Search Publications
Updated constraints from the Planck experiment on modified gravity
Salvatelli, Valentina; Marchini, Andrea
A modification of the action of the general relativity produces a different pattern for the growth of the cosmic structures below a certain length scale leaving an imprint on the cosmic microwave background anisotropies. We reexamine the upper limits on the length-scale parameter B0 of f(R) models using the recent data from the Planck s…
HST/WFC3 Near-infrared Spectroscopy of Quenched Galaxies at z ~ 1.5 from the WISP Survey: Stellar Population Properties
Scarlata, C.; Malkan, M.; Hathi, N. P. +15 more
We combine Hubble Space Telescope (HST) G102 and G141 near-IR (NIR) grism spectroscopy with HST/WFC3-UVIS, HST/WFC3-IR, and Spitzer/IRAC [3.6 µm] photometry to assemble a sample of massive (log (M star/M ⊙) ~ 11.0) and quenched (specific star formation rate <0.01 Gyr-1) galaxies at z ~ 1.5. Our sample of 4…
The Milky Way halo as a QSO absorption-line system. New results from an HST/STIS absorption-line catalogue of Galactic high-velocity clouds
Richter, P.; Charlton, J. C.; Masiero, J. R. +1 more
We use archival UV absorption-line data from HST/STIS to statistically analyse the absorption characteristics of the high-velocity clouds (HVCs) in the Galactic halo towards more than 40 extragalactic background sources. We determine absorption covering fractions of low- and intermediate ions (O i, C ii, Si ii, Mg ii, Fe ii, Si iii, C iv, and Si i…
Pulse-phase-dependent Variations of the Cyclotron Absorption Features of the Accreting Pulsars A0535+26, XTE J1946+274, and 4U 1907+09 with Suzaku
Maitra, Chandreyee; Paul, Biswajit
We have performed a detailed pulse-phase-resolved spectral analysis of cyclotron resonant scattering features (CRSFs) of the two Be/X-ray pulsars A0535+26 and XTE J1946+274 and the wind accreting HMXB pulsar 4U 1907+09 using Suzaku observations. The CRSF parameters vary strongly over the pulse phase and can be used to map the magnetic field, and a…
Extraordinary Luminous Soft X-Ray Transient MAXI J0158-744 as an Ignition of a Nova on a Very Massive O-Ne White Dwarf
Sakamoto, T.; Mihara, T.; Sugizaki, M. +29 more
We present the observation of an extraordinary luminous soft X-ray transient, MAXI J0158-744, by the Monitor of All-sky X-ray Image (MAXI) on 2011 November 11. This transient is characterized by a soft X-ray spectrum, a short duration (1.3 × 103 s < ΔTd < 1.10 × 104 s), a rapid rise (<5.5 × 103 …
The Pulsation Mode of the Cepheid Polaris
Kovtyukh, V. V.; Usenko, I. A.; Turner, D. G. +1 more
A previously derived photometric parallax of 10.10 ± 0.20 mas, d = 99 ± 2 pc, is confirmed for Polaris by a spectroscopic parallax derived using line ratios in high dispersion spectra for the Cepheid. The resulting estimates for the mean luminosity of langMV rang = -3.07 ± 0.01 s.e., average effective temperature of langT eff…
Evolution of the Global Temperature Structure of the Solar Corona during the Minimum between Solar Cycles 23 and 24
Jin, Meng; Huang, Zhenguang; Vásquez, Alberto M. +3 more
The combination of differential emission measure tomography with extrapolation of the photospheric magnetic field allows determination of the electron density and electron temperature along individual magnetic field lines. This is especially useful in quiet-Sun (QS) plasmas where individual loops cannot otherwise be identified. In Paper I, this ap…
Is the Sunyaev-Zeldovich effect responsible for the observed steepening in the spectrum of the Coma radio halo?
Brunetti, G.; Cassano, R.; Mazzotta, P. +3 more
Aims: The radio halo in the Coma cluster is unique in that its spectrum has been measured over almost two decades in frequency. The current radio data show a steepening of the spectrum at higher frequencies, which has implications for models of the radio halo origin. There is an on-going debate on the possibility that the observed steepening …
A multiwavelength study of the Magellanic-type galaxy NGC 4449 - I. Modelling the spectral energy distribution, the ionization structure and the star formation history
Cooray, A.; Page, M. J.; Lebouteiller, V. +16 more
We present an integrated photometric spectral energy distribution (SED) of the Magellanic-type galaxy NGC 4449 from the far-ultraviolet (UV) to the submillimetre, including new observations acquired by the Herschel Space Observatory. We include integrated UV photometry from the Swift Ultraviolet and Optical Telescope using a measurement technique …
X-ray spectroscopy of the ADC source X1822-371 with Chandra and XMM-Newton
Robba, N. R.; Papitto, A.; Di Salvo, T. +5 more
Context. The eclipsing low-mass X-ray binary X1822-371 is the prototype of the accretion disc corona (ADC) sources. Its inclination angle (≃82.5°) is high enough that flux from the neutron star is blocked by the edge-on accretion disc. Because the neutron star's direct emission is hidden, its ADC emission is visible. The physical properties of the…