New galaxies discovered in the first blind HI survey of the Centaurus A group

被引:84
作者
Banks, GD
Disney, MJ
Knezek, PM
Jerjen, H
Barnes, DG
Bhatal, R
de Blok, WJG
Boyce, PJ
Ekers, RD
Freeman, KC
Gibson, BK
Henning, PA
Kilborn, V
Koribalski, B
Kraan-Korteweg, RC
Malin, DF
Minchin, RF
Mould, JR
Oosterloo, T
Price, RM
Putman, ME
Ryder, SD
Sadler, EM
Staveley-Smith, L
Stewart, I
Stootman, F
Vaile, RA
Webster, RL
Wright, AE
机构
[1] Univ Wales, Dept Phys & Astron, Cardiff CF2 3YB, S Glam, Wales
[2] Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA
[3] Australian Natl Univ, Res Sch Astron & Astrophys, Weston, ACT 2611, Australia
[4] CSIRO, Australia Telescope Natl Facil, Epping, NSW 2121, Australia
[5] Univ Western Sydney Macarthur, Dept Phys, Campbelltown, NSW 2560, Australia
[6] Univ Melbourne, Sch Phys, Parkville, Vic 3052, Australia
[7] Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA
[8] Univ New Mexico, Dept Phys & Astron, Albuquerque, NM 87131 USA
[9] Univ Guanajuato, Dept Astron, Guanajuato 36000, Mexico
[10] Anglo Australian Observ, Epping, NSW 2121, Australia
[11] Ist Fis Cosm, I-20133 Milan, Italy
[12] Joint Astron Ctr, Hilo, HI 96720 USA
[13] Univ Sydney, Astrophys Dept, Sch Phys, Sydney, NSW 2006, Australia
关键词
galaxies : clusters : individual (Centaurus A); galaxies : distances and redshifts galaxies : ISM; radio lines : galaxies; surveys;
D O I
10.1086/307854
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We have commenced a 21 cm survey of the entire southern sky (delta < 0 degrees, -1200 km s(-1) < v. < 12,700 km s(-1)) that is "blind," i.e., unbiased by previous optical information. In the present paper we report on the results of a pilot project that is based on data from this all-sky survey. The project was carried out on an area of 600 deg(2) centered on the nearby Centaurus A (Cen A) group of galaxies at a mean velocity of v., similar to 500 km s(-1). This was recently the subject of a separate and thorough optical survey. We found 10 new group members to add to 21 galaxies already known in the Cen A group: five of these are previously uncataloged galaxies, while five were previously catalogued but not known to be associated with the group. Most of the new members have H I masses close to our survey limit of 10(7) M . at the assumed group distance of 3.5 Mpc. The new detection with the largest H I mass is ESO 174-G?001 with M-H I = 2.1 x 10(8) M .. Prior to our survey this galaxy was an uncertain optical identification because of high Galactic extinction. We found optical counterparts for all the H I detections, most of them intrinsically very faint (M (B) > - 13.0), low surface brightness dwarf galaxies with H I profile line-widths suggestive of dynamics dominated by dark matter. The new group members add approximately 6% to the H I mass of the group and 4% to its light. The H r mass function, derived from all the known group galaxies in the interval 10(7) M . <M-H I < 10(9) M . has a faint-end slope of 1.30 +/- 0.15, allowing us to rule out a slope of 1.7 at 95% confidence. Even if the number in the lowest mass bin is increased by 50%, the slope only increases to 1.45 +/- 0.15.
引用
收藏
页码:612 / 622
页数:11
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