Chemical and stellar properties of early-type dwarf galaxies around the Milky Way

Belokurov, Vasily; Evans, N. W.

doi:10.1038/s41550-022-01740-w

Cited by 5 publications

(3 citation statements)

References 287 publications

(314 reference statements)

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“…If cX lies at the distance of cNE or cW, the candidate host galaxy would have an absolute magnitude of −19.3 or −18.2, respectively. We cannot discard a dwarf galaxy association even if at such a redshift, as these absolute magnitudes are similar to that of the Large Magellanic Cloud (Belokurov & Evans 2022).…”

Section: Assuming CX Is the Host Galaxy For Xrt 210423mentioning

confidence: 99%

The Fast X-Ray Transient XRT 210423 and Its Host Galaxy

Eappachen

Jonker

Levan

et al. 2023

ApJ

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Fast X-ray Transients (FXTs) are X-ray flares with durations ranging from a few hundred seconds to a few hours. Possible origins include the tidal disruption of a white dwarf by an intermediate-mass black hole, a supernova shock breakout, or a binary neutron star merger. We present the X-ray light curve and spectrum as well as deep optical imaging of the FXT XRT 210423, which has been suggested to be powered by a magnetar produced in a binary neutron star merger. Our Very Large Telescope and Gran Telescopio Canarias (GTC) observations began on 2021 May 6, thirteen days after the onset of the flare. No transient optical counterpart is found in the 1.″ (3σ) X-ray uncertainty region of the source to a depth g s = 27.0 AB mag. (We use the word “counterpart” for any transient light in a wave band other than the original X-ray detection wave band, whereas the word “host” refers to the host galaxy.) A candidate host lies within the 1.″ X-ray uncertainty region with a magnitude of 25.9 ± 0.1 in the GTC/HiPERCAM g s filter. Due to its faintness, it was not detected in other bands, precluding a photometric redshift determination. We detect two additional candidate host galaxies: one with z spec = 1.5082 ± 0.0001 and an offset of 4.″2 ± 1.″ (37 ± 9 kpc) from the FXT, and another one with z phot = 1.04 − 0.14 + 0.22 and an offset of 3.″6 ± 1.″ (30 ± 8 kpc). Based on the properties of all the prospective hosts, we favor a binary neutron star merger, as previously suggested in the literature, as the explanation for XRT 210423.

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Section: Assuming CX Is the Host Galaxy For Xrt 210423mentioning

confidence: 99%

The Fast X-Ray Transient XRT 210423 and Its Host Galaxy

Eappachen

Jonker

Levan

et al. 2023

ApJ

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“…Ultra-Faint Dwarf galaxies (UFDs) are among the most dark matter dominated galaxies in the cosmos (e.g., see Battaglia & Nipoti 2022), observed to contain a total number of stars of the order 10 3 N * 10 5 and mass-to-light ratios as high as ≈ 10 3 𝑀/𝐿 (Hayashi et al 2022); as such they are difficult to observe, having very low surface brightness (Belokurov et al 2007;Simon & Geha 2007;Koch 2009;McConnachie 2012;Bechtol et al 2015;Simon 2019;Belokurov & Evans 2022). Currently, there are ≈ 21 spectroscopically confirmed UFDs scattered around the Milky Way (MW) halo, with a further 21 UFDs without detailed dynamical analysis yet (Simon 2019;Cerny et al 2022).…”

Section: Introductionmentioning

confidence: 99%

Inhomogeneous Galactic chemical evolution: modelling ultra-faint dwarf galaxies of the Large Magellanic Cloud

Alexander

Vincenzo

et al. 2023

Monthly Notices of the Royal Astronomical Society

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Ultra-faint dwarf galaxies are among the oldest and most metal-poor galaxies in the cosmos, observed to contain no gas and a high dark matter mass fraction. Understanding the chemical abundance dispersion in such extreme environments could shed light on the very first generations of stars. We present a novel inhomogeneous chemical evolution model, i-GEtool, that we apply to two ultra-faint dwarf galaxies, Carina II and Reticulum II, both satellites of the Large Magellanic Cloud. Our model is based on the Monte Carlo sampling of the initial mass function as star formation proceeds in different gas cells of the galaxy volume. We account for the chemical enrichment of Supernova bubbles as they spread in the interstellar medium, causing dispersion in the elemental abundances. We recreate the abundance patterns of α- and odd-Z elements, predicting two sequences in [C/Fe] and [N/Fe] at all metallicities. Our models underestimate [C/Fe] and [Ti/Fe] because of the large uncertainty in the adopted stellar nucleosynthesis yields. We discuss that the observed C and N abundances had likely been affected by internal mixing processes, which changed the initial surface abundances in the red giants. Our Supernova feedback scheme is responsible for driving galactic outflows, which quench the star formation activity at early times. We predict an average outflow mass-loading factor ≈103, which extrapolates towards very low galaxy stellar masses the trend observed at high masses. Finally, by combining our model with the MIST isochrone database, we compare our synthetic colour-magnitude diagrams to observations.

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“…These observational data sets have delivered a wealth of information about the systemic motions and internal chemodynamical properties of the Milky Way satellite population; for review articles, see Mateo (1998), Tolstoy et al (2009), McConnachie (2012), Simon (2019), Battaglia & Nipoti (2022), and Belokurov & Evans (2022). However, the available data sets leave room for substantial improvement.…”

Section: Introductionmentioning

confidence: 99%

Magellan/M2FS and MMT/Hectochelle Spectroscopy of Dwarf Galaxies and Faint Star Clusters within the Galactic Halo*

Walker,

Caldwell,

Mateo

et al. 2023

ApJS

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We present spectroscopic data for 16,369 stellar targets within and/or toward 38 dwarf spheroidal galaxies and faint star clusters within the Milky Way halo environment. All spectra come from observations with the multiobject, fiber-fed echelle spectrographs M2FS at the Magellan/Clay telescope or Hectochelle at the MMT, reaching a typical limiting magnitude G ≲ 21. Data products include processed spectra from all observations and catalogs listing estimates—derived from template model fitting—of line-of-sight velocity (median uncertainty 1.4 km s−1) effective temperature (255 K), (base-10 logarithm of) surface gravity (0.59 dex in cgs units), [Fe/H] (0.4 dex) and [Mg/Fe] (0.27 dex) abundance ratios. The sample contains multiepoch measurements for 3720 sources, with up to 15 epochs per source, enabling studies of intrinsic spectroscopic variability. The sample contains 6087 likely red giant stars (based on surface gravity), and 4492 likely members (based on line-of-sight velocity and Gaia-measured proper motion) of the target systems. The number of member stars per individual target system ranges from a few, for the faintest systems, to ∼850 for the most luminous. For most systems, our new samples extend over wider fields than have previously been observed; of the likely members in our samples, 820 lie beyond 2 times the projected half-light radius of their host system, and 42 lie beyond 5 R half.

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Chemical and stellar properties of early-type dwarf galaxies around the Milky Way

Cited by 5 publications

References 287 publications

The Fast X-Ray Transient XRT 210423 and Its Host Galaxy

The Fast X-Ray Transient XRT 210423 and Its Host Galaxy

Inhomogeneous Galactic chemical evolution: modelling ultra-faint dwarf galaxies of the Large Magellanic Cloud

Magellan/M2FS and MMT/Hectochelle Spectroscopy of Dwarf Galaxies and Faint Star Clusters within the Galactic Halo*

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