Evidence for a 3 x 10^8 solar mass black hole in NGC 7052 from HST observations of the nuclear gas disk

We present an HST study of the nuclear region of the E4 radio galaxy NGC 7052, which has a nuclear disk of dust and gas. The WFPC2 was used to obtain B, V and I broad-band images and an H_alpha+[NII] narrow-band image. The FOS was used to obtain H_alpha+[NII] spectra along the major axis, using a 0.26 arcsec diameter circular aperture. The observed rotation velocity of the ionized gas is V = 155 +/- 17 km/s at r = 0.2 arcsec from the nucleus. The Gaussian dispersion of the emission lines increases from sigma = 70 km/s at r=1 arcsec, to sigma = 400 km/s on the nucleus. To interpret the gas kinematics we construct axisymmetric models in which the gas and dust reside in a disk in the equatorial plane of the stellar body. It is assumed that the gas moves on circular orbits, with an intrinsic velocity dispersion due to turbulence. The circular velocity is calculated from the combined gravitational potential of the stars and a possible nuclear black hole (BH). Models without a BH predict a rotation curve that is shallower than observed (V_pred = 92 km/s at r = 0.2 arcsec), and are ruled out at > 99% confidence. Models with a BH of 3.3^{+2.3}_{-1.3} x 10^8 solar masses provide an acceptable fit. NGC 7052 can be added to the list of active galaxies for which HST spectra of a nuclear gas disk provide evidence for the presence of a central BH. The BH masses inferred for M87, M84, NGC 6251, NGC 4261 and NGC 7052 span a range of a factor 10, with NGC 7052 falling on the low end. By contrast, the luminosities of these galaxies are identical to within 25%. Any relation between BH mass and luminosity, as suggested by independent arguments, must therefore have a scatter of at least a factor 10.Comment: 39 pages, LaTeX, with 16 PostScript figures. Submitted to the Astronomical Journal. Postscript version with higher resolution figures available from http://sol.stsci.edu/~marel/abstracts/abs_R22.htm

Galaxy Occupation Statistics of Dark Matter Haloes: Observational Results

We study the occupation statistics of galaxies in dark matter haloes using galaxy groups identified from the 2-degree Field Galaxy Redshift Survey with the halo-based group finder of Yang et al. The occupation distribution is considered separately for early and late type galaxies, as well as in terms of central and satellite galaxies. The mean luminosity of the central galaxies scales with halo mass approximately as $L_c\propto M^{2/3}$ for haloes with masses M<10^{13}h^{-1}\msun, and as $L_c\propto M^{1/4}$ for more massive haloes. The characteristic mass of 10^{13} h^{-1} \Msun is consistent with the mass scale where galaxy formation models suggest a transition from efficient to inefficient cooling. Another characteristic halo mass scale, M\sim 10^{11} h^{-1}\msun, which cannot be probed directly by our groups, is inferred from the conditional luminosity function (CLF) that matches the observed galaxy luminosity function and clustering. For a halo of given mass, the distribution of $L_c$ is rather narrow. The satellite galaxies are found to follow a Poissonian number distribution. The central galaxies in low-mass haloes are mostly late type galaxies, while those in massive haloes are almost all early types. We also measure the CLF of galaxies in haloes of given mass. Over the mass range that can be reliably probed with the present data (13.3 \lta {\rm log}[M/(h^{-1}\Msun)] \lta 14.7), the CLF is reasonably well fit by a Schechter function. Contrary to recent claims based on semi-analytical models of galaxy formation, the presence of central galaxies does not show up as a strong peak at the bright end of the CLF. (Abridged)Comment: 17 pages, 11 figures, revised version. Two figures added. A few small changes. Main conclusions remain unchange

WFPC2 Images of the Central Regions of Early-Type Galaxies - I. The Data

We present high resolution R-band images of the central regions of 67 early-type galaxies obtained with the Wide Field and Planetary Camera 2 (WFPC2) aboard the Hubble Space Telescope (HST). Our sample strikingly confirms the complex morphologies of the central regions of early-type galaxies. In particular, we detect dust in 43 percent of all galaxies, and evidence for embedded stellar disks in a remarkably large fraction of 51 percent. In 14 of those galaxies the disk-like structures are misaligned with the main galaxy, suggesting that they correspond to stellar bars in S0 galaxies. We analyze the luminosity profiles of the galaxies in our sample, and classify galaxies according to their central cusp slope. To a large extent we confirm the clear dichotomy found in previous HST surveys: bright, boxy ellipticals with shallow inner cusps (`core' galaxies) on one hand and faint, disky ellipticals with steep central cusps (`power-law' galaxies) on the other hand. The advantages and shortcomings of classification schemes utilizing the extrapolated central cusp slope are discussed, and it is shown that this cusp slope might be an inadequate representation for galaxies whose luminosity profile slope changes smoothly with radius rather than resembling a broken power-law. In fact, we find evidence for an `intermediate' class of galaxies, that cannot unambiguously be classified as either core or power-law galaxies, and which have central cusp slopes and absolute magnitudes intermediate between those of core and power-law galaxies.Comment: 44 pages, 7 Postscript figures. Accepted for publication in the Astronomical Journal. The associated Appendix with figures of luminosity profiles, contour plots and isophotal parameters for all galaxies is available at http://www.astro.washington.edu/rest/centralpro

Diagnositic value of pelvic enthesitis on MRI of the sacroiliac joints in enthesitis related arthritis

Background: To determine the prevalence and diagnostic value of pelvic enthesitis on MRI of the sacroiliac (SI) joints in enthesitis related arthritis (ERA). Methods: We retrospectively studied 143 patients aged 6-18 years old who underwent MRI of the SI joints for clinically suspected sacroiliitis between 2006-2014. Patients were diagnosed with ERA according to the International League of Associations for Rheumatology (ILAR) criteria. All MRI studies were reassessed for the presence of pelvic enthesitis, which was correlated to the presence of sacroiliitis on MRI and to the final clinical diagnosis. The added value for detection of pelvic enthesitis and fulfilment of criteria for the diagnosis of ERA was studied. Results: Pelvic enthesitis was seen in 23 of 143 (16 %) patients. The most commonly affected sites were the entheses around the hip (35 % of affected entheses) and the retroarticular interosseous ligaments (32 % of affected entheses). MRI showed pelvic enthesitis in 21 % of patients with ERA and in 13 % of patients without ERA. Pelvic enthesitis was seen on MRI in 7/51 (14 %) patients with clinically evident enthesitis, and 16/92 (17 %) patients without clinically evident enthesitis. In 7 of 11 ERA-negative patients without clinical enthesitis but with pelvic enthesitis on MRI, the ILAR criteria could have been fulfilled, if pelvic enthesitis on MRI was included in the criteria. There is a high correlation between pelvic enthesitis and sacroiliitis, with sacroiliitis present in 17/23 (74 %) patients with pelvic enthesitis. Conclusions: Pelvic enthesitis may be present in children with or without clinically evident peripheral enthesitis. There is a high correlation between pelvic enthesitis and sacroiliitis on MRI of the sacroiliac joints in children. As pelvic enthesitis indicates active inflammation, it may play a role in assessment of the inflammatory status. Therefore, it should be carefully sought and noted by radiologists examining MRI of the sacroiliac joints in children

The Population of Dark Matter Subhaloes: Mass Functions and Average Mass Loss Rates

Using a cosmological N-Body simulation and a sample of re-simulated cluster-like haloes, we study the mass loss rates of dark matter subhaloes, and interpret the mass function of subhaloes at redshift zero in terms of the evolution of the mass function of systems accreted by the main halo progenitor. When expressed in terms of the ratio between the mass of the subhalo at the time of accretion and the present day host mass the unevolved subhalo mass function is found to be universal. However, the subhalo mass function at redshift zero clearly depends on $M_0$, in that more massive host haloes host more subhaloes. To relate the unevolved and evolved subhalo mass functions, we measure the subhalo mass loss rate as a function of host mass and redshift. We find that the average, specific mass loss rate of dark matter subhaloes depends mainly on redshift. These results suggest a pleasingly simple picture for the evolution and mass dependence of the evolved subhalo mass function. Less massive host haloes accrete their subhaloes earlier, which are thus subjected to mass loss for a longer time. In addition, their subhaloes are typically accreted by denser hosts, which causes an additional boost of the mass loss rate. To test the self-consistency of this picture, we use a merger trees constructed using the extended Press-Schechter formalism, and evolve the subhalo populations using the average mass loss rates obtained from our simulations, finding the subhalo mass functions to be in good agreement with the simulations. [abridged]Comment: 12 pages, 12 figures; submitted to MNRA

The syndrome of Capgras:Converging models

BACKGROUND: Various theories have been proposed concerning the syndrome of Capgras. AIM: To search for a concept that is common to the various theories relating to the aetiology of the syndrome of Caparas. METHODS: We begin by describing a new case of Capgras syndrome that we encountered recently, and thereafter we searched the literature using PubMed and PsycINFO. RESULTS: Various explanatory models converge in that they all assign a central role to a changed affect. A sensation of 'alienation' at a conscious or subconscious level, together with inadequate evaluation of beliefs, seems plausible. All models demonstrate some form of 'splitting' i.e. the separate processing of information in time, anatomy or mental representation. CONCLUSION: Although there is no conclusive evidence to support any one of the hypotheses, the models display striking similarities. They complement each other.</p