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Title: TIDAL DWARF GALAXIES AROUND A POST-MERGER GALAXY, NGC 4922

Abstract

One possible channel for the formation of dwarf galaxies involves birth in the tidal tails of interacting galaxies. We report the detection of a bright UV tidal tail and several young tidal dwarf galaxy (TDG) candidates in the post-merger galaxy NGC 4922 in the Coma cluster. Based on a two-component population model (combining young and old stellar populations), we find that the light of tidal tail predominantly comes from young stars (a few Myr old). The Galaxy Evolution Explorer ultraviolet data played a critical role in the parameter (age and mass) estimation. Our stellar mass estimates of the TDG candidates are {approx}10{sup 6-7} M {sub sun}, typical for dwarf galaxies.

Authors:
; ;  [1];  [2]; ; ;  [3];  [4]; ;  [5];  [6]; ; ; ; ; ;  [7];  [8];  [9];  [10]
  1. Department of Astronomy, Yonsei University, Seoul 120-749 (Korea, Republic of)
  2. Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey, RH5 6NT (United Kingdom)
  3. National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States)
  4. Lowell Observatory, Flagstaff, AZ 86001 (United States)
  5. Korea Astronomy and Space Science Institute, Hwaam 61-1, Yuseong, Daejeon 305-348 (Korea, Republic of)
  6. Observatories of the Carnegie Institution of Washington, 813 Santa Barbara St., Pasadena, CA 91101 (United States)
  7. California Institute of Technology, MC 405-47, 1200 E. California Blvd., Pasadena, CA 91125 (United States)
  8. Laboratory for Astronomy and Solar Physics, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
  9. Department of Astronomy, Columbia University, New York, NY 10027 (United States)
  10. (and others)
Publication Date:
OSTI Identifier:
21301501
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (New York, N.Y. Online); Journal Volume: 138; Journal Issue: 6; Other Information: DOI: 10.1088/0004-6256/138/6/1911; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; 99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; GALACTIC EVOLUTION; GALAXIES; MASS; STARS; VISIBLE RADIATION

Citation Formats

Sheen, Yun-Kyeong, Jeong, Hyunjin, Lee, Young-Wook, Ferreras, Ignacio, Lotz, Jennifer M., Olsen, Knut A. G., Dickinson, Mark, Barnes, Sydney, Park, Jang-Hyun, Ree, Chang H., Madore, Barry F., Barlow, Tom A., Conrow, Tim, Foster, Karl, Friendman, Peter G., Martin, D. Christopher, Morrissey, Patrick, Neff, Susan G., Schiminovich, David, and Yi, Sukyoung K., E-mail: yi@yonsei.ac.kr. TIDAL DWARF GALAXIES AROUND A POST-MERGER GALAXY, NGC 4922. United States: N. p., 2009. Web. doi:10.1088/0004-6256/138/6/1911; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
Sheen, Yun-Kyeong, Jeong, Hyunjin, Lee, Young-Wook, Ferreras, Ignacio, Lotz, Jennifer M., Olsen, Knut A. G., Dickinson, Mark, Barnes, Sydney, Park, Jang-Hyun, Ree, Chang H., Madore, Barry F., Barlow, Tom A., Conrow, Tim, Foster, Karl, Friendman, Peter G., Martin, D. Christopher, Morrissey, Patrick, Neff, Susan G., Schiminovich, David, & Yi, Sukyoung K., E-mail: yi@yonsei.ac.kr. TIDAL DWARF GALAXIES AROUND A POST-MERGER GALAXY, NGC 4922. United States. doi:10.1088/0004-6256/138/6/1911; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
Sheen, Yun-Kyeong, Jeong, Hyunjin, Lee, Young-Wook, Ferreras, Ignacio, Lotz, Jennifer M., Olsen, Knut A. G., Dickinson, Mark, Barnes, Sydney, Park, Jang-Hyun, Ree, Chang H., Madore, Barry F., Barlow, Tom A., Conrow, Tim, Foster, Karl, Friendman, Peter G., Martin, D. Christopher, Morrissey, Patrick, Neff, Susan G., Schiminovich, David, and Yi, Sukyoung K., E-mail: yi@yonsei.ac.kr. Tue . "TIDAL DWARF GALAXIES AROUND A POST-MERGER GALAXY, NGC 4922". United States. doi:10.1088/0004-6256/138/6/1911; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
@article{osti_21301501,
title = {TIDAL DWARF GALAXIES AROUND A POST-MERGER GALAXY, NGC 4922},
author = {Sheen, Yun-Kyeong and Jeong, Hyunjin and Lee, Young-Wook and Ferreras, Ignacio and Lotz, Jennifer M. and Olsen, Knut A. G. and Dickinson, Mark and Barnes, Sydney and Park, Jang-Hyun and Ree, Chang H. and Madore, Barry F. and Barlow, Tom A. and Conrow, Tim and Foster, Karl and Friendman, Peter G. and Martin, D. Christopher and Morrissey, Patrick and Neff, Susan G. and Schiminovich, David and Yi, Sukyoung K., E-mail: yi@yonsei.ac.kr},
abstractNote = {One possible channel for the formation of dwarf galaxies involves birth in the tidal tails of interacting galaxies. We report the detection of a bright UV tidal tail and several young tidal dwarf galaxy (TDG) candidates in the post-merger galaxy NGC 4922 in the Coma cluster. Based on a two-component population model (combining young and old stellar populations), we find that the light of tidal tail predominantly comes from young stars (a few Myr old). The Galaxy Evolution Explorer ultraviolet data played a critical role in the parameter (age and mass) estimation. Our stellar mass estimates of the TDG candidates are {approx}10{sup 6-7} M {sub sun}, typical for dwarf galaxies.},
doi = {10.1088/0004-6256/138/6/1911; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)},
journal = {Astronomical Journal (New York, N.Y. Online)},
number = 6,
volume = 138,
place = {United States},
year = {Tue Dec 15 00:00:00 EST 2009},
month = {Tue Dec 15 00:00:00 EST 2009}
}
  • The Giant GAlaxies, Dwarfs, and Debris Survey (GGADDS) concentrates on the nearby universe to study how galaxies have interacted in groups of different morphology, density, and richness. In these groups, we select the dominant spiral galaxy and search its surroundings for dwarf galaxies and tidal interactions. This paper presents the first results from deep wide-field imaging of NGC 7331, where we detect only four low-luminosity candidate dwarf companions and a stellar stream that may be evidence of a past tidal interaction. The dwarf galaxy candidates have surface brightnesses of {mu}{sub r} Almost-Equal-To 23-25 mag arcsec{sup -2} with (g - r){submore » 0} colors of 0.57-0.75 mag in the Sloan Digital Sky Survey filter system, consistent with their being dwarf spheroidal (dSph) galaxies. A faint stellar stream structure on the western edge of NGC 7331 has {mu}{sub g} Almost-Equal-To 27 mag arcsec{sup -2} and a relatively blue color of (g - r){sub 0} = 0.15 mag. If it is tidal debris, then this stream could have formed from a rare type of interaction between NGC 7331 and a dwarf irregular or transition-type dwarf galaxy. We compare the structure and local environments of NGC 7331 to those of other nearby giant spirals in small galaxy groups. NGC 7331 has a much lower ({approx}2%) stellar mass in the form of early-type satellites than found for M31 and lacks the presence of nearby companions like luminous dwarf elliptical galaxies or the Magellanic Clouds. However, our detection of a few dSph candidates suggests that it is not deficient in low-luminosity satellites.« less
  • We report the discovery of a UV-bright tidal dwarf galaxy (TDG) candidate in the NGC 4631/4656 galaxy group, which we designate NGC 4656UV. Using survey and archival data spanning from 1.4 GHz to the ultraviolet, we investigate the gas kinematics and stellar properties of this system. The H I morphologies of NGC 4656UV and its parent galaxy NGC 4656 are extremely disturbed, with significant amounts of counterrotating and extraplanar gas. From UV-FIR photometry, computed using a new method to correct for surface gradients on faint objects, we find that NGC 4656UV has no significant dust opacity and a blue spectralmore » energy distribution. We compute a star formation rate of 0.027 M{sub Sun} yr{sup -1} from the far-ultraviolet flux and measure a total H I mass of 3.8 Multiplication-Sign 10{sup 8} M{sub Sun} for the object. Evolutionary synthesis modeling indicates that NGC 4656UV is a low-metallicity system whose only major burst of star formation occurred within the last {approx}260-290 Myr. The age of the stellar population is consistent with a rough timescale for a recent tidal interaction between NGC 4656 and NGC 4631, although we discuss the true nature of the object-whether it is tidal or pre-existing in origin-in the context of its metallicity being a factor of 10 lower than its parent galaxy. We estimate that NGC 4656UV is either marginally bound or unbound. If bound, it contains relatively low amounts of dark matter. The abundance of archival data allows for a deeper investigation into this dynamic system than is currently possible for most TDG candidates.« less
  • The Magellanic System includes some of the nearest examples of galaxies disturbed by galaxy interactions. These interactions have redistributed much of their gas into the halos of the Milky Way (MW) and the Magellanic Clouds. We present Wisconsin H{alpha} Mapper kinematically resolved observations of the warm ionized gas in the Magellanic Bridge over the velocity range of +100 to +300 km s{sup -1} in the local standard of rest reference frame. These observations include the first full H{alpha} intensity map and the corresponding intensity-weighted mean velocity map of the Magellanic Bridge across (l, b) = (281 Degree-Sign .5, -30 Degree-Signmore » .0) to (302. Degree-Sign 5, -46. Degree-Sign 7). Using the H{alpha} emission from the Small Magellanic Cloud (SMC)-Tail and the Bridge, we estimate that the mass of the ionized material is between (0.7-1.7) Multiplication-Sign 10{sup 8} M{sub Sun }, compared to 3.3 Multiplication-Sign 10{sup 8} M{sub Sun} for the neutral mass over the same region. The diffuse Bridge is significantly more ionized than the SMC-Tail, with an ionization fraction of 36%-52% compared to 5%-24% for the Tail. The H{alpha} emission has a complex multiple-component structure with a velocity distribution that could trace the sources of ionization or distinct ionized structures. We find that incident radiation from the extragalactic background and the MW alone are insufficient to produced the observed ionization in the Magellanic Bridge and present a model for the escape fraction of the ionizing photons from both the SMC and Large Magellanic Cloud (LMC). With this model, we place an upper limit of 4.0% for the average escape fraction of ionizing photons from the LMC and an upper limit of 5.5% for the SMC. These results, combined with the findings of a half a dozen other studies for dwarf galaxies in different environments, provide compelling evidence that only a small percentage of the ionizing photons escape from dwarf galaxies in the present epoch to influence their surroundings.« less
  • A candidate diffuse stellar substructure was previously reported in the halo of the nearby dwarf starburst galaxy NGC 4449 by Karachentsev et al. We map and analyze this feature using a unique combination of deep integrated-light images from the BlackBird 0.5 m telescope, and high-resolution wide-field images from the 8 m Subaru Telescope, which resolve the nebulosity into a stream of red giant branch stars, and confirm its physical association with NGC 4449. The properties of the stream imply a massive dwarf spheroidal progenitor, which after complete disruption will deposit an amount of stellar mass that is comparable to themore » existing stellar halo of the main galaxy. The stellar mass ratio between the two galaxies is {approx}1:50, while the indirectly measured dynamical mass ratio, when including dark matter, may be {approx}1:10-1:5. This system may thus represent a 'stealth' merger, where an infalling satellite galaxy is nearly undetectable by conventional means, yet has a substantial dynamical influence on its host galaxy. This singular discovery also suggests that satellite accretion can play a significant role in building up the stellar halos of low-mass galaxies, and possibly in triggering their starbursts.« less
  • This work presents an extended, neutral hydrogen emission map around Magellanic-type dwarf irregular galaxy (dIm) NGC 1569. In the spring of 2010, the Robert C. Byrd Green Bank Telescope was used to map a 9 Degree-Sign Multiplication-Sign 2 Degree-Sign region in H I line emission that includes NGC 1569 and IC 342 as well as two other dwarf galaxies. The primary objective for these observations was to search for structures potentially connecting NGC 1569 with IC 342 group members in order to trace previous interactions and thus, provide an explanation for the starburst and peculiar kinematics prevalent in NGC 1569.more » A large, half-degree diameter H I cloud was detected that shares the same position and velocity as NGC 1569. Also, two long structures were discovered that are reminiscent of intergalactic filaments extending out in a V-shaped manner from NGC 1569 toward UGCA 92, a nearby dwarf galaxy. These filamentary structures extend for about 1. Degree-Sign 5, which is 77 kpc at NGC 1569. There is a continuous velocity succession with the 0. Degree-Sign 5 H I cloud, filaments, and main body of the galaxy. The 0. Degree-Sign 5 H I cloud and filamentary structures may be foreground Milky Way, but are suggestive as possible remnants of an interaction between NGC 1569 and UGCA 92. The data also show two tidal tails extending from UGCA 86 and IC 342, respectively. These structures may be part of a continuous H I bridge but more data are needed to determine if this is the case.« less