Search Publications
GOODS-Herschel: Gas-to-dust Mass Ratios and CO-to-H2 Conversion Factors in Normal and Starbursting Galaxies at High-z
Aussel, H.; Daddi, E.; Elbaz, D. +15 more
We explore the gas-to-dust mass ratio (M gas/M d) and the CO luminosity-to-M gas conversion factor (αCO) of two well-studied galaxies in the Great Observatories Origins Deep Survey North field that are expected to have different star-forming modes, the starburst GN20 at z = 4.05 and the normal star-formi…
Accretion Rate and the Physical Nature of Unobscured Active Galaxies
Koekemoer, Anton M.; Trump, Jonathan R.; Urry, C. Megan +15 more
We show how accretion rate governs the physical properties of a sample of unobscured broad-line, narrow-line, and lineless active galactic nuclei (AGNs). We avoid the systematic errors plaguing previous studies of AGN accretion rates by using accurate intrinsic accretion luminosities (L int) from well-sampled multiwavelength spectral en…
The XMM-Newton Wide Field Survey in the COSMOS Field: Redshift Evolution of AGN Bias and Subdominant Role of Mergers in Triggering Moderate-luminosity AGNs at Redshifts up to 2.2
Finoguenov, A.; Salvato, M.; Merloni, A. +14 more
We present a study of the redshift evolution of the projected correlation function of 593 X-ray selected active galactic nuclei (AGNs) with I AB < 23 and spectroscopic redshifts z < 4, extracted from the 0.5-2 keV X-ray mosaic of the 2.13 deg2 XMM- Cosmic Evolution Survey (COSMOS). We introduce a method to estimate the …
The Relative Abundance of Compact and Normal Massive Early-type Galaxies and Its Evolution from Redshift z ~ 2 to the Present
Dickinson, M.; Giavalisco, M.; Koekemoer, A. M. +11 more
We report on the evolution of the number density and size of early-type galaxies (ETGs) from z ~ 2 to z ~ 0. We select a sample of 563 massive (M > 1010 M ⊙), passively evolving (specific star formation rate <10-2 Gyr-1), and morphologically spheroidal galaxies at 0 < z < 2.5, using the panch…
Demographics of Bulge Types within 11 Mpc and Implications for Galaxy Evolution
Drory, Niv; Fisher, David B.
We present an inventory of galaxy bulge types (elliptical galaxy, classical bulge, pseudobulge, and bulgeless galaxy) in a volume-limited sample within the local 11 Mpc sphere using Spitzer 3.6 µm and Hubble Space Telescope data. We find that whether counting by number, star formation rate, or stellar mass, the dominant galaxy type in the lo…
Quenching of Carbon Monoxide and Methane in the Atmospheres of Cool Brown Dwarfs and Hot Jupiters
Moses, Julianne I.; Visscher, Channon
We explore CO\rightleftarrows CH_{4} quench kinetics in the atmospheres of substellar objects using updated timescale arguments, as suggested by a thermochemical kinetics and diffusion model that transitions from the thermochemical-equilibrium regime in the deep atmosphere to a quench-chemical regime at higher altitudes. More specifically, we exam…
Extended Schmidt Law: Role of Existing Stars in Current Star Formation
Papovich, Casey; Armus, Lee; Helou, George +4 more
We propose an "extended Schmidt law" with explicit dependence of the star formation efficiency (SFE = SFR/M gas) on the stellar mass surface density (Σstar). This relation has a power-law index of 0.48 ± 0.04 and a 1σ observed scatter on the SFE of 0.4 dex, which holds over five orders of magnitude in the stellar density for …
Establishing a Connection Between Active Region Outflows and the Solar Wind: Abundance Measurements with EIS/Hinode
Warren, Harry P.; Brooks, David H.
One of the most interesting discoveries from Hinode is the presence of persistent high-temperature high-speed outflows from the edges of active regions (ARs). EUV imaging spectrometer (EIS) measurements indicate that the outflows reach velocities of 50 km s-1 with spectral line asymmetries approaching 200 km s-1. It has been …
A Stochastic Model for the Luminosity Fluctuations of Accreting Black Holes
Siemiginowska, Aneta; Kelly, Brandon C.; Sobolewska, Małgorzata
In this work, we have developed a new stochastic model for the fluctuations in light curves of accreting black holes. The model is based on a linear combination of stochastic processes and is also the solution to the linear diffusion equation perturbed by a spatially correlated noise field. This allows flexible modeling of the power spectral densi…
Chandra Discovery of a Binary Active Galactic Nucleus in Mrk 739
Sanders, D. B.; Schawinski, Kevin; Koss, Michael +6 more
We have discovered a binary active galactic nucleus (AGN) in the galaxy Mrk 739 using Chandra and Swift BAT. We find two luminous (L 2-10 keV = 1.1 × 1043 and 1.0 × 1042 erg s-1), unresolved nuclei with a projected separation of 3.4 kpc (5farcs8 ± 0farcs1) coincident with two bulge components in the opti…