Eridanus IV: an Ultra-faint Dwarf Galaxy Candidate Discovered in the DECam Local Volume Exploration Survey

Cerny, W.; Pace, Andrew B.; Drlica-Wagner, A.; Koposov, S. E.; Vivas, A. Katherina; Mau, S.; Riley, A. H.; Carlin, Jeffrey L.; Choi, Yumi; Erkal, Denis; Ferguson, P. S.; James, D. J.; Li, T. S.; Martínez–Delgado, David; Martı́nez-Vázquez, C. E.; Muñoz, Ricardo R.; Mutlu-Pakdil, Burçin; Olsen, Knut; Pieres, A.; Sakowska, J. D.; Sand, David J.; Simon, Joshua D.; Smercina, Adam; Stringfellow, Guy S.; Tollerud, Erik; Adamów, M.; Hernández-Lang, D.; Kuropatkin, N.; Santana-Silva, L.; Tucker, D. L.; Zenteno, A.

doi:10.3847/2041-8213/ac2d9a

Cited by 31 publications

(25 citation statements)

References 57 publications

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“…This, in turn, is of great interest for the study of substructure in our Galactic halo (for example, see Lancaster et al 2019). At present, RR Lyrae observations are possible up to ∼2 Mpc distance (Da Costa et al 2010), just slightly beyond the Local Group, and we anticipate that new dwarf galaxies will be routinely discovered in various optical surveys (such as HSC-SSP and/or LSST); an example is Eridanus IV, recently reported in Cerny et al (2021).…”

Section: Discussionmentioning

confidence: 93%

Zwicky Transient Facility and Globular Clusters: The RR Lyrae gri-band Period–Luminosity–Metallicity and Period–Wesenheit–Metallicity Relations

Ngeow¹,

Bhardwaj²,

Dekany³

et al. 2022

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Based on time-series observations collected from the Zwicky Transient Facility (ZTF), we derived period–luminosity–metallicity (PLZ) and period–Wesenheit–metallicity (PWZ) relations for RR Lyrae located in globular clusters. We have applied various selection criteria to exclude RR Lyrae with problematic or spurious light curves. These selection criteria utilized information on the number of data points per light curve, amplitudes, colors, and residuals on the period–luminosity and/or period–Wesenheit relations. Due to blending, a number of RR Lyrae in globular clusters were found to be anomalously bright and have small amplitudes of their ZTF light curves. We used our final sample of ∼750 RR Lyrae in 46 globular clusters covering a wide metallicity range (−2.36 dex < [Fe/H] < −0.54 dex) to derive PLZ and PWZ relations in the gri bands. In addition, we have also derived the period–color–metallicity and, for the first time, the period-Q-index-metallicity relations, where the Q-index is extinction-free by construction. We have compared our various relations to empirical and theoretical relations available in the literature and found a good agreement with most studies. Finally, we applied our derived PLZ relation to a dwarf galaxy, Crater II, and found that its true distance modulus should be larger than the most recent determination.

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Section: Discussionmentioning

confidence: 93%

Zwicky Transient Facility and Globular Clusters: The RR Lyrae gri-band Period–Luminosity–Metallicity and Period–Wesenheit–Metallicity Relations

Ngeow¹,

Bhardwaj²,

Dekany³

et al. 2022

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“…The faint end of the galaxy luminosity function is important for understanding dark matter and astrophysics on small scales (see, e.g., Bullock & Boylan-Kolchin 2017;Simon 2019, for recent reviews). In the Local Group, observations continue to find a variety of ultra-faint galaxies (for instance, most recently Mau et al 2020;Cerny et al 2021Cerny et al , 2022, while numerical simulations work out how stars form in the smallest dark matter subhalos of Milky Way-like systems (e.g., Brooks et al 2013;Sawala et al 2016;Wetzel et al 2016;Samuel et al 2020;Applebaum et al 2021;Engler et al 2021). Outside of the Local Group, faint dwarf galaxies are being identified in resolved stars (Chiboucas et al 2013;Crnojević et al 2014;Sand et al 2014;Crnojević et al 2016b;Carlin et al 2016;Toloba et al 2016;Smercina et al 2018;Bennet et al 2019;Crnojević et al 2019;Bennet et al 2020;Mutlu-Pakdil et al 2022), diffuse or semiresolved light (e.g., Bennet et al 2017;Carlsten et al 2020;Davis et al 2021), as well as spectroscopic surveys (Geha et al 2017;Mao et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Tucana B: A Potentially Isolated and Quenched Ultra-faint Dwarf Galaxy at D ≈ 1.4 Mpc*

Sand

Mutlu-Pakdil

Jones

et al. 2022

ApJL

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We report the discovery of Tucana B, an isolated ultra-faint dwarf galaxy at a distance of D = 1.4 Mpc. Tucana B was found during a search for ultra-faint satellite companions to the known dwarfs in the outskirts of the Local Group, although its sky position and distance indicate the nearest galaxy to be ∼500 kpc distant. Deep ground-based imaging resolves Tucana B into stars, and it displays a sparse red giant branch consistent with an old, metal-poor stellar population analogous to that seen in the ultra-faint dwarf galaxies of the Milky Way, albeit at fainter apparent magnitudes. Tucana B has a half-light radius of 80 ± 40 pc and an absolute magnitude of M V = − 6.9 − 0.6 + 0.5 mag ( L V = ( 5 − 2 + 4 ) × 10 4 L ⊙), which is again comparable to the Milky Way’s ultra-faint satellites. There is no evidence for a population of young stars, either in the optical color–magnitude diagram or in GALEX archival ultraviolet imaging, with the GALEX data indicating log ( SFR NUV / M ⊙ yr − 1 ) < − 5.4 for star formation on ≲100 Myr timescales. Given its isolation and physical properties, Tucana B may be a definitive example of an ultra-faint dwarf that has been quenched by reionization, providing strong confirmation of a key driver of galaxy formation and evolution at the lowest mass scales. It also signals a new era of ultra-faint dwarf galaxy discovery at the extreme edges of the Local Group.

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“…At present RR Lyrae observations are possible up to ∼ 2 Mpc distance (Da Costa et al 2010), just slightly beyond the Local Group, and we anticipated new dwarf galaxies will be routinely discovered in various optical surveys (such as HSC-SSP and/or LSST), an example is Eridanus IV recently reported in Cerny et al (2021).…”

Section: Discussionmentioning

confidence: 99%

Zwicky Transient Facility and Globular Clusters: The RR Lyrae gri-Band Period-Luminosity-Metallicity and Period-Wesenheit-Metallicity Relations

Ngeow,

Bhardwaj,

Dekany

et al. 2022

Preprint

View full text Add to dashboard Cite

Based on time-series observations collected from Zwicky Transient Facility (ZTF), we derived periodluminosity-metallicity (PLZ) and period-Wesenheit-metallicity (PWZ) relations for RR Lyrae located in globular clusters. We have applied various selection criteria to exclude RR Lyrae with problematic or spurious light curves. These selection criteria utilized information on the number of data points per light curve, amplitudes, colors, and residuals on the period-luminosity and/or period-Wesenheit relations. Due to blending, a number of RR Lyrae in globular clusters were found to be anomalously bright and have small amplitudes of their ZTF light curves. We used our final sample of ∼ 750 RR Lyrae in 46 globular clusters covering a wide metallicity range (−2.36 < [Fe/H] < −0.54 dex) to derive PLZ and PWZ relations in gri bands. In addition, we have also derived the period-color-metallicity (PCZ) and for the first time, the PQZ relations where the Q-index is extinction-free by construction. We have compared our various relations to empirical and theoretical relations available in literature, and found a good agreement with most studies. Finally, we applied our derived PLZ relation to a dwarf galaxy, Crater II, and found its true distance modulus should be larger than the most recent determination.

show abstract

Eridanus IV: an Ultra-faint Dwarf Galaxy Candidate Discovered in the DECam Local Volume Exploration Survey

Abstract: We present the discovery of a candidate ultra-faint Milky Way satellite, Eridanus IV (DELVE J0505−0931), detected in photometric data from the DECam Local Volume Exploration survey

Cited by 31 publications

References 57 publications

Zwicky Transient Facility and Globular Clusters: The RR Lyrae gri-band Period–Luminosity–Metallicity and Period–Wesenheit–Metallicity Relations

Zwicky Transient Facility and Globular Clusters: The RR Lyrae gri-band Period–Luminosity–Metallicity and Period–Wesenheit–Metallicity Relations

Tucana B: A Potentially Isolated and Quenched Ultra-faint Dwarf Galaxy at D ≈ 1.4 Mpc*

Zwicky Transient Facility and Globular Clusters: The RR Lyrae gri-Band Period-Luminosity-Metallicity and Period-Wesenheit-Metallicity Relations

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