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Galaxies, Volume 12, Issue 1

2024 February - 8 articles

Cover Story: Narrow-line Seyfert 1 galaxies are a peculiar subclass of active galactic nuclei. Among them, TXS 1206+549 stands out with its radio and γ-ray emission. The inner section of its plasma jet responsible for these emissions can be imaged by combining measurements in a network of widely spaced radio telescopes, using the technique of very long baseline interferometry. A series of archival images with milliarcsecond angular resolution, spanning several years, allowed us to detect apparent superluminal motion in the approaching side of the jet. This led to an estimate of the Lorentz factor characteristic of the bulk motion of the plasma, as well as the inclination of the jet with respect to the line of sight. The jet in TXS 1206+549 resembles those of radio-loud quasars. We found no compelling evidence for a closely aligned blazar-type jet. View this paper
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Articles (8)

  • Article
  • Open Access
3 Citations
3,703 Views
13 Pages

17 February 2024

Narrow-line Seyfert 1 (NLS1) galaxies are a peculiar subclass of active galactic nuclei (AGN). Among them, TXS 1206+549 belongs to a small group of radio-loud and γ-ray-emitting NLS1 galaxies. We focus on the radio properties of this galaxy by...

  • Review
  • Open Access
26 Citations
7,111 Views
42 Pages

Spin Evolution of Neutron Stars

  • Pavel Abolmasov,
  • Anton Biryukov and
  • Sergei B. Popov

10 February 2024

In this paper we review the basics of magneto-rotational properties of neutron stars focusing on spin-up/spin-down behavior at different evolutionary stages. The main goal is to provide equations for the spin frequency changes in various regimes (rad...

  • Review
  • Open Access
21 Citations
4,547 Views
27 Pages

X-ray Polarization from Magnetar Sources

  • Roberto Taverna  and
  • Roberto Turolla 

10 February 2024

The launch of the IXPE telescope in late 2021 finally made polarization measurements in the 2–8keV band a reality, more than 40 years after the pioneering observations of the OSO-8 satellite. In the first two years of operations, IXPE targeted...

  • Article
  • Open Access
3 Citations
2,736 Views
16 Pages

Parameter Inference of a State-of-the-Art Physical Afterglow Model for GRB 190114C

  • Enrico Rinaldi,
  • Nissim Fraija and
  • Maria Giovanna Dainotti

7 February 2024

A state-of-the-art semi-analytic gamma-ray burst (GRB) afterglow model with synchrotron self-Compton (SSC) emission has been applied for the first time for parameter inference using real GRB data. We analyzed the famous GRB 190114C as a case study. G...

  • Article
  • Open Access
14 Citations
2,611 Views
34 Pages

The Scavenger Hunt for Quasar Samples to Be Used as Cosmological Tools

  • Maria Giovanna Dainotti,
  • Giada Bargiacchi,
  • Aleksander Łukasz Lenart and
  • Salvatore Capozziello

23 January 2024

Although the Λ Cold Dark Matter model is the most accredited cosmological model, information at high redshifts (z) between type Ia supernovae (z=2.26) and the Cosmic Microwave Background (z=1100) is crucial to validate this model further. To t...

  • Article
  • Open Access
1 Citations
2,438 Views
13 Pages

29 December 2023

We develop a lepton–hadron model for the possible origin of hard very high energy (VHE) spectra from a distant blazar. The model includes synchrotron self-Compton (SSC) and hadronic components. The lepton components include synchrotron radiatio...

  • Article
  • Open Access
8 Citations
3,190 Views
29 Pages

Formation of Transitional cE/UCD Galaxies through Massive/Dwarf Disc Galaxy Mergers

  • Alexander V. Khoperskov,
  • Sergey S. Khrapov and
  • Danila S. Sirotin

25 December 2023

The dynamics of the merger of a dwarf disc galaxy with a massive spiral galaxy of the Milky Way type were studied in detail. The remnant of such interaction after numerous crossings of the satellite through the disc of the main galaxy was a compact s...

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Galaxies - ISSN 2075-4434