A New Mass Estimate of the Central Supermassive Black Hole in NGC 4051 with Reverberation Mapping

Mathematical and Physical Sciences: 1st Place (The Ohio State University Edward F. Hayes Graduate Research Forum)There is increasingly strong evidence from observations of the local universe that every galaxy hosts a black hole at its center with a mass of hundreds of thousands to millions of times the mass of the sun.  It is also becoming clear that these supermassive' black holes are connected to the evolution of galaxies. Therefore, understanding how galaxies form requires an understanding of the demographics of their central black holes. One of the few direct methods of measuring black hole masses in distant galaxies is to apply a technique known as reverberation mapping to objects that are actively accreting matter (active galactic nuclei or AGNs) and for which we have a generally unobscured view of the galactic nucleus (type 1 AGNs). Reverberation mapping takes advantage of an observed time delay between brightness fluctuations in light originating from a continuum source very near the black hole (the hot accretion disk) and broad emission lines (i.e., resolved in Doppler velocity) that are produced by rapidly moving gas in the vicinity of the nucleus, the broad-line emitting region (BLR).  If the BLR gas is in virial equilibrium and under gravitational influence of the supermassive black hole, the velocity of the BLR gas, measured from the widths of broad emission lines, and the BLR radius are related through the mass of the black hole itself.  Long observing campaigns monitor the continuum and emission-line brightness variations to measure the time delay, t, which corresponds to the light travel time across the BLR. Measurements of t then allow for an estimate of the size of the region, R_BLR = c*t, with which we can then estimate the black hole mass.  We present the first results from a multi-month reverberation mapping campaign undertaken primarily at MDM Observatory but with supporting observations from telescopes around the world.  We feature the results for NGC 4051 because it was previously found to be a significant outlier from the relationship between the BLR radius and the optical continuum luminosity, the R_BLR-L relationship, found for other AGNs.  We measure a relatively small BLR radius and thus black hole mass for NGC 4051 that would have been impossible for past studies to resolve because the variations were previously undersampled. Our new results indicate that this AGN is actually completely consistent with the R_BLR-L relationship, thus resolving the previous discrepancy and strengthening the evidence for the homologous nature of AGNs --- an exciting interpretation of the tightness of the R_BLR-L relationship, given the diverse demographics of galaxies.No embarg

High Redshift Standard Candles: Predicted Cosmological Constraints

We investigate whether future measurements of high redshift standard candles (HzSCs) will be a powerful probe of dark energy, when compared to other types of planned dark energy measurements. Active galactic nuclei and gamma ray bursts have both been proposed as potential HzSC candidates. Due to their high luminosity, they can be used to probe unexplored regions in the expansion history of the universe. Information from these regions can help constrain the properties of dark energy, and in particular, whether it varies over time. We consider both linear and piecewise parameterizations of the dark energy equation of state, $w(z)$, and assess the optimal redshift distribution a high-redshift standard-candle survey could take to constrain these models. The more general the form of the dark energy equation of state $w(z)$ being tested, the more useful high-redshift standard candles become. For a linear parameterization of $w(z)$, HzSCs give only small improvements over planned supernova and baryon acoustic oscillation measurements; a wide redshift range with many low redshift points is optimal to constrain this linear model. However to constrain a general, and thus potentially more informative, form of $w(z)$, having many HzSCs can significantly improve limits on the nature of dark energy.Comment: Accepted MNRAS, 27 Pages, 15 figures, matches published versio

Reverberation Mapping Results from MDM Observatory

We present results from a multi-month reverberation mapping campaign undertaken primarily at MDM Observatory with supporting observations from around the world. We measure broad line region (BLR) radii and black hole masses for six objects. A velocity-resolved analysis of the H_beta response shows the presence of diverse kinematic signatures in the BLR.Comment: To appear in the Proceedings of the IAU Symposium No. 267: Co-Evolution of Central Black Holes and Galaxies, Rio de Janeiro, 200

The Importance of Broad Emission-Line Widths in Single Epoch Black Hole Mass Estimates

Estimates of the mass of super-massive black holes (BHs) in distant active galactic nuclei (AGNs) can be obtained efficiently only through single-epoch spectra, using a combination of their broad emission-line widths and continuum luminosities. Yet the reliability and accuracy of the method, and the resulting mass estimates, M_BH, remain uncertain. A recent study by Croom using a sample of SDSS, 2QZ and 2SLAQ quasars suggests that line widths contribute little information about the BH mass in these single-epoch estimates and can be replaced by a constant value without significant loss of accuracy. In this Letter, we use a sample of nearby reverberation-mapped AGNs to show that this conclusion is not universally applicable. We use the bulge luminosity (L_Bulge) of these local objects to test how well the known M_BH - L_Bulge correlation is recovered when using randomly assigned line widths instead of the measured ones to estimate M_BH. We find that line widths provide significant information about M_BH, and that for this sample, the line width information is just as significant as that provided by the continuum luminosities. We discuss the effects of observational biases upon the analysis of Croom and suggest that the results can probably be explained as a bias of flux-limited, shallow quasar samples.Comment: 10 text pages + 4 Figures + 1 Table. Accepted for publication in ApJ Letter

Influences on consumption of soft drinks and fast foods in adolescents

Soft drink and fast food are energy dense foodstuffs that are heavily marketed to adolescents, and are likely to be important in terms of risk of obesity. This study sought to examine the influences on soft drink and fast food consumption among adolescents as part of a cross-sectional survey of 2,719 adolescents (aged 11-16) from 93 randomly selected schools in New South Wales, Australia. Students provided information on soft drink and fast food consumption, and responded to statements examining influences over consumption. Over half of the boys and more than one third of the girls reported drinking soft drink daily, and consumption peaked in Grade 8 students. A quarter of students reported choosing soft drinks instead of water or milk, and around 40% agreed that soft drink was usually available in their homes. Availability in the home and drinking soft drinks with meals was most strongly associated with consumption in all age groups. Fast food consumption was higher among boys than girls in all age groups. Convenience and value for money yielded the strongest associations with fast foodconsumption in boys, while preferring fast food to meals at home and preferring to &ldquo;upsize&rdquo; meals were most strongly associated with consumption in girls. Interventions to reduce consumption of soft drinks should target availability in both the home and school environment by removing soft drinks and replacing them with more nutritive beverages. Fast food outlets should be encouraged to provide a greater range of healthy and competitively priced options in reasonable portions.<br /

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

A programmable SDN+NFV-based architecture for UAV telemetry monitoring

The explosive growth in the worldwide use of Unmanned Aerial Vehicles (UAVs) has raised a critical concern with respect to the adequate management of their ad hoc network configuration as required by their mobility management process. As UAVs migrate among ground control stations, associated network services, routing and operational control must also rapidly migrate to ensure a seamless transition. In this paper, we present a novel, lightweight and modular architecture which supports high mobility and situational-awareness through the application of Software Defined Networking (SDN) and Network Function Virtualization (NFV) principles on top of the UAV infrastructure. By combining SDN+NFV programmability we can achieve a robust migration of UAV-related network services, such as network monitoring and anomaly detection as well as smooth UAV migration that confronts high mobility requirements. The proposed container-based monitoring and anomaly detection Network Functions (NFs) as employed within our architecture can be tuned to specific UAV types providing operators better insight during live, high-mobility deployments. We evaluate our architecture against telemetry from over 80 flights from a scientific research UAV infrastructure showing our ability to tune and detect emerging challenges

The Mass of the Black Hole in the Quasar PG 2130+099

We present the results of a recent reverberation-mapping campaign undertaken to improve measurements of the radius of the broad line region and the central black hole mass of the quasar PG 2130+099. Cross correlation of the 5100 angstrom continuum and H-beta emission-line light curves yields a time lag of 22.9 (+4.4 - 4.3) days, corresponding to a central black hole mass MBH= 3.8 (+/- 1.5) x 10^7 Msun. This value supports the notion that previous measurements yielded an incorrect lag. We re-analyzed previous datasets to investigate the possible sources of the discrepancy and conclude that previous measurement errors were apparently caused by a combination of undersampling of the light curves and long-term secular changes in the H-beta emission-line equivalent width. With our new measurements, PG 2130+099 is no longer an outlier in either the R-L or the MBH-Sigma relationships.Comment: 21 pages, 7 figures; Accepted for publication in Ap