Akhil Ignatius Lasrado

• Lasrado, Akhil Ignatius; Cicone, Claudia & Weiss, Axel (2025). The extended molecular gas of the Circinus galaxy and NGC 1097 as seen by APEX. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 701. doi: 10.1051/0004-6361/202554402. Fulltekst i vitenarkiv Vis sammendrag

  The outer region of the interstellar medium (ISM) is often witness to dynamically important events in a galaxy’s evolutionary history such as outflows, inflows, tidal interactions, and mergers, as well as dynamical structures affecting its current evolution such as large-scale bars and spiral arms. Studying the imprints of these processes in the diffuse, extended molecular gas is best achieved by a single dish telescope which can cover a large field of view with good sensitivity to large-scale structures. In this work we present results from Atacama Pathfinder EXperiment (APEX) line emission maps of two nearby galaxies: the Circinus galaxy in the CO(3–2) transition, and NGC 1097 in CO(2–1), covering their full optical extents. We detect molecular gas at the largest extents seen for these galaxies yet, at up to 5′ (r ≈ 6 kpc) for the Circinus galaxy, and 4.′5 (r ≈ 18 kpc) for NGC 1097, and compute total CO luminosities of L′CO(3−2) = (1.5 ± 0.4) × 108 K km s−1 pc2 and L′CO(2−1) = (7.0 ± 1.7) × 108 K km s−1 pc2, corresponding to molecular gas masses (2.1 ± 1.0)×109 M⊙ and (4.7 ± 1.9)×109 M⊙, respectively. We further analyze the large-scale gas kinematics through position-velocity diagrams and 3D tilted ring modeling using the 3DBAROLO code. We detect notable features in both galaxies beyond their well-studied bright central regions: in the Circinus galaxy we detect molecular gas embedded in a bar-like structure, whose kinematic signature is also evident in the major axis position-velocity diagram, and in NGC 1097, we observe tidal molecular gas structures involved in the interaction of NGC 1097 with the companion galaxy NGC 1097A. The clear detection of such structures in the molecular gas shows promise in conducting large-scale molecular gas studies toward nearby galaxies with APEX and, in the future, the Atacama Large Aperture Submillimeter Telescope (AtLAST).

• Liu, Daizhong; Saintonge, Amelie; Bot, Caroline; Kemper, Francisca; Lopez-Rodriguez, Enrique & Smith, Matthew [Vis alle 28 forfattere av denne artikkelen] (2025). Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Gas and dust in nearby galaxies. Open Research Europe. 4. doi: 10.12688/openreseurope.17459.2. Fulltekst i vitenarkiv Vis sammendrag

  Understanding the physical processes that regulate star formation and galaxy evolution are major areas of activity in modern astrophysics. Nearby galaxies offer unique opportunities to inspect interstellar medium (ISM), star formation (SF), radiative, dynamic and magnetic ( B → ) physics in great detail from sub-galactic (kpc) scales to sub-cloud (sub-pc) scales, from quiescent galaxies to starbursts, and from field galaxies to overdensities. In this case study, we discuss the major breakthroughs in this area of research that will be enabled by the Atacama Large Aperture Submillimeter Telescope (AtLAST), a proposed 50-m single-dish submillimeter telescope. The new discovery space of AtLAST comes from its exceptional sensitivity, in particular to extended low surface brightness emission, a very large 2° field of view, and correspondingly high mapping efficiency. This paper focuses on four themes which will particularly benefit from AtLAST: 1) the LMC and SMC, 2) extragalactic magnetic fields, 3) the physics and chemistry of the interstellar medium, and 4) star formation and galaxy evolution. With ~ 1000 − 2000 hour surveys each, AtLAST could deliver deep dust continuum maps of the entire LMC and SMC fields at parsec-scale resolution, high-resolution maps of the magnetic field structure, gas density, temperature and composition of the dense and diffuse ISM in ~ 100 nearby galaxies, as well as the first large-scale blind CO survey in the nearby Universe, delivering molecular gas masses for up to 10 6 galaxies (3 orders of magnitude more than current samples). Through such observing campaigns, AtLAST will have a profound impact on our understanding of the baryon cycle and star formation across a wide range of environments.

• Hagedorn, Jan Bendix; Cicone, Claudia; Sarzi, M.; Saintonge, A.; Severgnini, P. & Vignali, C. [Vis alle 10 forfattere av denne artikkelen] (2024). Molecular gas scaling relations for local star-forming galaxies in the low-M* regime. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 687. doi: 10.1051/0004-6361/202449773. Fulltekst i vitenarkiv Vis sammendrag

  We derived molecular gas fractions (fmol = Mmol/M*) and depletion times (τmol = Mmol/SFR) for 353 galaxies representative of the local star-forming population with 108.5 M⊙ < M* < 1010.5 M⊙ drawn from the ALLSMOG and xCOLDGASS surveys of CO(2−1) and CO(1−0) line emission. By adding constraints from low-mass galaxies and upper limits for CO non-detections, we find the median molecular gas fraction of the local star-forming population to be constant at log fmol = −0.99−0.19+0.22, challenging previous reports of increased molecular gas fractions in low-mass galaxies. Above M* ∼ 1010.5 M⊙, we find the fmol versus M* relation to be sensitive to the selection criteria for star-forming galaxies. We tested the robustness of our results against different prescriptions for the CO-to-H2 conversion factor and different selection criteria for star-forming galaxies. The depletion timescale τmol weakly depends on M*, following a power law with a best-fit slope of 0.16 ± 0.03. This suggests that small variations in specific star formation rate (sSFR = SFR/M*) across the local main sequence of star-forming galaxies with M* < 1010.5 M⊙ are mainly driven by differences in the efficiency of converting the available molecular gas into stars. We tested these results against a possible dependence of fmol and τmol on the surrounding (group) environment of the targets by splitting them into centrals, satellites, and isolated galaxies, and find no significant variation between these populations. We conclude that the group environment is unlikely to have a large systematic effect on the molecular gas content of star-forming galaxies in the local Universe.

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