33 research outputs found
Interaction of Gravitational Waves with Charged Particles
It is shown here that a cloud of charged particles could in principle absorb
energy from gravitational waves (GWs) incident upon it, resulting in wave
attenuation. This could in turn have implications for the interpretation of
future data from early universe GWs.Comment: Appears in Gravitational Wave Astrophysics, Editor C.F. Sopuerta,
Astrophysics and Space Science Proceedings, Volume 40. ISBN
978-3-319-10487-4. Springer International Publishing Switzerland, 2015, p.
29
Quantifying Feedback from Narrow Line Region Outflows in Nearby Active Galaxies
Observations reveal that supermassive black holes (SMBHs) grow through the accretion of gas at the centers of galaxies as luminous active galactic nuclei (AGN), releasing radiation that drives powerful outflows of ionized and molecular gas. These winds are thought to play a critical role in galaxy evolution by regulating star formation and the growth of galaxies and their SMBHs. To test this model, we must quantify the dynamic impact of outflows by measuring their mass outflow rates and energetics. Using spatially resolved spectroscopy and imaging from the Hubble Space Telescope and Cloudy photoionization models we mapped the ionized gas kinematics and mass distributions of narrow line region (NLR) outflows in nearby active galaxies. We find that the outflows contain up to several million solar masses of ionized gas and are limited to distances of 1 - 2 kiloparsecs from the nucleus. The maximum mass outflow rates are M = 3 - 12 solar masses per year and the outflow gas mass, velocity, radial extent, and energetics are positively correlated with AGN luminosity. We use our results to test simplified techniques with less stringent data requirements and find that they significantly overestimate the gas mass. These results are crucial for modeling powerful outflows at higher redshift that may considerably influence star formation rates and the formation of galactic structure
Jansky Very Large Array detections of CO(1-0) emission in HI-absorption-selected galaxies at
We report a Karl G. Jansky Very Large Array search for redshifted CO(1-0)
emission from three HI-absorption-selected galaxies at ,
identified earlier in their CO(3-2) or CO(4-3) emission. We detect CO(1-0)
emission from DLA B1228-113 at and DLA J0918+1636 at
; these are the first detections of CO(1-0) emission in
high- HI-selected galaxies. We obtain high molecular gas masses, , for the two
objects with CO(1-0) detections, which are a factor of lower
than earlier estimates. We determine the excitation of the mid CO
rotational levels relative to the level, r, in HI-selected
galaxies for the first time, obtaining r and r for DLA J0918+1636, and r for DLA
B1228-113. These values are consistent with thermal excitation of the
levels. The excitation of the level in the HI-selected galaxies is
similar to that seen in massive main-sequence and sub-mm galaxies at
, but higher than that in main-sequence galaxies at ;
the higher excitation of the galaxies at is likely to be due to
their higher star-formation rate (SFR) surface density. We use Hubble Space
Telescope Wide Field Camera 3 imaging to detect the rest-frame near-ultraviolet
emission of DLA B1228-113, obtaining an NUV SFR of M
yr, significantly lower than that obtained from the total infrared
luminosity, indicating significant dust extinction in the
galaxy.Comment: 9 pages, 4 figures, and 2 tables. Accepted for publication in ApJ
A Catalog of 71 Coronal Line Galaxies in MaNGA: [NeV] is an Effective AGN Tracer
Despite the importance of AGN in galaxy evolution, accurate AGN
identification is often challenging, as common AGN diagnostics can be confused
by contributions from star formation and other effects (e.g.,
Baldwin-Phillips-Terlevich diagrams). However, one promising avenue for
identifying AGNs are ``coronal emission lines" (``CLs"), which are highly
ionized species of gas with ionization potentials 100 eV. These CLs may
serve as excellent signatures for the strong ionizing continuum of AGN. To
determine if CLs are in fact strong AGN tracers, we assemble and analyze the
largest catalog of optical CL galaxies using the Sloan Digital Sky Survey's
Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) catalog. We detect
CL emission in 71 MaNGA galaxies, out of the 10,010 unique galaxies from the
final MaNGA catalog, with 5 confidence. In our sample, we measure
[NeV]3347, 3427, [FeVII]3586, 3760,
6086, and [FeX]6374 emission and crossmatch the CL galaxies
with a catalog of AGNs that were confirmed with broad line, X-ray, IR, and
radio observations. We find that [NeV] emission, compared to [FeVII] and [FeX]
emission, is best at identifying high luminosity AGN. Moreover, we find that
the CL galaxies with the least dust extinction yield the most iron CL
detections. We posit that the bulk of the iron CLs are destroyed by dust grains
in the galaxies with the highest [OIII] luminosities in our sample, and that
AGN in the galaxies with low [OIII] luminosities are possibly too weak to be
detected using traditional techniques.Comment: 21 pages, 6 figures, 8 table
The MUSE Ultra Deep Field (MUDF). IV. A pair of X-ray weak quasars at the heart of two extended Ly{\alpha} nebulae
We present the results obtained from follow-up observations of the MUSE Ultra
Deep Field (MUDF) at X-ray energies with XMM-Newton. The MUDF is centred on a
unique field with two bright, physically associated quasars at ,
separated by 500 kpc in projection. Both quasars are embedded within
extended Ly nebulae ( at a surface brightness flux
level of ), whose
elongated morphology is suggestive of an extended filament connecting the
quasar haloes. The new X-ray observations presented here allow us to
characterise the physical properties (e.g. X-ray slope, luminosities, gas
column densities) in the innermost region of the MUDF quasars. We find that
both quasars are X-ray underluminous compared to objects at similar ultraviolet
luminosities. Based on our X-ray spectral analysis, absorbing columns of
10 cm appear unlikely, therefore such a weakness
is possibly intrinsic. When also including literature data, we do not observe
any detectable trend between the area of the nebulae and nuclear luminosities
at both the rest-frame 2 keV and 2500 . The area is also not
correlated with the X-ray photon index nor with the integrated band flux in the
hard band (210 keV). We also do not find any trend between the extended
Ly emission of the nebulae and the nuclear X-ray luminosity. Finally,
the properties of the MUDF quasars' nebulae are consistent with the observed
relation between the Ly integrated luminosity of the nebulae and their
area. Our results suggest that the quasar ionization power is not a strong
driver of the morphology and size of the nebulae.Comment: 15 pages, 9 figures, reference added, published in MNRA
Challenges and Techniques for Simulating Line Emission
Modeling emission lines from the millimeter to the UV and producing synthetic spectra is crucial for a good understanding of observations, yet it is an art filled with hazards. This is the proceedings of “Walking the Line”, a 3-day conference held in 2018 that brought together scientists working on different aspects of emission line simulations, in order to share knowledge and discuss the methodology. Emission lines across the spectrum from the millimeter to the UV were discussed, with most of the focus on the interstellar medium, but also some topics on the circumgalactic medium. The most important quality of a useful model is a good synergy with observations and experiments. Challenges in simulating line emission are identified, some of which are already being worked upon, and others that must be addressed in the future for models to agree with observations. Recent advances in several areas aiming at achieving that synergy are summarized here, from micro-physical to galactic and circum-galactic scale