Search Publications
Consistency relation for natural inflation with Planck 2015 data
Nozari, Kourosh; Kahvaee, H.; Rashidi, N.
We consider the cosine Natural inflation model that is a good candidate to explain the initial accelerating phase of the universe. By computing the inflationary parameters in Einstein frame, we construct a consistency relation between the scalar spectral index, tensor-to-scalar ratio, as well as the running of the scalar spectral index and compare…
Twisted Crab fingers revisited
Carlqvist, Per
Narrowband images of the Crab Nebula captured by the Hubble Space Telescope have earlier shown that the nebula does not only present a network of broad, bright filaments crossing the nebula but also numerous so-called fingers mostly pointing inwards. Using archival Hubble images we have in some detail studied the morphology of a great number of su…
WFPC2 UV survey of Galactic globular clusters. The Horizontal Branch temperature distribution
Dalessandro, E.; Salaris, M.; Lagioia, E. P. +2 more
Ultraviolet observations are the best tool to study hot stellar populations which emit most of their light at short wavelengths. As part of a large project devoted to the characterization of the UV properties of Galactic globular clusters (GGCs), we collected mid/far UV and optical images with the WFPC2@HST for 31 GGCs. These clusters cover a wide…
Constraining nonminimal DBI inflation with Planck2015 results
Asadi, Kosar; Nozari, Kourosh; Rashidi, Narges
We study cosmological inflation and perturbations in a nonminimally coupled Dirac-Born-Infeld setup in the light of the recent observational data reported by Planck collaboration. By adopting some important inflationary potentials, we analyze the scalar spectral index and the tensor-to-scalar ratio in confrontation with Planck 2015 data. In this m…
Ultraviolet spectroscopy of V Sagittae in high, intermediate and low states from HST and IUE satellites
Sanad, M. R.
We present the first phase resolved ultraviolet spectroscopic study of V Sge in high, intermediate and low states observed with the Hubble Space Telescope High Resolution Spectrograph (HST HRS) and International Ultraviolet Explorer (IUE) during the period 1978–1996 to diagnose the ultraviolet fluxes of C IV 1550 Å and He II 1640 Å emission lines …
SOUSA: the Swift Optical/Ultraviolet Supernova Archive
Kuin, Paul; Brown, Peter J.; Holland, Stephen +2 more
The Ultra-Violet Optical Telescope on the Swift spacecraft has observed hundreds of supernovae, covering all major types and most subtypes. Here we introduce the Swift Optical/Ultraviolet Supernova Archive (SOUSA), which will contain all of the supernova images and photometry. We describe the observation and reduction procedures and how they impac…
Probing the mass and anisotropy of the Milky Way gaseous halo: sight-lines toward Mrk 421 and PKS 2155-304
Krongold, Y.; Mathur, S.; Gupta, A. +1 more
We recently found that the halo of the Milky Way contains a large reservoir of warm-hot gas that accounts for large fraction of the missing baryons from the Galaxy. The average physical properties of this circumgalactic medium (CGM) are determined by combining average absorption and emission measurements along several extragalactic sightlines. How…
Serendipitous UV source catalogues for 10 years of XMM and 5 years of Swift
Yershov, V. N.
Two UV serendipitous source catalogues are presented which were compiled based on the observations with two similar UV telescopes, one being on-board the ESA's XMM Newton observatory and another—on-board the NASA's Swift satellite. Both telescopes have similar optical and registration systems providing photometry in three ultraviolet and three vis…
The distant galaxy cluster XLSSJ022403.9-041328 on the LX–TX–M scaling relations using Chandra and XMM–Newton observations
Babyk, I.; Vavilova, I.
We present a very detailed analysis of Chandra and XMM–Newton observations of XLSSJ022403.9-041328 galaxy cluster of z=1, which was detected during the XMM-Newton Large Scale Structure survey. To define the "luminosity-temperature-mass", LX–TX–M, scaling relations we built temperature, surface brightness, density, and mass pr…
Non-minimal braneworld inflation after the Planck
Nozari, Kourosh; Rashidi, Narges
The recently released Planck data have constrained 4-dimensional inflationary parameters even more accurately than ever. We consider an extension of the braneworld model with induced gravity and a non-minimally coupled scalar field on the brane. We constraint the inflation parameters in this setup, by adopting six types of potential, in confrontat…