Variance optimal hedging in the Black-Scholes model for a given number of transactions

Theme 4 - Simulation et optimisation de systemes complexes - Projet MATHFISIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 14802 E, issue : a.1999 n.3767 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

The Relation between Globular Cluster Systems and Supermassive Black Holes in Spiral Galaxies. III. The Link to the M <SUB>•</SUB>-M <SUB>*</SUB> Correlation

International audienceWe continue to explore the relationship between the total number of globular clusters (GCs), N GC, and the central black hole mass, M •, in spiral galaxies. We present here results for the Sab galaxies NGC 3368, NGC 4736 (M94), and NGC 4826 (M64), and the Sm galaxy NGC 4395. The GC candidate selection is based on the (u* - $i^{\prime}$ ) versus ( $i^{\prime}$ - K s ) color-color diagram, and $i^{\prime}$ -band shape parameters. We determine the M • versus N GC correlation for these spirals, plus NGC 4258, NGC 253, M104, M81, M31, and the Milky Way. We also redetermine the correlation for the elliptical sample in Harris et al., with updated galaxy types from Sahu et al. Additionally, we derive the total stellar galaxy mass, M *, from its two-slope correlation with N GC, and fit M • versus M * for both spirals and ellipticals. We obtain log M • ∝ (1.01 ± 0.13) log N GC for ellipticals, and log M • ∝ (1.64 ± 0.24) log N GC for late-type galaxies (LTGs). The linear M • versus N GC correlation in ellipticals could be due to statistical convergence through mergers, unlike the much steeper correlation for LTGs. However, in the M • versus total stellar mass (M *) parameter space, with M * derived from its correlation with N GC, M • ∝ (1.48 ± 0.18) log M * for ellipticals, and M • ∝ (1.21 ± 0.16) log M * for LTGs. The observed agreement between ellipticals and LTGs in this parameter space may imply that black holes and galaxies coevolve through calm accretion, active galactic nuclei feedback, and other secular processes

Faint dwarf galaxies in Hickson Compact Group 90

International audienceWe report the discovery of a very diverse set of five low-surface brightness (LSB) dwarf galaxy candidates in Hickson Compact Group 90 (HCG 90) detected in deep U-and I-band images obtained with Very Large Telescope/Visible Multi-Object Spectrograph. These are the first LSB dwarf galaxy candidates found in a compact group of galaxies. We measure spheroid half-light radii in the range 0.7 r eff /kpc 1.5 with luminosities of −11.65 M U −9.42 and −12.79 M I −10.58 mag, corresponding to a colour range of (U − I) 0 1.1-2.2 mag and surface brightness levels of μ U 28.1 mag arcsec −2 and μ I 27.4 mag arcsec −2. Their colours and luminosities are consistent with a diverse set of stellar population properties. Assuming solar and 0.02 Z metallicities we obtain stellar masses in the range M * | Z 10 5.7−6.3 M and M * | 0.02 Z 10 6.3−8 M. Three dwarfs are older than 1 Gyr, while the other two significantly bluer dwarfs are younger than ∼2 Gyr at any mass/metallicity combination. Altogether, the new LSB dwarf galaxy candidates share properties with dwarf galaxies found throughout the Local Volume and in nearby galaxy clusters such as Fornax. We find a pair of candidates with ∼2 kpc projected separation, which may represent one of the closest dwarf galaxy pairs found. We also find a nucleated dwarf candidate, with a nucleus size of r eff 46-63 pc and magnitude M U, 0 = −7.42 mag and (U − I) 0 = 1.51 mag, which is consistent with a nuclear stellar disc with a stellar mass in the range 10 4.9 − 6.5 M

The Next Generation Fornax Survey (NGFS). V. Discovery of a Dwarf–Dwarf Galaxy Pair at z = 0.30 and Its Characterization Using Deep VLT/MUSE Observations

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The Next Generation Fornax Survey (NGFS). IV. Mass and Age Bimodality of Nuclear Clusters in the Fornax Core Region

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The Next Generation Fornax Survey (NGFS). III. Revealing the Spatial Substructure of the Dwarf Galaxy Population Inside Half of Fornax's Virial Radius

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The Next Generation Fornax Survey (NGFS). II. The Central Dwarf Galaxy Population

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