Search Publications
The Galactic Bulge Diffuse Emission in Broadband X-Rays with NuSTAR
Wik, Daniel R.; Krivonos, Roman; Perez, Kerstin
The diffuse hard X-ray emission that fills the Galactic center, bulge, and ridge is believed to arise from unresolved populations of X-ray binary systems. However, the identity of the dominant class of accreting objects in each region remains unclear. Recent studies of Fe line properties and the low-energy (<10 keV) X-ray continuum of the bulge…
The behaviour of chemical elements in 62 Am star candidates
Giarrusso, M.; Leone, F.; Busà, I. +3 more
In this paper, we present the results of a spectroscopic campaign devoted to ascertain the actual nature of a sample of 155 objects reported as uncertain peculiar stars in the General catalogue of Ap, Am, and HgMn stars. Spectroscopic observations have been obtained with Catania Astrophysical Observatory Spectropolarimeter. We derive for all the o…
New type II Cepheids from VVV data towards the Galactic center
Minniti, D.; Zoccali, M.; Contreras Ramos, R. +5 more
Context. The Galactic center (GC) is the densest region of the Milky Way. Variability surveys towards the GC potentially provide the largest number of variable stars per square degree within the Galaxy. However, high stellar density is also a drawback due to blending. Moreover, the GC is affected by extreme reddening, therefore near infrared obser…
Cooling in the X-ray halo of the rotating, massive early-type galaxy NGC 7049
Simionescu, A.; Gaspari, M.; Sun, M. +9 more
The relative importance of the physical processes shaping the thermodynamics of the hot gas permeating rotating, massive early-type galaxies is expected to be different from that in non-rotating systems. Here, we report the results of the analysis of XMM-Newton data for the massive, lenticular galaxy NGC 7049. The galaxy harbours a dusty disc of c…
The course of the Orphan Stream in the Northern Galactic hemisphere traced with Gaia DR2
van der Marel, Roeland P.; Fardal, Mark A.; Sohn, Sangmo Tony +1 more
The Orphan Stream is one of the most prominent tidal streams in the Galactic halo. Using data on red giants, RR Lyrae, and horizontal branch stars from Gaia and other surveys, we determine the proper motion of the Orphan Stream over a path of more than 90° on the sky. We also provide updated tracks for the sky position, distance, and radial veloci…
The Carnegie Chicago Hubble Program. VI. Tip of the Red Giant Branch Distances to M66 and M96 of the Leo I Group
Madore, Barry F.; Freedman, Wendy L.; Beaton, Rachael L. +8 more
We determine the distances to the Type Ia supernova host galaxies M66 (NGC 3627) and M96 (NGC 3368) of the Leo I Group using the Tip of the Red Giant Branch (TRGB) method. We target the stellar halos of these galaxies using the Hubble Space Telescope ACS/WFC in the F606W and F814W bandpasses. By pointing to the stellar halos we sample RGB stars pr…
Weak lensing measurements of the APEX-SZ galaxy cluster sample
Israel, Holger; Klein, Matthias; Bertoldi, Frank +5 more
We present a weak lensing analysis for galaxy clusters from the APEX-SZ survey. For 39 massive galaxy clusters that were observed via the Sunyaev-Zel'dovich effect (SZE) with the APEX telescope, we analyse deep optical imaging data from WFI(@2.2mMPG/ESO) and Suprime-Cam(@SUBARU) in three bands. The masses obtained in this study, including an X-ray…
On the extraction of the power-law parts of probability density functions in star-forming clouds
Klessen, Ralf S.; Schneider, Nicola; Veltchev, Todor V. +5 more
We present a new approach to extract the power-law part of a density/column-density probability density function (ρ-pdf/N-pdf) in star-forming clouds. This approach is based on the mathematical method BPLFIT of Virkar & Clauset (2014, Annals of Applied Statistics, 8, 89) and it assesses the power-law part of an arbitrary distribution, without …
Constraining the Dark-matter Halo Mass of Isolated Low-surface-brightness Galaxies
Bogdán, Ákos; Canning, Rebecca E. A.; Kovács, Orsolya E.
Recent advancements in the imaging of low-surface-brightness objects revealed numerous ultra-diffuse galaxies in the local universe. These peculiar objects are unusually extended and faint: their effective radii are comparable to the Milky Way, but their surface brightnesses are lower than that of dwarf galaxies. Their ambiguous properties motivat…
Another relic bulge globular cluster: ESO 456-SC38 (Djorgovski 2)
Momany, Y.; Held, E. V.; Saviane, I. +7 more
Context. The object ESO 456-SC38 (Djorgovski 2) is one of the globular clusters that is closest to the Galactic center. It is on the blue horizontal branch and has a moderate metallicity of [Fe/H] ∼ -1.0. It is thus similar to the very old inner bulge globular clusters NGC 6522, NGC 6558, and HP 1, and therefore appears to be part of the primeval …