We present radio spectral analyses for a sample of 29 radio-quiet (RQ) and three radio-loud (RL) narrow-line Seyfert 1 galaxies (NLS1s) detected with the Australia Telescope Compact Array at both 5.5 and 9.0 GHz. The sample is characterized by Lbol/LEdd > 0.15. The radio slopes in 25 of the 29 RQ NLS1s are steep (α5.5–9.0 < −0.5), as found in earlier studies of RQ high Lbol/LEdd active galactic nuclei (AGN). This steep radio emission may be related to AGN-driven outflows, which are likely more prevalent in high Lbol/LEdd AGN. In two of the three RL NLS1s, the radio slopes are flat or inverted (α5.5–9.0 > −0.5), indicating a compact optically thick source, likely a relativistic jet. Archival data at 3.0, 1.4, and 0.843 GHz are also compiled, yielding a sample of 17 NLS1s detected in three bands or more. In nine objects, the radio spectra flatten at lower frequencies, with median slopes of α5.5–9.0 = −1.21 ± 0.17, flattening to α3.0–5.5 = −0.97 ± 0.27, and to α1.4–3.0 = −0.63 ± 0.16. A parabolic fit suggests a median spectral turnover of ∼1 GHz, which implies synchrotron self-absorption in a source with a size of only a fraction of 1 pc, possibly a compact wind or a weak jet. Two objects show significant spectral steepening to α < −2 above 3 or 5 GHz, which may suggest relic emission from past ejection of radio emitting plasma, of the order of a few years to a few decades ago. Finally, two objects present a single spectral slope consistent with star-forming activity.
- Home
- Search Results
- Page 1 of 1
Search for: All records
-
Total Resources2
- Resource Type
-
00020
- Availability
-
20
- Author / Contributor
- Filter by Author / Creator
-
-
Berton, Marco (2)
-
Andrews, Jennifer E. (1)
-
Anupama, G. C. (1)
-
Arcavi, I. (1)
-
Ashall, Chris (1)
-
Behar, Ehud (1)
-
Benetti, S. (1)
-
Bostroem, K. A. (1)
-
Brown, P. J. (1)
-
Bulla, M. (1)
-
Burke, J. (1)
-
Chen, S. (1)
-
Chen, Sina (1)
-
Chomiuk, L. (1)
-
Cikota, A. (1)
-
Congiu, E. (1)
-
Cseh, B. (1)
-
Dastidar, Raya (1)
-
Davis, Scott (1)
-
Edwards, Philip G. (1)
-
- Filter by Editor
-
-
& Spizer, S. M. (0)
-
& . Spizer, S. (0)
-
& Ahn, J. (0)
-
& Bateiha, S. (0)
-
& Bosch, N. (0)
-
& Brennan K. (0)
-
& Brennan, K. (0)
-
& Chen, B. (0)
-
& Chen, Bodong (0)
-
& Drown, S. (0)
-
& Ferretti, F. (0)
-
& Higgins, A. (0)
-
& J. Peters (0)
-
& Kali, Y. (0)
-
& Ruiz-Arias, P.M. (0)
-
& S. Spitzer (0)
-
& Sahin. I. (0)
-
& Spitzer, S. (0)
-
& Spitzer, S.M. (0)
-
(submitted - in Review for IEEE ICASSP-2024) (0)
-
-
Have feedback or suggestions for a way to improve these results?
!
Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher.
Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?
Some links on this page may take you to non-federal websites. Their policies may differ from this site.
-
ABSTRACT -
Andrews, Jennifer E. ; Sand, D. J. ; Valenti, S. ; Smith, Nathan ; Dastidar, Raya ; Sahu, D. K. ; Misra, Kuntal ; Singh, Avinash ; Hiramatsu, D. ; Brown, P. J. ; et al ( , The Astrophysical Journal)We present high-cadence UV, optical, and near-infrared data on the luminous Type II-P supernova SN 2017gmr from hours after discovery through the first 180 days. SN 2017gmr does not show signs of narrow, high-ionization emission lines in the early optical spectra, yet the optical light-curve evolution suggests that an extra energy source from circumstellar medium (CSM) interaction must be present for at least 2 days after explosion. Modeling of the early light curve indicates a ∼ 500 Re progenitor radius, consistent with a rather compact red supergiant, and late-time luminosities indicate that up to 0.130 ± 0.026 Me of 56Ni are present, if the light curve is solely powered by radioactive decay, although the 56Ni mass may be lower if CSM interaction contributes to the post-plateau luminosity. Prominent multipeaked emission lines of Hα and [O I] emerge after day 154, as a result of either an asymmetric explosion or asymmetries in the CSM. The lack of narrow lines within the first 2 days of explosion in the likely presence of CSM interaction may be an example of close, dense, asymmetric CSM that is quickly enveloped by the spherical supernova ejecta.more » « less