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Start Over Author "Brook C" Journal monthly notices of the royal astronomical society
29 results on '"Brook C"'

3. A probabilistic deep learning model to distinguish cusps and cores in dwarf galaxies.

Author

Expósito-Márquez, J, Brook, C B, Huertas-Company, M, Di Cintio, A, Macciò, A V, Grand, R J J, Battaglia, G, and Arjona-Gálvez, E

Subjects
*ELLIPTICAL galaxies, *DEEP learning, *DISTRIBUTION of stars, *PROBABILITY density function, *GALACTIC halos, *DARK matter, *DWARF galaxies
Abstract

Numerical simulations within a cold dark matter (DM) cosmology form haloes whose density profiles have a steep inner slope ('cusp'), yet observations of galaxies often point towards a flat central 'core'. We develop a convolutional mixture density neural network model to derive a probability density function (PDF) of the inner density slopes of DM haloes. We train the network on simulated dwarf galaxies from the NIHAO and AURIGA projects, which include both DM cusps and cores: line-of-sight velocities and 2D spatial distributions of their stars are used as inputs to obtain a PDF representing the probability of predicting a specific inner slope. The model recovers accurately the expected DM profiles: |$\sim 82{{\ \rm per\ cent}}$| of the galaxies have a derived inner slope within ±0.1 of their true value, while |$\sim 98{{\ \rm per\ cent}}$| within ±0.3. We apply our model to four Local Group dwarf spheroidal galaxies and find results consistent with those obtained with the Jeans modelling based code GravSphere : the Fornax dSph has a strong indication of possessing a central DM core, Carina and Sextans have cusps (although the latter with large uncertainties), while Sculptor shows a double peaked PDF indicating that a cusp is preferred, but a core cannot be ruled out. Our results show that simulation-based inference with neural networks provide a innovative and complementary method for the determination of the inner matter density profiles in galaxies, which in turn can help constrain the properties of the elusive DM. [ABSTRACT FROM AUTHOR]

Published
2023
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13. Thin disc, thick disc and halo in a simulated galaxy

Author

Brook, C. B., primary, Stinson, G. S., additional, Gibson, B. K., additional, Kawata, D., additional, House, E. L., additional, Miranda, M. S., additional, Macciò, A. V., additional, Pilkington, K., additional, Roškar, R., additional, Wadsley, J., additional, and Quinn, T. R., additional

Published
2012
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20. The cold gas content of bulgeless dwarf galaxies

Author

Pilkington, K., primary, Gibson, B. K., additional, Calura, F., additional, Brooks, A. M., additional, Mayer, L., additional, Brook, C. B., additional, Stinson, G. S., additional, Thacker, R. J., additional, Few, C. G., additional, Cunnama, D., additional, and Wadsley, J., additional

Published
2011
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21. Disc heating: comparing the Milky Way with cosmological simulations

Author

House, E. L., primary, Brook, C. B., additional, Gibson, B. K., additional, Sánchez-Blázquez, P., additional, Courty, S., additional, Few, C. G., additional, Governato, F., additional, Kawata, D., additional, Roškar, R., additional, Steinmetz, M., additional, Stinson, G. S., additional, and Teyssier, R., additional

Published
2011
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25. Forming a large disc galaxy from az< 1 major merger

Author

Governato, F., primary, Brook, C. B., additional, Brooks, A. M., additional, Mayer, L., additional, Willman, B., additional, Jonsson, P., additional, Stilp, A. M., additional, Pope, L., additional, Christensen, C., additional, Wadsley, J., additional, and Quinn, T., additional

Published
2009
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27. Making Galaxies In a Cosmological Context: the need for early stellar feedback.

Author

Stinson, G. S., Brook, C., Macciò, A. V., Wadsley, J., Quinn, T. R., and Couchman, H. M. P.

Subjects
*GALAXIES, *METAPHYSICAL cosmology, *STELLAR mass, *HYDRODYNAMICS, *SIMULATION methods & models, *REDSHIFT, *ULTRAVIOLET radiation
Abstract

We introduce the Making Galaxies In a Cosmological Context (MAGICC) programme of smoothed particle hydrodynamics simulations. We describe a parameter study of galaxy formation simulations of an L* galaxy that uses early stellar feedback combined with supernova feedback to match the stellar mass-halo mass relationship. While supernova feedback alone can reduce star formation enough to match the stellar mass-halo mass relationship, the galaxy forms too many stars before z = 2 to match the evolution seen using abundance matching. Our early stellar feedback is purely thermal and thus operates like an ultraviolet ionization source as well as providing some additional pressure from the radiation of massive, young stars. The early feedback heats gas to >106 K before cooling it to 104 K. The pressure from this hot gas creates a more extended disc and prevents more star formation prior to z = 1 than supernova feedback alone. The resulting disc galaxy has a flat rotation curve, an exponential surface brightness profile, and matches a wide range of disc scaling relationships. The disc forms from the inside-out with an increasing exponential scale length as the galaxy evolves. Overall, early stellar feedback helps to simulate galaxies that match observational results at low and high redshifts. [ABSTRACT FROM AUTHOR]

Published
2013
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28. Hierarchical formation of bulgeless galaxies - II. Redistribution of angular momentum via galactic fountains.

Author

Brook, C. B., Stinson, G., Gibson, B. K., Roškar, R., Wadsley, J., and Quinn, T.

Subjects
*GALAXY formation, *ANGULAR momentum (Nuclear physics), *EXCHANGE reactions, *METAPHYSICAL cosmology, *MATHEMATICAL models of hydrodynamics, *GALACTIC halos, *ROTATION of galaxies, *GALACTIC bulges, *SPIRAL galaxies
Abstract

ABSTRACT Within a fully cosmological hydrodynamical simulation, we form a galaxy which rotates at 140 km s−1, and it is characterized by two loose spiral arms and a bar, indicative of a Hubble-type SBc/d galaxy. We show that our simulated galaxy has no classical bulge, with a pure disc profile at z = 1, well after the major merging activity has ended. A long-lived bar subsequently forms, resulting in the formation of a secularly formed 'pseudo-'bulge, with the final bulge-to-total light ratio of 0.21. We show that the majority of gas which loses angular momentum and falls to the central region of the galaxy during the merging epoch is blown back into the hot halo, with much of it returning later to form stars in the disc. We propose that this mechanism of redistribution of angular momentum via a galactic fountain, when coupled with the results from our previous study which showed why gas outflows are biased to have low angular momentum, can solve the angular momentum/bulgeless disc problem of the cold dark matter paradigm. [ABSTRACT FROM AUTHOR]

Published
2012
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29. Forming a large disc galaxy from a z < 1 major merger.

Author

Governato, F., Brook, C. B., Brooks, A. M., Mayer, L., Willman, B., Jonsson, P., Stilp, A. M., Pope, L., Christensen, C., Wadsley, J., and Quinn, T.

Subjects
*ASTRONOMY, *GALAXIES, *STAR formation, *DARK matter, *INTERSTELLAR medium
Abstract

Using high-resolution SPH simulations in a fully cosmological Λ cold dark matter context, we study the formation of a bright disc-dominated galaxy that originates from a ‘wet’ major merger at . The progenitors of the disc galaxy are themselves disc galaxies that formed from early major mergers between galaxies with blue colours. A substantial thin stellar disc grows rapidly following the last major merger and the present-day properties of the final remnant are typical of early-type spiral galaxies, with an i-band bulge-to-disc ratio ∼0.65, a disc scalelength of 7.2 kpc, , an H i linewidth ( W20/2) of 238 km s−1 and total magnitude . The key ingredients for the formation of a dominant stellar disc component after a major merger are (i) substantial and rapid accretion of gas through cold flows followed at late times by cooling of gas from the hot phase, (ii) supernova feedback that is able to partially suppress star formation during mergers and (iii) relative fading of the spheroidal component. The gas fraction of the progenitors' discs does not exceed 25 per cent at , emphasizing that the continuous supply of gas from the local environment plays a major role in the regrowth of discs and in keeping the galaxies blue. The results of this simulation alleviate the problem posed for the existence of disc galaxies by the high likelihood of interactions and mergers for galaxy-sized haloes at relatively low z. [ABSTRACT FROM AUTHOR]

Published
2009
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