TY - JOUR
T1 - Pavo
T2 - Discovery of a Star-forming Dwarf Galaxy Just Outside the Local Group
AU - Jones, Michael G.
AU - Mutlu-Pakdil, Burçin
AU - Sand, David J.
AU - Donnerstein, Richard
AU - Crnojević, Denija
AU - Bennet, Paul
AU - Fielder, Catherine E.
AU - Karunakaran, Ananthan
AU - Spekkens, Kristine
AU - Strader, Jay
AU - Urquhart, Ryan
AU - Zaritsky, Dennis
N1 - Publisher Copyright:
© 2023. The Author(s). Published by the American Astronomical Society.
PY - 2023/11/1
Y1 - 2023/11/1
N2 - We report the discovery of Pavo, a faint (M V = −10.0), star-forming, irregular, and extremely isolated dwarf galaxy at D ≈ 2 Mpc. Pavo was identified in Dark Energy Camera Legacy Survey imaging via a novel approach that combines low surface brightness galaxy search algorithms and machine-learning candidate classifications. Follow-up imaging with the Inamori-Magellan Areal Camera and Spectrograph on the 6.5 m Magellan Baade telescope revealed a color-magnitude diagram (CMD) with an old stellar population, in addition to the young population that dominates the integrated light, and a tip of the red giant branch distance estimate of 1.99 − 0.22 + 0.20 Mpc. The blue population of stars in the CMD is consistent with the youngest stars having formed no later than 150 Myr ago. We also detected no Hα emission with SOAR telescope imaging, suggesting that we may be witnessing a temporary low in Pavo’s star formation. We estimate the total stellar mass of Pavo to be log M * / M ⊙ = 5.6 ± 0.2 and measure an upper limit on its H i gas mass of 1.0 × 106 M ⊙ based on the HIPASS survey. Given these properties, Pavo’s closest analog is Leo P (D = 1.6 Mpc), previously the only known isolated, star-forming, Local Volume dwarf galaxy in this mass range. However, Pavo appears to be even more isolated, with no other known galaxy residing within over 600 kpc. As surveys and search techniques continue to improve, we anticipate an entire population of analogous objects being detected just outside the Local Group.
AB - We report the discovery of Pavo, a faint (M V = −10.0), star-forming, irregular, and extremely isolated dwarf galaxy at D ≈ 2 Mpc. Pavo was identified in Dark Energy Camera Legacy Survey imaging via a novel approach that combines low surface brightness galaxy search algorithms and machine-learning candidate classifications. Follow-up imaging with the Inamori-Magellan Areal Camera and Spectrograph on the 6.5 m Magellan Baade telescope revealed a color-magnitude diagram (CMD) with an old stellar population, in addition to the young population that dominates the integrated light, and a tip of the red giant branch distance estimate of 1.99 − 0.22 + 0.20 Mpc. The blue population of stars in the CMD is consistent with the youngest stars having formed no later than 150 Myr ago. We also detected no Hα emission with SOAR telescope imaging, suggesting that we may be witnessing a temporary low in Pavo’s star formation. We estimate the total stellar mass of Pavo to be log M * / M ⊙ = 5.6 ± 0.2 and measure an upper limit on its H i gas mass of 1.0 × 106 M ⊙ based on the HIPASS survey. Given these properties, Pavo’s closest analog is Leo P (D = 1.6 Mpc), previously the only known isolated, star-forming, Local Volume dwarf galaxy in this mass range. However, Pavo appears to be even more isolated, with no other known galaxy residing within over 600 kpc. As surveys and search techniques continue to improve, we anticipate an entire population of analogous objects being detected just outside the Local Group.
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U2 - 10.3847/2041-8213/ad0130
DO - 10.3847/2041-8213/ad0130
M3 - Article
AN - SCOPUS:85176444325
SN - 2041-8205
VL - 957
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 1
M1 - L5
ER -