A. Pizzella

On the Inconsistency between the Black Hole Mass Function Inferred from M•-σ and M•-L Correlations

Black hole masses are tightly correlated with the stellar velocity dispersions of the bulges which surround them and slightly less well correlated with the bulge luminosity. It is common to use these correlations to estimate the expected abundance of massive black holes. This is usually done by starting from an observed distribution of velocity dispersions or luminosities and then changing variables. This procedure neglects the fact that there is intrinsic scatter in these black hole mass-observable correlations. Accounting for this scatter results in estimates of black hole abundances which are larger by almost an order of magnitude at masses >109 M☉. Including this scatter is particularly important for models which seek to infer quasar lifetimes and duty cycles from the local black hole mass function. However, even when scatter has been accounted for, the M•-σ relation predicts fewer massive black holes than does the M•-L relation. This is because the σ-L relation in the black hole samples currently available is inconsistent with that in the SDSS sample from which the distributions of L or σ are based: the black hole samples have smaller L for a given σ, or larger σ for a given L. The σ-L relation in the black hole samples is similarly discrepant with that in other samples of nearby early-type galaxies. This suggests that current black hole samples are biased: if this is a selection rather than a physical effect, then the M•-σ and M•-L relations currently in the literature are also biased from their true values.

ON THE RELATION BETWEEN CIRCULAR VELOCITY AND CENTRAL VELOCITY DISPERSION IN HIGH AND LOW SURFACE BRIGHTNESS GALAXIES

In order to investigate the correlation between the circular velocity Vc and the central velocity dispersion of the spheroidal componentc, we analyzed these quantities for a sample of 40 high surface brightness (HSB) disk galaxies, eight giant low surface brightness (LSB) spiral galaxies, and 24 elliptical galaxies characterized by flat rotation curves. Galaxieshave been selectedto have avelocity gradient � 2kms � 1 kpc � 1 forR � 0:35R25.We used these data to better define the previous Vc-� c correlation for spiral galaxies (which turned out to be HSB) and ellipticalgalaxies,especiallyatthelowerendofthecvalues.WefindthattheVc-� crelationisdescribedbyalinear law out to velocity dispersions as low asc � 50 km s � 1 , while in previous works a power law was adopted for galaxies withc > 80 km s � 1 . Elliptical galaxies with Vc based on dynamical models or directly derived from the H i rotation curves follow the same relation as the HSB galaxies in the Vc-� c plane. On the other hand, the LSB galaxies follow a different relation, since most of them show either higher Vc or lowerc with respect to the HSB galaxies.Thisarguesagainsttherelevanceofbaryoncollapsetotheradialdensityprofile ofthedarkmatterhalosof LSB galaxies. Moreover, if theVc-� c relation is equivalent to one between the mass of the dark matter halo and that of the supermassive black hole, then these results suggest that the LSB galaxies host a supermassive black hole (SMBH) with a smaller mass compared to HSB galaxies with an equal dark matter halo. On the other hand, if the fundamental correlation of SMBH mass is with the halo circular velocity, then LSB galaxies should have larger black hole masses for a given bulge dispersion. Elliptical galaxies with Vc derived from H i data and LSB galaxies were not considered in previous studies.

The X-Ray, optical, and infrared counterpart to GRB 980703

We report on X-ray, optical, and infrared follow-up observations of GRB 980703. We detect a previously unknown X-ray source in the GRB error box; assuming a power-law decline, we find for its decay index α 1.3 × 1017 Hz. For this epoch we obtain an extinction of AV = 1.50 ± 0.11. From the X-ray data we estimate the optical extinction to be AV = 20.2+12.3-7.3, inconsistent with the former value. Our optical spectra confirm the redshift of z = 0.966. We compare the afterglow of GRB 980703 with that of GRB 970508 and find that the fraction of the energy in the magnetic field, B < 6 × 10-5, is much lower in the case of GRB 980703, as a consequence of the high frequency of the cooling break.

Ionized gas and stellar kinematics of seventeen nearby spiral galaxies

Ionized gas and stellar kinematics have been measured along the major axes of seventeen nearby spiral galaxies of intermediate to late morphological type. We discuss the properties of each sample galaxy, distinguishing between those charac- terized by regular or peculiar kinematics. In most of the observed galaxies, ionized gas rotates more rapidly than stars and has a lower velocity dispersion, as is to be expected if the gas is confined in the disc and supported by rotation while the stars are mostly supported by dynamical pressure. In a few objects, gas and stars show almost the same rotational velocity and low veloc- ity dispersion, suggesting that their motion is dominated by rotation. Incorporating the spiral galaxies studied by Bertola et al. (1996), Corsini et al. (1999, 2003) and Vega Beltran et al. (2001) we have compiled a sample of 50 S0/a−Scd galaxies, for which the major-axis kinematics of the ionized gas and stars have been obtained with the same spatial (≈1 �� ) and spectral (≈50 km s −1 ) resolution, and measured with the same analysis techniques. This allowed us to address the frequency of counter-rotation in spiral galaxies. It turns out that less than 12% and less than 8% (at the 95% confidence level) of the sample galaxies host a counter-rotating gaseous and stellar disc, respectively. The comparison with S0 galaxies suggests that the retrograde acquisition of small amounts of external gas gives rise to counter-rotating gaseous discs only in gas-poor S0s, while in gas-rich spirals the newly acquired gas is swept away by the pre-existing gas. Counter-rotating gaseous and stellar discs in spirals are formed only from the retrograde acquisition of large amounts of gas exceeding that of pre-existing gas, and subsequent star formation, respectively.

Upper Limits on the Masses of 105 Supermassive Black Holes from Hubble Space Telescope/Space Telescope Imaging Spectrograph Archival Data

A method for the preparation of 1,3-diketones is disclosed wherein the method comprises the steps of:(A) mixing an alkali metal base with a hindered alcohol in an aromatic hydrocarbon solvent;(B) boiling the mixture and azeotropically distilling water formed by the reaction between the base and the alcohol, whereby a solution of a hindered alkali metal alkoxide is formed in situ in the solvent;(C) mixing an ester with the solution of the hindered alkali metal alkoxide in the aromatic hydrocarbon solvent; and then(D) adding a ketone to the mixture.

Stellar Populations of Bulges in 14 Cluster Disc Galaxies

Photometry and long-slit spectroscopy are presented for 14 S0 and spiral galaxies of the Fornax, Eridanus and Pegasus cluster, and NGC 7582 group. The structural parameters of the galaxies are derived from the R-band images by performing a two-dimensional photometric decomposition of the surface brightness distribution. This is assumed to be the sum of the contribution of a bulge and disc component characterized by elliptical and concentric isophotes with constant (but possibly different) ellipticity and position angles. The rotation curves and velocity dispersion profiles are measured from the spectra obtained along the major axis of galaxies. The radial profiles of the Hβ, Mg and Fe line-strength indices are presented too. Correlations between the central values of Mg2, � Fe� ,H β and σ are found. The age, metallicity and α/Fe enhancement of the stellar population in the centre and at the radius where bulge and disc give the same contribution to the total surface brightness are obtained using stellar population models with variable element abundance ratios. Three classes of bulges are identified. The youngest bulges (∼2 Gyr) with ongoing star formation, intermediate-age bulges (4–8 Gyr) have solar metallicity, and old bulges (∼10 Gyr) have high metallicity. Most of the sample bulges display solar α/Fe enhancement, no gradient in age and a negative gradient of metallicity. The presence of negative gradient in the metallicity radial profile favours a scenario with bulge formation via dissipative collapse. This implies strong insideout formation that should give rise to a negative gradient in the α/Fe enhancement too. But, no gradient is measured in the [α/Fe] radial profiles for all the galaxies, except for NGC 1366. In this galaxy there is a kinematically decoupled component, which is younger than the rest of host bulge. It possibly formed by enriched material probably acquired via interaction or minor merging. The bulge of NGC 1292 is the most reliable pseudo-bulge of our sample. The properties of its stellar population are consistent with a slow build-up within a scenario of secular evolution.

The Effect of Dust Geometry on the Lyα Output of Galaxies

We present the optical spectroscopic follow-up of 31 z = 0.3 Lyα emitters, previously identified by Deharveng et al. We find that 17% of the Lyα emitters have line ratios that require the hard ionizing continuum produced by an active galactic nucleus. The uniform dust screen geometry traditionally used in studies similar to ours is not able to simultaneously reproduce the observed high Lyα/Hα and Hα/Hβ line ratios. We consider different possibilities for the geometry of the dust around the emitting sources. We find that also a uniform mixture of sources and dust does not reproduce the observed line ratios. Instead, these are well reproduced by a clumpy dust screen. This more realistic treatment of the geometry results in extinction corrected (Lyα/Hα) C values consistent with case B recombination theory, whereas a uniform dust screen model would imply values (Lyα/Hα) C higher than 8.7. Our analysis shows that there is no need to invoke ad hoc multiphase media in which the Lyα photons only scatter between the dusty clouds and eventually escape

THE HIGH-MASS END OF THE BLACK HOLE MASS FUNCTION: MASS ESTIMATES IN BRIGHTEST CLUSTER GALAXIES*

We present Hubble Space Telescope imaging and spectroscopic observations of three Brightest Cluster Galaxies, Abell 1836-BCG, Abell 2052-BCG, and Abell 3565-BCG, obtained with the Wide Field and Planetary Camera 2, the Advanced Camera for Surveys and the Space Telescope Imaging Spectrograph. The data provide detailed information on the structure and mass profile of the stellar component, the dust optical depth, and the spatial distribution and kinematics of the ionized gas within the innermost region of each galaxy. Dynamical models, which account for the observed stellar mass profile and include the contribution of a central supermassive black hole (SBH), are constructed to reproduce the kinematics derived from the H? and [N II]??6548,6583 emission lines. Secure SBH detection with M ? = 3.61+0.41 ?0.50 ? 109 M ? and M ? = 1.34+0.21 ?0.19 ? 109 M ?, respectively, are obtained for Abell 1836-BCG and Abell 3565-BCG, which show regular rotation curves and strong central velocity gradients. In the case of Abell 2052-BCG, the lack of an orderly rotational motion prevents a secure determination, although an upper limit of M ? 4.60 ? 109 M ? can be placed on the mass of the central SBH. These measurements represent an important step forward in the characterization of the high-mass end of the SBH mass function.

Dark Matter Halos in Elliptical Galaxies

Values of the M/L B ratio in the inner regions of elliptical (E) galaxies are determined using ionized gas disks as tracers of the triaxial potential. These data, when combined with those provided by the H I disks extending to the outer regions, show that the variation of M/L B with galactocentric radius in Es is similar to that of spirals. In particular, it is found that in spirals and Es of the same visible mass the radius where the density of the dark matter equals that of the visible matter occurs at the same distance in units of r e , namely at 1.2r e . This suggests a similar picture of baryonic collapse into a preexisting DM halo for both Es and spirals

Performance report on FEROS, the new fiber-linked echelle spectrograph at the ESO 1.52-m telescope

FEROS is a new fiber-fed bench-mounted prism-cross dispersed echelle spectrograph which has been recently commissioned at the ESO 1.52-m telescope at La Silla. The opto-mechanical concept and performance predictions have been presented by Kaufer and Pasquini. In this contribution we present the test results as obtained during two commissioning runs in October and December 1998. Special emphasis is given to the measured performance sin efficiency, spectral resolution, straylight contamination, and spectral stability. The definite highlight of the FEROS instrument performance is the high peak detection quantum efficiency of 17 percent at 550nm. These measured numbers include the 20mirror telescope, the fiber link, the instrument, and the detector while the whole wavelength range is covered by a single exposure on a thinned EEV 2k by 4k 15 micron pixel CCD and a constant resolving power of R equals 48.000. In addition the FEROS instrument proved its high spectral stability by radial-velocity observations as carried out on the known radial-velocity standard star (tau) Ceti over a time base of 2 months. By recording a calibration-lamp spectrum in parallel with the object spectrum and by the use of a simple cross-correlation technique, a rms of 21 m/s has been obtained for a data set of 130 individual measurements. FEROS has ben made available to the ESO community in January 1999.