Search Publications
Transverse Oscillations of Loops with Coronal Rain Observed by Hinode/Solar Optical Telescope
Verwichte, E.; Antolin, P.
The condensations composing coronal rain, falling down along loop-like structures observed in cool chromospheric lines such as Hα and Ca II H, have long been a spectacular phenomenon of the solar corona. However, considered a peculiar sporadic phenomenon, it has not received much attention. This picture is rapidly changing due to recent high-resol…
A Multiwavelength Study on the High-energy Behavior of the Fermi/LAT Pulsars
De Luca, Andrea; Marelli, Martino; Caraveo, Patrizia A.
Using archival as well as freshly acquired data, we assess the X-ray behavior of the Fermi/Large Area Telescope γ-ray pulsars listed in the First Fermi source catalog. After revisiting the relationships between the pulsars' rotational energy losses and their X-ray and γ-ray luminosities, we focus on the distance-independent γ-to-X-ray flux ratios.…
Constraining the Minimum Mass of High-redshift Galaxies and their Contribution to the Ionization State of the Intergalactic Medium
Muñoz, J. A.; Loeb, A.
We model the latest HST WFPC3/IR observations of gsim100 galaxies at redshifts z = 7-8 in terms of a hierarchical galaxy formation model with starburst activity. Our model provides a distribution of UV luminosities per dark matter halo of a given mass and a natural explanation for the fraction of halos hosting galaxies. The observed luminosity fun…
Hα and 4000 Å Break Measurements for ~3500 K-selected Galaxies at 0.5 < z < 2.0
van Dokkum, Pieter G.; Franx, Marijn; Labbé, Ivo +3 more
We measure spectral features of ~3500 K-selected galaxies at 0.5 < z < 2.0 from high-quality medium-band photometry using a new technique. First, we divide the galaxy sample in 32 subsamples based on the similarities between the full spectral energy distributions (SEDs) of the galaxies. For each of these 32 galaxy types we construct a compos…
Photometric and Spectroscopic Evolution of the IIP SN 2007it to Day 944
Welch, D. L.; Gallagher, J. S.; Barlow, M. J. +9 more
SN 2007it is a bright, Type IIP supernova which shows indications of both pre-existing and newly formed dust. The visible photometry shows a bright late-time luminosity, powered by the 0.09 M sun of 56Ni present in the ejecta. There is also a sudden drop in optical brightness after day 339, and a corresponding brightening in …
Black Hole Mass and Bulge Luminosity for Low-mass Black Holes
Ho, Luis C.; Greene, Jenny E.; Jiang, Yan-Fei
We study the scaling between bulge magnitude and central black hole (BH) mass in galaxies with virial BH masses <~ 106 M sun. Based on careful image decomposition of a snapshot Hubble Space Telescope I-band survey, we found that these BHs are found predominantly in galaxies with pseudobulges. Here we show that the M B…
Evidence Against an Edge-on Disk Around the Extrasolar Planet, 2MASS 1207 b and a New Thick-cloud Explanation for Its Underluminosity
Pascucci, Ilaria; Apai, Dániel; Biller, Beth A. +3 more
Since the discovery of the first directly imaged, planetary-mass object, 2MASS 1207 b, several works have sought to explain a disparity between its observed temperature and luminosity. Given its known age, distance, and spectral type, 2MASS 1207 b is underluminous by a factor of ~10 (~2.5 mag) when compared to standard models of brown-dwarf/giant-…
Spatially Resolved Nonthermal Line Broadening during the Impulsive Phase of a Solar Flare
Milligan, Ryan O.
This paper presents a detailed study of excess line broadening in extreme ultraviolet (EUV) emission lines during the impulsive phase of a C-class solar flare. In this work, which utilizes data from the EUV Imaging Spectrometer on board Hinode, the broadened line profiles were observed to be cospatial with the two hard X-ray footpoints as observed…
Can the Soft X-Ray Opacity Toward High-redshift Sources Probe the Missing Baryons?
Laor, Ari; Behar, Ehud; Dar, Arnon +1 more
Observations with the Swift satellite of X-ray afterglows of more than a hundred gamma-ray bursts (GRBs) with known redshift reveal ubiquitous soft X-ray absorption. The directly measured optical depth τ at a given observed energy is found to be constant on average at redshift z > 2, i.e., langτ(0.5 keV)rang z > 2 = 0.40 ± 0.02. S…
A Deep Chandra ACIS Study of NGC 4151. II. The Innermost Emission Line Region and Strong Evidence for Radio Jet-NLR Cloud Collision
Elvis, Martin; Zezas, Andreas; Risaliti, Guido +4 more
We have studied the X-ray emission within the inner ~150 pc radius of NGC 4151 by constructing high spatial resolution emission line images of blended O VII, O VIII, and Ne IX. These maps show extended structures that are spatially correlated with the radio outflow and optical [O III] emission. We find strong evidence for jet-gas cloud interaction…