Extragalactic class I methanol maser: A new probe for starbursts and feedback of galaxies

2017 ◽  
Vol 13 (S336) ◽  
pp. 99-104
Author(s):  
Xi Chen ◽  
Simon P. Ellingsen
Keyword(s):  
Active Galactic Nuclei ◽  
Angular Resolution ◽  
Galactic Nuclei ◽  
Active Galaxies ◽  
Class I ◽  
High Angular Resolution ◽  
Methanol Maser ◽  
Methanol Masers

AbstractWe report progress on research relating to 36.2 GHz extragalactic class I methanol masers, including a review of published work and new observations at high angular resolution. These observations reveal that extragalactic class I masers are excited in shocked gas and maybe associated with starbursts, galactic-scale outflows from active galactic nuclei (AGNs) feedback, or the inner-end region of the galactic bar. The current observational results suggests that extragalactic class I methanol masers provide a new probe for starbursts and feedback in active galaxies.

scholarly journals Interferometry of class I methanol masers, statistics and the distance scale

2017 ◽  
Vol 13 (S336) ◽  
pp. 158-161
Author(s):  
Maxim A. Voronkov ◽  
Shari L. Breen ◽  
Simon P. Ellingsen ◽  
Christopher H. Jordan
Keyword(s):  
Angular Resolution ◽  
Class I ◽  
High Angular Resolution ◽  
Current Form ◽  
Young Stellar Object ◽  
Linear Distance ◽  
Kinematic Method ◽  
Future Potential ◽  
Methanol Masers ◽  
Compact Array

AbstractThe Australia Telescope Compact Array (ATCA) participated in a number of survey programs to search for and image common class I methanol masers (at 36 and 44 GHz) with high angular resolution. In this paper, we discuss spatial and velocity distributions revealed by these surveys. In particular, the number of maser regions is found to fall off exponentially with the linear distance from the associated young stellar object traced by the 6.7-GHz maser, and the scale of this distribution is 263±15 milliparsec. Although this relationship still needs to be understood in the context of the broader field, it can be utilised to estimate the distance using methanol masers only. This new technique has been analysed to understand its limitations and future potential. It turned out, it can be very successful to resolve the ambiguity in kinematic distances, but, in the current form, is much less accurate (than the kinematic method) if used on its own.

scholarly journals Imaging of selected sources from the Methanol Multibeam Survey

2007 ◽  
Vol 3 (S242) ◽  
pp. 184-185
Author(s):  
D. Wong-McSweeney ◽  
G. A. Fuller ◽  
S. Etoka
Keyword(s):  
Angular Resolution ◽  
Galactic Plane ◽  
High Angular Resolution ◽  
Maser Emission ◽  
Methanol Maser ◽  
Preliminary Results ◽  
Methanol Masers ◽  
Maser Sources

AbstractHigh angular resolution observations are essential for understanding the nature of maser emission and the sources which excite it. Here we present preliminary results from MERLIN observations of three methanol masers from the Toruń survey. These MERLIN observations are being analysed as part of the interferometric component of the Methanol Multibeam (MMB) Survey which is surveying the Galactic plane at |b|≤2° for 6.67 GHz methanol maser sources.

scholarly journals NuSTAR observations of four nearby X-ray faint AGNs: low luminosity or heavy obscuration?

2020 ◽  
Vol 497 (1) ◽  
pp. 229-245 ◽  
Author(s):  
A Annuar ◽  
D M Alexander ◽  
P Gandhi ◽  
G B Lansbury ◽  
D Asmus ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Active Galactic Nuclei ◽  
Angular Resolution ◽  
Broad Band ◽  
Galactic Nuclei ◽  
Current Data ◽  
High Angular Resolution ◽  
X Ray ◽  
Ir Imaging ◽  
Nuclear Dust

ABSTRACT We present NuSTAR (Nuclear Spectroscopic Telescope Array) observations of four active galactic nuclei (AGNs) located within 15 Mpc. These AGNs, namely ESO 121-G6, NGC 660, NGC 3486, and NGC 5195, have observed X-ray luminosities of L2–10 keV,obs ≲ 1039 erg s−1, classifying them as low-luminosity AGN (LLAGN). We perform broad-band X-ray spectral analysis for the AGN by combining our NuSTAR data with Chandra or XMM–Newton observations to directly measure their column densities (NH) and infer their intrinsic power. We complement our X-ray data with archival and new high-angular resolution mid-infrared (mid-IR) data for all objects, except NGC 5195. Based on our X-ray spectral analysis, we found that both ESO 121-G6 and NGC 660 are heavily obscured (NH > 1023 cm−2; L2–10 keV,int ∼ 1041 erg s−1), and NGC 660 may be Compton thick. We also note that the X-ray flux and spectral slope for ESO 121-G6 have significantly changed over the last decade, indicating significant changes in the obscuration and potentially accretion rate. On the other hand, NGC 3486 and NGC 5195 appear to be unobscured and just mildly obscured, respectively, with L2–10 keV,int < 1039 erg s−1, i.e. genuine LLAGN. Both of the heavily obscured AGNs have Lbol > 1041 erg s−1 and λEdd ≳ 10−3, and are detected in high-angular resolution mid-IR imaging, indicating the presence of obscuring dust on nuclear scale. NGC 3486, however, is undetected in high-resolution mid-IR imaging, and the current data do not provide stringent constraints on the presence or absence of obscuring nuclear dust in the AGN.

JET CONFINEMENT BY NONLINEAR MAGNETO-TORSIONAL OSCILLATIONS

2008 ◽  
Vol 17 (10) ◽  
pp. 1695-1706
Author(s):  
G. S. BISNOVATYI-KOGAN
Keyword(s):  
Magnetic Field ◽  
Active Galactic Nuclei ◽  
Angular Resolution ◽  
Galactic Nuclei ◽  
Simplified Model ◽  
High Angular Resolution ◽  
Cylinder Axis ◽  
Azimuthal Magnetic Field ◽  
Torsional Oscillations ◽  
Oscillations Of A Cylinder

Many quasars and active galactic nuclei are connected with long, thin jets. When observed with high angular resolution, these jets show a structure with bright knots separated by relatively dark regions. We consider magnetic collimation, connected with torsional oscillations of a cylinder with elongated magnetic field, and periodically distributed initial rotation around the cylinder axis. The stabilizing azimuthal magnetic field is created here by torsional oscillations. An approximate, simplified model is developed. The parameters for which jets may be stabilized by torsional oscillations are estimated quantitatively.

scholarly journals The sharpest view of the local AGN population at mid-infrared wavelengths

2013 ◽  
Vol 9 (S304) ◽  
pp. 225-226
Author(s):  
Daniel Asmus ◽  
Sebastian F. Hönig ◽  
Poshak Gandhi ◽  
Alain Smette ◽  
Wolfgang J. Duschl
Keyword(s):  
Active Galactic Nuclei ◽  
Angular Resolution ◽  
Spatial Scales ◽  
Galactic Nuclei ◽  
High Angular Resolution ◽  
Mid Infrared ◽  
X Ray ◽  
Infrared Wavelengths ◽  
Photometric Measurements

AbstractWe present the largest mid-infrared (MIR) atlas of active galactic nuclei at sub-arcsec spatial scales containing 253 objects with a median redshift of 0.016. It comprises all available ground-based high-angular resolution MIR observations performed to date with 8-meter class telescopes and includes 895 photometric measurements. All types of AGN are present in the atlas, which also includes 80 per cent of the 9-month BAT AGN sample. Therefore, this atlas and its subsamples are very well-suited for AGN unification studies. A first application of the atlas is the extension of the MIR–X-ray luminosity correlation for AGN.

scholarly journals Radio spectral properties of cores and extended regions in blazars in the MHz regime

2019 ◽  
Vol 490 (4) ◽  
pp. 5798-5806 ◽  
Author(s):  
D d’Antonio ◽  
M Giroletti ◽  
G Giovannini ◽  
A Maini
Keyword(s):  
Radio Frequency ◽  
Active Galactic Nuclei ◽  
High Frequency ◽  
Spectral Properties ◽  
Gamma Ray ◽  
Angular Resolution ◽  
Low Frequency ◽  
Galactic Nuclei ◽  
High Angular Resolution ◽  
Murchison Widefield Array

ABSTRACT Low-frequency radio surveys allow in-depth studies and new analyses of classes of sources that were previously known and characterized only in other bands. In recent years, low radio frequency observations of blazars have become available as a result of new surveys, such as the GaLactic and Extragalactic All-sky Murchison Widefield Array (MWA) survey (GLEAM). We search for gamma-ray blazars in a low-frequency (ν < 240 MHz) survey, to characterize the spectral properties of the spatial components. We cross-correlate GLEAM with the fourth catalogue of active galactic nuclei (4LAC) detected by the Fermi satellite. This improves on previous works by using a low-frequency catalogue that is wider and deeper, with a better spectral coverage and the latest and most sensitive gamma-ray source list. Compared with a previous study based on the commissioning survey, the detection rate increased from 35 to 70 per cent. We include data from the Australia Telescope 20-GHz (AT20G) survey in order to extract high-frequency high-angular resolution information about the radio cores of blazars. We find low radio frequency counterparts for 1274 out of 1827 blazars in the range of 72–231 MHz. Blazars have flat spectra at the ∼100-MHz regime, with a mean spectral index α = −0.44 ± 0.01 (assuming Sν ∝ να). Low synchrotron peaked objects have a flatter spectrum than high synchrotron peaked objects. Low frequency radio and gamma-ray emissions show a significant but scattered correlation. The ratio between lobe and core radio emission in gamma-ray blazars is smaller than previously estimated.

scholarly journals The next generation space VLBI project, VSOP-2

2007 ◽  
Vol 3 (S242) ◽  
pp. 517-521 ◽  
Author(s):  
Yasuhiro Murata ◽  
Nanako Mochizuki ◽  
Hirofumi Saito ◽  
Hisashi Hirabayashi ◽  
Makoto Inoue ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Angular Resolution ◽  
Galactic Nuclei ◽  
Continuum Emission ◽  
High Angular Resolution ◽  
Space Observatory ◽  
Space Agency ◽  
Maser Line ◽  
Successful Launch ◽  
Astronomical Satellite

AbstractThe first dedicated space-VLBI project, the VLBI Space Observatory Programme (VSOP), commenced with the successful launch of radio-astronomical satellite HALCA in 1997. Plans for a second generation space-VLBI project have been made by a working group over a number of years. This project, VSOP-2, has now been approved by Japan's space agency, JAXA, as the ASTRO-G project. It is planned for the spacecraft to observe in the 8, 22 and 43 GHz bands with cooled receivers for the two higher bands, which include important maser lines. It will have a maximum angular resolution at 43 GHz (7 mm) of about 40 micro-arcseconds. Although the VSOP project mainly observed continuum emission from active galactic nuclei (AGN), VSOP-2/ASTRO-G is expected to enable a variety of high angular resolution maser line observations.

Statistical analysis of the physical properties of the 6.7 GHz methanol maser features based on VLBI data

2017 ◽  
Vol 13 (S336) ◽  
pp. 321-322 ◽  
Author(s):  
R. Sarniak ◽  
M. Szymczak ◽  
A. Bartkiewicz
Keyword(s):  
Statistical Analysis ◽  
Star Formation ◽  
Physical Properties ◽  
Angular Resolution ◽  
High Mass ◽  
High Angular Resolution ◽  
Mass Star ◽  
Methanol Maser ◽  
Vlbi Data ◽  
Methanol Masers

AbstractMethanol masers observed at high angular resolution are useful tool to investigate the processes of high-mass star formation. Here, we present the results of statistical analysis of the 6.7 GHz methanol maser structures in 60 sources observed with the EVN. The parameters of the maser clouds and exciting stars were derived. There is evidence that the emission structures composed of larger number of maser clouds are formed in the vicinity of more luminous exciting stars.

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