Search Publications
Measuring the Mass of the Central Black Hole in the Bulgeless Galaxy NGC 4395 from Gas Dynamical Modeling
Ho, Luis C.; Neumayer, Nadine; Barth, Aaron J. +7 more
NGC 4395 is a bulgeless spiral galaxy, harboring one of the nearest known type 1 Seyfert nuclei. Although there is no consensus on the mass of its central engine, several estimates suggest it is one of the lightest massive black holes (MBHs) known. We present the first direct dynamical measurement of the mass of this MBH from a combination of two-…
The Origin of Double-peaked Narrow Lines in Active Galactic Nuclei. I. Very Large Array Detections of Dual AGNs and AGN Outflows
Cooper, M. C.; Comerford, J. M.; Greene, J. E. +3 more
We have examined a subset of 18 active galactic nuclei (AGNs) drawn from a sample of 81 galaxies that possess double-peaked narrow optical emission line spectra in the Sloan Digital Sky Survey, have 2 optical AGN emission components separated by >0.″2, and are detected in the Faint Images of the Radio Sky at Twenty-centimeters survey. Without f…
High-J CO versus Far-infrared Relations in Normal and Starburst Galaxies
Daddi, Emanuele; van der Werf, Paul; Liu, Daizhong +4 more
We present correlations between 9 CO transitions (J=4-3 to 12-11) and beam-matched far-infrared (far-IR) luminosities ({L}{FIR,b}) among 167 local galaxies, using Herschel Spectral and Photometric Imaging Receiver Fourier Transform Spectrometer (SPIRE; FTS) spectroscopic data and Photoconductor Array Camera and Spectrometer (PACS) photo…
The ACS LCID Project: On the Origin of Dwarf Galaxy Types—A Manifestation of the Halo Assembly Bias?
Dolphin, Andrew E.; Skillman, Evan D.; Cole, Andrew A. +13 more
We discuss how knowledge of the whole evolutionary history of dwarf galaxies, including details on the early star formation events, can provide insight on the origin of the different dwarf galaxy types. We suggest that these types may be imprinted by the early conditions of formation rather than only being the result of a recent morphological tran…
Galaxy Structure as a Driver of the Star Formation Sequence Slope and Scatter
van Dokkum, Pieter G.; Franx, Marijn; Labbé, Ivo +12 more
It is well established that (1) star-forming galaxies follow a relation between their star formation rate (SFR) and stellar mass ({M}\star ), the “star formation sequence,” and (2) the SFRs of galaxies correlate with their structure, where star-forming galaxies are less concentrated than quiescent galaxies at fixed mass. Here, we consid…
Molecular clouds have power-law probability distribution functions
Alves, João; Lada, Charles J.; Lombardi, Marco
In this Letter we investigate the shape of the probability distribution of column densities (PDF) in molecular clouds. Through the use of low-noise, extinction-calibrated Herschel/Planck emission data for eight molecular clouds, we demonstrate that, contrary to common belief, the PDFs of molecular clouds are not described well by log-normal functi…
Excitation of kink oscillations of coronal loops: statistical study
Zimovets, I. V.; Nakariakov, V. M.
Context. Solar flares are often accompanied by kink (transverse) oscillations of coronal loops. Despite intensive study of these oscillations in recent years, the mechanisms that excite them are still not known.
Aims: We aim to clarify the excitation mechanisms for these kink oscillations of coronal loops.
Methods: We analysed 58 kink-os…
Probing the Fermi Bubbles in Ultraviolet Absorption: A Spectroscopic Signature of the Milky Way's Biconical Nuclear Outflow
Bowen, David V.; Jenkins, Edward B.; Hernandez, Svea +9 more
Giant lobes of plasma extend ≈55° above and below the Galactic center, glowing in emission from gamma rays (the Fermi Bubbles) to microwaves and polarized radio waves. We use ultraviolet absorption-line spectra from the Hubble Space Telescope to constrain the velocity of the outflowing gas within these regions, targeting the quasar PDS 456 (l, b =…
Wolf-Rayet stars in the Small Magellanic Cloud. I. Analysis of the single WN stars
Sander, A.; Hamann, W. -R.; Shenar, T. +3 more
Context. Wolf-Rayet (WR) stars have a severe impact on their environments owing to their strong ionizing radiation fields and powerful stellar winds. Since these winds are considered to be driven by radiation pressure, it is theoretically expected that the degree of the wind mass-loss depends on the initial metallicity of WR stars.
Aims: Foll…
BICEP2/Keck Array V: Measurements of B-mode Polarization at Degree Angular Scales and 150 GHz by the Keck Array
Ade, P. A. R.; Bock, J. J.; Crill, B. P. +58 more
The Keck Array is a system of cosmic microwave background polarimeters, each similar to the Bicep2 experiment. In this paper we report results from the 2012 to 2013 observing seasons, during which the Keck Array consisted of five receivers all operating in the same (150 GHz) frequency band and observing field as Bicep2. We again find an excess of …