Article
Astronomy & Astrophysics
Yu-Qing Lou, Ming Lin
Summary: This study investigates the hydrodynamic behavior of filamentary clouds obeying a general polytropic equation of state, including collapses, expansions, and shocks. Analytical and numerical similarity solutions are explored for cylindrical models, with a focus on asymptotic dynamic solutions, sonic critical curves, and global features such as envelope expansion or contraction. New types of global similarity solutions, with or without outgoing shocks, are numerically constructed, providing insights into the collapse and fragmentation of massive filaments and their implications for the formation of chains of stellar objects, black holes, galaxies, or galaxy clusters in cosmological contexts.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
R. Siebenmorgen
Summary: Distance estimates are unified by considering extinction by large grains and adding a population of dark dust to models of the interstellar medium. The dark dust model explains the typical reddening, extinction, and light emission at different wavelengths by interstellar dust particles. Dark dust consists of micrometer-sized particles and contributes to reddening in the far-UV to near-infrared range. It also re-emits light in the submillimeter region at very cold temperatures. The presence of dark dust has implications for understanding supernova Ia light curves and the unification of distance scales.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Qian Jiao, Yu Gao, Yinghe Zhao
Summary: The study estimated the conversion factors of [CI]-to-H2 and CO-to-H2 at a linear resolution scale for six nearby galaxies and found that alpha([CI](2 - 1)) and alpha(CO) values decrease in the inner regions of galaxies. Metallicity and infrared luminosity moderately correlate with alpha(CO), whereas there is only weak correlation with alpha([CI](1 - 0)) or carbon abundance, and no correlation with alpha([CI](2 - 1)).
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Ka Ho Yuen, Avi Chen, Ka Wai Ho, Alex Lazarian
Summary: A recent study using high-resolution observations from the Five-hundred-meter Aperture Spherical radio Telescope has identified a large filamentary neutral hydrogen feature called Cattail, which may be a new galactic arm in the Milky Way. The researchers analyzed the turbulent and phase properties of Cattail using a new Velocity Decomposition Algorithm and Force Balancing Model and found that it is unlikely to be in the cold neutral media phase if a phase transition exists. They also discovered that Cattail consists of two separate features in caustics space, indicating the presence of two distinct turbulent systems. The researchers confirmed their argument through spectral analysis of the individual systems separated using the Velocity Decomposition Algorithm and did not rule out the possibility of smaller scale cold media within this structure.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Ka Wai Ho, Ka Ho Yuen, Alex Lazarian
Summary: A new type of instability caused by the attractive nature of pressure force in the unstable phase has been recognized. The average aspect ratio of cold neutral medium (CNM) filaments is estimated to be around 5-20, which is smaller than predicted or observed. This suggests that the 'cold filaments' identified in observations might not be in pressure equilibrium or generated via other mechanisms.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
K. W. Ho, A. Lazarian
Summary: The recent development of the velocity gradient technique has shown its capability in tracing magnetic field morphology in diffuse interstellar gas and molecular clouds. This paper systematically studies the performance of velocity and synchrotron gradient at various levels of magnetization in a subsonic environment. The formation of velocity caustics in spectroscopic channel maps in the presence of thermal broadening is also addressed, with the recovery of velocity caustics in the cold neutral medium and reliable magnetic field tracing using the gradient technique (GT). The changes in anisotropy of observed structure functions when applying GT analysis procedures are discussed.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Maria Galloway-Sprietsma, Yancy L. Shirley, James Di Francesco, Jared Keown, Samantha Scibelli, Olli Sipilae, Rachel Smullen
Summary: Understanding the chemical processes during starless core and prestellar core evolution is crucial for comprehending the initial stages of star and disc formation. This study examines deuterated ammonia in the L1251 star-forming region and finds no strong trends in deuterium fraction with any physical or evolutionary variables.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
H. Liszt, M. Gerin
Summary: This study investigates the atomic or molecular character of the dark neutral medium (DNM) by observing 33 background continuum sources. The HCO+ absorption is detected in 28 new directions, and CO emission is observed in 19 of them. The research finds that the DNM is predominantly molecular.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
E. Fiorellino, D. Elia, Ph Andre, A. Men'shchikov, S. Pezzuto, E. Schisano, V Konyves, D. Arzoumanian, M. Benedettini, D. Ward-Thompson, A. Bracco, J. Di Francesco, S. Bontemps, J. Kirk, F. Motte, S. Molinari
Summary: The Herschel Gould Belt survey investigated the distribution and characteristics of dense cores in the Serpens star-forming region, revealing the influence of the prestellar phase on the star formation process. The majority of prestellar cores were found to form on filamentary structures, supporting the hypothesis that prestellar cores mostly form on filaments.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
A. Maragkoudakis, E. Peeters, A. Ricca, C. Boersma
Summary: This study examines the dependence of polycyclic aromatic hydrocarbon (PAH) band intensity ratios on the average number of carbon atoms and assesses their effectiveness as tracers for PAH size using the NASA Ames PAH Infrared Spectroscopic Database. The research finds that band ratios including the 3.3 μm PAH band provide the best PAH size tracers for small-to-intermediate sized PAHs. Additionally, band ratios including the sum of the 15-20 μm PAH features and the 6.2 or 7.7 μm bands also serve as good tracers for PAH size in this range.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Tyler Schmaltz, Yue Hu, Alex Lazarian
Summary: Star formation is a complex process that occurs in dense regions of molecular clouds, and is regulated by magnetic fields, MHD turbulence, and self-gravity. The velocity gradient technique (VGT), based on the anisotropic properties of MHD turbulence, is proposed to trace the magnetic field and determine regions of gravitational collapse. In this study, the VGT is applied to two regions of the giant California Molecular Cloud (CMC) and the physical properties are analyzed.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Pooja Chahal, T. J. Dhilip Kumar
Summary: Computations are performed to obtain cross-sections and excitation rates of the PO+ species in interstellar molecular clouds. A new potential energy surface (PES) is constructed using ab initio methods and trained using neural networks to compute the rotational (de-)excitation cross-sections. The thermally averaged rate coefficients for rotational transitions are found, with the odd transitions favored.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Shu Liu, Junzhi Wang, Fei Li, Jingwen Wu, Zhi-Yu Zhang, Di Li, Ningyu Tang, Pei Zuo
Summary: Spatial variations of optical depths have been detected in Galactic massive star-forming regions. In this study, we mapped 51 Galactic massive star-forming regions using the SMT telescope and obtained reliable measurements of spatially resolved optical depths for 30 regions.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Kathryn Kreckel, Oleg Egorov, Francesco Belfiore, Brent Groves, Simon C. O. Glover, Ralf S. Klessen, Karin Sandstrom, Frank Bigiel, Daniel A. Dale, Kathryn Grasha, Fabian Scheuermann, Eva Schinnerer, Thomas G. Williams
Summary: This study developed and applied a new technique to infer electron temperatures of nebulae in 19 nearby spiral galaxies using the PHANGS-MUSE large program. The results revealed radial temperature gradients, increased homogeneity on small scales, and azimuthal temperature variations in the disks.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
H. Luthra, V Wakelam, M. K. Sharma, S. Chandra
Summary: Since the 1930s, more than 250 molecules have been discovered in the interstellar medium, and with the development of more sensitive telescopes, we keep detecting new, more complex species. Among them, methanimine (CH2NH) is considered a pre-biotic molecule and has been observed in various interstellar sources. However, previous models failed in reproducing the observed abundance of CH2NH in cold cores. In this study, we tested new proposed reactions and explored the sensitivity of CH2NH abundance to different factors, and successfully reproduced the detections in cold cores Ori-3N and L183.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
G. Marti-Devesa, O. Reimer, J. Li, D. F. Torres
ASTRONOMY & ASTROPHYSICS
(2020)
Article
Astronomy & Astrophysics
E. Mestre, E. de Ona Wilhelmi, R. Zanin, D. F. Torres, L. Tibaldo
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2020)
Article
Astronomy & Astrophysics
D. de Martino, A. Papitto, M. Burgay, A. Possenti, F. Coti Zelati, N. Rea, D. F. Torres, T. M. Belloni
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2020)
Article
Astronomy & Astrophysics
B. Olmi, D. F. Torres
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2020)
Editorial Material
Astronomy & Astrophysics
Diego F. Torres, Shuang-Nan Zhang
JOURNAL OF HIGH ENERGY ASTROPHYSICS
(2020)
Article
Astronomy & Astrophysics
Jian Li, Diego F. Torres, Ruo-Yu Liu, Matthew Kerr, Emma de Ona Wilhelmi, Yang Su
Article
Astronomy & Astrophysics
Harsha Blumer, Samar Safi-Harb, Alice Borghese, Jonatan Martin, Maura A. McLaughlin, Diego F. Torres, George Younes
Summary: The article reports on a deep Chandra observation of the high-magnetic-field pulsar J1119-6127 and its compact pulsar wind nebula, revealing that the pulsar has returned to quiescence after the outburst and the nebula shows evidence of spectral softening post-outburst. This suggests that magnetar outbursts can impact pulsar wind nebulae, with a rapidly cooling process leading to a return to quiescence within just a few years.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Jian Li, Ruo-Yu Liu, Emma de Ona Wilhelmi, Diego F. Torres, Qian-Cheng Liu, Matthew Kerr, Rolf Buehler, Yang Su, Hao-Ning He, Meng-Yuan Xiao
Summary: The multiwavelength analysis of the unidentified TeV source MGRO J1908+06 showed an extended GeV source as its counterpart and possibly associated with molecular clouds. The GeV spectrum exhibits two components, with the lower-energy part likely related to nearby dense molecular clouds and the higher-energy component resembling inverse Compton emission. This scenario provides a satisfactory explanation for the data observed, but raises questions about the interpretation of emission at hundreds of TeV.
ASTROPHYSICAL JOURNAL LETTERS
(2021)
Article
Astronomy & Astrophysics
Daniel Iniguez-Pascual, Diego F. Torres, Daniele Vigano
Summary: The period and period derivative of a pulsar are crucial for defining the magnetospheric size and plasma dynamics. These timing properties are closely related to the radiative properties of pulsars and can be used to constrain the timing properties of potential pulsar candidates among unidentified gamma-ray sources. Using a radiative synchro-curvature model, it is found that the spin period of pulsars can be constrained within a range of about 1 order of magnitude in the majority of cases.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Daniel Iniguez-Pascual, Daniele Vigano, Diego F. Torres
Summary: In this study, the existing synchro-curvature radiation model is improved by better handling of particle injection and implementing a fast and accurate minimization technique. The results show that most of the detected X-ray radiation in high-energy pulsars is produced in a small fraction of their trajectory, and synchrotron radiation is significant for most of the gamma-ray pulsars detected. Additionally, J0357+3205 and J2055+2539 are suggested as MeV pulsar candidates based on the obtained results.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Luis A. Anchordoqui, Diego F. Torres
Article
Astronomy & Astrophysics
N. Rea, F. Coti Zelati, D. Vigano, A. Papitto, F. Baganoff, A. Borghese, S. Campana, P. Esposito, D. Haggard, G. L. Israel, S. Mereghetti, R. P. Mignani, R. Perna, J. A. Pons, G. Ponti, L. Stella, D. F. Torres, R. Turolla, S. Zane
ASTROPHYSICAL JOURNAL
(2020)
Article
Astronomy & Astrophysics
S. Abdollahi, F. Acero, M. Ackermann, M. Ajello, W. B. Atwood, M. Axelsson, L. Baldini, J. Ballet, G. Barbiellini, D. Bastieri, J. Becerra Gonzalez, R. Bellazzini, A. Berretta, E. Bissaldi, R. D. Blandford, E. D. Bloom, R. Bonino, E. Bottacini, T. J. Brandt, J. Bregeon, P. Bruel, R. Buehler, T. H. Burnett, S. Buson, R. A. Cameron, R. Caputo, P. A. Caraveo, J. M. Casandjian, D. Castro, E. Cavazzuti, E. Charles, S. Chaty, S. Chen, C. C. Cheung, G. Chiaro, S. Ciprini, J. Cohen-Tanugi, L. R. Cominsky, J. Coronado-Blazquez, D. Costantin, A. Cuoco, S. Cutini, F. D'Ammando, M. DeKlotz, P. de la Tone Luque, F. de Palma, A. Desai, S. W. Digel, N. Di Lalla, M. Di Mauro, L. Di Venere, A. Dominguez, D. Dumora, F. Fana Dirirsa, S. J. Fegan, E. C. Ferrara, A. Franckowiak, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, D. Gaspanini, N. Giglietto, P. Giommi, F. Giordano, M. Giroletti, T. Glanzman, D. Green, I. A. Grenier, S. Griffin, M-H Grondin, J. E. Grove, S. Guiriec, A. K. Harding, K. Hayashi, E. Hays, J. W. Hewitt, D. Horan, G. Johannesson, T. J. Johnson, T. Kamae, M. Kerr, D. Kocevski, M. Kovac'evic, M. Kuss, D. Landriu, S. Larsson, L. Latronico, M. Lemoine-Goumard, J. Li, I Liodakis, F. Longo, F. Loparco, B. Lott, M. N. Lovellette, P. Lubrano, G. M. Madejski, S. Maldera, D. Malyshev, A. Manfreda, J. Marchesini, L. Marcotulli, G. Marti-Devesa, P. Martin, F. Massaro, M. N. Mazziotta, J. E. McEnery, I Mereu, M. Meyer, P. F. Michelson, N. Mirabal, T. Mizuno, M. E. Monzani, A. Morselli, I. Moskalenko, M. Negro, E. Nuss, R. Ojha, N. Omodei, M. Orienti, E. Orlando, J. F. Ormes, M. Palatiello, V. S. Paliya, D. Paneque, Z. Pei, H. Pena-Herazo, J. S. Perkins, M. Persic, M. Pesce-Rollms, V Petrosian, L. Petrov, F. Piron, H. Poon, T. A. Porter, G. Principe, S. Raino, R. Rando, M. Razzano, S. Razzaque, A. Reimer, O. Reimer, Q. Remy, T. Reposeur, R. W. Romani, P. M. Saz Parkinson, F. K. Schinzel, D. Serini, C. Sgro, E. J. Siskind, D. A. Smith, G. Spandre, P. Spinelli, A. W. Strong, D. J. Suson, H. Tajima, M. N. Takahashi, D. Tak, J. B. Thayer, D. J. Thompson, L. Tibaldo, D. F. Torres, E. Torresi, J. Valverde, B. Van Klaveren, P. van Zyl, K. Wood, M. Yassine, G. Zaharijas
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2020)
Article
Astronomy & Astrophysics
M. Ajello, M. Arimoto, M. Axelsson, L. Baldini, G. Barbiellini, D. Bastieri, R. Bellazzini, A. Berretta, E. Bissaldi, R. D. Blandford, R. Bonino, E. Bottacini, J. Bregeon, P. Bruel, R. Buehler, E. Burns, S. Buson, R. A. Cameron, R. Caputo, P. A. Caraveo, E. Cavazzuti, S. Chen, G. Chiaro, S. Ciprini, J. Cohen-Tanugi, D. Costantin, S. Cutini, F. D'Ammando, M. DeKlotz, P. de la Torre Luque, F. de Palma, A. Desai, N. Di Lalla, L. Di Venere, F. Fana Dirirsa, S. J. Fegan, A. Franckowiak, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, D. Gasparrini, N. Giglietto, R. Gill, F. Giordano, M. Giroletti, J. Granot, D. Green, I. A. Grenier, M. -H. Grondin, S. Guiriec, E. Hays, D. Horan, G. Johannesson, D. Kocevski, M. Kovac'evic', M. Kuss, S. Larsson, L. Latronico, M. Lemoine-Goumard, J. Li, I. Liodakis, F. Longo, F. Loparco, M. N. Lovellette, P. Lubrano, S. Maldera, D. Malyshev, A. Manfreda, G. Marti-Devesa, M. N. Mazziotta, J. E. McEnery, I. Mereu, M. Meyer, P. F. Michelson, W. Mitthumsiri, T. Mizuno, M. E. Monzani, E. Moretti, A. Morselli, I. V. Moskalenko, M. Negro, E. Nuss, N. Omodei, M. Orienti, E. Orlando, M. Palatiello, V. S. Paliya, D. Paneque, Z. Pei, M. Persic, M. Pesce-Rollins, V. Petrosian, F. Piron, H. Poon, T. A. Porter, G. Principe, J. L. Racusin, S. Raino, R. Rando, B. Rani, M. Razzano, S. Razzaque, A. Reimer, O. Reimer, F. Ryde, P. M. Saz Parkinson, D. Serini, C. Sgro, E. J. Siskind, G. Spandre, P. Spinelli, H. Tajima, K. Takagi, M. N. Takahashi, D. Tak, J. B. Thayer, D. J. Thompson, D. F. Torres, E. Troja, J. Valverde, B. Van Klaveren, K. Wood, M. Yassine, G. Zaharijas, B. Mailyan, P. N. Bhat, M. S. Briggs, W. Cleveland, M. Giles, A. Goldstein, M. Hui, Christian Malacaria, R. Preece, O. J. Roberts, P. Veres, C. Wilson-Hodge, A. von Kienlin, S. B. Cenko, P. O'Brien, A. P. Beardmore, A. Lien, J. P. Osborne, A. Tohuvavohu, V. D'Elia, A. D'Ai, M. Perri, J. Gropp, N. Klingler, M. Capalbi, G. Tagliaferri, M. Stamatikos, M. De Pasquale
ASTROPHYSICAL JOURNAL
(2020)
Article
Astronomy & Astrophysics
M. Ajello, R. Angioni, M. Axelsson, J. Ballet, G. Barbiellini, D. Bastieri, J. Becerra Gonzalez, R. Bellazzini, E. Bissaldi, E. D. Bloom, R. Bonino, E. Bottacini, P. Bruel, S. Buson, F. Cafardo, R. A. Cameron, E. Cavazzuti, S. Chen, C. C. Cheung, S. Ciprini, D. Costantin, S. Cutini, F. D'Ammando, P. de la Torre Luque, R. de Menezes, F. de Palma, A. Desai, N. Di Lalla, L. Di Venere, A. Dominguez, F. Fana Dirirsa, E. C. Ferrara, J. Finke, A. Franckowiak, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, S. Garrappa, D. Gasparrini, N. Giglietto, F. Giordano, M. Giroletti, D. Green, I. A. Grenier, S. Guiriec, S. Harita, E. Hays, D. Horan, R. Itoh, G. Johannesson, M. Kovac'evic', F. Krauss, M. Kreter, M. Kuss, S. Larsson, C. Leto, J. Li, I Liodakis, F. Longo, F. Loparco, B. Lott, M. N. Lovellette, P. Lubrano, G. M. Madejski, S. Maldera, A. Manfreda, G. Marti-Devesa, F. Massaro, M. N. Mazziotta, I Mereu, M. Meyer, G. Migliori, N. Mirabal, T. Mizuno, M. E. Monzani, A. Morselli, I. Moskalenko, M. Negro, R. Nemmen, E. Nuss, L. S. Ojha, R. Ojha, N. Omodei, M. Orienti, E. Orlando, J. F. Ormes, V. S. Paliya, Z. Pei, H. Pena-Herazo, M. Persic, M. Pesce-Rollins, L. Petrov, F. Piron, H. Poon, G. Principe, S. Raino, R. Rando, B. Rani, M. Razzano, S. Razzaque, A. Reimer, O. Reimer, F. K. Schinzel, D. Serini, C. Sgro, E. J. Siskind, G. Spandre, P. Spinelli, D. J. Suson, Y. Tachibana, D. J. Thompson, D. F. Torres, E. Torresi, E. Troja, J. Valverde, P. van Zyl, M. Yassine
ASTROPHYSICAL JOURNAL
(2020)