Search Publications
Using Hα Morphology and Surface Brightness Fluctuations to Age-date Star Clusters in M83
Mutchler, Max; McCarthy, Patrick J.; Calzetti, Daniela +22 more
We use new WFC3 observations of the nearby grand-design spiral galaxy M83 to develop two independent methods for estimating the ages of young star clusters. The first method uses the physical extent and morphology of Hα emission to estimate the ages of clusters younger than τ ≈ 10 Myr. It is based on the simple premise that the gas in very young (…
A deep probe of the galaxy stellar mass functions at z∼ 1-3 with the GOODS NICMOS Survey
Conselice, Christopher J.; Bluck, Asa F. L.; Mortlock, Alice +4 more
We use a sample of 8298 galaxies observed as part of the Hubble Space Telescope (HST) H160-band GOODS NICMOS Survey (GNS) to construct the galaxy stellar mass function both as a function of redshift and as stellar mass up to z= 3.5. Our mass functions are constructed within the redshift range z= 1-3.5 and consist of galaxies with stella…
A close nuclear black-hole pair in the spiral galaxy NGC3393
Elvis, M.; Fabbiano, G.; Wang, Junfeng +1 more
The current picture of galaxy evolution advocates co-evolution of galaxies and their nuclear massive black holes, through accretion and galactic merging. Pairs of quasars, each with a massive black hole at the centre of its galaxy, have separations of 6,000 to 300,000 light years (refs 2 and 3; 1parsec = 3.26light years) and exemplify the first st…
A New Method for Polar Field Interpolation
Liu, Y.; Sun, X.; Hoeksema, J. T. +2 more
The photospheric magnetic field in the Sun's polar region is not well observed compared to the low-latitude regions. Data are periodically missing due to the Sun's tilt angle, and the noise level is high due to the projection effect on the line-of-sight (LOS) measurement. However, the large-scale characteristics of the polar magnetic field data ar…
The role of secular evolution in the black hole growth of narrow-line Seyfert 1 galaxies
Marconi, A.; Komossa, S.; Tacconi, L. +5 more
Narrow-line Seyfert 1 (NLS1) galaxies show extreme properties with respect to the other Seyfert galaxies. Indeed, they are thought to be accreting at Eddington rates and to possess low-mass black holes. Therefore, they may represent a key class of objects for understanding the co-evolution of black holes and their host galaxies. We propose that NL…
MUSTANG High Angular Resolution Sunyaev-Zel'dovich Effect Imaging of Substructure in Four Galaxy Clusters
Sun, M.; Sarazin, C. L.; Devlin, M. J. +6 more
We present resolved images of four massive clusters of galaxies through the Sunyaev-Zel'dovich effect (SZE). These measurements, made at 90 GHz with the MUSTANG receiver on the Green Bank Telescope (GBT), reveal pressure substructure to the intracluster medium (ICM) in three of the four systems. The SZE and X-ray morphology of MACS0744.8+3927 are …
The Spectroscopic Signature of Quasi-periodic Upflows in Active Region Timeseries
De Pontieu, Bart; McIntosh, Scott W.; Tian, Hui
Quasi-periodic propagating disturbances are frequently observed in coronal intensity image sequences. These disturbances have historically been interpreted as being the signature of slow-mode magnetoacoustic waves propagating into the corona. The detailed analysis of Hinode EUV Imaging Spectrometer (EIS) timeseries observations of an active region…
Hubble flow around Fornax cluster of galaxies
Karachentsev, I. D.; de Freitas Pacheco, J. A.; Nasonova, O. G.
Aims: This work aims to provide a new mass estimate for the Fornax cluster and the Fornax-Eridanus complex, avoiding methods like the virial or fits of the X-ray emission profile, which assume that the system is in equilibrium. This is probably not the case for Fornax, because it is still in process of formation.
Methods: Our mass estima…
Studying Extreme Ultraviolet Wave Transients with a Digital Laboratory: Direct Comparison of Extreme Ultraviolet Wave Observations to Global Magnetohydrodynamic Simulations
Lugaz, Noé; Downs, Cooper; Roussev, Ilia I. +3 more
In this work, we describe our effort to explore the signatures of large-scale extreme ultraviolet (EUV) transients in the solar corona (EUV waves) using a three-dimensional thermodynamic magnetohydrodynamic model. We conduct multiple simulations of the 2008 March 25 EUV wave (~18:40 UT), observed both on and off of the solar disk by the STEREO-A a…
The Hubble Space Telescope GOODS NICMOS Survey: overview and the evolution of massive galaxies at 1.5< z< 3
Daddi, E.; Lucas, Ray A.; Chary, R. -R. +27 more
We present the details and early results from a deep near-infrared survey utilizing the NICMOS instrument on the Hubble Space Telescope centred around massive M* > 1011 M⊙ galaxies at 1.7 < z < 2.9 found within the Great Observatories Origins Deep Survey (GOODS) fields North and South. The GOODS NICMOS Sur…