Black holes are believed to be one of the key ingredients of galaxy formation models, but it has been notoriously challenging to simulate them due to the very complex physics and large dynamical range of spatial scales involved. Here we address a significant shortcoming of a Bondi-Hoyle-like prescription commonly invoked to estimate black hole accretion in cosmological hydrodynamic simulations of galaxy formation, namely that the Bondi-Hoyle radius is frequently unresolved. We describe and implement a novel super-Lagrangian refinement scheme to increase, adaptively and 'on the fly', the mass and spatial resolution in targeted regions around the accreting black holes at limited computational cost. While our refinement scheme is generically applicable and flexible, for the purpose of this paper we select the smallest resolvable scales to match black holes' instantaneous Bondi radii, thus effectively resolving BondiHoyle-like accretion in full galaxy formation simulations. This permits us to not only estimate gas properties close to the Bondi radius much more accurately, but also allows us to improve black hole accretion and feedback implementations. We thus devise a more generic feedback model where accretion and feedback depend on the geometry of the local gas distribution and where mass, energy and momentum loading are followed simultaneously. We present a series of tests of our refinement and feedback methods and apply them to models of isolated disc galaxies. Our simulations demonstrate that resolving gas properties in the vicinity of black holes is necessary to follow black hole accretion and feedback with a higher level of realism and that doing so allows us to incorporate important physical processes so far neglected in cosmological simulations.

There is growing observational evidence of high-redshift quasars launching energetic, fast outflows, but the effects that these have on their host galaxies is poorly understood. We employ the moving-mesh code AREPO to study the feedback from a quasar that has grown to ∼ 10 9 M by z ∼ 5 and the impact that this has on its host galaxy. Our simulations use a super-Lagrangian refinement technique to increase the accuracy with which the interface of the quasar-driven wind and the surrounding gas is resolved. We find that the feedback injected in these simulations is less efficient at removing gas from the galaxy than in an identical simulation with no super-Lagrangian refinement. This leads to the growth of a massive, rotationally supported, star-forming disc, co-existing with a powerful quasar-driven outflow. The properties of our host galaxy, including the kinematical structure of the gaseous disc and of the outflow, are in good agreement with current observations. Upcoming ALMA and JWST observations will be an excellent test of our model and will provide further clues as to the variance in properties of high-redshift quasar hosts.

Cosmological simulations almost invariably estimate the accretion of gas on to supermassive black holes using a Bondi-Hoyle-like prescription. Doing so ignores the effects of the angular momentum of the gas, which may prevent or significantly delay accreting material falling directly on to the black hole. We outline a black hole accretion rate prescription using a modified Bondi-Hoyle formulation that takes into account the angular momentum of the surrounding gas. Meaningful implementation of this modified Bondi-Hoyle formulation is only possible when the inner vorticity distribution is well resolved, which we achieve through the use of a super-Lagrangian refinement technique around black holes within our simulations. We then investigate the effects on black hole growth by performing simulations of isolated as well as merging disc galaxies using the moving-mesh code AREPO. We find that the gas angular momentum barrier can play an important role in limiting the growth of black holes, leading also to a several Gyr delay between the starburst and the quasar phase in major merger remnants. We stress, however, that the magnitude of this effect is highly sensitive to the thermodynamical state of the accreting gas and to the nature of the black hole feedback present.

Light curves in the B, V , and I c passbands have been obtained for the type II Cepheids V154 in M3 and V42 and V84 in M5. Alternating cycle behavior, similar to that seen among RV Tauri variables, is confirmed for V84. Old and new observations, spanning more than a century, show that V154 has increased in period while V42 has decreased in period. V84, on the other hand, has shown large, erratic changes in period that do not appear to reflect the long term evolution of V84 through the HR diagram.

This paper was prepared for the 48th Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Las Vegas, Nev., Sept. 30-Oct. 3, 1973. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Abstract In the literature on Temperature logging, relationships exist which may be used to predict the temperature responses in producing wells as a function of volumetric flow rate, time of production, fluid gravity, geothermal gradient, and various thermal coefficients. These relationships indicate that under "ideal conditions" the temperature curve recorded above a producing zone as a function of depth exponentially approaches an asymptote parallel to the natural geothermal profile. This asymptote is displaced from the geothermal profile by an amount depending on the mass flow rate and the time the well has been produced. Theoretical examples will illustrate the use of these relationships to predict the temperature responses in producing wells for cases of flow rates up to 1,000 B/D producing wells for cases of flow rates up to 1,000 B/D and for production times up to 1,000 days. With the knowledge of the predictive equations, the reverse problem is considered. Temperature logs are examined to locate intervals exhibiting this exponential behavior. A coefficient in the basic relation is adjusted to make the relation fit a given exponential segment. Then, knowing the time the well has been produced, the mass flow rate is computed. If fluid-density information is available, the volumetric flow rate is computed. This method has its greatest applicability when used in conjunction with spinner-type flowmeters to detect fluid flow in the casing annulus. For use of the method, production times should be greater than 10 days, and producing zones should be separated by at least 100 feet.