2010A&A...509A..19J


Query : 2010A&A...509A..19J

2010A&A...509A..19J - Astronomy and Astrophysics, volume 509, A19-19 (2010/1-1)

The molecular gas content of the advanced S+E merger NGC 4441. Evidence for an extended decoupled nuclear disc?

JUETTE E., AALTO S. and HUETTEMEISTER S.

Abstract (from CDS):

Despite their importance to galaxy evolution, mergers between a spiral and an elliptical (S+E mergers) have been poorly studied so far. NGC4441 is a nearby candidate of an advanced remnant of such a merger, showing typical tidal structures such as an optical tail and two shells as well as two Hi tails. Studying the molecular gas content provides clues about the impact of a recent merger event on the star formation. Simulations of S+E mergers yield conflicting predictions about both the strength and the extent of an induced starburst. Thus, observations of the amount and the distribution of the molecular gas, the raw material of star formation, are needed to understand the influence of the merger on the star formation history 12CO and 13CO (1-0) and (2-1) observations were obtained using the Onsala Space Observatory 20 m and IRAM 30 m telescope as well as the Plateau de Bure interferometer. These data allow us to carry out a basic analysis of the molecular gas properties, such as estimates of the molecular gas mass, temperature, and density and the star formation efficiency. The CO observations detect an extended molecular gas reservoir out to ∼4kpc, with a total molecular gas mass of ∼5x108M. Furthermore, high resolution imaging shows a central molecular gas feature, which is probably a rotating disc hosting most of the molecular gas (∼4x108M). This nuclear disc has a different sense of rotation to the large-scale Hi structure, indicating a kinematically decoupled core. We modeled the state of the interstellar medium with the radiative transfer code RADEX, using the ratios of the 12CO to 13CO line strenghts. The results are consistent with a diffuse (n≤103cm–3) molecular medium with no significant indications of cold, dense cores of ongoing star formation. This is in agreement with the moderate star formation rate of 1-2M/yr measured for NGC 4441. Assuming a constant star formation rate, the gas depletion time is τ=4.8x108yr. NGC 4441 might be a nearby candidate early-type galaxy with a dominant A-star population, a so-called E+A galaxy, which is in a post-starburst phase several 108yr after a merger event.

Abstract Copyright:

Journal keyword(s): galaxies: interactions - galaxies: starburst - galaxies: individual: NGC 4441 - radio lines: galaxies - radio lines: ISM

Simbad objects: 13

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Number of rows : 13
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 NGC 1316 GiP 03 22 41.789 -37 12 29.52 9.81 9.15 8.53 7.66   ~ 1279 1
2 3C 111 Sy1 04 18 21.2772425736 +38 01 35.801359968   19.75 18.05     ~ 893 1
3 PN A66 21 PN 07 29 02.7096654192 +13 14 48.587555184   15.67 15.99     DOZ 186 0
4 V* R Leo Mi* 09 47 33.4839808805 +11 25 43.823283729 9.22 8.94 7.53 3.39 0.12 M7-9e 891 1
5 6C 095456+654857 BLL 09 58 47.2451872176 +65 33 54.819354600     17.0 15.75   ~ 650 1
6 6C 104451+715930 QSO 10 48 27.6198768456 +71 43 35.939809416     19.0 17.49   ~ 202 1
7 NGC 4194 AGN 12 14 09.615 +54 31 35.93   13.79 13.30     ~ 435 2
8 NGC 4441 GiG 12 27 20.402 +64 48 05.64   13.5       ~ 75 0
9 3C 273 BLL 12 29 06.6998257176 +02 03 08.597629980   13.05 14.830 14.11   ~ 5555 1
10 NAME Centaurus A Sy2 13 25 27.6039817176 -43 01 09.493008456   8.18 6.84 6.66   ~ 4230 3
11 NGC 5195 GiP 13 29 59.590 +47 15 58.06 10.76 10.45 9.55 9.31   ~ 735 3
12 3C 454.0 QSO 22 51 34.7277468096 +18 48 40.087264428   18.52 18.4     ~ 219 2
13 V* R Cas Mi* 23 58 24.8682785040 +51 23 19.713029388 6.71 6.63 4.80     M6.5-9e 690 0

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2022.05.22-13:34:30

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