The SKA view of the Neutral Interstellar Medium in Galaxies

Blok, W. J. G. de; Fraternali, Filippo; Heald, G.; Adams, Betsey; Bosma, A.; Koribalski, Baerbel

doi:10.22323/1.215.0129

Cited by 8 publications

(6 citation statements)

References 74 publications

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“…Future astronomical surveys: Over the next decade, upcoming instruments will boost the statistics and resolution for all observations relevant for SIDM. The Square Kilometer Array (SKA) radio telescope has the potential to observe hundreds of nearby spiral galaxies at resolutions below 100 pc, providing a deep look into their gas kinematics [591]. This will provide a large and detailed sample of rotation curves, clarifying statistical arguments for the consistency of feedbackgenerated cores with ΛCDM cosmology [173,174], with an eye on potential outliers with large core sizes, few kpc, that appear inconsistent with feedback (see Fig.…”

Section: B Outlookmentioning

confidence: 99%

“…8). SKA will also provide new insights into the cooling and collapse of H gas-an important consideration for the conversion of gas into stars in numerical simulations [591]. In addition, the Giant Magellan Telescope (GMT) [592] and the European Extremely Large Telescope (E-ELT) [593] can provide improved measurements of stellar kinematics of nearby dwarf galaxies.…”

Section: B Outlookmentioning

confidence: 99%

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Dark matter self-interactions and small scale structure

2018

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We review theories of dark matter (DM) beyond the collisionless paradigm, known as self-interacting dark matter (SIDM), and their observable implications for astrophysical structure in the Universe. Selfinteractions are motivated, in part, due to the potential to explain long-standing (and more recent) small scale structure observations that are in tension with collisionless cold DM (CDM) predictions. Simple particle physics models for SIDM can provide a universal explanation for these observations across a wide range of mass scales spanning dwarf galaxies, low and high surface brightness spiral galaxies, and clusters of galaxies. At the same time, SIDM leaves intact the success of ΛCDM cosmology on large scales. This report covers the following topics: (1) small scale structure issues, including the core-cusp problem, the diversity problem for rotation curves, the missing satellites problem, and the too-big-to-fail problem, as well as recent progress in hydrodynamical simulations of galaxy formation; (2) N-body simulations for SIDM, including implications for density profiles, halo shapes, substructure, and the interplay between baryons and selfinteractions;(3) semi-analytic Jeans-based methods that provide a complementary approach for connecting particle models with observations; (4) merging systems, such as cluster mergers (e.g., the Bullet Cluster) and minor infalls, along with recent simulation results for mergers; (5) particle physics models, including light mediator models and composite DM models; and (6) complementary probes for SIDM, including indirect and direct detection experiments, particle collider searches, and cosmological observations. We provide a summary and critical look for all current constraints on DM self-interactions and an outline for future directions.

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Section: B Outlookmentioning

confidence: 99%

Section: B Outlookmentioning

confidence: 99%

Dark matter self-interactions and small scale structure

2018

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“…This gas would be undetectable with current instrumentation, even if it were fully neutral. For example, a high-sensitivity survey such as HIPASS sets the limit at 4 × 10 17 cm −2 (Meyer et al 2004), and values of 10 17 cm −2 will be achieved by SKA after a 1000 hour integration (de Blok et al 2015). Moreover, at these low column densities the intergalactic ultraviolet (UV) background will keep the gas fully ionized, which makes it even more elusive.…”

Section: Other Interpretationsmentioning

confidence: 99%

Kinematics of Extremely Metal-Poor Galaxies: Evidence for Stellar Feedback

Olmo-García

Alméida

Muñoz–Tuñón

et al. 2017

ApJ

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The extremely metal-poor (XMP) galaxies analyzed in a previous paper have large star-forming regions with a metallicity lower than the rest of the galaxy. Such a chemical inhomogeneity reveals the external origin of the metal-poor gas fueling star formation, possibly indicating accretion from the cosmic web. This paper studies the kinematic properties of the ionized gas in these galaxies. Most XMPs have rotation velocity around a few tens of km s −1 . The star-forming regions appear to move coherently. The velocity is constant within each region, and the velocity dispersion sometimes increases within the star-forming clump towards the galaxy midpoint, suggesting inspiral motion toward the galaxy center. Other regions present a local maximum in velocity dispersion at their center, suggesting a moderate global expansion. The Hα line wings show a number of faint emission features with amplitudes around a few percent of the main Hα component, and wavelength shifts between 100 and 400 km s −1 . The components are often paired, so that red and blue emission features with similar amplitudes and shifts appear simultaneously. Assuming the faint emission to be produced by expanding shell-like structures, the inferred mass loading factor (mass loss rate divided by star formation rate) exceeds 10. Since the expansion velocity exceeds by far the rotational and turbulent velocities, the gas may eventually escape from the galaxy disk. The observed motions involve energies consistent with the kinetic energy released by individual core-collapse supernovae. Alternative explanations for the faint emission have been considered and discarded.

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“…Indeed, extensive HI imaging surveys of relatively nearby galaxies will start next year with SKA pathfinders, such as the WSRT Apertif survey, and the SKA precursors ASKAP (the WAL-LABY survey) and MeerKAT (the deep, targeted MHONGOOSE survey, and also the MALS survey). Some of the projects for the first phase of the SKA telescope, SKA1, are described in the SKA science book (e.g., Blyth et al 2015;de Blok et al 2015). All these new surveys will bring fresh data of high quality, which can be brought to bear on the scientific problems discussed above and on other, related subjects, and will most likely lead to new insights and discoveries.…”

Section: Discussionmentioning

confidence: 99%

Hi in the Outskirts of Nearby Galaxies

Bosma

2017

Astrophysics and Space Science Library

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The HI in disk galaxies frequently extends beyond the optical image, and can trace the dark matter there. I briefly highlight the history of high spatial resolution HI imaging, the contribution it made to the dark matter problem, and the current tension between several dynamical methods to break the disk-halo degeneracy. I then turn to the flaring problem, which could in principle probe the shape of the dark halo. Instead, however, a lot of attention is now devoted to understanding the role of gas accretion via galactic fountains. The current Λ cold dark matter theory has problems on galactic scales, such as the core-cusp problem, which can be addressed with HI observations of dwarf galaxies. For a similar range in rotation velocities, galaxies of type Sd have thin disks, while those of type Im are much thicker. After a few comments on modified Newtonian dynamics and on irregular galaxies, I close with statistics on the HI extent of galaxies.

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The SKA view of the Neutral Interstellar Medium in Galaxies

Cited by 8 publications

References 74 publications

Dark matter self-interactions and small scale structure

Dark matter self-interactions and small scale structure

Kinematics of Extremely Metal-Poor Galaxies: Evidence for Stellar Feedback

Hi in the Outskirts of Nearby Galaxies

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