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1. A global view on star formation: The GLOSTAR Galactic plane survey: IV. Radio continuum detections of young stellar objects in the Galactic Centre region

   https://doi.org/10.1051/0004-6361/202140802  

   Nguyen, H. ; Rugel, M. R. ; Menten, K. M. ; Brunthaler, A. ; Dzib, S. A. ; Yang, A. Y. ; Kauffmann, J. ; Pillai, T. G. ; Nandakumar, G. ; Schultheis, M. ; et al ( July 2021 , Astronomy & Astrophysics)

   Context. The Central Molecular Zone (CMZ), a ∼200 pc sized region around the Galactic Centre, is peculiar in that it shows a star formation rate (SFR) that is suppressed with respect to the available dense gas. To study the SFR in the CMZ, young stellar objects (YSOs) can be investigated. Here we present radio observations of 334 2.2 μm infrared sources that have been identified as YSO candidates. Aims: Our goal is to investigate the presence of centimetre wavelength radio continuum counterparts to this sample of YSO candidates which we use to constrain the current SFR in the CMZ. Methods: As part of the GLObal view on STAR formation (GLOSTAR) survey, D-configuration Very Large Array data were obtained for the Galactic Centre, covering −2° < l < 2° and −1° < b < 1° with a frequency coverage of 4-8 GHz. We matched YSOs with radio continuum sources based on selection criteria and classified these radio sources as potential H II regions and determined their physical properties. Results: Of the 334 YSO candidates, we found 35 with radio continuum counterparts. We find that 94 YSOs are associated with dense dust condensations identified in the 870 μm ATLASGAL survey, of which 14 have a GLOSTAR counterpart. Of the 35 YSOs with radio counterparts, 11 are confirmed as H II regions based on their spectral indices and the literature. We estimated their Lyman continuum photon flux in order to estimate the mass of the ionising star. Combining these with known sources, the present-day SFR in the CMZ is calculated to be ∼0.068 M⊙ yr−1, which is ∼6.8% of the Galactic SFR. Candidate YSOs that lack radio counterparts may not have yet evolved to the stage of exhibiting an H II region or, conversely, are older and have dispersed their natal clouds. Since many lack dust emission, the latter is more likely. Our SFR estimate in the CMZ is in agreement with previous estimates in the literature. 

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2. Galactic Extinction: How Many Novae Does It Hide and How Does It Affect the Galactic Nova Rate?

   https://doi.org/10.3847/1538-4357/ac1f1a  

   Kawash, A. ; Chomiuk, L. ; Rodriguez, J. A. ; Strader, J. ; Sokolovsky, K. V. ; Aydi, E. ; Kochanek, C. S. ; Stanek, K. Z. ; Mukai, K. ; De, K. ; et al ( November 2021 , The Astrophysical Journal)

   Abstract There is a long-standing discrepancy between the observed Galactic classical nova rate of ∼10 yr −1 and the predicted rate from Galactic models of ∼30–50 yr −1 . One explanation for this discrepancy is that many novae are hidden by interstellar extinction, but the degree to which dust can obscure novae is poorly constrained. We use newly available all-sky three-dimensional dust maps to compare the brightness and spatial distribution of known novae to that predicted from relatively simple models in which novae trace Galactic stellar mass. We find that only half (53%) of the novae are expected to be easily detectable ( g ≲ 15) with current all-sky optical surveys such as the All-Sky Automated Survey for Supernovae (ASAS-SN). This fraction is much lower than previously estimated, showing that dust does substantially affect nova detection in the optical. By comparing complementary survey results from the ASAS-SN, OGLE-IV, and Palomar Gattini IR surveys using our modeling, we find a tentative Galactic nova rate of ∼30 yr −1 , though this could be as high as ∼40 yr −1 , depending on the assumed distribution of novae within the Galaxy. These preliminary estimates will be improved in future work through more sophisticated modeling of nova detection in ASAS-SN and other surveys. 

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3. The Detectability of Kiloparsec-scale Dual Active Galactic Nuclei: The Impact of Galactic Structure and Black Hole Orbital Properties

   https://doi.org/10.3847/1538-4357/ac06a0  

   Li, Kunyang ; Ballantyne, David R. ; Bogdanović, Tamara ( August 2021 , The Astrophysical Journal)
4. IceCube Search for Galactic Neutrino Sources based on HAWC Observations of the Galactic Plane

   https://doi.org/10.22323/1.358.0932  

   Kheirandish, Ali ; Wood, Joshua ( January 2020 , Pos proceedings of science)
5. The environmental dependence of the stellar mass of active galactic nucleus host galaxies and dependence of the clustering properties of active galactic nucleus host galaxies on the stellar mass

   https://doi.org/10.1002/asna.202113861  

   Deng, Xin‐Fa ; Wen, Xiao‐Qing ( June 2021 , Astronomische Nachrichten)

   We used two volume‐limited active galactic nucleus (AGN) host galaxy samples constructed by Deng & Wen (2020,RMxAA, 56, 87), and explored the environmental dependence of the stellar mass of AGN host galaxies. In the luminous volume‐limited AGN host galaxy sample, the stellar mass of AGN host galaxies apparently depends on local environments: high mass AGN host galaxies exist preferentially in the dense regions of the universe, while low mass AGN host galaxies are located preferentially in low density regions. But in the faint volume‐limited AGN host galaxy sample, this dependence is fairly weak. We also examined the dependence of the clustering properties of AGN host galaxies on the stellar mass by cluster analysis, and found that in the luminous volume‐limited AGN host galaxy sample, low mass AGN host galaxies preferentially form isolated galaxies, close pairs, and small groups, while high mass AGN host galaxies preferentially inhabit the dense groups and clusters. A substantial dependence of the clustering properties of AGN host galaxies on the stellar mass is also observed in the faint volume‐limited AGN host galaxy sample, which is inconsistent with the environmental dependence of the stellar mass of AGN host galaxies in the faint volume‐limited AGN host galaxy sample. This is likely due to the galaxy number of the faint volume‐limited AGN host galaxy sample being too small to ensure an ideal statistical analysis.

    

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