AGN Jets, Bubbles, and Heat Pumps

2018 ◽  
Vol 14 (S342) ◽  
pp. 149-153
Author(s):  
Yi-Hao Chen ◽  
Sebastian Heinz
Keyword(s):  
Thermal Conduction ◽  
Thermal Evolution ◽  
Heat Pumps ◽  
Clusters Of Galaxies ◽  
Relativistic Jets ◽  
Term Evolution ◽  
Radio Lobe ◽  
Low Entropy ◽  
Perseus Cluster

AbstractRadio-mode feedback from relativistic jets is one of the prominent heating mechanisms in clusters of galaxies. We present a long-term evolution of high-resolution MHD simulation of jets interacting with an environment modeled to represent the Perseus cluster. We investigate the thermodynamics of the ICM due to the gas motion triggered by the action of the jets and show that low-entropy gas is lifted efficiently in the wake of the inflating radio lobe. We look into the uplift mechanism and estimate the energy budget and the rate of thermal conduction. The redistribution of entropy suggests that heat conduction can play a more significant role in the thermal evolution of the cluster core in the presence of jets, which act effectively as a heat pump, thus heating the ICM more efficiently than jets would by themselves in an isentropic cluster.

scholarly journals Jets, bubbles, and heat pumps in galaxy clusters

2019 ◽  
Vol 489 (2) ◽  
pp. 1939-1949 ◽  
Author(s):  
Yi-Hao Chen ◽  
Sebastian Heinz ◽  
Torsten A Enßlin
Keyword(s):  
Galaxy Clusters ◽  
Thermal Conduction ◽  
Heat Pumps ◽  
Maximum Efficiency ◽  
Heating Process ◽  
Geothermal Heat ◽  
Geothermal Heat Pump ◽  
Direct Energy ◽  
Magnetohydrodynamic Simulations ◽  
Low Entropy

Abstract Feedback from active galactic nucleus (AGN) jets has been proposed to counteract the catastrophic cooling in many galaxy clusters. However, it is still unclear which physical processes are acting to couple the energy from the bi-directional jets to the intra-cluster medium (ICM). We study the long-term evolution of rising bubbles that were inflated by AGN jets using magnetohydrodynamic simulations. In the wake of the rising bubbles, a significant amount of low-entropy gas is brought into contact with the hot cluster gas. We assess the energy budget of the uplifted gas and find it comparable to the total energy injected by the jets. Although our simulation does not include explicit thermal conduction, we find that, for reasonable assumptions about the conduction coefficient, the rate is fast enough that much of the uplifted gas may be thermalized before it sinks back to the core. Thus, we propose that the AGN can act like a geothermal heat pump to move low-entropy gas from the cluster core to the heat reservoir and will be able to heat the inner cluster more efficiently than would be possible by direct energy transfer from jets alone. We show that the maximum efficiency of this mechanism, i.e. the ratio between the conductive thermal energy and the work needed to lift the gas, ξmax, can exceed 100 per cent. While ξ < ξmax in realistic scenarios, AGN-induced thermal conduction has the potential to significantly increase the efficiency with which AGN can heat cool-core clusters and transform the bursty AGN activities into a smoother and enduring heating process.

scholarly journals Thermal evolution of rocky exoplanets with a graphite outer shell

2019 ◽  
Vol 630 ◽  
pp. A152
Author(s):  
Kaustubh Hakim ◽  
Arie van den Berg ◽  
Allona Vazan ◽  
Dennis Höning ◽  
Wim van Westrenen ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Thermal Evolution ◽  
Outer Shell ◽  
Graphite Layer ◽  
Term Evolution ◽  
High Pressure High Temperature ◽  
Parameterized Model ◽  
Heat Transport Mechanism ◽  
Carbon Inventory

Context. The presence of rocky exoplanets with a large refractory carbon inventory is predicted by chemical evolution models of protoplanetary disks of stars with photospheric C/O > 0.65, and by models studying the radial transport of refractory carbon. High-pressure high-temperature laboratory experiments show that most of the carbon in these exoplanets differentiates into a graphite outer shell. Aims. Our aim is to evaluate the effects of a graphite outer shell on the thermal evolution of rocky exoplanets containing a metallic core and a silicate mantle. Methods. We implemented a parameterized model of mantle convection to determine the thermal evolution of rocky exoplanets with graphite layer thicknesses up to 1000 km. Results. We find that because of the high thermal conductivity of graphite, conduction is the dominant heat transport mechanism in a graphite layer for long-term evolution (>200 Myr). The conductive graphite shell essentially behaves like a stagnant lid with a fixed thickness. Models of Kepler-37b (Mercury-size) and a Mars-sized exoplanet show that a planet with a graphite lid cools faster than a planet with a silicate lid, and a planet without a stagnant lid cools the fastest. A graphite lid needs to be approximately ten times thicker than a corresponding silicate lid to produce similar thermal evolution.

scholarly journals Does the plasma composition affect the long-term evolution of relativistic jets?

2002 ◽  
Vol 331 (3) ◽  
pp. 615-634 ◽  
Author(s):  
L. Scheck ◽  
M. A. Aloy ◽  
J. M. Martí ◽  
J. L. Gómez ◽  
E. Müller
Keyword(s):  
Long Term Evolution ◽  
Plasma Composition ◽  
Relativistic Jets ◽  
Term Evolution

Link-Level Simulator for Wireless local Area Network

2018 ◽  
Vol 6 (7) ◽  
pp. 314
Author(s):  
Chaithra. H. U ◽  
Vani H.R
Keyword(s):  
Wireless Local Area Network ◽  
Local Area Network ◽  
Local Area Networks ◽  
Local Area ◽  
Long Term Evolution ◽  
Wireless Local Area Networks ◽  
Area Network ◽  
Network Simulator ◽  
Term Evolution

Now a days in Wireless Local Area Networks (WLANs) used in different fields because its well-suited simulator and higher flexibility. The concept of WLAN  with  advanced 5th Generation technologies, related to a Internet-of-Thing (IOT). In this project, representing the Network Simulator (NS-2) used linked-level simulators for Wireless Local Area Networks and still utilized IEEE 802.11g/n/ac with advanced IEEE 802.11ah/af technology. Realization of the whole Wireless Local Area Networking linked-level simulators inspired by the recognized Vienna Long Term Evolution- simulators. As a outcome, this is achieved to link together that simulator to detailed performances of Wireless Local Area Networking with Long Term Evolution, operated in the similar RF bands. From the advanced 5th Generation support cellular networking, such explore is main because different coexistences scenario can arise linking wireless communicating system to the ISM and UHF bands.

Simulación de cobertura del modelo de radio propagación 3GPP para un entorno urbano en una red 4G – LTE

2013 ◽  
Vol 8 (15) ◽  
pp. 33-40
Author(s):  
Javier Enrique Arévalo Peña
Keyword(s):  
Long Term Evolution ◽  
Term Evolution ◽  
Nuevas Tecnologías ◽  
4G Lte ◽  
3Rd Generation Partnership Project

En la planeación de las próximas generaciones de redes inalámbricas es importante contar con estudios de radio propagación que permitan establecer diseños adecuados para ofrecer los servicios proyectados por las nuevas tecnologías a los usuarios móviles. En este artículo se presentan aspectos relacionados con el comportamiento de cobertura de radio propagación del modelo propuesto por el 3GPP (3rd Generation Partnership Project) para un entorno urbano en una red LTE (Long Term Evolution) empleando sistemas de antenas convencionales y sistemas de antena adaptativas (AAS). Para ello se utiliza la herramienta de software ICS Designer y se establece como escenario los alrededores la Fundación Universidad Autónoma de Colombia ubicada en el centro urbano de la ciudad de Bogotá D. C.

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