Rho meson form factors in a confining Nambu--Jona-Lasinio model

Elastic electromagnetic form factors for the $\rho^+$ meson are calculated in a Nambu--Jona-Lasinio model which incorporates quark confinement through the use of the proper-time regularization scheme. A comparison is made with recent lattice QCD results and previous quark model calculations for static quantities and the Sachs form factors. The results are qualitatively in good agreement with the lattice QCD calculations, with the exception of the quadrupole moment and corresponding form factor, which may be related to a lack of spherical symmetry on the lattice.Comment: 8 pages, 11 figure

Baryon Octet Electromagnetic Form Factors in a confining NJL model

Electromagnetic form factors of the baryon octet are studied using a Nambu--Jona-Lasinio model which utilizes the proper-time regularization scheme to simulate aspects of colour confinement. In addition, the model also incorporates corrections to the dressed quarks from vector meson correlations in the t-channel and the pion cloud. Comparison with recent chiral extrapolations of lattice QCD results shows a remarkable level of consistency. For the charge radii we find the surprising result $r_{E}^p < r_{E}^{\Sigma^+}$ and $|r_{E}^n| < |r_{E}^{\Xi^0}|$, whereas the magnetic radii have a pattern largely consistent with a naive expectation based on the dressed quark masses.Comment: 7 pages, 4 figure

Swift/UVOT grism monitoring of NGC 5548 in 2013: an attempt at MgII reverberation mapping

Reverberation-mapping-based scaling relations are often used to estimate the masses of black holes from single-epoch spectra of AGN. While the radius-luminosity relation that is the basis of these scaling relations is determined using reverberation mapping of the H$\beta$ line in nearby AGN, the scaling relations are often extended to use other broad emission lines, such as MgII, in order to get black hole masses at higher redshifts when H$\beta$ is redshifted out of the optical waveband. However, there is no radius-luminosity relation determined directly from MgII. Here, we present an attempt to perform reverberation mapping using MgII in the well-studied nearby Seyfert 1, NGC 5548. We used Swift to obtain UV grism spectra of NGC 5548 once every two days from April to September 2013. Concurrent photometric UV monitoring with Swift provides a well determined continuum lightcurve that shows strong variability. The MgII emission line, however, is not strongly correlated with the continuum variability, and there is no significant lag between the two. We discuss these results in the context of using MgII scaling relations to estimate high-redshift black hole masses.Comment: 8 pages, 7 figures, accepted for publication in Ap

Light echoes

The first light echo - scattered light from a stellar outburst arriving at the Earth months or years after the direct light from the event - was detected more than 100 years ago, around Nova Persei 1901. Renewed interest in light echoes has come from the spectacular echo around V838 Monocerotis, and from discoveries of light echoes from historical and prehistorical supernovæ in the Milky Way and Large Magellanic Cloud as well as from the 19 th-century Great Eruption of η Carinae. A related technique is reverberation mapping of active galactic nuclei. This report of a workshop on Light Echoes gives an introduction to light echoes, and summarizes presentations on discoveries of light echoes from historical and prehistorical events, light and shadow echoes around R CrB stars, and reverberation mapping. © 2012 International Astronomical Union

The Lick AGN Monitoring Project: Alternate Routes to a Broad-line Region Radius

It is now possible to estimate black hole masses across cosmic time, using broad emission lines in active galaxies. This technique informs our views of how galaxies and their central black holes coevolve. Unfortunately, there are many outstanding uncertainties associated with these "virial" mass estimates. One of these comes from using the accretion luminosity to infer a size for the broad-line region. Incorporating the new sample of low-luminosity active galaxies from our recent monitoring campaign at Lick Observatory, we recalibrate the radius-luminosity relation with tracers of the accretion luminosity other than the optical continuum. We find that the radius of the broad-line region scales as the square root of the X-ray and Hbeta luminosities, in agreement with recent optical studies. On the other hand, the scaling appears to be marginally steeper with narrow-line luminosities. This is consistent with a previously observed decrease in the ratio of narrow-line to X-ray luminosity with increasing total luminosity. The radius of the broad-line region correlates most tightly with Hbeta luminosity, while the X-ray and narrow-line relations both have comparable scatter of a factor of two. These correlations provide useful alternative virial BH masses in objects with no detectable optical/UV continuum emission, such as high-redshift galaxies with broad emission lines, radio-loud objects, or local active galaxies with galaxy-dominated continua.Comment: 8 pages, 1 figure, accepted for publication in Ap

The Size of the Narrow-Line Emitting Region in the Seyfert 1 Galaxy NGC 5548 from Emission-Line Variability

The narrow [O III] 4959, 5007 emission-line fluxes in the spectrum of the well-studied Seyfert 1 galaxy NGC 5548 are shown to vary with time. From this we show that the narrow line-emitting region has a radius of only 1-3 pc and is denser (n ~ 10^5 cm^{-3}) than previously supposed. The [O III] line width is consistent with virial motions at this radius given previous determinations of the black hole mass.Since the [O III] emission-line flux is usually assumed to be constant and is therefore used to calibrate spectroscopic monitoring data, the variability has ramifications for the long-term secular variations of continuum and emission-line fluxes, though it has no effect on shorter-term reverberation studies. We present corrected optical continuum and broad Hbeta emission-line light curves for the period 1988 to 2008.Comment: 11 pages, 5 figures, 6 tables. Accepted for publication in Ap

BENEFITS ACCRUING TO THE DOE COMPLEX ATTRIBUTABLE TO THE DISPOSAL OF OFF-SITE LOW-LEVEL WASTE AT THE NEVADA TEST SITE

ABSTRACT The Nevada Test Site (NTS) has been consistently identified in national U.S. Department of Energy (DOE) reports as playing a key role in the future disposal of low-level radioactive waste (LLW) originating from waste management, site remediation, and other programs of the DOE nuclear weapons complex. This key NTS role was confirmed by the December 10, 1999 Identification of Preferred Alternatives for the Department of Energy&apos;s Waste Management Program: Low-Level Waste and Mixed Low-Level Waste Disposal Sites. (1) The findings presented in this paper represent part of a larger effort to develop information to respond to stewardship issues that have been documented by DOE stakeholders in Nevada with regard to DOE LLW disposal at the NTS. The authors identify factors that affect DOE LLW disposal options and disposal costs, including both waste generator and disposal facility costs. Based on current, national DOE analyses, cost comparisons of disposal at the NTS vs. other operational DOE disposal sites are made, as well as comparisons of anticipated facility disposal limitations. The authors&apos; present their preliminary estimates of significant historical and projected cost savings to the DOE Complex associated with LLW disposal at the NTS. The paper concludes with a discussion of the limitations of the current, DOE volumes-based cost estimates, and a discussion of the steps currently being taken in Nevada to perform waste-steam-specific analyses. FACTORS AFFECTING DISPOSAL OPTIONS AVAILABLE TO DOE LLW GENERATORS The primary factors governing LLW disposal options available to DOE LLW generators are the availability of on-site land for LLW disposal facilities, site-specific hydrogeologic constraints on on-site LLW disposal, applicable on-site regulatory compliance restrictions, and the limited availability and high cost of alternative, off-site commercial LLW disposal options. Limited On-site Land Availability. The availability of on-site land for disposal of LLW is a threshhold issue, which must be considered in evaluating the potential option of on-site disposal of LLW at DOE sites. Some DOE Complex sites are privately-owned (e.g. ETEC, RMI, General Atomics). In such cases, DOE has no land available on-site on which to dispose of LLW. The relatively small size of other, DOE-owned sites (e.g. Grand Junction Projects Office, ITRI, SNL/CA) also limits the availability of on-site disposal. The land available for LLW disposal at some of these small sites (e.g. ITRI, SNL/CA) is further limited by on-going requirements to support DOE missions, and the need for an adequate buffer zone (the smallest area required as controlled space for monitoring and for taking mitigative measures, as may be necessary) around disposal cells. The small size of these DOE Complex sites is also an indirect measure of two other, associated characteristics important to the suitability of a site for LLW disposal: • The size and proximity of potential populations at risk (larger sites exclude population growth from ext ensive areas and provide a larger buffer); and • The likelihood contaminants in down-gradient groundwater would appear in publicly-accessible water sources (off-site population centers near small sites would tend to be located in closer proximity to these sites). On-Site Hydrogeologic Constraints on Disposal. The siting of a LLW disposal facility is the first, and arguably the most important, step for ensuring the long-term isolation of the waste. Historically, DOE and commercial disposal facilities have relied on the site hydrogeological characteristics as the principal means to mitigate nuclide migration from disposal sites (i.e., dependence on natural isolation barriers). Therefore, site-specific hydrogeological characteristics are of primary concern in determining the suitability of DOE sites for on-site disposal. DOE Orders require that disposal sites have hydrological characteristics which will protect groundwater resources. In addition, the potential for floods, erosion, earthquakes, and volcanoes must be considered in site selection (see The hydrogeologic characteristics at several DOE generator sites restrict the suitability of these sites for on-site disposal of LLW (see On-Site Regulatory Compliance Restrictions (Land Use). Several DOE sites have been placed on the U.S. Environmental Protection Agency (EPA) National Priorities List (NPL), requiring environmental remediation consistent with the regulatory requirements of the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA). Fernald was placed on the NPL in 1989. The Records of Decision (RODs) for environmental remediation at Fernald (developed consistent with the requirements of CERCLA) include disposal of large volumes of LLW in an on-site disposal facility (OSDF). The OSDF represents Fernald&apos;s &quot;balanced approach&quot; to waste management. Fernald&apos;s OSDF will contain approximately 1.9 million cubic meters of soil and debris from site remediation. An estimated 83,591 cubic meters of LLW not meeting OSDF acceptance criteria is expected to be shipped off-site to the NTS for disposal. The waste acceptance criteria for the OSDF include concentration limits on specific radionuclides and WM&apos;00 Conference, February 27 -March 2, 2000, Tucson, AZ chemicals, and prohibited items. The criteria were developed to protect the Great Miami Aquifer to EPA&apos;s maximum contaminant levels under the Safe Drinking Water Act for a period of 1,000 years. • Small site (90 acres). • Privately-owned DOE Complex site (DOE has no on-site disposal authority). Fernald • Location near Great Miami River. • Location atop a major sole source aquifer (State of Ohio waiver required). • Disposal limited to low concentrations to protect aquifer to maximum contaminant levels (MCLs) for 1000 years. General Atomics • Small site (120 acres). • Privately-owned DOE Complex site (DOE has no on-site disposal authority). Grand Junction Projects Office • Small site (56.4 acres). • Location on a river and adjacent to City of Grand Junction, Colorado. • On-site facility for limited volumes would likely not be cost-effective. Kansas City Plant • Small site (141 acres). • Location in an urban setting. • On-site facility for limited volumes would likely not be cost-effective. LRRI (ITRI) • Small site (135 acres). • Location on an Air Force Base. • High seismic activity (with potential for damaging event every 100 years). • On-site facility for limited volumes would likely not be cost-effective. LLNL • Major faults in the area (San Andreas, Hayward, Calaveras, and Greenville). • Local faults have the potential for damaging earthquakes. • Potential for slope instability in Site 300. Oak Ridge • Climate is humid and relatively high precipitation (53.75 inches/yr.). • Depth to groundwater is shallow (less than 20 feet in some areas). • Groundwater is discharged to the surface in some areas. • Above-ground &quot;tumulus&quot; facility is expensive and long-term disposal use questionable. Mound • Small site (306 acres). • Location within City of Miamisburg near residential populations. • Location within ½ mile of Great Miami River. • Location atop a major sole source aquifer (State of Ohio waiver required). Pantex Plant • On-site facility for limited volumes would likely not be cost-effective. RMI • Small site (60 acres). • Privately-owned DOE Complex site (DOE has no on-site disposal authority). Rocky Flats • Relatively small (384 acres) secured area inside the buffer zone. • Proximity to large (2.1 million) population and growing residential areas. Sandia/CA • Relatively small site (413 acres). • No LLW anticipated to be generated in future. Sandia/NM • Location on an Air Force Base. • Four faults (including 2 capable of major seismic activity) cut across site. • High seismic activity (with potential for damaging event every 100 years). &quot;In 1979, [DOE] adopted a policy of disposing of its LLW at its sites to ensure the availability of reliable disposal capacity for wastes generated by its defense production mission and to limit its potential legal liability for claims by or against commercial disposal facility operators.&quot; • The commercial facility must meet applicable Federal, State, and local requirements, and have the necessary permits, licenses, and approvals; • The facility, based on DOE review, must have an adequate history of operational and regulatory performance; • Disposal of these wastes at a commercial facility must be cost-effective and in the best interests of the Department; • The waste must be sufficiently characterized and verified to meet the facility&apos;s waste acceptance criteria; • Appropriate National Environmental Policy Act (NEPA) review must be completed; and • Host states and state compacts must be consulted before the exemption is approved. Based on the results of a recent policy analysis (4), DOE has decided to continue the policy under its new DOE Order 435.1, Radioactive Waste Management, which replaced DOE Order 5820.2A effective September 1, 1999. Available options for commercial disposal of DOE LLW are currently both limited and expensive (compared to DOE disposal facility costs) for all but the lowest-activity LLW. Most DOE LLW sent to commercial facilities under the current policy has been disposed at the Envirocare facility near Clive, Utah. Envirocare is the only commercial LLW disposal facility to have opened since the Low-Level Radioactive Waste Policy Act (LLWPA) was enacted in 1980. The Envirocare facility is not a &quot;compact facility&quot; (as defined by 42 U.S.C. § § 2021(b)-2021(j) of the LLWPA). Hence, it can accept LLW from sites throughout the country. However, disposal at Envirocare is limited to very low-activity, NRC Class A waste. The site cannot accept LLW containing special nuclear materials in quantities sufficient to form a critical mass, as defined by 10 CFR §150.11. Large quantities of DOE LLW would not meet these restrictions. The DOE waste shipped to Envirocare has, in general, been of very low activity. In fact, most of the DOE waste disposed at Envirocare has been Section 11(e)(2) byproduct material generated during cleanups undertaken pursuant to the Formerly Utilized Sites Remedial Action Program (FUSRAP). These wastes are of such low activity that they are generally excluded from both the NRC and DOE definitions of LLW. DOE contracts with Envirocare for disposal of these low-activity wastes have experienced charges ranging from $170 -$600 per cubic meter of waste. Only two commercial LLW disposal facilities are currently licensed by the NRC to accept LLW classified as greater than NRC Class A: the facility operated by U.S. Ecology at Richland, Washington (U.S. Ecology facility) and the facility operated by Chem-Nuclear, LLC, at Barnwell, South Carolina (Barnwell facility). Only the Barnwell facility accepts LLW from generators outside of a regional compact. The U.S. Ecology facility is a &quot;compact facility&quot; which serves the Northwest and the Rocky Mountain Compacts. As a compact facility, the State of Washington and the Northwest Compact must approve the disposal of DOE waste at the facility. (6) The State of Washington has made approval of disposal of DOE LLW at the facility subject to certain conditions. Among the conditions are: 1) that only waste from DOE&apos;s Hanford site could be disposed at the facility; and 2) that U.S. Ecology must establish that disposal of the Hanford waste at the facility &quot;would result in cost savings when compared to available disposal options.&quot; (7) According to available information, U.S. Ecology charges between $1,000 and$3,000 per cubic meter for the disposal of LLW. A comparison of LLW disposal cost WM&apos;00 Conference, February 27 -March 2, 2000, Tucson, AZ ranges at commercial and DOE WM disposal sites is provided in FACTORS WHICH AFFECT THE COST OF DISPOSAL OF LLW AT DOE WM DISPOSAL SITES Within the DOE Complex, DOE maintains operational Waste Management (WM) facilities for disposal of LLW at six DOE sites: the NTS, Hanford Site, Idaho National Engineering and Environmental Laboratory (INEEL), Los Alamos National Laboratory (LANL), Oak Ridge National Laboratory (ORNL), and Savannah River Site (SRS). Three of these sites (INEEL, LANL, and ORNL) almost exclusively dispose of on-site generated LLW. Of the remaining three sites, Hanford and Savannah River have primarily accepted on-site generated waste for disposal, although they have the capability to accept off-site LLW if the waste meets site-specific acceptance criteria (stringent for Savannah River -see In addition, DOE&apos;s Environmental Restoration (ER) program operates CERCLA -regulated LLW disposal facilities at certain sites. These CERCLA facilities are limited to disposal of wastes generated from on-site environmental restoration activities, which meet facility-specific acceptance requirements. At present, there are two of these cells in operation --one at Hanford (the ERDF) and the other at Fernald (the OSDF). Two additional DOE CERCLA disposal cells dispose of waste other than LLW. These cells (at the Weldon Spring Site in Missouri and the Monticello Site in Utah) are used for disposal of Section 11(e)(2) byproduct material generated by on-site cleanup WM&apos;00 Conference, February 27 -March 2, 2000, Tucson, AZ activities pursuant to FUSRAP. DOE is considering construction of two additional CERCLA disposal cells (at INEEL and Oak Ridge); a decision as to whether to build these cells will be made pursuant to the CERCLA process. The total cost to DOE for LLW disposal at the various DOE LLW disposal sites is affected by several factors, including the availability of disposal facility volumetric capacity and potential for expansion, the cost to operate and maintain a facility, and the cost incurred by generators to prepare and ship LLW for disposal at a facility. DOE&apos;s July 1997 Low-Level Waste Disposal Cost Comparison Report (1997 Cost Comparison Report) Only three of the WM disposal facilities (NTS, Hanford, and Savannah River) currently accept substantial amounts of LLW for disposal from off-site generators. The facilities at INEEL and ORNL are very limited in their expansion capability, and accept only on-site generated waste. At LANL, the expansion capacity is limited by the size of the mesa upon which it is located. The available expansion capacity at LANL is dedicated to supporting the LLW disposal needs of the on-site Defense Programs and National Laboratory missions. At Savannah River, the site hydrogeology permits the use of slit trenches only for slightly contaminated soil, rubble, and oversized equipment/packages. The use of engineered vaults allows disposal of a wide range of radionuclides. However, this is a much more costly method of disposal, and facility expansion costs would be much higher than for slit trench disposal. Both the NTS and Hanford have the expansion capacity and capability to dispose of large volumes of LLW with a wide range of radionuclides. Table IV provides a summary of the DOE-estimated expansion capacity at the six DOE LLW disposal facilities, and important factors restricting use of that capacity. 3 out of the total 3,572,030 m 3 of LLW projected to be disposed at Hanford over the next twenty years is anticipated to come from off-site generators. This represents less than 1 % of the total LLW projected to be disposed at Hanford during that period. Facility Disposal Costs. The DOE 1997 Cost Comparison Report found that the costs to operate and maintain a LLW disposal facility are comprised of both fixed costs and variable costs: • Fixed costs are loosely defined as those costs that are independent of waste volumes disposed. Fixed costs are recurring costs that do not vary with the rate of waste disposal activities, &quot;such as labor and material costs to maintain the capability to receive and dispose of the first cubic meter of LLW. Examples of fixed costs are permitting, monitoring, training, and program management.&quot; • Variable costs are defined as those costs that are incurred relative to the amount of waste disposed, &quot;such as labor, materials, and contract costs, above and beyond fixed costs necessary to dispose of LLW.&quot; The variable factor having a key impact on a facility&apos;s cost of disposal is presumed to be the volume disposed. Variable costs are considered to increase or decrease as the volume of LLW disposed increases or decreases. &quot;Most disposal operations, maintenance, and trench development costs are a function of volume disposed and are, therefore, variable costs. For example, if each trench has a capacity of 10,000 m 3 and the facility disposes of 20,000 m 3 one year and 10,000 m 3 the next year, the facility will incur the cost of the development of two trenches the first year and the cost of one trench in the second year.&quot; The authors of this paper propose that variable costs are also highly dependent on the characteristics of the wastes being disposed, as is reflected in commercial disposal pricing schedules. The 1997 Cost Comparison Report analyzes the total disposal costs (fixed and variable) for each DOE WM facility for the years FY 1996 -FY 1998. Facility unit disposal costs are calculated by dividing the annual disposal costs by the annual volumes disposed (or anticipated to be disposed) at each facility. The 1997 Cost Comparison Report did not investigate cost impacts attributable to waste characteristics. A summary of the historical FY 1997 disposal facility unit costs is provided by Table V. • Waste Documentation for, and Acceptance or Certification by, Disposal Facilities. These activities include &quot;verification/characterization when required for dis posal such as monitoring or assays for radioactivity, RCRA compliance sampling and analysis, visual container inspections, weight, dose rate, truck survey and vehicle release survey.&quot

The Lick AGN Monitoring Project: Photometric Light Curves and Optical Variability Characteristics

The Lick AGN Monitoring Project targeted 13 nearby Seyfert 1 galaxies with the intent of measuring the masses of their central black holes using reverberation mapping. The sample includes 12 galaxies selected to have black holes with masses roughly in the range 10^6-10^7 solar masses, as well as the well-studied AGN NGC 5548. In conjunction with a spectroscopic monitoring campaign, we obtained broad-band B and V images on most nights from 2008 February through 2008 May. The imaging observations were carried out by four telescopes: the 0.76-m Katzman Automatic Imaging Telescope (KAIT), the 2-m Multicolor Active Galactic Nuclei Monitoring (MAGNUM) telescope, the Palomar 60-in (1.5-m) telescope, and the 0.80-m Tenagra II telescope. Having well-sampled light curves over the course of a few months is useful for obtaining the broad-line reverberation lag and black hole mass, and also allows us to examine the characteristics of the continuum variability. In this paper, we discuss the observational methods and the photometric measurements, and present the AGN continuum light curves. We measure various variability characteristics of each of the light curves. We do not detect any evidence for a time lag between the B- and V-band variations, and we do not find significant color variations for the AGNs in our sample.Comment: 16 pages, 20 figures, 8 tables, accepted for publication in ApJ

The Lick AGN Monitoring Project: Broad-Line Region Radii and Black Hole Masses from Reverberation Mapping of Hbeta

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 M_sun 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 Hbeta emission. We present here the light curves for the objects in this sample and the subsequent Hbeta time lags for the nine objects where these measurements were possible. The Hbeta lag time is directly related to the size of the broad-line region, and by combining the lag time with the measured width of the Hbeta emission line in the variable part of the spectrum, we determine the virial mass of the central supermassive black hole in these nine AGNs. The absolute calibration of the black hole masses is based on the normalization derived by Onken et al. We also examine the time lag response as a function of velocity across the Hbeta line profile for six of the AGNs. The analysis of four leads to 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 gravitational infall model. Further investigation will be necessary to fully understand the constraints placed on physical models of the BLR by the velocity-resolved response in these objects.Comment: 24 pages, 16 figures and 13 tables, submitted to Ap

A Revised Broad-Line Region Radius and Black Hole Mass for the Narrow-Line Seyfert 1 NGC 4051

We present the first results from a high sampling rate, multi-month reverberation mapping campaign undertaken primarily at MDM Observatory with supporting observations from telescopes around the world. The primary goal of this campaign was to obtain either new or improved Hbeta reverberation lag measurements for several relatively low luminosity AGNs. We feature results for NGC 4051 here because, until now, this object has been a significant outlier from AGN scaling relationships, e.g., it was previously a ~2-3sigma outlier on the relationship between the broad-line region (BLR) radius and the optical continuum luminosity - the R_BLR-L relationship. Our new measurements of the lag time between variations in the continuum and Hbeta emission line made from spectroscopic monitoring of NGC 4051 lead to a measured BLR radius of R_BLR = 1.87 (+0.54 -0.50) light days and black hole mass of M_BH = 1.73 (+0.55 -0.52) x 10^6 M_sun. This radius is consistent with that expected from the R_BLR-L relationship, based on the present luminosity of NGC 4051 and the most current calibration of the relation by Bentz et al. (2009a). We also present a preliminary look at velocity-resolved Hbeta light curves and time delay measurements, although we are unable to reconstruct an unambiguous velocity-resolved reverberation signal.Comment: 38 pages, 7 figures, accepted for publication in ApJ, changes from v1 reflect suggestions from anonymous refere