arXiv subjects

Silvano Tosi

Publications and source records attributed to Silvano Tosi.

10 recordsLinked to original sources

arXiv2026

BL Lac host galaxies: how to systematically characterise them in optical-NIR spectroscopy

Host galaxies of Active Galactic Nuclei give crucial information on the interaction between accreting Supermassive Black Holes and their surroundings, and on their common evolution. Their study in the case of aligned jetted AGN - BL Lacertae objects in particular - is complicated by the non-thermal jet component, whose bright and multi-frequency emission easily dominates over the whole electromagnetic spectrum. BL Lac host galaxies have thus been sparsely studied, and their elliptical nature is currently a hypothesis supported by few observations. With the broad aim of a systematic analysis of these sources, and in light of the many optical and NIR spectroscopic facilities that are now available, we implement an easily applicable method to determine whether a BL Lac is hosted in an elliptical or spiral galaxy. Building on the only systematic study currently available on BL Lac hosts, we worked on a sample of realistic BL Lac synthetic spectra. We analysed them and characterized their statistics using QSFit, a publicly available spectroscopy software. If BL Lac host galaxies were both elliptical and spiral, our method would be able to discriminate between them, provided that BL Lac jets are fainter than $L_γ\sim10^{46}$erg/s. Just two runs of QSFit for each BL Lac spectrum would return a single parameter, that would allow for a first broad distinction between the two classes. We finally discuss the two galaxy types that introduce some uncertainty in their classification, that might lead to possible classification biases.

astro-ph.HE↗

arXiv2025

Probing the geological setting of exoplanets through atmospheric analysis: using Mars as a test case

One of the frontier research fields of exoplanetary science is the study of the composition and variability of exoplanetary atmospheres. This field is now moving from the gas giant planets towards the smaller and colder telluric planets, and future instruments like ANDES will focus on the observations of the atmosphere of telluric planets in the habitable zone in reflected light. These future observations will possibly find variable signals due to the view of different hemispheres of the planet. Particularly, the strength of the signal may be linked to the thickness of the atmospheric layer probed, and therefore to the average altitude variations of the planetary surface, that are related to the global geodynamic evolution of the planet. To better prepare for the interpretation and exploitation of these future data, we used Mars as a Solar System analog of a spatially resolved telluric exoplanet. We observed the reflected light of Mars with the high-resolution near-infrared (NIR) spectrograph GIANO-B (widely used in exoplanetary atmospheric studies) during a 3 month period: we studied the spatial and temporal variations of the Martian CO2 signal using the least-squared deconvolution technique (LSD), to mimic as closely as possible the standard exoplanetary atmospheric analysis. We linked the variations found to the well-known Martian geological surface characteristics: we found a clear dependence of the strength of the CO2 signal with the thickness of the Martian atmospheric layer by comparing the retrieved CO2 signal with the altitudes of our pointings. The proposed strategy is promising: it proved to be effective on Mars and may shed light on the variations in the strength of atmospheric signal of telluric exoplanets.

astro-ph.EP↗

arXiv2025

Toward the remotization and robotization of the OARPAF telescope

OARPAF (Osservatorio Astronomico Regionale Parco Antola Comune di Fascia, Italy) hosts an 80cm Astelco telescope with a Gambato Dome, SBIG-STX camera, Davis weather station, and SBIG AllSky camera. We present a layer-structured python3 framework to control these devices. Layer 1 provides straightforward getter/setter interface for "atomic" operations on devices. Layer 2 wraps the above mentioned atomic operations into "ESO-style" Templates, to perform sequences of common pointing, observation, and calibration operations called "Observation Blocks" (OBs) that are run by a sequencer. Layer 3 is a REST API based on HTTP verbs to expose methods that control Layer 1 devices and Layer 2. We also present a web interface built on top of this layer. The work is part of the frame for remoting and robotizing the observatory.

astro-ph.IM↗

arXiv2025

Easy remote observations using web interfaces: controlling an Italian telescope from Japan, and more

Remote observations are often limited by user interfaces, which seem frozen to another computer era: low performances, outdated programming languages, command-line scripting, high version-dependent software. Instead, web-based tools are standard: using nothing more than a browser, astronomers can interact with a generic observatory in a native cross-platform, remote-born way. We used this approach while advancing in the remotization of the 1m-class OARPAF telescope, located in Northern Italy. The web-based control software provides easy and integrated management of its components. This solution can be exported not only to similar hardware/software facilities, but also to large instruments such as SHARK-NIR at LBT; not only for single operations, but also for procedure scripting. In this contribution we describe our best practices and present two recent, orthogonal use cases: an in-place professional use for exoplanetary transit follow-ups, and the first remote control of the telescope from a Japanese high school, allowing students to independently observe, in their daytime, globular clusters

astro-ph.IM↗

arXiv2021

Commissioning and improvements of the instrumentation and launch of the scientific exploitation of OARPAF, the Regional Astronomical Observatory of the Antola Park

The \oarpaf telescope is an $80\rm cm$-diameter optical telescope installed in the Antola Mount Regional Reserve, in Northern Italy. This work presents the results of the characterization of the site, as well as developments and interventions that have been implemented, with the goal of exploiting the facility for scientific and educational purposes. During the characterization of the site, an average background brightness of $22.40 \, m_{AB}$ ($B$ filter) -- $21.14 \, m_{AB}$ ($I$) per arcsecond squared, and a $1.5$--$3.0"$ seeing, have been measured. An estimate of the magnitude zero points for photometry is also reported. The material under commissioning includes 3 CCD detectors for which we provide the linearity range, gain, and dark current; a 31 orders échelle Northern Italy. This work presents the results of the characterization of the site, as well as developments andspectrograph with $R\sim 8500$--$15000$, and a dispersion of $n = 1.39\times 10^{-6}\rm px^{-1}λ+ 1.45\times 10^{-4}\rm nm/px$, where $λ$ is expressed in $\rm nm$. The scientific and outreach potential of the facility is proven in different science cases, such as exoplanetary transits and active galactic nuclei variability. The determination of time delays of gravitationally lensed quasars, the microlensing phenomenon and the tracking and the study of asteroids are also discussed as prospective science cases.

astro-ph.IM↗

arXiv2020

Cerberus: A three-headed instrument for the OARPAF telescope

We present the preliminary design of Cerberus, a new scientific instrument for the alt-az, 80cm OARPAF telescope in the Ligurian mountains above Genoa, Italy. Cerberus will provide three focal stations at the Nasmyth focus, allowing: imaging and photometry with standard Johnson-Cousins UBVRI+Ha+Free filters, an on-axis guiding camera, and a tip-tilt lens for image stabilization up to 10Hz; long slit spectroscopy at R 5900 thanks to a LHIRES III spectrograph provided with a 1200l/mm grism; échelle spectroscopy at R 9300 using a FLECHAS spectrograph with optical fiber.

astro-ph.IM↗

arXiv2018

Analysis of the angular dependence of time delay in gravitational lensing

We consider an alternative formula for time delay in gravitational lensing. Imposing a smoothness condition on the gravitationally deformed paths followed by the photons from the source to the observer, we show that our formula displays the same degrees of freedom as the standard one. In addition to this, it is shown that the standard expression for time delay is recovered when small angles are involved. These two features strongly support the claim that the formula for time delay studied in this paper is the generalization to the arbitrary angles of the standard one, which is valid at small angles. This could therefore result in a useful tool in Astrophysics and Cosmology which may be applied to investigate the discrepancy between the various estimates of the Hubble constant. As an aside, two interesting consequences of our proposal for time delay are discussed: the existence of a constraint on the gravitational potential generated by the lens and a formula for the mass of the lens in the case of central potential.

astro-ph.CO↗

arXiv2017

Multi-filter transit observations of HAT-P-3b and TrES-3b with multiple Northern Hemisphere telescopes

We present a photometric follow-up of transiting exoplanets HAT-P-3b and TrES-3b, observed by using several optical and near-infrared filters, with four small-class telescopes (D = 36--152cm) in the Northern Hemisphere. Two of the facilities present their first scientific results. New 10 HAT-P-3b light curves and new 26 TrES-3b light curves are reduced and combined by filter in order to improve the quality of the photometry. Combined light curves fitting is carried out independently by using two different analysis packages, allowing the corroboration of the orbital and physical parameters in the literature. Results find no differences in the relative radius with the observing filter. In particular, we report for HAT-P-3b a first estimation of the planet-to-star radius Rp/R* = 0.1112+0.0025-0.0026 in the B band which is coherent with values found in the VRIz'JH filters. Concerning TrES-3b, we derive a value for the orbital period of P = 1.3061862+-0.0000001 days which shows no linear variations over nine years of photometric observations.

astro-ph.EP↗

arXiv2011

Four tops on the real projective plane at LHC

We explore the four top signal ttbar ttbar at the 7 TeV Large Hadron Collider as a probe of physics beyond the standard model. Enhancement of the corresponding cross-section with respect to the Standard Model value can probe the electroweak symmetry breaking sector or test extra dimensional models with heavy Kaluza-Klein gluons and quarks. We perform a detailed analysis including background and detector simulation in the specific case of a universal extra-dimensional model with two extra dimensions compactified using the geometry of the real projective plane. For masses around 600 GeV, a discovery is possible for an effective cross section above 210 fb (36 fb) for 1/fb (10/fb) of integrated luminosity. This implies a branching ratio in tops of the (1,1) heavy photon above 13% (5%). Furthermore, the 4-top signal from the (2,0) and (0,2) tiers can be discovered with an integrated luminosity of 3.5/fb. The results of our simulation can be easily adapted to other models since the background processes are identical. Concerning the signal, typical production mechanisms for the ttbar ttbar signal are similar even if cross-section values may vary considerably depending on the model and the spectrum of the new particles.

hep-ph↗

arXiv2011

Results on top-quark physics from the CMS experiment

The most recent results on top-quark physics reported by the CMS experiment at the Large Hadron Collider (LHC) are presented in this talk. The results are based on a data sample of about 36/pb of data collected during 2010 at a pp center-of-mass energy of 7 TeV.

hep-ex↗