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A S Evans - One of the best experts on this subject based on the ideXlab platform.
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a new detection of extragalactic anomalous microwave emission in a compact optically faint region of ngc 4725
The Astrophysical Journal, 2018Co-Authors: E J Murphy, S T Linden, Dillon Dong, Brandon S Hensley, Emmanuel Momjian, G Helou, A S EvansAbstract:We discuss the nature of a discrete, compact Radio source (NGC 4725 B) located ≈1.9 kpc from the nucleus in the nearby star-forming galaxy NGC 4725, which we believe to be a new detection of extragalactic anomalous microwave emission (AME). Based on detections at 3, 15, 22, 33, and 44 GHz, NGC 4725 B is a microjansky Radio source peaking at ≈33 GHz. While the source is not identified in optical (BVRI) photometry, we detect counterparts in the midinfrared Spitzer/IRAC bands (3.6, 4.5, 5.8, 8.0 μm) that appear to be associated with dust emission in the central region of NGC 4725. Consequently, we conclude that NGC 4725 B is a new detection of AME and is very similar to a recent detection of AME in an outer-disk star-forming region in NGC 6946. We find that models of electric dipole emission from rapidly rotating ultra-small grains are able to reproduce the Radio Spectrum for reasonable interstellar medium conditions. Given the lack of an optical counterpart and the shape of the Radio Spectrum, NGC 4725 B appears consistent with a nascent star-forming region in which young (≾ 3 Myr) massive stars are still highly enshrouded by their natal cocoons of gas and dust with insufficient supernovae occurring to produce a measurable amount of synchrotron emission.
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a new detection of extragalactic anomalous microwave emission in a compact optically faint region of ngc 4725
arXiv: Astrophysics of Galaxies, 2018Co-Authors: E J Murphy, S T Linden, Dillon Dong, Brandon S Hensley, Emmanuel Momjian, G Helou, A S EvansAbstract:We discuss the nature of a discrete, compact Radio source (NGC 4725 B) located $\approx$1.9 kpc from the nucleus in the nearby star-forming galaxy NGC 4725, which we believe to be a new detection of extragalactic Anomalous Microwave Emission (AME). Based on detections at 3, 15, 22, 33, and 44 GHz, NGC 4725 B is a $\mu$Jy Radio source peaking at $\approx$33 GHz. While the source is not identified in $BVRI$ photometry, we detect counterparts in the mid-infrared $Spitzer$/IRAC bands (3.6, 4.5, 5.8, 8.0 $\mu$m) that appear to be associated with dust emission in the central region of NGC 4725. Consequently, we conclude that NGC 4725 B is a new detection of AME, and very similar to a recent detection of AME in an outer-disk star-forming region in NGC 6946. We find that models of electric dipole emission from rapidly rotating ultra-small grains are able to reproduce the Radio Spectrum for reasonable interstellar medium conditions. Given the lack of an optical counterpart and the shape of the Radio Spectrum, NGC 4725 B appears consistent with a nascent star-forming region in which young ($\lesssim 3$ Myr) massive stars are still highly enshrouded by their natal cocoons of gas and dust with insufficient supernovae occurring to produce a measurable amount of synchrotron emission.
E J Murphy - One of the best experts on this subject based on the ideXlab platform.
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a new detection of extragalactic anomalous microwave emission in a compact optically faint region of ngc 4725
The Astrophysical Journal, 2018Co-Authors: E J Murphy, S T Linden, Dillon Dong, Brandon S Hensley, Emmanuel Momjian, G Helou, A S EvansAbstract:We discuss the nature of a discrete, compact Radio source (NGC 4725 B) located ≈1.9 kpc from the nucleus in the nearby star-forming galaxy NGC 4725, which we believe to be a new detection of extragalactic anomalous microwave emission (AME). Based on detections at 3, 15, 22, 33, and 44 GHz, NGC 4725 B is a microjansky Radio source peaking at ≈33 GHz. While the source is not identified in optical (BVRI) photometry, we detect counterparts in the midinfrared Spitzer/IRAC bands (3.6, 4.5, 5.8, 8.0 μm) that appear to be associated with dust emission in the central region of NGC 4725. Consequently, we conclude that NGC 4725 B is a new detection of AME and is very similar to a recent detection of AME in an outer-disk star-forming region in NGC 6946. We find that models of electric dipole emission from rapidly rotating ultra-small grains are able to reproduce the Radio Spectrum for reasonable interstellar medium conditions. Given the lack of an optical counterpart and the shape of the Radio Spectrum, NGC 4725 B appears consistent with a nascent star-forming region in which young (≾ 3 Myr) massive stars are still highly enshrouded by their natal cocoons of gas and dust with insufficient supernovae occurring to produce a measurable amount of synchrotron emission.
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a new detection of extragalactic anomalous microwave emission in a compact optically faint region of ngc 4725
arXiv: Astrophysics of Galaxies, 2018Co-Authors: E J Murphy, S T Linden, Dillon Dong, Brandon S Hensley, Emmanuel Momjian, G Helou, A S EvansAbstract:We discuss the nature of a discrete, compact Radio source (NGC 4725 B) located $\approx$1.9 kpc from the nucleus in the nearby star-forming galaxy NGC 4725, which we believe to be a new detection of extragalactic Anomalous Microwave Emission (AME). Based on detections at 3, 15, 22, 33, and 44 GHz, NGC 4725 B is a $\mu$Jy Radio source peaking at $\approx$33 GHz. While the source is not identified in $BVRI$ photometry, we detect counterparts in the mid-infrared $Spitzer$/IRAC bands (3.6, 4.5, 5.8, 8.0 $\mu$m) that appear to be associated with dust emission in the central region of NGC 4725. Consequently, we conclude that NGC 4725 B is a new detection of AME, and very similar to a recent detection of AME in an outer-disk star-forming region in NGC 6946. We find that models of electric dipole emission from rapidly rotating ultra-small grains are able to reproduce the Radio Spectrum for reasonable interstellar medium conditions. Given the lack of an optical counterpart and the shape of the Radio Spectrum, NGC 4725 B appears consistent with a nascent star-forming region in which young ($\lesssim 3$ Myr) massive stars are still highly enshrouded by their natal cocoons of gas and dust with insufficient supernovae occurring to produce a measurable amount of synchrotron emission.
Zhuo Chen - One of the best experts on this subject based on the ideXlab platform.
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convolutional neural network for classification of solar Radio Spectrum
International Conference on Multimedia and Expo, 2017Co-Authors: Sisi Chen, Long Xu, Weiqiang Zhang, Zhuo ChenAbstract:This paper makes the first attempt to utilize convolutional neural network (CNN) for classification of solar Radio Spectrums. The solar Radio Spectrum is a two-dimensional gray-scale image with one dimension of frequency and the other of time. Taking the advantages of CNN, we can efficiently learn the distinct characteristic of different types of Spectrum, and further classify them even more accurate. The proposed CNN-based network consists of four convolution layers, four pooling layers and one fully connected layer. Its input is Spectrums of the size 120×120. The output gives the type of each Spectrum among “burst”, “non-burst” and “calibration”. Experimental results demonstrate that the proposed CNN can achieve more accuracy of classification of solar Radio Spectrum beyond our previous efforts by employing deep belief network (DBN) and autoencoder (AE).
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Multimodal deep learning for solar Radio burst classification
Pattern Recognition, 2017Co-Authors: Zhuo Chen, Yihua YanAbstract:Abstract In this paper, multimodal deep learning for solar Radio burst classification is proposed. We make the first attempt to build multimodal learning network to learn the joint representation of the solar Radio Spectrums captured from different frequency channels, which are treated as different modalities. In order to learn the representation of each modality and the correlation and interaction between different modalities, autoencoder together with the structured regularization is used to enforce and learn the modality-specific sparsity and density of each modality, respectively. Fully connected layers are further employed to exploit the relationships between different modalities for the joint representation generation of the solar Radio Spectrums. Based on the learned joint representation, solar Radio burst classification is performed. With the validation on the constructed solar Radio Spectrum database, experimental results have demonstrated that the proposed multimodal learning network can effectively learn the representation of the solar Radio Spectrum, and improve the classification accuracy.
Thomas W Hazlett - One of the best experts on this subject based on the ideXlab platform.
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exactitude in defining rights Radio Spectrum and the harmful interference conundrum
Berkeley Technology Law Journal, 2013Co-Authors: Thomas W HazlettAbstract:In the century since the Radio Act of 1912 initiated U.S. Spectrum allocation rules, a precise definition of “harmful interference”—the control of which forms the rationale for regulation—has eluded policymakers. In one sense, that result is unsurprising; rights are always defined incompletely. In another sense, however, the regulatory system is dysfunctional, severely limiting the productive use of Spectrum while locked down in yearslong border disputes. These disagreements have, in turn, triggered calls to develop brighter lines and fuller engineering specifications of harmful interference. However, this emphasis on exact definitions is misguided. Spectrum use rights generate more robust market development when they feature technically fuzzy borders but are awarded in economically efficient bundles. The key ingredients are (a) exclusive, flexible rights; (b) frequency borders set via standardized edge emission limits; (c) large bundles of complementary rights that limit fragmentation; and (d) fluid secondary trading that allows mergers to end border disputes by eliminating borders. Regulators should focus less on delineating precise interference contours, and instead expeditiously distribute standard bandwidth rights to economically responsible agents, taking care to avoid undue fragmentation (and tragedy of the anticommons). Many episodes illustrate these lessons, including those involving reallocation of the broadcast TV band, the emergence of HD Radio, the Nextel/public safety “Spectrum swap,” and the ongoing WCS/SDARS dispute. Each instance reveals that economic incentives, not engineering complexity, drive—or block—productive coordination of Radio Spectrum use. © 2013 Thomas W. Hazlett and Sarah Oh. All Rights Reserved. † Professor of Law and Economics, George Mason University School of Law; FCC Chief Economist, 1991–1992. This Article follows from a presentation on Creating Efficient Spectrum Property, Towards an Economic Definition of “Harmful Interference” in Radio Transmissions, Presentation at the Conference on Spectrum Markets: Challenges Ahead, Kellogg School of Management, Northwestern University (June 2–3, 2011). The author thanks Brent Skorup for excellent research assistance. †† Research Fellow, Information Economy Project. Ph.D. Student in Economics, George Mason University; J.D. George Mason University; B.S. Stanford University, Management Science & Engineering. 0227-0340_HAZLETT_081313_WEB (DO NOT DELETE) 8/13/2013 5:00 PM 228 BERKELEY TECHNOLOGY LAW JOURNAL [Vol. 28:227
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exactitude in defining rights Radio Spectrum and the harmful interference conundrum
Social Science Research Network, 2012Co-Authors: Thomas W HazlettAbstract:In the century since the Radio Act of 1912 initiated U.S. Spectrum allocation rules, a precise definition of “harmful interference” – the control of which forms the rationale for regulation – has eluded policymakers. In one sense, that result is unsurprising; rights are always defined incompletely. In another sense, however, the regulatory system is dysfunctional, severely limiting the productive use of Spectrum while locked down in years-long border disputes. These disagreements have, in turn, triggered calls to develop brighter lines and fuller engineering specifications of “harmful interference.” Yet, Spectrum use rights featuring technically fuzzy borders, awarded in economically efficient bundles, generate robust market development. The key ingredients are (a) exclusive, flexible use rights; (b) frequency borders set via standardized edge emission limits; (c) large bundles of complementary rights, limiting fragmentation; and (d) fluid secondary trading, allowing mergers to end border disputes by eliminating borders. Regulators should focus less on delineating precise interference contours, and instead expeditiously distribute standard bandwidth rights to economically responsible agents, taking care to avoid undue fragmentation (and tragedy of the anti-commons). These lessons are illustrated in many episodes, including those involving reallocation of the broadcast TV band, the emergence of HD Radio, the Nextel/public safety “Spectrum swap,” and the ongoing WCS/SDARS dispute. Each instance reveals that economic incentives, not engineering complexity, drives productive coordination of Radio Spectrum use – or blocks it.
G Helou - One of the best experts on this subject based on the ideXlab platform.
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a new detection of extragalactic anomalous microwave emission in a compact optically faint region of ngc 4725
The Astrophysical Journal, 2018Co-Authors: E J Murphy, S T Linden, Dillon Dong, Brandon S Hensley, Emmanuel Momjian, G Helou, A S EvansAbstract:We discuss the nature of a discrete, compact Radio source (NGC 4725 B) located ≈1.9 kpc from the nucleus in the nearby star-forming galaxy NGC 4725, which we believe to be a new detection of extragalactic anomalous microwave emission (AME). Based on detections at 3, 15, 22, 33, and 44 GHz, NGC 4725 B is a microjansky Radio source peaking at ≈33 GHz. While the source is not identified in optical (BVRI) photometry, we detect counterparts in the midinfrared Spitzer/IRAC bands (3.6, 4.5, 5.8, 8.0 μm) that appear to be associated with dust emission in the central region of NGC 4725. Consequently, we conclude that NGC 4725 B is a new detection of AME and is very similar to a recent detection of AME in an outer-disk star-forming region in NGC 6946. We find that models of electric dipole emission from rapidly rotating ultra-small grains are able to reproduce the Radio Spectrum for reasonable interstellar medium conditions. Given the lack of an optical counterpart and the shape of the Radio Spectrum, NGC 4725 B appears consistent with a nascent star-forming region in which young (≾ 3 Myr) massive stars are still highly enshrouded by their natal cocoons of gas and dust with insufficient supernovae occurring to produce a measurable amount of synchrotron emission.
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a new detection of extragalactic anomalous microwave emission in a compact optically faint region of ngc 4725
arXiv: Astrophysics of Galaxies, 2018Co-Authors: E J Murphy, S T Linden, Dillon Dong, Brandon S Hensley, Emmanuel Momjian, G Helou, A S EvansAbstract:We discuss the nature of a discrete, compact Radio source (NGC 4725 B) located $\approx$1.9 kpc from the nucleus in the nearby star-forming galaxy NGC 4725, which we believe to be a new detection of extragalactic Anomalous Microwave Emission (AME). Based on detections at 3, 15, 22, 33, and 44 GHz, NGC 4725 B is a $\mu$Jy Radio source peaking at $\approx$33 GHz. While the source is not identified in $BVRI$ photometry, we detect counterparts in the mid-infrared $Spitzer$/IRAC bands (3.6, 4.5, 5.8, 8.0 $\mu$m) that appear to be associated with dust emission in the central region of NGC 4725. Consequently, we conclude that NGC 4725 B is a new detection of AME, and very similar to a recent detection of AME in an outer-disk star-forming region in NGC 6946. We find that models of electric dipole emission from rapidly rotating ultra-small grains are able to reproduce the Radio Spectrum for reasonable interstellar medium conditions. Given the lack of an optical counterpart and the shape of the Radio Spectrum, NGC 4725 B appears consistent with a nascent star-forming region in which young ($\lesssim 3$ Myr) massive stars are still highly enshrouded by their natal cocoons of gas and dust with insufficient supernovae occurring to produce a measurable amount of synchrotron emission.
