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The Distance of the Dark Matter Deficient Galaxy NGC 1052-DF2
被引:52
|作者:
van Dokkum, Pieter
[1
]
Danieli, Shany
[1
]
Cohen, Yotam
[1
]
Romanowsky, Aaron J.
[2
,3
]
Conroy, Charlie
[4
]
机构:
[1] Yale Univ, Astron Dept, 52 Hillhouse Ave, New Haven, CT 06511 USA
[2] Univ Calif Observ, 1156 High St, Santa Cruz, CA 95064 USA
[3] San Jose State Univ, Dept Phys & Astron, San Jose, CA 95192 USA
[4] Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA
关键词:
galaxies: evolution;
galaxies: structure;
RED GIANT BRANCH;
SURFACE BRIGHTNESS FLUCTUATIONS;
VIRGO CLUSTER SURVEY;
GLOBULAR-CLUSTERS;
ADVANCED CAMERA;
TIP;
CALIBRATION;
IV;
D O I:
10.3847/2041-8213/aada4d
中图分类号:
P1 [天文学];
学科分类号:
0704 ;
摘要:
We recently inferred that the galaxy NGC 1052-DF2 has little or no dark matter and a rich system of unusual globular clusters. We assumed that the galaxy is a satellite of the luminous elliptical galaxy NGC 1052 at X20 Mpc, on the basis of its surface brightness fluctuations (SBFs) distance of 19.0 +/- 1.7 Mpc, its radial velocity of approximate to 1800 km s(-1), and its projected position. Here we analyze the color-magnitude diagram (CMD) of NGC 1052-DF2, following the suggestion by Trujillo et al. that the tip of the red giant branch (TRGB) can be detected in currently available Hubble Space Telescope (HST) data and the galaxy is at similar to 13 Mpc. Using fully populated galaxy models we show that the CMD is strongly influenced by blends. These blends produce a "phantom" TRGB-2 times brighter than the true TRGB, which can lead to erroneous distance estimates similar to 1.4 times smaller than the actual distance. We compare NGC 1052-DF2 to model images as well as other galaxies in our HST sample, and show that the large population of unblended RGB stars expected for distances of similar to 13 Mpc is not detected. We also provide a new distance measurement to NGC 1052-DF2 that is free of calibration uncertainties, by anchoring it to a satellite of the megamaser host galaxy NGC 4258. From a megamaser-TRGB-SBF distance ladder we obtain D = 18.7 +/- 1.7 Mpc, consistent with our previous measurement and with the distance to the elliptical galaxy NGC 1052.
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