Tidal dwarf candidates in a sample of interacting galaxies

Weilbacher, Peter M.; Duc, Pierre–Alain; Alvensleben, U. Fritze–v.

doi:10.1051/0004-6361:20021522

Cited by 118 publications

(157 citation statements)

References 57 publications

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“…In addition, luminosity-metallicity relations are very useful to discern between pre-existing dwarf galaxies and tidal dwarf galaxy (TDG) candidates (Duc & Mirabel 1998;Duc et al 2000) because these objects should have a metallicity similar to that observed in their parent spiral galaxies (Weilbacher et al 2003) and not a low-metallicity as it is found in dwarf objects.…”

Section: Metallicity-luminosity Relationsmentioning

confidence: 99%

Massive star formation in Wolf-Rayet galaxies

López-Sánchez

Esteban

2010

A&A

121

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Aims. We have performed a comprehensive multiwavelength analysis of a sample of 20 starburst galaxies that show a substantial population of very young massive stars, most of them classified as Wolf-Rayet (WR) galaxies. In this paper, the forth of the series, we present the global analysis of the derived photometric and chemical properties. Methods. We compare optical/NIR colours and the physical properties (reddening coefficient, equivalent widths of the emission and underlying absorption lines, ionization degree, electron density, and electron temperature) and chemical properties (oxygen abundances and N/O, S/O, Ne/O, Ar/O, and Fe/O ratios) with previous observations and galaxy evolution models. We compile 41 independent star-forming regions -with oxygen abundances between 12 + log(O/H) = 7.58 and 8.75 -, of which 31 have a direct estimate of the electron temperature of the ionized gas.Results. According to their absolute B-magnitude, many of them are not dwarf galaxies, but they should be during their quiescent phase. We found that both c(Hβ) and W abs increase with increasing metallicity. The differences in the N/O ratio is explained assuming differences in the star formation histories. We detected a high N/O ratio in objects showing strong WR features (HCG 31 AC, UM 420, IRAS 0828+2816, III Zw 107, ESO 566-8 and NGC 5253). The ejecta of the WR stars may be the origin of the N enrichment in these galaxies. We compared the abundances provided by the direct method with those obtained through empirical calibrations, finding that (i) the Pilyugin method is the best suited empirical calibration for these star-forming galaxies; (ii) the relations provided by Pettini & Pagel (2004, MNRAS, 348, 59) give acceptable results for objects with 12 + log(O/H) > 8.0; and (iii) the results provided by empirical calibrations based on photoionization models are systematically 0.2-0.3 dex higher than the values derived from the direct method. The O and N abundances and the N/O ratios are clearly related to the optical/NIR luminosity; the dispersion of the data is a consequence of the differences in the star-formation histories. The L-Z relations tend to be tighter when using NIR luminosities, which facilitates distinguishing tidal dwarf galaxies candidates and pre-existing dwarf objects. Galaxies with redder colours tend to have higher oxygen and nitrogen abundances. Conclusions. Our detailed analysis is fundamental to understand the nature of galaxies that show strong starbursts, as well as to know their star formation history and the relationships with the environment. This study is complementary -but usually more powerful-to the less detailed analysis of large galaxy samples that are very common nowadays.

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Section: Metallicity-luminosity Relationsmentioning

confidence: 99%

Massive star formation in Wolf-Rayet galaxies

López-Sánchez

Esteban

2010

A&A

121

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“…In addition to atomic gas pulled from the parent galaxies, these collisional debris actually contain surprisingly large amounts of molecular gas formed in-situ (Braine et al 2000(Braine et al , 2001Lisenfeld et al 2002Lisenfeld et al , 2004Petitpas & Taylor 2005;Duc et al 2007). As the gas subsequently collapses, starforming regions are created with masses ranging from a few hundred solar masses, creating OB associations, the "emission line dots" (Gerhard et al 2002;Yoshida et al 2002;Sakai et al 2002;Weilbacher et al 2003;Ryan-Weber et al 2004;Mendes de Oliveira et al 2004;Cortese et al 2006;Werk et al 2008Werk et al , 2010 to objects as massive as dwarf galaxies named tidal dwarf galaxies (TDGs, Duc 1995;Duc & Mirabel 1998;Duc et al 2000Duc et al , 2007Hancock et al 2007Hancock et al , 2009). These objects, A&A 533, A19 (2011) even though formed from material once pertaining to their parent galaxies, have a radically different and simpler environment.…”

Section: Introductionmentioning

confidence: 99%

Studying the spatially resolved Schmidt-Kennicutt law in interacting galaxies: the case of Arp 158

Boquien¹,

Lisenfeld²,

Duc³

et al. 2011

A&A

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Context. Recent studies have shown that star formation in mergers does not seem to follow the same Schmidt-Kennicutt relation as in spiral disks, presenting a higher star formation rate (SFR) for a given gas column density. Aims. In this paper we study why and how different models of star formation arise. To do so we examine the process of star formation in the interacting system Arp 158 and its tidal debris. Methods. We perform an analysis of the properties of specific regions of interest in Arp 158 using observations tracing the atomic and the molecular gas, star formation, the stellar populations as well as optical spectroscopy to determine their exact nature and their metallicity. We also fit their spectral energy distribution with an evolutionary synthesis code. Finally, we compare star formation in these objects to star formation in the disks of spiral galaxies and mergers. Results. Abundant molecular gas is found throughout the system and the tidal tails appear to have many young stars compared to their old stellar content. One of the nuclei is dominated by a starburst whereas the other is an active nucleus. We estimate the SFR throughout the systems using various tracers and find that most regions follow closely the Schmidt-Kennicutt relation seen in spiral galaxies with the exception of the nuclear starburst and the tip of one of the tails. We examine whether this diversity is due to uncertainties in the manner the SFR is determined or whether the conditions in the nuclear starburst region are such that it does not follow the same Schmidt-Kennicutt law as other regions. Conclusions. Observations of the interacting system Arp 158 provide the first evidence in a resolved fashion that different star-forming regions in a merger may be following different Schmidt-Kennicutt laws. This suggests that the physics of the interstellar medium at a scale no larger than 1 kpc, the size of the largest gravitational instabilities and the injection scale of turbulence, determines the origin of these laws.

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“…These so-called tidal dwarf galaxies (TDGs) share the high metallicity of the giant galaxies from which they formed, so are unusually metal-rich for their small size (e.g. Mirabel et al 1992; Duc et al 2000;Weilbacher et al 2003). They also have no or little non-baryonic DM, though may contain a significant fraction of baryonic DM (Bournaud et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Kinematics of dwarf galaxies in gas-rich groups, and the survival and detectability of tidal dwarf galaxies

Sweet

Drinkwater

Meurer

et al. 2015

Mon. Not. R. Astron. Soc.

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We present DEIMOS multi-object spectroscopy (MOS) of 22 star-forming dwarf galaxies located in four gas-rich groups, including six newly-discovered dwarfs. Two of the galaxies are strong tidal dwarf galaxy (TDG) candidates based on our luminosity-metallicity relation definition. We model the rotation curves of these galaxies. Our sample shows low mass-to-light ratios (M/L=0.73±0.39M /L ) as expected for young, star-forming dwarfs. One of the galaxies in our sample has an apparently strongly-falling rotation curve, reaching zero rotational velocity outside the turnover radius of r turn = 1.2r e . This may be 1) a polar ring galaxy, with a tilted bar within a face-on disk; 2) a kinematic warp. These scenarios are indistinguishable with our current data due to limitations of slit alignment inherent to MOS-mode observations. We consider whether TDGs can be detected based on their tidal radius, beyond which tidal stripping removes kinematic tracers such as Hα emission. When the tidal radius is less than about twice the turnover radius, the expected falling rotation curve cannot be reliably measured. This is problematic for as much as half of our sample, and indeed more generally, galaxies in groups like these. Further to this, the Hα light that remains must be sufficiently bright to be detected; this is only the case for three (14%) galaxies in our sample. We conclude that the falling rotation curves expected of tidal dwarf galaxies are intrinsically difficult to detect.

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Tidal dwarf candidates in a sample of interacting galaxies

Cited by 118 publications

References 57 publications

Massive star formation in Wolf-Rayet galaxies

Massive star formation in Wolf-Rayet galaxies

Studying the spatially resolved Schmidt-Kennicutt law in interacting galaxies: the case of Arp 158

Kinematics of dwarf galaxies in gas-rich groups, and the survival and detectability of tidal dwarf galaxies

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