Publications (86)
Exoplanetary searches with gravitational microlensing: polarization issues
A. F. Zakharov, G. Ingrosso, F. De Paolis +4
There are different methods for finding exoplanets such as radial spectral shifts, astrometrical measurements, transits, timing etc. Gravitational microlensing (including pixel-len…
Microlensing towards the Large Magellanic Cloud
Ph. Jetzer, L. Mancini, G. Scarpetta
The nature and the location of the lenses discovered in the microlensing surveys done so far towards the LMC remain unclear. Motivated by these questions we compute the optical dep…
Halo dark clusters of brown dwarfs and molecular clouds
F. De Paolis, G. Ingrosso, Ph. Jetzer +1
The observations of microlensing events in the Large Magellanic Cloud suggest that a sizable fraction (\sim 50%) of the galactic halo is in the form of MACHOs (Massive Astrophysica…
Pixel-lensing as a way to detect extrasolar planets in M31
G. Ingrosso, S. Calchi Novati, F. De Paolis +3
We study the possibility to detect extrasolar planets in M31 through pixel-lensing observations. Using a Monte Carlo approach, we select the physical parameters of the binary lens…
The POINT-AGAPE Survey I: The Variable Stars in M31
Jin H. An, N. W. Evans, P. Hewett +14
The POINT-AGAPE collaboration has been monitoring M31 for three seasons with the Wide Field Camera on the Isaac Newton Telescope. In each season, data are taken for one hour per ni…
Thermal equilibrium of cold clouds in PKS 0745-191
L. Grenacher, Ph. Jetzer, D. Puy
PKS 0745-191 is a powerful radio source with one of the largest known cooling flows (De Grandi, Molendi 1999). A fraction of the cool gas could accumulate into small molecular clou…
Merging Processes and SZ Effect
P. M. Koch, Ph. Jetzer
Recent observations reveal detailed structures of mergers in galaxy clusters. Moving cold fronts could be identified as remnants of subclusters. They are believed to mark the late…
Microlensing towards the SMC: a new analysis of OGLE and EROS results
S. Calchi Novati, S. Mirzoyan, Ph. Jetzer +1
We present a new analysis of the results of the EROS-2, OGLE-II, and OGLE-III microlensing campaigns towards the Small Magellanic Cloud (SMC). Through a statistical analysis we add…
Gravitational waves from intermediate-mass black holes in young clusters
M. Mapelli, C. Huwyler, L. Mayer +2
Massive young clusters (YCs) are expected to host intermediate-mass black holes (IMBHs) born via runaway collapse. These IMBHs are likely in binaries and can undergo mergers with o…
Dark matter vs. modifications of the gravitational inverse-square law. Results from planetary motion in the solar system
M. Sereno, Ph. Jetzer
Dark matter or modifications of the Newtonian inverse-square law in the solar-system are studied with accurate planetary astrometric data. From extra-perihelion precession and poss…
Microlensing search towards M31
S. Calchi Novati, G. Iovane, A. A. Marino +26
We present the first results of the analysis of data collected during the 1998-99 observational campaign at the 1.3 meter McGraw-Hill Telescope, towards the Andromeda galaxy (M31),…
Microlensing results and the galactic models
F. De Paolis, Ph. Jetzer, G. Ingrosso
Microlensing results towards the LMC strongly depend on the properties of both the luminous and the dark matter distribution in the Galaxy. The two main sources of uncertainty come…
Stellar mass-to-light ratio gradients in galaxies: correlations with mass
C. Tortora, N. R. Napolitano, A. J. Romanowsky +3
We analyze the stellar mass-to-light ratio (M/L) gradients in a large sample of local galaxies taken from the Sloan Digital Sky Survey, spanning a wide range of stellar masses and…
Probing MACHOs by observation of M31 pixel lensing with the 1.5m Loiano telescope
S. Calchi Novati, G. Covone, F. De Paolis +9
We analyse a series of pilot observations in order to study microlensing of (unresolved) stars in M31 with the 1.5m Loiano telescope, including observations on both identified vari…
Triangulum galaxy viewed by Planck
F. De Paolis, V. G. Gurzadyan, A. A. Nucita +9
We used Planck data to study the M33 galaxy and find a substantial temperature asymmetry with respect to its minor axis projected onto the sky plane. This temperature asymmetry cor…
Halo dark clusters of brown dwarfs and molecular clouds
F. De Paolis, G. Ingrosso, Ph. Jetzer +1
The discovery of Massive Astrophysical Compact Halo Objects (MACHOs) in microlensing experiments makes it compelling to understand their physical nature, as well as their formation…
Microlensing by Compact Objects associated to Gas Clouds
V. Bozza, Ph. Jetzer, L. Mancini +1
We investigate gravitational microlensing of point-like lenses surrounded by diffuse gas clouds. Besides gravitational bending, one must also consider refraction and absorption phe…
The POINT-AGAPE survey II: An Unrestricted Search for Microlensing Events towards M31
V. Belokurov, J. An, N. W. Evans +16
An automated search is carried out for microlensing events using a catalogue of 44554 variable superpixel lightcurves derived from our three-year monitoring program of M31. Each st…
Planck's confirmation of the M31 disk and halo rotation
F. De Paolis, V. G. Gurzadyan, A. A. Nucita +8
Planck's data acquired during the first 15.4 months of observations towards both the disk and halo of the M31 galaxy are analyzed. We confirm the existence of a temperature asymmet…
Classical novae from the POINT-AGAPE microlensing survey of M31 -- I. The nova catalogue
M. J. Darnley, M. F. Bode, E. Kerins +16
The POINT-AGAPE survey is an optical search for gravitational microlensing events towards the Andromeda Galaxy (M31). As well as microlensing, the survey is sensitive to many diffe…
The first confirmed microlens in a globular cluster
P. Pietrukowicz, D. Minniti, Ph. Jetzer +2
In 2000 July/August a microlensing event occurred at a distance of 2.33 arcmin from the center of the globular cluster M22 (NGC6656), observed against the dense stellar field of th…
Classical novae from the POINT-AGAPE microlensing survey of M31 -- II. Rate and statistical characteristics of the nova population
M. J. Darnley, M. F. Bode, E. Kerins +17
We report the results of our statistical study of the POINT-AGAPE CNe catalogue. The first Sloan and analysis of the MMRD relationship in M31 is performed using the resul…
Gamma ray astronomy and baryonic dark matter
F. De Paolis, G. Ingrosso, Ph. Jetzer +1
Recently, Dixon et al. have re-analyzed the EGRET data, finding a statistically significant diffuse -ray emission from the galactic halo. We show that this emission can natural…
Polarization in microlensing towards the Galactic bulge
G. Ingrosso, S. Calchi Novati, F. De Paolis +4
Gravitational microlensing, when finite size source effects are relevant, provides an unique tool for the study of source star stellar atmospheres through an enhancement of a chara…
Probing the dark matter issue in f(R)-gravity via gravitational lensing
M. Lubini, C. Tortora, J. Näf +2
For a general class of analytic f(R)-gravity theories, we discuss the weak field limit in view of gravitational lensing. Though an additional Yukawa term in the gravitational poten…
MACHOs as brown dwarfs
F. De Paolis, G. Ingrosso, Ph. Jetzer +1
Recent observations of microlensing events in the Large Magellanic Cloud suggest that a sizable fraction of the galactic halo is in the form of Massive Astrophysical Compact Halo O…
On the over-concentration problem of strong lensing clusters
M. Sereno, Ph. Jetzer, M. Lubini
Lambda cold dark matter paradigm predicts that galaxy clusters follow an universal mass density profile and fit a well defined mass-concentration relation, with lensing clusters be…
Local dark matter searches with LISA
M. Cerdonio, R. De Pietri, Ph. Jetzer +1
The drag-free satellites of LISA will maintain the test masses in geodesic motion over many years with residual accelerations at unprecedented small levels and time delay interfero…
Rotating baryonic dark halos
F. De Paolis, A. V. Gurzadyan, A. A. Nucita +8
Galactic halos are of great importance for our understanding of both the dark matter nature and primordial non-Gaussianity in the perturbation spectrum, a powerful discriminant of…
Cosmological Parameter Determination in Free-Form Strong Gravitational Lens Modeling
M. Lubini, M. Sereno, J. Coles +2
We develop a novel statistical strong lensing approach to probe the cosmological parameters by exploiting multiple redshift image systems behind galaxies or galaxy clusters. The me…
A case for a baryonic dark halo
F. De Paolis, G. Ingrosso, Ph. Jetzer +1
Recent observations of microlensing events in the Large Magellanic Cloud by the MACHO and EROS collaborations suggest that an important fraction of the galactic halo is in the form…
Color and stellar population gradients in galaxies. Correlation with mass
C. Tortora, N. R. Napolitano, V. F. Cardone +3
We analyze the color gradients (CGs) of ~50000 nearby SDSS galaxies. From synthetic spectral models based on a simplified star formation recipe, we derive the mean spectral propert…
The influence of magnetic fields on the Sunyaev Zel'dovich effect in clusters of galaxies
P. M. Koch, Ph. Jetzer, D. Puy
We study the influence of intracluster large scale magnetic fields on the thermal Sunyaev-Zel'dovich (SZ) effect. In a macroscopic approach we complete the hydrostatic equilibrium…
Asphericity of galaxy clusters and Sunyaev-Zel'dovich effect
D. Puy, L. Grenacher, Ph. Jetzer +1
In this paper we investigate the Sunyaev-Zel'dovich (SZ) effect and the X-ray surface brightness for clusters of galaxies with a non-spherical mass distribution. In particular, we…
Microlensing towards M31 with MDM data
S. Calchi Novati, Ph. Jetzer, G. Scarpetta +4
We report the final analysis of a search for microlensing events in the direction of the Andromeda galaxy, which aimed to probe the MACHO composition of the M31 halo using data col…
Microlensing rates from self-consistent galactic models
F. De Paolis, G. Ingrosso, Ph. Jetzer
We study different models of dark matter distribution for the halo of our galaxy. In particular, we consider Eddington and King-Michie models, which [C[C, which include anisotropy…
Possible detection of the M31 rotation in WMAP data
F. De Paolis, V. G. Gurzadyan, G. Ingrosso +7
Data on the cosmic microwave background (CMB) radiation by the Wilkinson Microwave Anisotropy Probe (WMAP) had a profound impact on the understanding of a variety of physical proce…
Polarization profiles for selected microlensing events towards the galactic bulge
A. A. Nucita, G. Ingrosso, F. De Paolis +4
Gravitational microlensing, in case of relevant finite source size effects, provides an unique tool for the study of stellar atmospheres through the enhancement of a characteristic…
A multi-wavelength strong lensing analysis of baryons and dark matter in the dynamically active cluster AC 114
M. Sereno, M. Lubini, Ph. Jetzer
Strong lensing studies can provide detailed mass maps of the inner regions even in dynamically active galaxy clusters. It is shown that proper modelling of the intracluster medium,…
Achromatic variability in the BL Lac object PKS 2155-304. A case for microlensing?
A. Treves, F. Rovetti, Ph. Jetzer +1
PKS 2155-304 is the only BL Lac object for which well-sampled multiwavelength light curves resolve the intraday variability at UV and X-ray wavelengths. In particular we focus on t…
Binary brown dwarfs in the galactic halo?
F. De Paolis, G. Ingrosso, Ph. Jetzer +1
Microlensing events towards the Large Magellanic Cloud entail that a sizable fraction of dark matter is in the form of MACHOs (Massive Astrophysical Compact Halo Objects), presumab…
Detection of Exoplanets in M31 with Pixel-Lensing: The Event Pa-99-N2 Case
G. Ingrosso, F. De Paolis, S. Calchi Novati +3
We show that exoplanets in the M31 galaxy may be detected with the pixel-lensing method by using telescopes making high cadence observations of an ongoing microlensing event. Altho…
Cooling flow bulk motion corrections to the Sunyaev Zel'dovich effect
P. M. Koch, Ph. Jetzer, D. Puy
We study the influence of converging cooling flow bulk motions on the Sunyaev-Zel'dovich (SZ) effect. To that purpose we derive a modified Kompaneets equation which takes into acco…
Microlensing implications for halo dark matter
F. De Paolis, Ph. Jetzer, G. Ingrosso +1
The observations of microlensing events in the Large Magellanic Cloud suggest that a sizable fraction ( 50%) of the galactic halo is in the form of MACHOs (Massive Astrophysi…
Solar and stellar system tests of the cosmological constant
M. Sereno, Ph. Jetzer
Some tests of gravity theories - periastron shift, geodetic precession, change in mean motion and gravitational redshift - are applied in solar and stellar systems to constrain the…
Microlensing constraints on the Galactic Bulge Initial Mass Function
S. Calchi Novati, F. De Luca, Ph. Jetzer +2
Aims. We seek to probe the Galactic bulge IMF starting from microlensing observations. Methods. We analyse the recent results of the microlensing campaigns carried out towards the…
CMB as a possible new tool to study the dark baryons in galaxies
F. De Paolis, G. Ingrosso, A. A. Nucita +7
Baryons constitute about 4% of our universe, but most of them are missing and we do not know where and in what form they are hidden. This constitute the so-called missing baryon pr…
Baryonic dark matter
F. De Paolis, G. Ingrosso, Ph. Jetzer +1
Reasons supporting the idea that most of the dark matter in galaxies and clusters of galaxies is baryonic is discussed. Moreover it is argued that most of the dark matter in galact…
A Scenario for a Baryonic Dark Halo
F. DePaolis, G. Ingrosso, Ph. Jetzer +1
The recent observations of microlensing events in the LMC by the MACHO and EROS collaborations suggest that an important fraction of the galactic halo is in the form of Massive Hal…
Planck view of the M82 galaxy
V. G. Gurzadyan, F. De Paolis, A. A. Nucita +8
Planck data towards the galaxy M82 are analyzed in the 70, 100 and 143 GHz bands. A substantial north-south and East-West temperature asymmetry is found, extending up to 1 degree f…
Microlensing towards LMC: a study of the LMC halo contribution
S. Calchi Novati, F. De Luca, Ph. Jetzer +1
We carry on a new analysis of the sample of MACHO microlensing candidates towards the LMC. Our main purpose is to determine the lens population to which the events may belong. We g…
X-ray emission from dark clusters of MACHOs
F. De Paolis, G. Ingrosso, Ph. Jetzer +1
MACHOs (Massive Astrophysical Compact Halo Objects) - as discovered by microlensing experiments towards the LMC - provide a natural explanation for the galactic halo dark matter. A…
Cosmography with strong lensing of LISA gravitational wave sources
M. Sereno, Ph. Jetzer, A. Sesana +1
LISA might detect gravitational waves from mergers of massive black hole binaries strongly lensed by intervening galaxies (Sereno et al. 2010). The detection of multiple gravitatio…
Planck revealed bulk motion of Centaurus A lobes
F. De Paolis, V. G. Gurzadyan, A. A. Nucita +8
Planck data towards the active galaxy Centaurus A are analyzed in the 70, 100 and 143 GHz bands. We find a temperature asymmetry of the northern radio lobe with respect to the sout…
Strong lensing of gravitational waves as seen by LISA
M. Sereno, A. Sesana, A. Bleuler +3
We discuss strong gravitational lensing of gravitational waves from merging of massive black hole binaries in the context of the LISA mission. Detection of multiple events would pr…
Morphology of Galaxy Clusters and Sunyaev-Zel'dovich effect
Ph. Jetzer, P. Koch, R. Piffaretti +2
Observations of the X-ray band wavelength reveal an evident ellipticity of many galaxy clusters atmospheres. The modeling of the intracluster gas with an ellipsoidal -model lea…
LMC Self-lensing from a new perspective
L. Mancini, S. Calchi Novati, Ph. Jetzer +1
We present a new analysis on the issue of the location of the observed microlensing events in direction of the Large Magellanic Cloud (LMC). This is carried out starting from a rec…
Messier 81's Planck view vs its halo mapping
V. G. Gurzadyan, F. De Paolis, A. A. Nucita +8
This paper is a follow-up of a previous paper about the M82 galaxy and its halo based on Planck observations. As in the case of M82, so also for the M81 galaxy a substantial North-…
Sunyaev-Zel'dovich Effect and Morphology of Galaxy Clusters
R. Piffaretti, Ph. Jetzer, D. Puy +1
We investigate the influence of the finite extension and the aspherical geometry of a galaxy cluster on the estimate of the Hubble constant through the Sunyaev-Zel'dovich effect. A…
MOND and IMF variations in early-type galaxies from
C. Tortora, A. J. Romanowsky, V. F. Cardone +2
MOdified Newtonian dynamics (MOND) represents a phenomenological alternative to dark matter (DM) for the missing mass problem in galaxies and clusters of galaxies. We analyze the c…
Baryonic Dark Matter
F. De Paolis, Ph. Jetzer, G. Ingrosso +1
Reasons supporting the idea that most of the dark matter in galaxies and clusters of galaxies is baryonic are discussed. Moreover, it is argued that most of the dark matter in gala…
Molecular clouds in cooling flow cluster of galaxies
L. Grenacher, Ph. Jetzer, D. Puy
In many clusters of galaxies there is evidence for cooling flow in the central regions. A possibility is that a fraction of the gas forms cold molecular clouds. We investigate the…
POINT-AGAPE Pixel Lensing Survey of M31 : Evidence for a MACHO contribution to Galactic Halos
S. Calchi Novati, S. Paulin-Henriksson, J. An +15
The POINT-AGAPE collaboration is carrying out a search for gravitational microlensing toward M31 to reveal galactic dark matter in the form of MACHOs (Massive Astrophysical Compact…
Two-body problem with the cosmological constant and observational constraints
Ph. Jetzer, M. Sereno
We discuss the influence of the cosmological constant on the gravitational equations of motion of bodies with arbitrary masses and eventually solve the two-body problem. Observatio…
Gravitational microlensing and dark matter in the galactic halo
Ph. Jetzer
We present the basics of microlensing and give an overview of the results obtained so far. We also describe a scenario in which dark clusters of MACHOs (Massive Astrophysical Compa…
Monte Carlo analysis of the MEGA microlensing events towards M31
G. Ingrosso, S. Calchi-Novati, F. De Paolis +3
We perform an analytical study and a Monte Carlo (MC) analysis of the main features for microlensing events in pixel lensing observations towards M31. Our main aim is to investigat…
On the mass of the gravitational lenses in LMC
L. Mancini, S. Calchi Novati, Ph. Jetzer +1
In the self--lensing framework, we estimate the modal values of the mass of the gravitational lenses found by the MACHO collaboration towards the Large Magellanic Cloud (LMC). Our…
Is the galactic halo baryonic?
F. De Paolis, G. Ingrosso, Ph. Jetzer +1
Recent observations of microlensing events in the Large Magellanic Cloud suggest that a sizeable fraction of the galactic halo is in form of MACHOs with mass less than abou 0.1 M_{…
H2 molecules and cold clouds in cooling flow clusters
L. Grenacher, Ph. Jetzer, D. Puy
We investigated the cooling mechanism due to H2 and HD molecules in order to determine the minimum temperature achievable by cold H2-HD clouds in cooling flow clusters.
MACHOs and molecular clouds in galactic halos
F. De Paolis, G. Ingrosso, Ph. Jetzer +1
Recent observations of microlensing events in the Large Magellanic Cloud by the MACHO and EROS collaborations suggest that an important fraction of the galactic halo is in form of…
Messier 90 galactic halo rotation in the microwaves
F. De Paolis, V. G. Gurzadyan, A. L. Kashin +4
We used Planck data to study the Virgo Cluster's galaxy M 90 and its surroundings. We find, as in the case of certain galaxies of the Local Group and its vicinity, a substantial te…
Evolution of gravitational orbits in the expanding universe
M. Sereno, Ph. Jetzer
The gravitational action of the smooth energy-matter components filling in the universe can affect the orbit of a planetary system. Changes are related to the acceleration of the c…
Gamma ray emission from a baryonic dark halo
F. De Paolis, G. Ingrosso, Ph. Jetzer +1
A recent re-analysis of EGRET data by Dixon et al. has led to the discovery of a statistically significant diffuse -ray emission from the galactic halo. We show that this emiss…
Candidate microlensing events from M31 observations with the Loiano telescope
S. Calchi Novati, V. Bozza, F. De Paolis +9
Microlensing observations towards M31 are a powerful tool for the study of the dark matter population in the form of MACHOs both in the Galaxy and the M31 halos, a still unresolved…
Cold clouds in cooling flows
L. Grenacher, Ph. Jetzer, D. Puy
In many clusters of galaxies there is evidence for cooling flows which deposit large quantities of cool gas in the central regions. A fraction of this gas might accumulate as dense…
Shape and geometry of galaxy clusters and the SZ effect
L. Grenacher, R. Piffaretti, D. Puy +2
We discuss the influence of the finite extension and the geometry of clusters of galaxies, as well as of the polytropic temperature profile, on the determination of the Hubble cons…
M31 pixel lensing event OAB-N2: a study of the lens proper motion
S. Calchi Novati, M. Dall'Ora, A. Gould +12
We present an updated analysis of the M31 pixel lensing candidate event OAB-N2 previously reported in Calchi Novati et al. (2009). Here we take advantage of new data both astrometr…
Observing molecular hydrogen clouds and dark massive objects in galactic halos
F. De Paolis, G. Ingrosso, Ph. Jetzer +2
Molecular hydrogen clouds can contribute substantially to the galactic halo< dark matter and may lead to the birth of massive halo objects (MHOs) observed indirectly by microlensin…
Central dark matter trends in early-type galaxies from strong lensing, dynamics and stellar populations
C. Tortora, N. R. Napolitano, A. J. Romanowsky +1
We analyze the correlations between central dark matter (DM) content of early-type galaxies and their sizes and ages, using a sample of intermediate-redshift (z ~ 0.2) gravitationa…
A new analysis of the MEGA M31 microlensing events
G. Ingrosso, S. Calchi-Novati, F. De Paolis +4
We discuss the results of the MEGA microlensing campaign towards M31. Our analysis is based on an analytical evaluation of the microlensing rate, taking into account the observatio…
M31 Pixel Lensing PLAN Campaign: MACHO Lensing and Self Lensing Signals
S. Calchi Novati, V. Bozza, I. Bruni +14
We present the final analysis of the observational campaign carried out by the PLAN (Pixel Lensing Andromeda) collaboration to detect a dark matter signal in form of MACHOs through…
Search for exoplanets in M31 with pixel-lensing and the PA-99-N2 event revisited
G. Ingrosso, S. Calchi-Novati, F. De Paolis +3
Several exoplanets have been detected towards the Galactic bulge with the microlensing technique. We show that exoplanets in M31 may also be detected with the pixel-lensing method,…
Measuring Polarization in microlensing events
G. Ingrosso, S. Calchi Novati, F. De Paolis +3
We re-consider the polarization of the star light that may arise during microlensing events due to the high gradient of magnification across the atmosphere of the source star, by e…
Dark Matter in the Dwarf Galaxy NGC 247
M. Straessle, M. Huser, Ph. Jetzer +1
Dwarf galaxies are dominated by dark matter even in the innermost regions and, therefore, provide excellent probes for the investigation of dark halos. To that purpose, we analyse…
Polarization in binary microlensing events
G. Ingrosso, F. De Paolis, A. A. Nucita +5
The light received by source stars in microlensing events may be significantly polarized if both an efficient photon scattering mechanism is active in the source stellar atmosphere…
On the Mass of the Dark Compact Objects in the Galactic Disk
Ph. Jetzer
Recently the Polish-American collaboration OGLE has reported the observation of four possible microlensing events by monitoring, over several months, the brightness of millions of…