The extremely asymmetric radio structure of the z=3.1 radio galaxy B3 J2330+3927

We report on 1.7 and 5.0 GHz observations of the z=3.087 radio galaxy B3 J2330+3927, using the Very Long Baseline Array (VLBA), and archival 1.4 and 8.4 GHz Very Large Array (VLA) data. Our VLBA data identify a compact, flat spectrum (\alpha_{1.7 GHz}^{5 GHz} = -0.2 +/- 0.1; S_\nu ~ \nu^\alpha) radio component as the core. The VLA images show that the fraction of core emission is very large (f_c \approx 0.5 at 8.4 GHz), and reveal a previously undetected, very faint counterjet, implying a radio lobe flux density ratio R >= 11 and a radio lobe distance ratio Q \approx 1.9. Those values are much more common in quasars than in radio galaxies, but the optical/near-IR spectra show a clear type II AGN for B3 J2330+3927, confirming that it is indeed a radio galaxy. Unlike all other radio galaxies, the bright Ly-\alpha emitting gas is located towards the furthest radio arm. We argue against environmental and relativistic beaming effects being the cause of the observed asymmetry, and suggest this source has intrinsically asymmetric radio jets. If this is the case, B3 J2330+3927 is the first example of such a source at high redshift, and seems to be difficult to reconcile with the unified model, which explains the differences between quasars and radio galaxies as being due to orientation effects.Comment: 6 pages, 3 figures, to appear as a Letter to MNRA

Resource Provisioning Exploiting Cost and Performance Diversity within IaaS Cloud Providers

IaaS platforms such as Amazon EC2 allow clients access to massive computational power in the form of instances. Amazon hosts three different instance purchasing options, each with its own SLA covering pricing and availability. Amazon also offers access to a number of geographical regions, zones, and instance types to select from. In this thesis, the problem of utilizing Spot and On-Demand instances is analyzed and two approaches are presented in order to exploit the cost and performance diversity among different instance types and availability zones, and among the Spot markets they represent. We first develop RAMP, a framework designed to calculate the expected profit of using a specific Spot or On-Demand instance through an evaluation of instance reliability. RAMP is extended to develop RAMC-DC, a framework designed to allocate the most cost effective instance through strategies that facilitate interchangeability of instances among short jobs, reliability of instances among long jobs, and a comparison of the estimated costs of possible allocations. RAMC-DC achieves fault tolerance through comparisons of the price dynamics across instance types and availability zones, and through an examination of three basic checkpointing methods. Evaluations demonstrate that both frameworks take a large step toward low-volatility, high cost-efficiency resource provisioning. While achieving early-termination rates as low as 2.2%, RAMP can completely offset the total cost when charging the user just 17.5% of the On-Demand price. Moreover, the increases in profit resulting from relatively small additional charges to users are notably high, i.e., 100% profit compared to the resource provisioning cost with 35% of the equivalent On-Demand price. RAMC-DC can maintain deadline breaches below 1.8% of all jobs, achieve both early-termination and deadline breach rates as low as 0.5% of all jobs, and lowers total costs by between 80% and 87% compared to using only On-Demand instances

Molecular gas and nuclear activity in early-type galaxies: any link with radio-loudness?

Aims. We want to study the amount of molecular gas in a sample of nearby early-type galaxies (ETGs) which host low-luminosity Active Galactic Nuclei (AGN). We look for possible differences between the radio-loud (RL) and radio-quiet (RQ) AGN. Methods. We observed the CO(1-0) and CO(2-1) spectral lines with the IRAM 30m and NRO 45m telescopes for eight galaxies. They belong to a large sample of 37 local ETGs which host both RQ and RL AGN. We gather data from the literature for the entire sample. Results. We report the new detection of CO(1-0) emission in four galaxies (UGC0968, UGC5617, UGC6946, and UGC8355) and CO(2-1) emission in two of them (UGC0968 and UGC5617). The CO(2-1)/CO(1-0) ratio in these sources is $\sim0.7\pm0.2$. Considering both the new observations and the literature, the detection rate of CO in our sample is 55 $\pm$ 9%, with no statistically significant difference between the hosts of RL and RQ AGNs. For all the detected galaxies we converted the CO luminosities into the molecular masses, $M_{H_2}$, that range from 10$^{6.5}$ to 10$^{8.5}$ M$_{\odot}$, without any statistically significant differences between RL and RQ galaxies. This suggests that the amount of molecular gas does not likely set the radio-loudness of the AGN. Furthermore, despite the low statistical significance, the presence of a weak trend between the H$_{2}$ mass with various tracers of nuclear activity (mainly [O III] emission line nuclear power) cannot be excluded.Comment: Accepted for publication on A&A, 9 pages, 5 figure