Papers by Michela Uslenghi
Astronomy and Astrophysics, 2001
We report on UBVRI polarimetry of the recently identified Intermediate Polar 1WGA J1958.2+3232, c... more We report on UBVRI polarimetry of the recently identified Intermediate Polar 1WGA J1958.2+3232, carried out on 2000 August, 4-6 at the Nordic Optical Telescope. Circular polarization was detected in R and I bands with an increasing absolute mean value with wavelength. There is evidence of possible modulation of the circular polarization at twice the previously reported white dwarf spin period, suggesting that it is the true period and that the modulation in optical and X-ray is dominated by the first harmonic. Indication of modulation at the orbital period is also present.
Nanostructured Materials for UV>VIS Wavelength Shifting:. a New Method to Improve the QE of Optical Detectors in Nuv
ABSTRACT
AIDA: a software tool for QSO images decomposition
The availability of high-speed data from high-energy satellites (in particular RXTE) allowed inve... more The availability of high-speed data from high-energy satellites (in particular RXTE) allowed investigating phenomena on time scales much faster than those accessible with the CCD, the astronomical detector for the optical range par excellence. That resulted in a rising interest for optical detectors able to perform observations coordinated with X and γ-Ray instruments and with similar time resolution. In this context, we developed a detector based on a Photon Counting Intensified CCD optimized for the optical range, with format 2048 × 2048 pixels and time resolution down to 4.5 ms. The detector has been calibrated at the 182 cm Asiago Cima Ekar telescope. Some results of the observations carried out have been reported in this paper.
METIS, the Multi Element Telescope for Imaging and Spectroscopy, is one of the instruments select... more METIS, the Multi Element Telescope for Imaging and Spectroscopy, is one of the instruments selected in 2009 by ESA to be part of the payload of the Solar Orbiter mission. The instrument design has been conceived to perform both multiband imaging and UV spectroscopy of the solar corona. The two sensors of the detecting system will produce images in visible
This paper reports on the current status of the World Space Observatory WSO-UV, a space mission f... more This paper reports on the current status of the World Space Observatory WSO-UV, a space mission for UV astronomy, planned for launch at the beginning of next decade. It is based on a 1.7 m telescope, with focal plane instruments including high resolution spectrographs, long slit low resolution spectrographs and imaging cameras.
The World Space Observatory (WSO) is a space telescope conceived to observe the universe in the U... more The World Space Observatory (WSO) is a space telescope conceived to observe the universe in the UV. The instrument payload consists of three spectrographs and one Field Camera Unit (FCU) composed by three cameras for UV and visible light imaging. FCU instrument will produce a huge quantity of data to be transferred in a short time to the on board computer. Presently, the proposed satellite interface is the MIL1553B which represents a bottleneck due to its low data rate. In order to avoid very long images transfer time,we are designing a communication interface that uses an hybrid architecture which is capable o f high-speed and reliable data transfer.
<title>VELA: a fast DEPFET readout circuit for the NHXM Mission</title>
Space Telescopes and Instrumentation 2010: Ultraviolet to Gamma Ray, 2010
NHXM, under study by ASI (Agenzia Spaziale Italiana), is an X-ray observatory in the energy band ... more NHXM, under study by ASI (Agenzia Spaziale Italiana), is an X-ray observatory in the energy band between 0.5 and 80 keV and will have 3 telescopes dedicated to X-ray imaging with a field of view diameter of 12 arcmin and a focal length of 10 m. We report on the development of high-speed and low-noise readout of a monolithic array
PKS 2155-304 is one of the brightest BL Lac object in the sky and a very well studied target from... more PKS 2155-304 is one of the brightest BL Lac object in the sky and a very well studied target from radio to TeV bands. We report on high-resolution (~ 0.12 arcsec) direct imaging of the field of PKS 2155-304 using adaptive optics near-IR observations in J and Ks bands obtained with the ESO multi-conjugate adaptive optic demonstrator (MAD) at the Very Large Telescope. These data are complemented with archival VLA images at various frequencies to investigate the properties of the close environment of the source. We characterized the faint galaxies that form the poor group associated to the target. No radio emission is present for these galaxies, while an old radio jet at ~ 20 kpc from the nucleus of PKS 2155-304 and a jet-like structure of ~ 2 kpc (~ 1 arcsec) in the eastern direction are revealed. No counterparts of these radio jets are found in the NIR or in archival Chandra observations.
We present first results from our study of the properties of ~400 low redshift (z < 0.5) quasa... more We present first results from our study of the properties of ~400 low redshift (z < 0.5) quasars, based on a large homogeneous dataset derived from the Stripe 82 area of the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7). For this sky region, deep (r~22.4) u,g,r,i,z images are available, up to ~2 mag deeper than standard SDSS images, allowing us to study both the host galaxies and the Mpc-scale environments of the quasars. This sample greatly outnumbers previous studies of low redshift quasar hosts, from the ground or from space. Here we report the preliminary results for the quasar host galaxies. We are able to resolve the host galaxy in ~80 % of the quasars. The quasar hosts are luminous and large, the majority of them in the range between M*-1 and M*-2, and with ~10 kpc galaxy scale-lengths. Almost half of the host galaxies are best fit with an exponential disk, while the rest are spheroid-dominated. There is a reasonable relation between the central black hole mass and ...
We present a photometrical and morphological study of the properties of low redshift (z < 0.5)... more We present a photometrical and morphological study of the properties of low redshift (z < 0.5) quasars based on a large and homogeneous dataset of objects derived from the Sloan Digital Sky Survey (DR7). This study over number by a factor about 5 any other previous study of QSO host galaxies at low redshift undertaken either on ground or on space surveys. We used about 400 quasars that were imaged in the SDSS Stripe82 that is up to 2 mag deeper than standard Sloan images. For these quasars we undertake a study of the host galaxies and of their environments. In this paper we report the results for the quasar hosts. We are able to detect the host galaxy for more than 3/4 of the whole dataset and characterise the properties of their hosts. We found that QSO hosts are dominated by luminous galaxies of absolute magnitude M*-3 < M(R) < M*. For the unresolved objects we computed a upper limit to the host luminosity. For each well resolved quasar we are also able to characterise th...
Modelling and Simulation in Science - Proceedings of the 6th International Workshop on Data Analysis in Astronomy ≪Livio Scarsi≫, 2007
Monthly Notices of the Royal Astronomical Society
Recently, the relation between the masses of the black hole ($M_{BH}$) and the host galaxy ($M_{h... more Recently, the relation between the masses of the black hole ($M_{BH}$) and the host galaxy ($M_{host}$) in quasars has been probed down to the parameter space of $M_{BH}\sim10^8 M_\odot$ and $M_{host}\sim10^{11} M_\odot$ at z $<$ 0.5. In this study, we have investigated the $M_{BH}$ - $M_{host}$ log-linear relation for a sample of 37 quasars with low black hole masses ($10^7 M_\odot < M_{BH} < 10^{8.3} M_\odot$) at 0.5 $<$ z $<$ 1.0. The black hole masses were derived using virial mass estimates from SDSS optical spectra. For 25 quasars, we detected the presence of the host galaxy from deep near-infrared H-band imaging, whereas upper limits for the host galaxy luminosity (mass) were estimated for the 12 unresolved quasars. We combined our previous studies with the results from this work to create a sample of 89 quasars at z $<$ 1.0 having a large range of black hole masses ($10^7 M_\odot < M_{BH} < 10^{10} M_\odot$) and host galaxy masses ($10^{10} M_\odot &l...
Performance evaluation of a photon-counting intensified CCD
Proceedings of SPIE, 1997
The performance of a prototype photon counting imaging detector, being developed for the internat... more The performance of a prototype photon counting imaging detector, being developed for the international UV space mission spectrum-UV, is presented. The detector is based on a 4-cm diameter, Z stack, high gain microchannel plate (MCP) intensifier endowed with a RbTe photocathode. The electron cascade generated by the MCP intensifier is transduced, via a phosphor screen and a 1:3.6 fiber optics
Hardware and software architecture on board solar orbiter/METIS: an update
Space Telescopes and Instrumentation 2014: Ultraviolet to Gamma Ray, 2014
ABSTRACT For developing advanced query formulation methods for general multimedia data, we descri... more ABSTRACT For developing advanced query formulation methods for general multimedia data, we describe the issues related to video data. We distinguish between the requirements for image retrieval and video retrieval by identifying queryable attributes unique to video data, namely audio, temporal structure, motion, and events. Our approach is based on visual query methods to describe predicates interactively while providing feedback that is as similar as possible to the video data. An initial prototype of our visual query system for video data is presented.
Astronomy and Astrophysics, 2001
We report on UBVRI polarimetry of the recently identified Intermediate Polar 1WGA J1958.2+3232, c... more We report on UBVRI polarimetry of the recently identified Intermediate Polar 1WGA J1958.2+3232, carried out on 2000 August, 4-6 at the Nordic Optical Telescope. Circular polarization was detected in R and I bands with an increasing absolute mean value with wavelength. There is evidence of possible modulation of the circular polarization at twice the previously reported white dwarf spin period, suggesting that it is the true period and that the modulation in optical and X-ray is dominated by the first harmonic. Indication of modulation at the orbital period is also present.
The Astrophysical Journal, 2009
We present near-infrared imaging obtained with ESO VLT/ISAAC of a sample of 16 low luminosity rad... more We present near-infrared imaging obtained with ESO VLT/ISAAC of a sample of 16 low luminosity radio-quiet quasars at the epoch around the peak of the quasar activity (2 < z < 3), aimed at investigating their host galaxies. For 11 quasars, we are able to detect the host galaxies and derive their properties, while for the other five quasars, upper limits to the host luminosity are estimated. The luminosities of the host galaxies of radio-quiet quasars at high redshift are in the range of those of massive inactive elliptical galaxies.
Quasar activity in the neighbor Universe
Proceedings of the International Astronomical Union, 2012
ABSTRACT We investigate the properties of the galaxies hosting quasars in ~400 low redshift (z &a... more ABSTRACT We investigate the properties of the galaxies hosting quasars in ~400 low redshift (z &lt; 0.5) SDSS QSO that are in the “Stripe 82” sky area. For this region deep (r ~ 22.4 mag) u, b, v, r and i images are available and allow us to study both the host galaxies and the Mpc scale environments. This sample outnumbers previous studies of low-z QSOs. We present preliminary results of the properties of quasars activity and in particular we focus on the relationships among host galaxy luminosity, black hole mass, radio emission and the surrounding galaxy environments. We select from the SDSS - QSO Catalogue all the QSOs in the range of redshift 0.1&lt;z&lt;0.5 and in the Stripe82 region. This gives a total of 416 QSO. In this sample we are dominated by radio quiet quasars (about 5% are radio loud). In Fig. 1 we report the distribution of QSO in the plane redshift-MR (H 0 = 70). The mean redshift of the sample is = 0.39 and the average absolute magnitude is: = −22.68. We implemented an automated procedure using AIDA (Uslenghi &amp; Falomo 2011) to decompose the QSO images into nucleus and host galaxy luminosity. After masking of all contaminating sources in the field a 2D fitting is performed using PSF + galaxy model. In Fig. 1 we show an example of a QSO image in the sample and the distribution of the host galaxy absolute magnitude of the resolved objects.
The SOHO mission has achieved important results in the physics of solar wind and coronal mass eje... more The SOHO mission has achieved important results in the physics of solar wind and coronal mass ejection acceleration, but most of the processes that drive this acceleration have not yet been explained. The Advanced Spectroscopic and Coronagraphic Explorer (ASCE) mission will carry on-board spectroscopic and polarimetric instrumentation of new generation that is designed to address the fundamental questions on this processes. Following a brief description of ASCE scientific objectives and instrumentation, the EUV polarimetric channel is described. The EUV Polarimeter (EUVP) is designed to measure for the first time the magnetic field vector in the extended corona through the Hanle effect, and the anisotropy of the ion velocity. The EUVP represents the contribution of the Italian solar physics community to the ASCE mission.
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Papers by Michela Uslenghi