Search Publications

Are Nuclear Star Clusters the Precursors of Massive Black Holes?

Neumayer, Nadine; Walcher, C. Jakob

We present new upper limits for black hole masses in extremely late type spiral galaxies. We confirm that this class of galaxies has black holes with masses less than 10^6 Msolar, if any. We also derive new upper limits for nuclear star cluster (NC) masses in massive galaxies with previously determined black hole masses. We use the newly derived u…

The Impact of Polarized Extragalactic Radio Sources on the Detection of CMB Anisotropies in Polarization

Tucci, Marco; Toffolatti, Luigi

Recent polarimetric surveys of extragalactic radio sources (ERS) at frequencies \nu>1GHz are reviewed. By exploiting all the most relevant data on the polarized emission of ERS we study the frequency dependence of polarization properties of ERS between 1.4 and 86GHz. For flat-spectrum sources the median (mean) fractional polarization increases …

Observations of the Polarisation of the Anomalous Microwave Emission: A Review

Rebolo, R.; Rubiño-Martín, J. A.; Génova-Santos, R. +1 more

Do Nuclear Star Clusters and Supermassive Black Holes Follow the Same Host-Galaxy Correlations?

Erwin, Peter; Gadotti, Dimitri Alexei

Studies have suggested that there is a strong correlation between the masses of nuclear star clusters (NSCs) and their host galaxies, a correlation which said to be an extension of the well-known correlations between supermassive black holes (SMBHs) and their host galaxies. But careful analysis of disk galaxies -- including 2D bulge/disk/bar decom…

AGN Triggering in the Infall Regions of Distant X-Ray Luminous Galaxy Clusters at 0.9 < z <~ 1.6

Šuhada, R.; Fassbender, R.; Nastasi, A.

Observational constraints on the average radial distribution profile of AGN in distant galaxy clusters can provide important clues on the triggering mechanisms of AGN activity in dense environments and are essential for a completeness evaluation of cluster selection techniques in the X-ray and mm-wavebands. The aim of this work is a statistical st…

The Low-Mass End of the MBH/Mhost Relation in Quasars

Uslenghi, Michela; Decarli, Roberto; Treves, Aldo +3 more

The Mbh-Mhost relation in quasars has been probed only in a limited parameter space, namely at Mbh~10^9 Msun and Mhost~10^12 Msun. Here we present a study of 26 quasars lying in the low-mass end of the relation, down to Mbh~10^7 Msun. We selected quasars from the SDSS and HST-FOS archives, requiring modest Mbh (as derived through the virial paradi…

M94 as a Unique Testbed for Black Hole Mass Estimates and AGN Activity at Low Luminosities

Seth, Anil C.; Constantin, Anca

We discuss the peculiar nature of the nucleus of M94 (NGC 4736) in the context of new measurements of the broad H_alpha emission from HST-STIS observations. We show that this component is unambiguously associated with the high-resolution X-ray, radio, and variable UV sources detected at the optical nucleus of this galaxy. These multi-wavelength ob…

Preliminary Results on Irradiance Measurements from Lyra and Swap

Berghmans, D.; Kariyappa, R.; Damé, L. +5 more

Rapid Disappearance of Penumbra-Like Features near a Flaring Polarity Inversion Line: The Hinode Observations

Gosain, Sanjay; Ravindra, B.

We present the observations of penumbra like features (PLFs) near a polarity inversion line (PIL) of flaring region. The PIL is located at the moat boundary of active region (NOAA 10960). The PLFs appear similar to sunspot penumbrae in morphology but occupy small area, about 6$\times10^{7}$ km$^{2}$, and are not associated with sunspot or pore. We…

Pulsar-Driven Jets in Supernovae, Gamma-Ray Bursts, and the Universe

Middleditch, John

The bipolarity of Supernova 1987A can be understood through its very early light curve observed from the CTIO 0.4-m telescope and IUE FES, and following speckle observations of the `Mystery Spot' by two groups. These indicate a highly directional beam/jet of light/particles, with initial collimation factors in excess of 10,000 and velocities in ex…