8628404
THE LOW-LUMINOSITY END OF THE RADIUS-LUMINOSITY RELATIONSHIP FOR ACTIVE GALACTIC NUCLEI
We present an updated and revised analysis of the relationship between the H{beta} broad-line region (BLR) radius and the luminosity of the active galactic nucleus (AGN). Specifically, we have carried out two-dimensional surface brightness decompositions of the host galaxies of nine new AGNs imaged with the Hubble Space Telescope Wide Field Camera 3. The surface brightness decompositions allow us to create ''AGN-free'' images of the galaxies, from which we measure the starlight contribution to the optical luminosity measured through the ground-based spectroscopic aperture. We also incorporate 20 new reverberation-mapping measurements of the H{beta} time lag, which is assumed to yield the average H{beta} BLR radius. The final sample includes 41 AGNs covering four orders of magnitude in luminosity. The additions and updates incorporated here primarily affect the low-luminosity end of the R{sub BLR}-L relationship. The best fit to the relationship using a Bayesian analysis finds a slope of {alpha}= 0.533{sup +0.035}{sub -0.033}, consistent with previous work and with simple photoionization arguments. Only two AGNs appear to be outliers from the relationship, but both of them have monitoring light curves that raise doubt regarding the accuracy of their reported time lags. The scatter around the relationship is found to be 0.19more » {+-} 0.02 dex, but would be decreased to 0.13 dex by the removal of these two suspect measurements. A large fraction of the remaining scatter in the relationship is likely due to the inaccurate distances to the AGN host galaxies. Our results help support the possibility that the R{sub BLR}-L relationship could potentially be used to turn the BLRs of AGNs into standardizable candles. This would allow the cosmological expansion of the universe to be probed by a separate population of objects, and over a larger range of redshifts.« less
118898696
OPTICAL PHOTOMETRY OF THE TYPE II-P SUPERNOVA 2004dj IN NGC 2403
We present photometric data of the Type II-P supernova (SN) 2004dj in NGC 2403. The multicolor light curves cover the SN from ~60 to 200 days after explosion and are measured with a set of intermediate-band filters that have the advantage of tracing the strength variations of some spectral features. The light curves show a flat evolution in the middle of the plateau phase, then decline exponentially at the late times, with a rate of 0.10 ± 0.03 mag (10 days)-1 in most of the filters. In the nebular phase, the spectral energy distribution of SN 2004dj shows a steady increase in the flux near 6600 and 8500 A, which may correspond to the emission lines of Hα and the Ca II near-IR triplet, respectively. The photometric behavior suggests that SN 2004dj is a normal SN II-P. Compared with the light curves of another typical SN II-P, 1999em, we estimate the explosion date to be 2004 June 10 ± 21 UT (JD 2,453,167 ± 21) for SN 2004dj. We also estimate the ejected nickel mass during the explosion to be M(56Ni) = 0.023 ± 0.005 M⊙ from two different methods, which is typical for a SN II-P. We derive the explosion energy to be E ≈ 0.75 × 1051 ergs, the ejecta mass to be M ≈ 10.0 M⊙, and the initial radius to be R ≈ 282 R⊙ for the presupernova star of SN 2004dj, which are consistent with other typical SNe II-P.
119196087
OPTICAL OBSERVATIONS OF THE TYPE Ic SUPERNOVA 2007gr IN NGC 1058
We present extensive optical observations of the normal Type Ic supernova (SN) 2007gr, spanning from about one week before maximum light to more than one year thereafter. The optical light and color curves of SN 2007gr are very similar to those of the broad-lined Type Ic SN 2002ap, but the spectra show remarkable differences. The optical spectra of SN 2007gr are characterized by unusually narrow lines, prominent carbon lines, and slow evolution of the line velocity after maximum light. The earliest spectrum (taken at t = –8 days) shows a possible signature of helium (He I λ5876 at a velocity of ~19,000 km s–1). Moreover, the larger intensity ratio of the [O I] λ6300 and λ6364 lines inferred from the early nebular spectra implies a lower opacity of the ejecta shortly after the explosion. These results indicate that SN 2007gr perhaps underwent a less energetic explosion of a smaller-mass Wolf-Rayet star (~8-9 M ☉) in a binary system, as favored by an analysis of the progenitor environment through pre-explosion and post-explosion Hubble Space Telescope images. In the nebular spectra, asymmetric double-peaked profiles can be seen in the [O I] λ6300 and Mg I] λ4571 lines. We suggest that the two peaks are contributed by the blueshifted and rest-frame components. The similarity in velocity structure and the different evolution of the strength of the two components favor an aspherical explosion with the ejecta distributed in a torus or disk-like geometry, but inside the ejecta the O and Mg have different distributions.
495485
Supernova 2008bk and its red supergiant progenitor
We have obtained limited photometric and spectroscopic data for supernova (SN) 2008bk in NGC 7793, primarily at ≳ 150 days after explosion. We find that it is a Type II-Plateau (II-P) SN that most closely resembles the low-luminosity SN 1999br in NGC 4900. Given the overall similarity between the observed light curves and colors of SNe 2008bk and 1999br, we infer that the total visual extinction to SN 2008bk (A_V = 0.065 mag) must be almost entirely due to the Galactic foreground, similar to what has been assumed for SN 1999br. We confirm the identification of the putative red supergiant (RSG) progenitor star of the SN in high-quality g'r'i' images we had obtained in 2007 at the Gemini-South 8 m telescope. Little ambiguity exists in this progenitor identification, qualifying it as the best example to date, next to the identification of the star Sk –69°202 as the progenitor of SN 1987A. From a combination of photometry of the Gemini images with that of archival, pre-SN, Very Large Telescope JHK_s images, we derive an accurate observed spectral energy distribution (SED) for the progenitor. We find from nebular strong-intensity emission-line indices for several H II regions near the SN that the metallicity in the environment is likely subsolar (Z ≈ 0.6 Z_☉). The observed SED of the star agrees quite well with synthetic SEDs obtained from model RSG atmospheres with effective temperature T_(eff) = 3600 ± 50 K. We find, therefore, that the star had a bolometric luminosity with respect to the Sun of log (L_(bol)/L_☉) = 4.57 ± 0.06 and radius R* = 496 ± 34 R_☉ at ~6 months prior to explosion. Comparing the progenitor's properties with theoretical massive-star evolutionary models, we conclude that the RSG progenitor had an initial mass in the range of 8-8.5 M_☉. This mass is consistent with, albeit at the low end of, the inferred range of initial masses for SN II-P progenitors. It is also consistent with the estimated upper limit on the initial mass of the progenitor of SN 1999br, and it agrees with the low initial masses found for the RSG progenitors of other low-luminosity SNe II-P.
28101827
THE PROGENITOR OF SUPERNOVA 2011 dh / PTF 11 eon IN MESSIER 51
We have identified a luminous star at the position of supernova (SN) 2011dh/PTF11eon, in pre-SN archival, multi-band images of the nearby, nearly face-on galaxy Messier 51 (M51) obtained by the Hubble Space Telescope with the Advanced Camera for Surveys. This identification has been confirmed, to the highest available astrometric precision, using a Keck-II adaptive-optics image. The available early-time spectra and photometry indicate that the SN is a stripped-envelope, core-collapse Type IIb, with a more compact progenitor (radius ∼ 1011 cm) than was the case for the well-studied SN IIb 1993J. We infer that the extinction to SN 2011dh and its progenitor arises from a low Galactic foreground contribution, and that the SN environment is of roughly solar metallicity. The detected object has absolute magnitude M0 V ≈ −7.7 and effective temperature ∼6000 K. The star’s radius, ∼1013 cm, is more extended than what has been inferred for the SN progenitor. We speculate that the detected star is either an unrelated star very near the position of the actual progenitor, or, more likely, the progenitor’s companion in a mass-transfer binary system. The position of the detected star in a Hertzsprung–Russell diagram is consistent with an initial mass of 17–19 M . The light of this star could easily conceal, even in the ultraviolet, the presence of a stripped, compact, very hot (∼105 K), nitrogen-rich Wolf–Rayet star progenitor.
30616044
A Massive Progenitor of the Luminous Type IIn Supernova 2010jl
The bright, nearby, recently discovered supernova (SN) 2010jl is a luminous Type IIn SN. Here, we report archival Hubble Space Telescope (HST) observations of its host galaxy UGC 5189A taken roughly 10 yr prior to explosion, as well as early-time optical spectra of the SN. The HST images reveal a luminous, blue point source at the position of the SN, with an absolute magnitude of –12.0 in the F300W filter. If it is not just a chance alignment, the source at the SN position could be (1) a massive young (<6 Myr) star cluster in which the SN resided, (2) a quiescent, luminous blue star with an apparent temperature around 14,000 K, (3) a star caught during a bright outburst akin to those of luminous blue variables, or (4) a combination of option (1) and option (2) or (3). Although we cannot confidently choose between these possibilities with the present data, any of them imply that the progenitor of SN 2010jl had an initial mass above 30 M_☉. This reinforces mounting evidence that many SNe IIn result from very massive stars, that massive stars can produce visible SNe without collapsing quietly to black holes, and that massive stars can sometimes retain their H envelopes until shortly before explosion. Standard stellar evolution models fail to account for these observed properties.
119107054
Optical characterization of RTV615 silicone rubber compound
Room Temperature Vulcanized (RTV) silicone compounds are commonly used to bond optical components. For our application, we needed to identify an adhesive with good ultraviolet transmission characteristics, to couple photomultipliers to quartz windows in a Heavy Gas Cerenkov detector that is being constructed for Experimental Hall C of Jefferson Lab to provide π/K separation up to 11 GeV/c. To this end, we present the light transmission results for Momentive RTV615 silicone rubber compound for wavelengths between 195-400 nm, obtained with an adapted reflectivity apparatus at Jefferson Lab. All samples cured at room temperature have transmissions ~ 93% for wavelengths between 360-400 nm and fall sharply below 230 nm. Wavelength dependent absorption coefficients were extracted with four samples of different thicknesses cured at normal temperature (25° C for 7 days). The absorption coefficient drops approximately two orders in magnitude from 220-400 nm, exhibiting distinct regions of flattening near 250 nm and 330 nm. We also investigated the effect of a high temperature curing method (100° C for 1 hour) and found 5-10% better transmission than with the normal method. The effect was more significant with larger sample thickness (3.35 mm) over the wavelength range of 220-280 nm.
61821975
DATA ACCESS VIA WWW IN NSRL CONTROL SYSTEM
The control system of NSRL electron storage ring is being upgraded using EPICS. The control data are hold in the distributed database, which rested on several IOCs. To make these data archived for further use, we developed a system to periodically collects data from distributed database using Channel Access. A number of CGI programs make it easy to access the archived data via WWW. The program also provides several functions for analyzing the data. The results can be displayed in various modes.
123608448
Experience of BESIII data production with local cluster and distributed computing model
The BES III detector is a new spectrometer which works on the upgraded high-luminosity collider, BEPCII. The BES III experiment studies physics in the tau-charm energy region from 2 GeV to 4.6 GeV . From 2009 to 2011, BEPCII has produced 106M ψ(2S) events, 225M J/ψ events, 2.8 fb−1 ψ(3770) data, and 500 pb−1 data at 4.01 GeV. All the data samples were processed successfully and many important physics results have been achieved based on these samples. Doing data production correctly and efficiently with limited CPU and storage resources is a big challenge. This paper will describe the implementation of the experiment-specific data production for BESIII in detail, including data calibration with event-level parallel computing model, data reconstruction, inclusive Monte Carlo generation, random trigger background mixing and multi-stream data skimming. Now, with the data sample increasing rapidly, there is a growing demand to move from solely using a local cluster to a more distributed computing model. A distributed computing environment is being set up and expected to go into production use in 2012. The experience of BESIII data production, both with a local cluster and with a distributed computing model, is presented here.
2014815
An upgrade proposal of injection bump system for HLS
The current injection bump system in HLS storage ring, which is designed 8 years ago, has been operated 5 years up to the present with acceptable performance. Due to inherent limitation of HLS (Hefei Light Source) storage ring, there are some deficiencies of the design. For the potential of full energy injection, reasonable design objective was summed up. Then, physical design of new bump system was brought forward. Using simple formula, the acceptance to injected beam and perturbation on stored beam were estimated approximately. Finally, the ELEGANT software was used to simulate the injection process with new designed bump system. The simulation results showed that, the injection efficiency would be higher than 90% and perturbation on stored beam would be small enough, which are very essential to full energy injection and top-up operation of HLS.
178557411
THE STATUS OF BESIII PROJECT