ORCID Profile
0000-0001-8782-1992
Current Organisation
Brandeis University
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Publisher: American Astronomical Society
Date: 18-12-2018
Publisher: American Astronomical Society
Date: 12-08-2020
Publisher: American Astronomical Society
Date: 30-10-2020
Abstract: The nearby (3.8 Mpc) galaxy NGC 4945 hosts a nuclear starburst and Seyfert type 2 active galactic nucleus (AGN). We use the Atacama Large Millimeter/submillimeter Array (ALMA) to image the 93 GHz (3.2 mm) free–free continuum and hydrogen recombination line emission (H40 α and H42 α ) at 2.2 pc (0.″12) resolution. Our observations reveal 27 bright, compact sources with FWHM sizes of 1.4–4.0 pc, which we identify as candidate super star clusters. Recombination line emission, tracing the ionizing photon rate of the candidate clusters, is detected in 15 sources, six of which have a significant synchrotron component to the 93 GHz continuum. Adopting an age of ∼5 Myr, the stellar masses implied by the ionizing photon luminosities are ( M ⋆ /M ⊙ ) ≈ 4.7–6.1. We fit a slope to the cluster mass distribution and find β = −1.8 ± 0.4. The gas masses associated with these clusters, derived from the dust continuum at 350 GHz, are typically an order of magnitude lower than the stellar mass. These candidate clusters appear to have already converted a large fraction of their dense natal material into stars and, given their small freefall times of ∼0.05 Myr, are surviving an early volatile phase. We identify a pointlike source in 93 GHz continuum emission that is presumed to be the AGN. We do not detect recombination line emission from the AGN and place an upper limit on the ionizing photons that leak into the starburst region of Q 0 10 52 s −1 .
Publisher: American Astronomical Society
Date: 29-09-2021
Publisher: American Astronomical Society
Date: 21-05-2015
Publisher: American Astronomical Society
Date: 05-02-2018
Publisher: Cambridge University Press (CUP)
Date: 10-2013
DOI: 10.1017/S1743921314000398
Abstract: We present a radio survey of molecules in a s le of Galactic center molecular clouds, including M0.25 + 0.01, the clouds near Sgr A, and Sgr B2. The molecules detected are primarily NH 3 and HC 3 N in Sgr B2-N we also detect non-metastable NH 3 , vibrationally-excited HC 3 N, torsionally-excited CH 3 OH, and numerous isotopologues of these species. 36 GHz Class I CH 3 OH masers are ubiquitous in these fields, and in several cases are associated with new NH 3 (3,3) maser candidates. We also find that NH 3 and HC 3 N are depleted or absent toward several of the highest dust column density peaks identified in submillimeter observations, which are associated with water masers and are thus likely in the early stages of star formation.
Publisher: EDP Sciences
Date: 19-11-2015
Publisher: EDP Sciences
Date: 26-01-2016
Publisher: American Astronomical Society
Date: 18-12-2018
Publisher: Cambridge University Press (CUP)
Date: 07-2017
DOI: 10.1017/S1743921316012242
Abstract: We present NH 3 and H64α+H63α VLA observations of the Radio Arc region, including the M0.20 – 0.033 and G0.10 – 0.08 molecular clouds. These observations suggest the two velocity components of M0.20 – 0.033 are physically connected in the south. Additional ATCA observations suggest this connection is due to an expanding shell in the molecular gas, with the centroid located near the Quintuplet cluster. The G0.10 – 0.08 molecular cloud has little radio continuum, strong molecular emission, and abundant CH 3 OH masers, similar to a nearby molecular cloud with no star formation: M0.25+0.01. These features detected in G0.10 – 0.08 suggest dense molecular gas with no signs of current star formation.
Publisher: American Astronomical Society
Date: 20-11-2017
Publisher: American Astronomical Society
Date: 27-12-2018
Publisher: Oxford University Press (OUP)
Date: 12-02-2016
DOI: 10.1093/MNRAS/STW121
Publisher: EDP Sciences
Date: 09-2016
Publisher: Oxford University Press (OUP)
Date: 19-03-2019
DOI: 10.1093/MNRAS/STZ796
Publisher: American Astronomical Society
Date: 12-08-2019
Publisher: American Astronomical Society
Date: 02-08-2016
Publisher: American Astronomical Society
Date: 16-07-2020
Publisher: American Astronomical Society
Date: 05-11-2018
Publisher: American Astronomical Society
Date: 09-11-2020
Publisher: American Astronomical Society
Date: 12-2021
Abstract: We present the ALMA detection of molecular outflowing gas in the central regions of NGC 4945, one of the nearest starbursts and also one of the nearest hosts of an active galactic nucleus (AGN). We detect four outflow plumes in CO J = 3 − 2 at ∼0.″3 resolution that appear to correspond to molecular gas located near the edges of the known ionized outflow cone and its (unobserved) counterpart behind the disk. The fastest and brightest of these plumes has emission reaching observed line-of-sight projected velocities of over 450 km s −1 beyond systemic, equivalent to an estimated physical outflow velocity v ≳ 600 km s −1 for the fastest emission. Most of these plumes have corresponding emission in HCN or HCO + J = 4 − 3. We discuss a kinematic model for the outflow emission where the molecular gas has the geometry of the ionized gas cone and shares the rotation velocity of the galaxy when ejected. We use this model to explain the velocities we observe, constrain the physical speed of the ejected material, and account for the fraction of outflowing gas that is not detected due to confusion with the galaxy disk. We estimate a total molecular mass outflow rate M ̇ mol ∼ 20 M ⊙ yr −1 flowing through a surface within 100 pc of the disk midplane, likely driven by a combination of the central starburst and AGN.
Publisher: American Astronomical Society
Date: 14-10-2019
Publisher: American Astronomical Society
Date: 26-08-2020
Publisher: American Astronomical Society
Date: 29-04-2021
Abstract: Young massive clusters play an important role in the evolution of their host galaxies, and feedback from the high-mass stars in these clusters can have profound effects on the surrounding interstellar medium. The nuclear starburst in the nearby galaxy NGC 253 at a distance of 3.5 Mpc is a key laboratory in which to study star formation in an extreme environment. Previous high-resolution (1.9 pc) dust continuum observations from the Atacama Large Millimeter/submillimeter Array (ALMA) discovered 14 compact, massive super star clusters (SSCs) still in formation. We present here ALMA data at 350 GHz with 28 mas (0.5 pc) resolution. We detect blueshifted absorption and redshifted emission (P-Cygni profiles) toward three of these SSCs in multiple lines, including CS 7−6 and H 13 CN 4−3, which represent direct evidence for previously unobserved outflows. The mass contained in these outflows is a significant fraction of the cluster gas masses, which suggests we are witnessing a short but important phase. Further evidence of this is the finding of a molecular shell around the only SSC visible at near-IR wavelengths. We model the P-Cygni line profiles to constrain the outflow geometry, finding that the outflows must be nearly spherical. Through a comparison of the outflow properties with predictions from simulations, we find that none of the available mechanisms completely explains the observations, although dust-reprocessed radiation pressure and O star stellar winds are the most likely candidates. The observed outflows will have a very substantial effect on the clusters’ evolution and star formation efficiency.
Location: United States of America
Location: United States of America
No related grants have been discovered for Elisabeth Mills.