Dynamical Simulations of NGC 2523 and NGC 4245

We present dynamical simulations of NGC 2523 and NGC 4245, two barred galaxies (types SB(r)b and SB(r)0/a, respectively) with prominent inner rings. Our goal is to estimate the bar pattern speeds in these galaxies by matching a sticky-particle simulation to the $B$-band morphology, using near-infrared $K_s$-band images to define the gravitational potentials. We compare the pattern speeds derived by this method with those derived in our previous paper using the well-known Tremaine-Weinberg continuity equation method. The inner rings in these galaxies, which are likely to be resonance features, help to constrain the dynamical models. We find that both methods give the same pattern speeds within the errors.Comment: 29 pages, 3 tables, 13 figures. Accepted for publication in The Astronomical Journa

The Bar Pattern Speed of NGC 1433 Estimated Via Sticky-Particle Simulations

We present detailed numerical simulations of NGC 1433, an intermediate-type barred spiral showing strong morphological features including a secondary bar, nuclear ring, inner ring, outer pseudoring, and two striking, detached spiral arcs known as ``plumes.'' This galaxy is an ideal candidate for recreating the observed morphology through dynamical models and determining the pattern speed. We derived a gravitational potential from an $H$-band image of the galaxy and simulated the behavior of a two-dimensional disk of 100,000 inelastically colliding gas particles. We find that the closest matching morphology between a $B$-band image and a simulation occurs with a pattern speed of 0.89 km s$^{-1}$ arcsec$^{-1}$ $\pm$ 5-10%. We also determine that the ratio of corotation radius to the average published bar radius is 1.7 $\pm$ 0.3, with the ambiguity in the bar radius being the largest contributor to the error.Comment: Accepted for publication by The Astronomical Journal. 34 pages, 13 figures, 2 table

The Kinematically Measured Pattern Speeds of NGC 2523 and NGC 4245

We have applied the Tremaine-Weinberg continuity equation method to derive the bar pattern speed in the SB(r)b galaxy NGC 2523 and the SB(r)0/a galaxy NGC 4245 using the Calcium Triplet absorption lines. These galaxies were selected because they have strong inner rings which can be used as independent tracers of the pattern speed. The pattern speed of NGC 2523 is 26.4 $\pm$ 6.1 km s$^{-1}$ kpc$^{-1}$, assuming an inclination of 49.7$^{\circ}$ and a distance of 51.0 Mpc. The pattern speed of NGC 4245 is 75.5 $\pm$ 31.3 km s$^{-1}$ kpc$^{-1}$, assuming an inclination of 35.4$^{\circ}$ and a distance of 12.6 Mpc. The ratio of the corotation radius to the bar radius of NGC 2523 and NGC 4245 is 1.4 $\pm$ 0.3 and 1.1 $\pm$ 0.5, respectively. These values place the bright inner rings near and slightly inside the corotation radius, as predicted by barred galaxy theory. Within the uncertainties, both galaxies are found to have fast bars that likely indicate dark halos of low central concentration. The photometric properties, bar strengths, and disk stabilities of both galaxies are also discussed.Comment: Accepted for publication in The Astronomical Journal, 11 figures, 2 table

Study of the Relation between the Spiral Arm Pitch Angle and the Kinetic Energy of Random Motions of the Host Spiral Galaxies, A

In this work, we report a relation between the kinetic energy of random motions of the corresponding host galaxies and spiral arm pitch angles (Mdynσ2- P), (M*σ2- P) where Mdyn is the bulge dynamical mass, M* is bulge stellar mass, and σ is the velocity dispersion of the host galaxy bulge. We measured the spiral arm pitch angle (P) for a sample of Spitzer/IRAC 3.6-μm images of 54 spiral galaxies, estimated by using a 2D Fast Fourier Transform decomposition technique (2DFFT). We selected a sample of nearly face-on spiral galaxies and used IRAF ellipse to determine the ellipticity and major-axis position angle in order to deproject the images to face-on, and using a 2D Fast Fourier Transform decomposition technique, we determined the spiral arm pitch angles. We estimated the kinetic energy of random motions of the corresponding host galaxies (Mdynσ, M*σ2) by using Mdyn, M*, and σ, where the stellar velocity dispersion (σ) of the bulge was taken from the literature. We determined the bulge dynamical mass (Mdyn) using the virial theorem, and the bulge stellar mass (M*) was estimated by using the bulge 3.6-μm luminosity with the appropriate stellar mass-to-light ratio (M/L)

N-body simulations in reconstruction of the kinematics of young stars in the Galaxy

We try to determine the Galactic structure by comparing the observed and modeled velocities of OB-associations in the 3 kpc solar neighborhood. We made N-body simulations with a rotating stellar bar. The galactic disk in our model includes gas and stellar subsystems. The velocities of gas particles averaged over large time intervals ($\sim 8$ bar rotation periods) are compared with the observed velocities of the OB-associations. Our models reproduce the directions of the radial and azimuthal components of the observed residual velocities in the Perseus and Sagittarius regions and in the Local system. The mean difference between the model and observed velocities is $\Delta V=3.3$ km s$^{-1}$. The optimal value of the solar position angle $\theta_b$ providing the best agreement between the model and observed velocities is $\theta_b=45\pm5^\circ$, in good accordance with several recent estimates. The self-gravitating stellar subsystem forms a bar, an outer ring of subclass $R_1$, and slower spiral modes. Their combined gravitational perturbation leads to time-dependent morphology in the gas subsystem, which forms outer rings with elements of the $R_1$- and $R_2$-morphology. The success of N-body simulations in the Local System is likely due to the gravity of the stellar $R_1$-ring, which is omitted in models with analytical bars.Comment: 13 pages, 13 figures, accepted to Astronomy and Astrophysic

Model-based pattern speed estimates for 38 barred galaxies

We have modelled 38 barred galaxies by using near-IR and optical data from the Ohio State University Bright Spiral Galaxy Survey. We constructed the gravitational potentials of the galaxies from $H$-band photometry, assuming constant mass-to-light ratio. The halo component we chose corresponds to the so called universal rotation curve. In each case, we used the response of gaseous and stellar particle disc to rigidly rotating potential to determine the pattern speed. We find that the pattern speed of the bar depends roughly on the morphological type. The average value of corotation resonance radius to bar radius, $\mathcal{R}$, increases from $1.15 \pm 0.25$ in types SB0/a -- SBab to $1.44 \pm 0.29$ in SBb and $1.82\pm 0.63$ in SBbc -- SBc. Within the error estimates for the pattern speed and bar radius, all galaxies of type SBab or earlier have a fast bar ($\mathcal{R} \le 1.4$), whereas the bars in later type galaxies include both fast and slow rotators. Of 16 later type galaxies with a nominal value of $\mathcal{R} > 1.4$, there are five cases, where the fast rotating bar is ruled out by the adopted error estimates. We also study the correlation between the parameter $\mathcal{R}$ and other galactic properties. The clearest correlation is with the bar size: the slowest bars are also the shortest bars when compared to the galaxy size. A weaker correlation is seen with bar strength in a sense that slow bars tend to be weaker. These correlations leave room for a possibility that the determined pattern speed in many galaxies corresponds actually that of the spiral, which rotates more slowly than the bar. No clear correlation is seen with either the galaxy luminosity or colour.Comment: 18 pages, 13 figures, accepted for publication in MNRA

The structure of spiral galaxies: radial profiles in stellar Mass-to-Light ratio and the Dark Matter distribution

The colour and metallicity gradients observed in spiral galaxies suggest that the mass-to-light ratio (M*/L) of the stellar disc is a function of radius. This is indeed predicted by chemo-photometric models of galactic discs. We investigate the distribution of luminous and dark matter in spiral galaxies, taking into account the radial dependence of the stellar M*/L - which is usually assumed to be constant in studies of the mass structure. From the chemo-photometric models of Portinari et al. (2004) and in agreement with the observed radial profiles of galaxy colours, we derive the typical average M*/L profile of the stellar discs of spiral galaxies. We compute the corresponding Variable Mass-to-Light (VML) stellar surface density profile and then the VML disc contribution to the circular velocity. We use the latter, combined with a well studied dark matter velocity profile, to mass model the co-added rotation curves of Persic et al. (1996). (See http://www.facebook.com/home.php#!/group.php?gid=310260450630 to retrieve extra information on the kinematics of galaxies) By investigating rotation curves in the framework of VML stellar discs, we confirm, to a first approximation, the scenario obtained with the constant M*/L assumption: a dark matter halo with a shallow core, an inner baryon-dominated region and a larger proportion of Dark Matter in smaller objects. However, the resulting size of the the dark halo core and of the inner baryon dominance region are somewhat smaller. The stronger role that VML discs have in the innermost regions is important to constrain the galaxy mass structure in both Lambda Cold Dark Matter and MOND scenarios.Comment: 12 pages, 10 figures, in press on Astronomy and Astrophysics. Minor text revisions to match published version. Reference added to web-link to http://www.facebook.com/home.php#!/group.php?gid=31026045063

Galaxy bulges and their massive black holes: a review

With references to both key and oft-forgotten pioneering works, this article starts by presenting a review into how we came to believe in the existence of massive black holes at the centres of galaxies. It then presents the historical development of the near-linear (black hole)-(host spheroid) mass relation, before explaining why this has recently been dramatically revised. Past disagreement over the slope of the (black hole)-(velocity dispersion) relation is also explained, and the discovery of sub-structure within the (black hole)-(velocity dispersion) diagram is discussed. As the search for the fundamental connection between massive black holes and their host galaxies continues, the competing array of additional black hole mass scaling relations for samples of predominantly inactive galaxies are presented.Comment: Invited (15 Feb. 2014) review article (submitted 16 Nov. 2014). 590 references, 9 figures, 25 pages in emulateApJ format. To appear in "Galactic Bulges", E. Laurikainen, R.F. Peletier, and D.A. Gadotti (eds.), Springer Publishin

Images in clinical urology. Nail of glans penis.

A 56-year-old man presented with a "nail" growing at the base of his glans penis. The tumor was locally excised, and microscopic examination revealed papillomatosis and hyperkeratosis of the malpighian epithelium, with a strong inflammatory reaction of the chorion and signs of local microinvasion, as well as the presence of well-differentiated squamous epithelial cells. The surgical margins were negative. The differential diagnosis was made between a benign papillomatous proliferation and verrucous carcinoma

Néphrectomie par laparoscopie: aspects techniques [Laparoscopic nephrectomy: technical aspects]

The laparoscopic approach has emerged as a valid option for surgical management of kidney cancer, as well as a few benign pathologies. The immediate benefits of laparoscopy are well established and include less estimated blood loss, decreased pain, shorter perioperative convalescence, and improved cosmesis. Long-term oncologic outcomes of patients treated laparoscopically for kidney tumors are similar to those of open surgery