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We report optical spectroscopic observations of a sample of 6 low-galactic latitude microquasar candidates selected by cross-identification of X-ray and radio point source catalogs for |b|<5 degrees. Two objects resulted to be of clear…

Astrophysics · Physics 2007-05-23 J. Marti , J. M. Paredes , J. S. Bloom , J. Casares , M. Ribo , E. E. Falco

Centaurus B is a nearby radio galaxy positioned in the Southern hemisphere close to the Galactic plane. Here we present a detailed analysis of about 43 months of accumulated Fermi-LAT data of the gamma-ray counterpart of the source…

High Energy Astrophysical Phenomena · Physics 2015-06-12 J. Katsuta , Y. T. Tanaka , L. Stawarz , S. P. O'Sullivan , C. C. Cheung , J. Kataoka , S. Funk , T. Yuasa , H. Odaka , T. Takahashi , J. Svoboda

Optical frequency combs have the potential to improve the precision of the radial velocity measurement of celestial bodies, leading to breakthroughs in such fields as exoplanet exploration. For these purposes, the comb must have a broad…

Instrumentation and Methods for Astrophysics · Physics 2023-06-06 Keisuke Nakamura , Ken Kashiwagi , Sho Okubo , Hajime Inaba

Emission from the nucleus of the closest radio galaxy, Centaurus A, is observed from the radio to the gamma ray band. We build, for the first time, its overall Spectral Energy Distribution (SED) that appears to be intriguingly similar to…

Astrophysics · Physics 2009-11-06 Marco Chiaberge , Alessandro Capetti , Annalisa Celotti

We study the quasi-simultaneous near-IR, optical, UV, and X-ray photometry of eleven gamma-ray selected blazars for which redshift estimates larger than 1.2 have been recently provided. Four of these objects turn out to be high-power…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 P. Padovani , P. Giommi , A. Rau

We report Spitzer Space Telescope observations during predicted transits of the exoplanet Proxima Centauri b. As the nearest terrestrial habitable-zone planet we will ever discover, any potential transit of Proxima b would place strong…

The aim of the search for extraterrestrial intelligence (SETI) is to find technologically-capable life beyond Earth through their technosignatures. On 2019 April 29, the Breakthrough Listen SETI project observed Proxima Centauri with the…

A sub-parsec scale radio counterjet has been detected in the nucleus of the closest radio galaxy, Centaurus A (NGC 5128), with VLBI imaging at 2.3 and 8.4 GHz. This is one of the first detections of a VLBI counterjet and provides new…

We present numerical simulations for energy spectra and angular distributions of nucleons above 10^{19} eV injected by the radio-galaxy Centaurus A at a distance 3.4 Mpc and propagating in extra-galactic magnetic fields in the sub-micro…

Astrophysics · Physics 2009-11-06 C. Isola , M. Lemoine , G. Sigl

The extended lobes of radio galaxies are examined as sources of X-ray and gamma-ray emission via inverse Compton scattering of 3K background photons. The Compton spectra of two exemplary examples, Fornax A and Centaurus A, are estimated…

Astrophysics · Physics 2009-06-23 C. C. Cheung

We investigate retrieval of the stellar rotation signal for Proxima Centauri. We make use of high-resolution spectra taken with uves and harps of Proxima Centauri over a 13-year period as well as photometric observations of Proxima Centauri…

Solar and Stellar Astrophysics · Physics 2017-06-07 John M. Collins , Hugh R. A. Jones , John R. Barnes

Context: The nearby pair of solar-type stars Alpha Centauri is a favorable target for an imaging search for extrasolar planets. Indications exist that the gravitational mass of Alpha Cen B could be higher than its modeled mass, the…

Astrophysics · Physics 2016-08-15 Pierre Kervella , Frédéric Thévenin

We study the $\gamma$-ray and broadband spectral energy distribution (SED) properties of a complete sample of 104 bright, radio-selected low-synchrotron peaked (LSP) blazars. Most of the sources have already been detected in the…

High Energy Astrophysical Phenomena · Physics 2018-08-08 B. Arsioli , G. Polenta

We recently announced the detection of an unknown submillimeter source in our ALMA observations of alpha Cen AB. The source was detected in two epochs, a strong detection at 445~GHz and one at lower significance at 343.5~GHz. After valuable…

Solar and Stellar Astrophysics · Physics 2015-12-18 R. Liseau , W. Vlemmings , E. O'Gorman , E. Bertone , M. Chavez , V. De la Luz

The spectral energy distribution of giant lobes shows one main peak detected by the Wilkinson Microwave Anisotropy Probe at low energy of $10^{-5}$ eV and a faint $\gamma$-ray flux imaged by Fermi Large Area Telescope at energy $\geq$ 100…

High Energy Astrophysical Phenomena · Physics 2015-06-18 Nissim Fraija

We have studied the X-ray point source population of Centaurus A (NGC 5128) using data from four archival CHANDRA observations. We detected 272 point-like X-ray sources within a radius of 10 arcmin from the centre. Approximately half of…

Astrophysics · Physics 2009-11-11 R. Voss , M. Gilfanov

Precision laser spectroscopy is key to many developments in atomic and molecular physics and the advancement of related technologies such as atomic clocks and sensors. However, in important spectroscopic scenarios, such as astronomy and…

It was recently demonstrated that broadband quantum cascade lasers can operate as frequency combs. As such, they operate under direct electrical pumping at both mid-infrared and THz frequencies, making them very attractive for dual-comb…

Blazars are among the most variable objects in the universe. They feature energetic jets of plasma that launch from the cores of these active galactic nuclei (AGN), triggering activity from radio up to gamma-ray energies. Spatial…

Proxima Centauri, the star closest to our Sun, is known to host at least one terrestrial planet candidate in a temperate orbit. Here we report the ALMA detection of the star at 1.3 mm wavelength and the discovery of a belt of dust orbiting…