fluctuations and the response to these fluctuations in the broad Hβ emission, which we have previously reported. We present here the light curves for the Hα, Hγ, He II λ4686, and He I λ5876 emission lines and the time lags for the emission-line responses relative to changes in the continuum flux. Combining each emission-line time lag with the measured width of the line in the variable part of the spectrum, we determine a virial mass of the central supermassive black hole from several independent emission lines. We find that the masses are generally consistent within the uncertainties. The time-lag response as a function of velocity across the Balmer line profiles is examined for six of the AGNs. We find similar responses across all three Balmer lines for Arp 151, which shows a strongly asymmetric profile, and for SBS 1116+583A and NGC 6814, which show a symmetric response about zero velocity. For the other three AGNs, the data quality is somewhat lower and the velocity-resolved time-lag response is less clear. Finally, we compare several trends seen in the data set against the predictions from photoionization calculations as presented by Korista & Goad. We confirm several of their predictions, including an increase in responsivity and a decrease in the mean time lag as the excitation and ionization level for the species increases. Specifically, we find the time lags of the optical recombination lines to have weighted mean ratios of τ(Hα):τ(Hβ):τ(Hγ):τ(He I):τ(He II) = 1.54:1.00:0.61:0.36:0.25. Further confirmation of photoionization predictions for broad-line gas behavior will require additional monitoring programs for these AGNs while they are in different luminosity states.
15737210
CORONAL LINES AND DUST FORMATION IN SN 2005ip: NOT THE BRIGHTEST, BUT THE HOTTEST TYPE IIn SUPERNOVA
We present optical photometry and spectroscopy of SN 2005ip for the first 3 yr after discovery, showing an underlying Type II-L supernova (SN) interacting with a steady wind to yield an unusual Type IIn spectrum. For the first ~160 days, it had a fast linear decline from a modest peak absolute magnitude of about –17.4 (unfiltered), followed by a plateau at roughly –14.8 for more than 2 yr. Initially having a normal broad-lined spectrum superposed with sparse narrow lines from the photoionized circumstellar medium (CSM), it quickly developed signs of strong CSM interaction with a spectrum similar to that of SN 1988Z. As the underlying SN II-L faded, SN 2005ip exhibited a rich high-ionization spectrum with a dense forest of narrow coronal lines, unprecedented among SNe but reminiscent of some active galactic nuclei. The line-profile evolution of SN 2005ip confirms that dust formation caused its recently reported infrared excess, but these lines reveal that it is the first SN to show clear evidence for dust in both the fast SN ejecta and the slower postshock gas. SN 2005ip's complex spectrum confirms the origin of the strange blue continuum in SN 2006jc, which also had postshock dust formation. We suggest that SN 2005ip's late-time plateau and coronal spectrum result from rejuvenated CSM interaction between a sustained fast shock and a clumpy stellar wind, where X-rays escape through the optically thin interclump regions to heat the preshock CSM to coronal temperatures.
55046954
Berkeley Supernova Ia Program - I. Observations, data reduction and spectroscopic sample of 582 low-redshift Type Ia supernovae
In this first paper in a series, we present 1298 low-redshift (z ≲ 0.2) optical spectra of 582 Type Ia supernovae (SNe Ia) observed from 1989 to 2008 as part of the Berkeley Supernova Ia Program (BSNIP). 584 spectra of 199 SNe Ia have well-calibrated light curves with measured distance moduli, and many of the spectra have been corrected for host-galaxy contamination. Most of the data were obtained using the Kast double spectrograph mounted on the Shane 3 m telescope at Lick Observatory and have a typical wavelength range of 3300–10 400 A, roughly twice as wide as spectra from most previously published data sets. We present our observing and reduction procedures, and we describe the resulting SN Database, which will be an online, public, searchable data base containing all of our fully reduced spectra and companion photometry. In addition, we discuss our spectral classification scheme (using the SuperNova IDentification code, snid; Blondin & Tonry), utilizing our newly constructed set of snid spectral templates. These templates allow us to accurately classify our entire data set, and by doing so we are able to reclassify a handful of objects as bona fide SNe Ia and a few other objects as members of some of the peculiar SN Ia subtypes. In fact, our data set includes spectra of nearly 90 spectroscopically peculiar SNe Ia. We also present spectroscopic host-galaxy redshifts of some SNe Ia where these values were previously unknown. The sheer size of the BSNIP data set and the consistency of our observation and reduction methods make this sample unique among all other published SN Ia data sets and complementary in many ways to the large, low-redshift SN Ia spectra presented by Matheson et al. and Blondin et al. In other BSNIP papers in this series, we use these data to examine the relationships between spectroscopic characteristics and various observables such as photometric and host-galaxy properties.
16104319
The Lick AGN Monitoring Project: Broad-line Region Radii and Black Hole Masses from Reverberation Mapping of Hβ
We have recently completed a 64-night spectroscopic monitoring campaign at the Lick Observatory 3-m Shane telescope with the aim of measuring the masses of the black holes in 12 nearby (z < 0: 05) Seyfert 1 galaxies with expected masses in the range � 10 6 -10 7 Mand also the well-studied nearby active galactic nucleus (AGN) NGC 5548. Nine of the objects in the sample (including NGC 5548) showed optical variability of sufficient strength during the monitoring campaign to all ow for a time lag to be measured between the continuum fluctuations and the response to these fluctuation s in the broad Hemission. We present here the light curves for all the objects in this sample and the subseq uent Htime lags for the nine objects where these measurements were possible. The Hlag time is directly related to the size of the broad-line reg ion in AGNs, and by combining the Hlag time with the measured width of the Hemission line in the variable part of the spectrum, we determine the virial mass of the central sup ermassive black hole in these nine AGNs. The absolute calibration of the black hole masses is based on the normalization derived by Onken et al., which brings the masses determined by reverberation mapping into agreement with the local MBH -�? relationship for quiescent galaxies. We also examine the time lag response as a function of velocity across the Hline profile for six of the AGNs. The analysis of four leads to rather ambiguous results with relatively flat time lags as a function of velocity. However, SBS 1116+583A exhibits a symmetric time lag response around the line center reminiscent of simple models for circularly orbiting broad -line region (BLR) clouds, and Arp 151 shows an asymmetric profile that is most easily explained by a simple g ravitational infall model. Further investigation will be necessary to fully understand the constraints place d on physical models of the BLR by the velocity- resolved response in these objects. Subject headings:galaxies: active - galaxies: nuclei - galaxies: Seyfert
118664939
Nearby supernova rates from the Lick Observatory Supernova Search – III. The rate–size relation, and the rates as a function of galaxy Hubble type and colour
This is the third paper of a series in which we present new measurements of the observed rates of supernovae (SNe) in the local Universe, determined from the Lick Observatory Supernova Search (LOSS). We have considered a sample of ∼1000 SNe and used an optimal subsample of 726 SNe (274 SNe Ia, 116 SNe Ibc and 324 SNe II) to determine our rates. We study the trend of the rates as a function of a few quantities available for our galaxy sample, such as luminosity in the B and K bands, stellar mass and morphological class. We discuss different choices (SN samples, input SN luminosity functions, inclination correction factors) and their effect on the rates and their uncertainties. A comparison between our SN rates and the published measurements shows that they are consistent with each other to within the uncertainties when the rate calculations are done in the same manner. Nevertheless, our data demonstrate that the rates cannot be adequately described by a single parameter using either galaxy Hubble types or B ― K colours. A secondary parameter in galaxy 'size', expressed by luminosity or stellar mass, is needed to adequately describe the rates in the rate-size relation: the galaxies of smaller sizes have higher SN rates per unit mass or per unit luminosity. The trends of the SN rates in galaxies of different Hubble types and colours are discussed. We examine possible causes for the rate-size relation. Physically, such a relation for the core-collapse SNe is probably linked to the correlation between the specific star-formation rate and the galaxy sizes, but it is not clear whether the same link can be established for SNe Ia. We discuss the two-component ('tardy' and 'prompt') model for SN Ia rates, and find that the SN Ia rates in young stellar populations might have a strong correlation with the core-collapse SN rates. We derive volumetric rates for the different SN types [e.g. for SNe Ia, a rate of (0.301 ± 0.062) x 10 ―4 SN Mpc ―3 yr ―1 at redshift 0] and compare them to the measurements at different redshifts. Finally, we estimate the SN rate for the Milky Way Galaxy to be 2.84 ± 0.60 SNe per century (with a systematic uncertainty of a factor of ∼2), consistent with published SN rates based on several different techniques.
118550346
Exotic collective excitations at high spin: Triaxial rotation and octupole condensation
In this thesis work, two topics, triaxiality and reflection asymmetry, have been discussed. Band structures in $^{163}$Tm were studied in a "thin" target experiment as well as in a DSAM lifetime measurement. Two new excited bands were shown to be characterized by a deformation larger than that of the yrast sequence. These structures have been interpreted as Triaxial Strongly Deformed bands associated with particle-hole excitations, rather than with wobbling. Moreover, the Tilted-Axis Cranking calculations provide a natural explanation for the presence of wobbling bands in the Lu isotopes and their absence in the neighboring Tm, Hf and Ta nuclei. A series of so-called "unsafe" Coulomb excitation experiments as well as one-neutron transfer measurements was carried out to investigate the role of octupole correlations in the $^{238,240,242}$Pu isotopes. Some striking differences exist between the level scheme and deexcitation patterns seen in $^{240}$Pu, and to a lesser extent in $^{238}$Pu, and those observed in $^{242}$Pu and in many other actinide nuclei such as $^{232}$Th and $^{238}$U, for example. The differences can be linked to the strength of octupole correlations, which are strongest in $^{240}$Pu. Further, all the data find a natural explanation within the recently proposed theoretical framework of octupole condensation.
119188222
Gluon shadowing and hadron production in heavy-ion collisions at LHC
Abstract The recently published first measurement of charged hadron multiplicity density at mid-rapidity d N c h / d η = 1584 ± 4 ( stat. ) ± 76 ( sys. ) in central Pb + Pb collisions at s = 2.76 TeV by the ALICE experiment at LHC is in good agreement with the HIJING2.0 prediction within the experimental errors and theoretical uncertainties. The new data point is used to carry out a combined fit together with the RHIC data to reduce the uncertainty in the gluon shadowing parameter s g which controls the overall magnitude of gluon shadowing at small fractional momentum x in HIJING2.0 model. Predictions on the centrality dependence of charged hadron multiplicity density at mid-rapidity with reduced uncertainties are given for Pb + Pb collisions at s = 2.76 and 5.5 TeV. The centrality dependence is surprisingly independent of the colliding energy similar to that in Au + Au collisions at RHIC for most of centralities starting at N part = 50 (100) at s = 2.76 (7) TeV. However, it becomes stronger in peripheral collisions at higher colliding energies.
117822936
Simulations of ultrarelativistic heavy ion collisions
Recent development in simulation of ultrarelativistic heavy ion collisions is reviewed. Hard and semihard collisions on the parton level are shown to play important roles both in particle production and initial thermalization of the dense matter. Various nuclear and medium effects are studied some of which in turn can provide unique signatures of the quark gluon plasma formation.
122234832
EXTRA NEUTRAL GAUGE BOSON FROM THE 3-3-1 MODEL AND THE SPIN CORRECTION OF TOP QUARK PAIR PRODUCTION AT THE ILC
In the off-diagonal basis, we explore the effects of extra neutral gauge boson Z' predicted in two versions of SU(3)C × SU(3)L × U(1)X model on the spin configuration of the top quark pair production in the high energy linear e+e- collider (ILC). Our numerical results show that, the cross sections for the suppressed spin configurations can be enhanced with the effects of the Z' boson through the modification of the spin configuration by producing enough top quark pairs to be measured in the future ILC experiments, which provides the way to observe the effects of Z' predicted in the 3-3-1 model and discriminate the various versions of 3-3-1 model.
119481484
Open spin chain and open spinning string
In this Letter, we study the open spinning strings and their SYM duals. A new class of folded open spinning strings is found. At planar one-loop level in SYM, by solving the thermodynamic limit of the Bethe ansatz equations for an integrable open spin chain, we find good agreement with string theory predictions for energies of both circular and folded two-spin solutions. A universal relation between the open and closed spinning strings is verified in the spin chain approach.
10358981
Fluctuations of rare particles as a measure of chemical equilibration
LBL-47721 Mc-Gill-preprint-01-09 GSI-Preprint/2001-10 Fluctuations of rare particles as a measure of chemical equilibration Nuclear Science Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 GSI, D-64291 Darmstadt, Germany and Institute of Theoretical Physics, University of Wroclaw, PL-50204 Wroclaw, Poland †Department of Physics, McGill University, 3600 University Street, Montreal, QC H3A-2T8, Canada ∗RIKEN-BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973 (August 17, 2001) We calculate the time evolution of ﬂuctuations for rare particles such as e.g. kaons in 1 AGeV or charmonium in 200 AGeV heavy ion collisions. We ﬁnd that these ﬂuctuations are a very sensitive probe of the degree of chemical equilibration reached in these collisions. Furthermore, measuring the second factorial moment the size of the initial population can be determined. a S. Jeon a †∗ , V. Koch a , K. Redlich a,c , and X.-N. Wang a c arXiv:nucl-th/0105035 v1 15 May 2001 I. INTRODUCTION Statistical models have long been used as a tool to de- scribe particle production in heavy ion and in high energy particle collisions [1–3]. Recent analysis have shown that these models can indeed give a satisfactory description of the multiplicities of most hadrons measured in A-A collisions for bombarding energies ranging from 1 AGeV (SIS) to 160 AGeV (SPS) [4,5]. Especially at the low energies (SIS) and for the rare particles such as kaons, the success of the statistical description has been a puz- zle and could not be understood within the state-of-the- art transport models [6]. For instance a recent analy- sis for chemical equilibration within a transport model [6] gives chemical equilibration time of the order of 300 fm/c for a situation relevant to 1 AGeV heavy ion col- lisions, considerably larger than the typical duration of such reaction, which is of the order of 30-50 fm/c. On the other hand the success of the statistical model cannot be disputed. Not only are the particle ratios reproduced for central collision over a wide range of bombarding en- ergy, but also the centrality dependence at low energies is consistent with the predictions of the statistical mod- els. In particular the almost quadratic dependence of the kaon multiplicity on the number of participating nucleon at SIS follows directly from the statistical model, once strangeness conservation is taken into account exactly [7]. Transport models on the other hand fail to reproduce the observed centrality dependence and particularly energy dependence of the K/π-ratio [8]. In a recent paper [9] some of us have shown, that the chemical equilibration time is considerably shortened if the strangeness conservation is taken into account ex- plicitly. However, using the new rate equations derived in this work combined with the cross sections as given in [14] one still arrives at equilibration time substantially exceeding the lifetime of the system. Does this mean that the success of the statistical model is a pure coincidence? This is very unlikely as statistical model naturally explains most of the basic features of experimental data in a very broad energy range from SIS up to SPS. It is conceivable that there are additional processes at work, like e.g. many particle collisions [15] or in medium modiﬁcations of hadron properties [16], which are not yet taken into account in transport models. Thus, a direct experimental determination of the rate of equilibration in heavy ion collisions is called for as it would possibly provide evidence for new physics. In this paper we will demonstrate that the ﬂuctuations of rare particles is a very sensitive probe of the degree of equili- bration reached in these collisions. Such a measurement, though certainly diﬃcult, could for the ﬁrst time provide a direct experimental evidence for chemical equilibration in heavy ion reactions. This paper is organized as follows. In the following sec- tion we set up the formalism. Then we present the results for the time dependence of the second factorial moment for several initial conditions. Before we turn to observa- tional issues we also will discuss the case when no con- straints from any U (1) charge conservation are present. II. FORMALISM In Ref. [9] the rate equation for particles which are sub- ject to an explicit U (1) “charge” conservation has been derived. Considering a binary process a 1 a 2 → b 1 b 2 with a = b one arrives at the following master equation for the probabilities P n to ﬁnd n particles dP n = [P n−1 − P n ] dτ