Search Publications
The Effect of Surface Brightness Dimming in the Selection of High-z Galaxies
Kim, S.; Stiavelli, M.; Bradley, L. +2 more
Cosmological surface brightness (SB) dimming of the form (1 + z)-4 affects all sources. The strong dependence of SB dimming on redshift z suggests the presence of a selection bias when searching for high-z galaxies, i.e., we tend to detect only those galaxies with a high SB. However, unresolved knots of emission are not affected by SB d…
Hard X-ray emission of Sco X-1
Tsygankov, Sergey S.; Revnivtsev, Mikhail G.; Krivonos, Roman A. +1 more
We study hard X-ray emission of the brightest accreting neutron star Sco X-1 with INTEGRAL observatory. Up to now INTEGRAL have collected ∼4 Ms of deadtime corrected exposure on this source. We show that hard X-ray tail in time average spectrum of Sco X-1 has a power-law shape without cutoff up to energies ∼200-300 keV. An absence of the high ener…
Analysis of X-ray spectral variability and black hole mass determination of the NLS1 galaxy Mrk 766
Titarchuk, L.; Gilli, R.; Giacchè, S.
We present an XMM-Newton time-resolved spectral analysis of the narrow-line Seyfert 1 galaxy Mrk 766. We analysed eight available observations taken between May 2000 and June 2005 with the EPIC-pn camera in order to investigate the X-ray spectral variability produced by changes in the mass accretion rate. The 0.2 - 10 keV spectra are extracted in …
Searching for highly obscured AGNs in the XMM-Newton serendipitous source catalog
Ranalli, P.; Georgantopoulos, I.; Lanzuisi, G. +9 more
The majority of active galactic nuclei (AGNs) are obscured by large amounts of absorbing material that makes them invisible at many wavelengths. X-rays, given their penetrating power, provide the most secure way for finding these AGNs. The XMM-Newton serendipitous source catalog, of which 3XMM-DR4 is the latest version, is the largest catalog of X…
Spectral detection of multiple stellar populations in z ∼ 1 early-type galaxies
Longhetti, M.; Gargiulo, A.; Saracco, P. +2 more
We present a spectroscopic analysis based on measurements of two mainly age-dependent spectrophotometric indices in the 4000 Å rest-frame region, i.e. H+K(Ca II) and Δ4000, for a sample of 15 early-type galaxies (ETGs) at 0.7 < zspec < 1.1, morphologically selected in the GOODS-South field. Ages derived from the two different indi…
The ages of pedestal craters on Mars: Evidence for a late-Amazonian extended period of episodic emplacement of decameters-thick mid-latitude ice deposits
Head, James W.; Kadish, Seth J.
There is significant geomorphologic evidence for the past presence of longitudinally widespread, latitudinally zoned deposits composed of ice-rich material at the northern and southern mid latitudes on Mars (lobate debris aprons, lineated valley fill, concentric crater fill, pedestal craters, etc.). Among these features, pedestal craters (Pd) are …
Hot Topic, Warm Loops, Cooling Plasma? Multithermal Analysis of Active Region Loops
Schmelz, J. T.; Pathak, S.; Brooks, D. H. +2 more
We have found indications of a relationship between the differential emission measure (DEM) weighted temperature and the cross-field DEM width for coronal loops. The data come from the Hinode X-ray Telescope, the Hinode EUV Imaging Spectrometer, and the Solar Dynamics Observatory Atmospheric Imaging Assembly. These data show that cooler loops tend…
Swift J2218.4+1925: a new hard-X-ray-selected polar observed with XMM-Newton
Mukai, K.; de Martino, D.; Bernardini, F. +1 more
Swift J2218.4+1925, a hard-X-ray source detected by Swift Burst Alert Telescope (BAT), has been proposed as a candidate magnetic cataclysmic variable of the polar type from optical spectroscopy. Using XMM-Newton we perform detailed timing and spectral analysis with simultaneous X-ray (0.3-10 keV) and optical B-band data. We complement the spectral…
Observations of the Interplanetary Hydrogen during Solar Cycles 23 and 24. What can We Deduce about the Local Interstellar Medium?
Harris, Walter M.; Quémerais, Eric; Koutroumpa, Dimitra +5 more
Observations of interstellar helium atoms by the Interstellar Boundary Explorer (IBEX) spacecraft in 2009 reported a local interstellar medium (LISM) velocity vector different from the results of the Ulysses spacecraft between 1991 and 2002. The interplanetary hydrogen (IPH), a population of neutrals that fills the space between planets inside the…
Long-term X-Ray Stability and Ultraviolet Variability of the Ionized Absorption in NGC 3783
Brandt, W. N.; Behar, E.; Turner, T. J. +6 more
We present the results of recent Chandra High-Energy Transmission Grating Spectrometer and Hubble Space Telescope Cosmic Origins Spectrograph observations of the nearby Seyfert 1 galaxy NGC 3783, which show a strong, nonvarying X-ray warm absorber and physically related and kinematically varying UV absorption. We compare our new observations to hi…