Search Publications
Modeling the 2012 May 17 Solar Energetic Particle Event Using the AWSoM and iPATH Models
Lario, D.; Li, Gang; de Nolfo, G. A. +6 more
We model the 2012 May 17 solar energetic particle event by combining the AWSoM and iPATH codes. Using this combined approach, we investigate particle acceleration when the parent coronal mass ejection (CME) is still close to the Sun. We have obtained reasonable agreements between our simulation and observations made by multiple spacecraft. We foll…
Isotropic x-ray bound on primordial black hole dark matter
Serpico, P. D.; Siegert, T.; Iguaz, J.
We revisit the constraints on evaporating primordial black holes (PBHs) from the isotropic x-ray and soft gamma-ray background in the mass range 1016- 1018 g . We find that they are stronger than usually inferred due to two neglected effects: (i) The contribution of the annihilation radiation due to positrons emitted in the e…
Source Counts Spanning Eight Decades of Flux Density at 1.4 GHz
Mauch, T.; Condon, J. J.; Cotton, W. D. +1 more
Brightness-weighted differential source counts S2n(S) spanning the eight decades of flux density between 0.25 µJy and 25 Jy at 1.4 GHz were measured from (1) the confusion brightness distribution in the MeerKAT DEEP2 image below 10 µJy, (2) counts of DEEP2 sources between 10 µJy and 2.5 mJy, and (3) counts of NVSS sour…
Proplyds in the flame nebula NGC 2024
Hines, Dean C.; Stapelfeldt, Karl R.; Clarke, Cathie J. +5 more
A recent survey of the inner 0.35 × 0.35 pc of the NGC 2024 star-forming region revealed two distinct millimetre continuum disc populations that appear to be spatially segregated by the boundary of a dense cloud. The eastern (and more embedded) population is ~0.2-0.5 Myr old, with an ALMA mm continuum disc detection rate of about $45\,$ per cent. …
New star clusters discovered towards the Galactic bulge direction using Gaia DR2
Corradi, W. J. B.; Ferreira, F. A.; Maia, F. F. S. +2 more
We report the discovery of 34 new open clusters and candidates as a result of a systematic search carried out in 200 adjacent fields of 1 × 1 deg2 area projected towards the Galactic bulge, using Gaia DR2 data. The objects were identified and characterized by a joint analysis of their photometric, kinematic, and spatial distribution tha…
The GRAVITY young stellar object survey. VII. The inner dusty disks of T Tauri stars
Lutz, D.; Genzel, R.; Sturm, E. +55 more
Context. T Tauri stars are surrounded by dust and gas disks. As material reservoirs from which matter is accreted onto the central star and planets are built, these protoplanetary disks play a central role in star and planet formation.
Aims: We aim at spatially resolving at sub-astronomical unit (sub-au) scales the innermost regions of the pr…
Nonparametric reconstruction of interaction in the cosmic dark sector
Mukherjee, Purba; Banerjee, Narayan
The possibility of a nongravitational interaction between dark matter and dark energy is reconstructed using some recent data sets. The crucial aspect is that the interaction is not parametrized at the outset, but rather reconstructed directly from the data in a nonparametric way. The cosmic chronometer Hubble data, the Pantheon supernova compilat…
Re-observing the NLS1 galaxy RE J1034+396 - II. New insights on the soft X-ray excess, QPO, and the analogy with GRS 1915+105
Done, Chris; Ward, Martin; Jin, Chichuan
The active galactic nucleus (AGN) RE J1034+396 displays the most significant X-ray quasi-periodic oscillation (QPO) detected so far. We perform a detailed spectral-timing analysis of our recent simultaneous XMM-Newton, NuSTAR, and Swift observations. We present the energy dependence of the QPO's frequency, rms, coherence, and phase lag, and model …
Thermal and Turbulent Properties of the Warm Neutral Medium in the Solar Neighborhood
Miville-Deschênes, Marc-Antoine; Marchal, Antoine
The transition from the diffuse warm neutral medium (WNM) to the dense cold neutral medium (CNM) is what set the initial conditions to the formation of molecular clouds. The properties of the turbulent cascade in the WNM, essential to describe this radiative condensation process, have remained elusive in part due to the difficulty in mapping out t…
Cepheids with Giant Companions. I. Revealing a Numerous Population of Double-lined Binary Cepheids
Anderson, Richard I.; Gieren, Wolfgang; Pietrzyński, Grzegorz +5 more
Masses of classical Cepheids of 3-11 M⊙ are predicted by theory but those measured clump between 3.6-5 M⊙. As a result, their mass-luminosity relation is poorly constrained, impeding our understanding of basic stellar physics and the Leavitt Law. All Cepheid masses come from the analysis of 11 binary systems, including only f…