scholarly journals The CO(3–2)/CO(1–0) Luminosity Line Ratio in Nearby Star-forming Galaxies and Active Galactic Nuclei from xCOLD GASS, BASS, and SLUGS

2020 ◽  
Vol 889 (2) ◽  
pp. 103 ◽  
Author(s):  
Isabella Lamperti ◽  
Amélie Saintonge ◽  
Michael Koss ◽  
Serena Viti ◽  
Christine D. Wilson ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Line Ratio ◽  
Nearby Star ◽  
Star Forming

scholarly journals Constraining photoionization models with a reprojected optical diagnostic diagram

2020 ◽  
Vol 499 (4) ◽  
pp. 5749-5764 ◽  
Author(s):  
Xihan Ji ◽  
Renbin Yan
Keyword(s):  
Star Formation ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Theoretical Models ◽  
Line Ratio ◽  
Star Forming ◽  
Optical Diagnostic ◽  
Diagnostic Diagram ◽  
Upper Limits ◽  
Nitrogen Abundance

ABSTRACT Optical diagnostic diagrams are powerful tools to separate different ionizing sources in galaxies. However, the model-constraining power of the most widely used diagrams is very limited and challenging to visualize. In addition, there have always been classification inconsistencies between diagrams based on different line ratios, and ambiguities between regions purely ionized by active galactic nuclei (AGNs) and composite regions. We present a simple reprojection of the 3D line ratio space composed of [N ii]λ6583/H α, [S ii]λλ6716, 6731/H α, and [O iii]λ5007/H β, which reveals its model-constraining power and removes the ambiguity for the true composite objects. It highlights the discrepancy between many theoretical models and the data loci. With this reprojection, we can put strong constraints on the photoionization models and the secondary nitrogen abundance prescription. We find that a single nitrogen prescription cannot fit both the star-forming locus and AGN locus simultaneously, with the latter requiring higher N/O ratios. The true composite regions stand separately from both models. We can compute the fractional AGN contributions for the composite regions, and define demarcations with specific upper limits on contamination from AGN or star formation. When the discrepancy about nitrogen prescriptions gets resolved in the future, it would also be possible to make robust metallicity measurements for composite regions and AGNs.

Multiwavelength analysis of OH Megamaser galaxies: The case of IRAS11506-3851

2020 ◽  
Vol 15 (S359) ◽  
pp. 347-349
Author(s):  
Carpes P. Hekatelyne ◽  
Thaisa Storchi-Bergmann
Keyword(s):  
Active Galactic Nuclei ◽  
Hubble Space Telescope ◽  
Galactic Nuclei ◽  
Large Array ◽  
Very Large Array ◽  
Star Forming ◽  
Star Forming Regions ◽  
Field Unit ◽  
Mixed Transition ◽  
Integral Field

AbstractWe present Multi-Object Spectrograph (GMOS) Integral Field Unit (IFU), Hubble Space Telescope (HST) and Very Large Array (VLA) observations of the inner kpc of the OH Megamaser galaxy IRAS 11506-3851. In this work we discuss the kinematics and excitation of the gas as well as its radio emission. The HST images reveal an isolated spiral galaxy and the combination with the GMOS-IFU flux distributions allowed us to identify a partial ring of star-forming regions surrounding the nucleus with a radius of ≍500 pc. The emission-line ratios and excitation map reveal that the region inside the ring present mixed/transition excitation between those of Starbursts and Active Galactic Nuclei (AGN), while regions along the ring are excited by Starbursts. We suggest that we are probing a buried or fading AGN that could be both exciting the gas and originating an outflow.

scholarly journals Constraints on the production and escape of ionizing radiation from the emission-lines of metal-poor star-forming galaxies

2019 ◽  
Vol 15 (S352) ◽  
pp. 121-122
Author(s):  
A. Plat ◽  
S. Charlot ◽  
G. Bruzual ◽  
A. Feltre ◽  
A. Vidal-Garca ◽  
...  
Keyword(s):  
Ionizing Radiation ◽  
Emission Line ◽  
Active Galactic Nuclei ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Emission Lines ◽  
High Redshift Galaxies ◽  
Star Forming ◽  
Radiative Shocks ◽  
Metal Poor Star

AbstractTo understand how the nature of the ionizing sources and the leakage of ionizing photons in high-redshift galaxies can be constrained from their emission-line spectra, we compare emission-line models of star-forming galaxies including leakage of ionizing radiation, active galactic nuclei (AGN) and radiative shocks, with observations of galaxies at various redshifts with properties expected to approach those of primeval galaxies.

scholarly journals Molecular hydrogen and [Fe ii] in active galactic nuclei – III. Low-ionization nuclear emission-line region and star-forming galaxies

2013 ◽  
Vol 430 (3) ◽  
pp. 2002-2017 ◽  
Author(s):  
R. Riffel ◽  
A. Rodríguez-Ardila ◽  
I. Aleman ◽  
M. S. Brotherton ◽  
M. G. Pastoriza ◽  
...  
Keyword(s):  
Emission Line ◽  
Active Galactic Nuclei ◽  
Molecular Hydrogen ◽  
Galactic Nuclei ◽  
Star Forming ◽  
Line Region

The Fall of Active Galactic Nuclei and the Rise of Star-forming Galaxies: A Close Look at the Chandra Deep Field X-Ray Number Counts

2004 ◽  
Vol 128 (5) ◽  
pp. 2048-2065 ◽  
Author(s):  
F. E. Bauer ◽  
D. M. Alexander ◽  
W. N. Brandt ◽  
D. P. Schneider ◽  
E. Treister ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
X Ray ◽  
Star Forming ◽  
Number Counts

scholarly journals Atacama Cosmology Telescope: Dusty Star-forming Galaxies and Active Galactic Nuclei in the Equatorial Survey

2020 ◽  
Vol 893 (2) ◽  
pp. 104 ◽  
Author(s):  
Megan B. Gralla ◽  
Tobias A. Marriage ◽  
Graeme Addison ◽  
Andrew J. Baker ◽  
J. Richard Bond ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Atacama Cosmology Telescope ◽  
Star Forming

scholarly journals VSOP, A Space VLBI Programme

1990 ◽  
Vol 123 ◽  
pp. 263-269
Author(s):  
H. Hirabayashi
Keyword(s):  
Active Galactic Nuclei ◽  
Phase Transfer ◽  
Galactic Nuclei ◽  
Satellite Orbit ◽  
Radio Sources ◽  
Space Observatory ◽  
Stellar Objects ◽  
Radio Observatory ◽  
Star Forming ◽  
Star Forming Regions

AbstractVSOP, VLBI Space Observatory Programme, is an approved space VLBI programme of ISAS for the study of very compact radio sources with the synthesized aperture of 30,000 km diameter, by connecting an orbiting radio observatory with ground radiotelescopes. The VSOP satellite carrying 10 m antenna with 1.6, 5, and 22 GHz band receivers will be launched in early 1995 by M-V rocket of ISAS into an eccentric orbit with 20,000 km in apogee height. The tracking network will be formed for the satellite orbit determination, phase transfer and IF down-link. VSOP aims imaging capability with best resolution of 0.0001 arc second in 22 GHz band. Imaging of active galactic nuclei, star forming regions and stellar objects, and radioastrometry are main scientific targets.

scholarly journals Obscured active galactic nuclei triggered in compact star-forming galaxies

2016 ◽  
Vol 466 (1) ◽  
pp. L103-L107 ◽  
Author(s):  
Yu-Yen Chang ◽  
Emeric Le Floc'h ◽  
Stéphanie Juneau ◽  
Elisabete da Cunha ◽  
Mara Salvato ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Compact Star ◽  
Galactic Nuclei ◽  
Star Forming
Sign in / Sign up

Export Citation Format

Share Document