Search Publications
Extended Main-sequence Turn-offs in Intermediate-age Star Clusters: Stellar Rotation Diminishes, but Does Not Eliminate, Age Spreads
Girardi, Léo; Goudfrooij, Paul; Correnti, Matteo
Extended main-sequence turn-off (eMSTO) regions are a common feature in color-magnitude diagrams of young- and intermediate-age star clusters in the Magellanic Clouds. The nature of eMSTOs remains debated in the literature. The currently most popular scenarios are extended star formation activity and ranges of stellar rotation rates. Here we study…
A search for sterile neutrinos with the latest cosmological observations
Feng, Lu; Zhang, Jing-Fei; Zhang, Xin
We report the result of a search for sterile neutrinos with the latest cosmological observations. Both cases of massless and massive sterile neutrinos are considered in the
Constraints on the Lyman continuum escape fraction for faint star-forming galaxies
Tozzi, P.; Balestra, I.; Rosati, P. +6 more
Star-forming galaxies have long been considered the dominant sources of the cosmic ultraviolet background radiation at early epochs. However, observing and characterizing the galaxy population with significant ionizing emission have proven to be challenging. In particular, the fraction of ionizing radiation that escapes the local environment to th…
SNR 1E 0102.2-7219 as an X-ray calibration standard in the 0.5-1.0 keV bandpass and its application to the CCD instruments aboard Chandra, Suzaku, Swift and XMM-Newton
Miller, Eric D.; Haberl, Frank; Plucinsky, Paul P. +4 more
Context. The flight calibration of the spectral response of charge-coupled device (CCD) instruments below 1.5 keV is difficult in general because of the lack of strong lines in the on-board calibration sources typically available. This calibration is also a function of time due to the effects of radiation damage on the CCDs and/or the accumulation…
Dissecting the extended main-sequence turn-off of the young star cluster NGC 1850
Bellini, Andrea; Goudfrooij, Paul; Puzia, Thomas H. +2 more
We use the Wide Field Camera 3 onboard the Hubble Space Telescope to obtain deep, high-resolution photometry of the young (∼100 Myr) star cluster NGC 1850 in the Large Magellanic Cloud. We analyse the cluster colour-magnitude diagram (CMD) and find that it hosts an extended main-sequence turn-off (MSTO) and a double main sequence (MS). We demonstr…
Revealing the structure of the outer disks of Be stars
Carciofi, A. C.; Štefl, S.; Vieira, R. G. +9 more
Context. The structure of the inner parts of Be star disks (≲ 20 stellar radii) is well explained by the viscous decretion disk (VDD) model, which is able to reproduce the observable properties of most of the objects studied so far. The outer parts, on the other hand, are not observationally well-explored, as they are observable only at radio wave…
Cosmic microwave background constraints on secret interactions among sterile neutrinos
Mirizzi, Alessandro; Lattanzi, Massimiliano; Natoli, Paolo +3 more
Secret contact interactions among eV sterile neutrinos, mediated by a massive gauge boson X (with MX ll MW), and characterized by a gauge coupling gX, have been proposed as a mean to reconcile cosmological observations and short-baseline laboratory anomalies. We constrain this scenario using the latest Planck data …
A Unified tool to estimate Distances, Ages, and Masses (UniDAM) from spectrophotometric data
Hekker, Saskia; Mints, Alexey
Context. Galactic archaeology, the study of the formation and evolution of the Milky Way by reconstructing its past from its current constituents, requires precise and accurate knowledge of stellar parameters for as many stars as possible. To achieve this, a number of large spectroscopic surveys have been undertaken and are still ongoing.
Aim…
Bimodal Long-lasting Components in Short Gamma-Ray Bursts: Promising Electromagnetic Counterparts to Neutron Star Binary Mergers
Sakamoto, Takanori; Kisaka, Shota; Ioka, Kunihito
Long-lasting emission of short gamma-ray bursts (GRBs) is crucial to reveal the physical origin of the central engine as well as to detect electromagnetic (EM) counterparts to gravitational waves (GWs) from neutron star binary mergers. We investigate 65 X-ray light curves of short GRBs, which is six times more than previous studies, by combining b…
Neutral gas heating by X-rays in primitive galaxies: Infrared observations of the blue compact dwarf I Zw 18 with Herschel
Kunth, D.; Lebouteiller, V.; Galliano, F. +8 more
Context. The neutral interstellar medium of galaxies acts as a reservoir to fuel star formation. The dominant heating and cooling mechanisms in this phase are uncertain in extremely metal-poor star-forming galaxies. The low dust-to-gas mass ratio and low polycyclic aromatic hydrocarbon abundance in such objects suggest that the traditional photoel…