scholarly journals Properties of extragalactic thick discs recovered from ultra-deep Stripe82 imaging

2019 ◽  
Vol 629 ◽  
pp. A12 ◽  
Author(s):  
C. Martínez-Lombilla ◽  
J. H. Knapen
Keyword(s):  
Surface Brightness ◽  
Vertical Surface ◽  
Thick Disc ◽  
Deep Imaging ◽  
Low Surface Brightness ◽  
The Galaxy ◽  
History Of ◽  
Formation And Evolution ◽  
Disc Galaxies ◽  
Good Agreement

Context. Thick discs can give invaluable information on the formation and evolution history of galaxies as most, if not all, disc galaxies have a thin (classical) disc and a thick disc. Aims. We study the structure of thick discs in extraordinary depth by reaching a surface brightness limit of μrdeep ∼ 28.5−29 mag arcsec−2 with combined g, r, i band images from the IAC Stripe 82 Legacy Project. Methods. We present the characterisation of the thick discs in a sample of five edge-on galaxies. A study of the radial and vertical surface brightness profiles is presented by comparing our data with point spread function (PSF) deconvolved models. Our method begins with an analysis of the background and masking processes. Then we consider the effects of the PSF through galaxy modelling. The galaxy disc components are fitted considering that the thin and thick discs are two stellar fluids that are gravitationally coupled in hydrostatic equilibrium. Results. We find that effects due to the PSF are significant when low surface brightness is reached, especially in the vertical profiles, but it can be accounted for by careful modelling. The galaxy outskirts are strongly affected by the faint wings of the PSF, mainly by PSF-redistributed light from the thin disc. This is a central problem for ultra-deep imaging. The thick-disc component is required to reach satisfactory fit results in the more complex galaxies in our sample, although it is not required for all galaxies. When the PSF is ignored, the brightness of these structures may be overestimated by up to a factor of ∼4. Conclusions. In general, our results are in good agreement with those of previous works, although we reach deeper surface brightness levels, so that the PSF effects are stronger. We obtain scale heights and mass ratios of thin and thick discs (zt, zT, and MT/Mt), which provide excellent agreement with previous studies. Our small initial sample provides evidence for aspects of a wide variety of formation theories for the thick discs in disc galaxies.

scholarly journals The haloes and environments of nearby galaxies (HERON) – II. The outer structure of edge-on galaxies

2020 ◽  
Vol 494 (2) ◽  
pp. 1751-1770 ◽  
Author(s):  
Aleksandr Mosenkov ◽  
R Michael Rich ◽  
Andreas Koch ◽  
Noah Brosch ◽  
David Thilker ◽  
...  
Keyword(s):  
Surface Brightness ◽  
3D Model ◽  
Interacting Galaxies ◽  
Deep Imaging ◽  
Low Surface Brightness ◽  
The Galaxy ◽  
Nearby Galaxies

ABSTRACT The haloes and environments of nearby galaxies (HERON) project is aimed at studying haloes and low surface brightness (LSB) details near galaxies. In this second HERON paper, we consider in detail deep imaging (down to surface brightness of ∼28 mag arcsec−2 in the r band) for 35 galaxies, viewed edge-on. We confirm a range of LSB features previously described in the literature but also report new ones. We classify the observed outer shapes of the galaxies into three main types (and their prototypes): disc/diamond-like (NGC 891), oval (NGC 4302), and boxy (NGC 3628). We show that the shape of the outer disc in galaxies does not often follow the general 3D model of an exponential disc: 17 galaxies in our sample exhibit oval or even boxy isophotes at the periphery. Also, we show that the less flattened the outer disc, the more oval or boxy its structure. Many galaxies in our sample have an asymmetric outer structure. We propose that the observed diversity of the galaxy outer shapes is defined by the merger history and its intensity: if no recent multiple minor or single major merging took place, the outer shape is diamond-like or discy. On the contrary, interacting galaxies show oval outer shapes, whereas recent merging appears to transform the outer shape to boxy.

scholarly journals Compact, bulge dominated structures of spectroscopically confirmed quiescent galaxies at z ≈ 3

2020 ◽  
Author(s):  
Peter Lustig ◽  
Veronica Strazzullo ◽  
Chiara D’Eugenio ◽  
Emanuele Daddi ◽  
Maurilio Pannella ◽  
...  
Keyword(s):  
Structural Properties ◽  
Surface Brightness ◽  
Cosmic Time ◽  
Stellar Populations ◽  
Statistical Estimates ◽  
The Galaxy ◽  
Mass Size ◽  
Formation And Evolution ◽  
Size Relation ◽  
Good Agreement

Abstract We study structural properties of spectroscopically confirmed massive quiescent galaxies at z ≈ 3 with one of the first sizeable samples of such sources, made of ten 10.8 < log (M⋆/M⊙) < 11.3 galaxies at 2.4 < z < 3.2 in the COSMOS field whose redshifts and quiescence are confirmed by HST grism spectroscopy. Although affected by a weak bias toward younger stellar populations, this sample is deemed to be largely representative of the majority of the most massive and thus intrinsically rarest quiescent sources at this cosmic time. We rely on targeted HST/WFC3 observations and fit Sérsic profiles to the galaxy surface brightness distributions at ≈4000Årestframe. We find typically high Sérsic indices and axis ratios (medians ≈4.5 and 0.73, respectively) suggesting that, at odds with some previous results, the first massive quiescent galaxies may largely be already bulge-dominated systems. We measure compact galaxy sizes with an average of ≈1.4kpc at log (M⋆/M⊙) ≈ 11.2, in good agreement with the extrapolation at the highest masses of previous determinations of the stellar mass - size relation of quiescent galaxies, and of its redshift evolution, from photometrically selected samples at lower and similar redshifts. This work confirms the existence of a population of compact, bulge dominated, massive, quiescent sources at z ≈ 3, providing one of the first statistical estimates of their structural properties, and further constraining the early formation and evolution of the first quiescent galaxies.

scholarly journals An excessively massive thick disc of the enormous edge-on lenticular galaxy NGC 7572

2020 ◽  
Vol 493 (4) ◽  
pp. 5464-5478
Author(s):  
Anastasia V Kasparova ◽  
Ivan Yu Katkov ◽  
Igor V Chilingarian
Keyword(s):  
Stellar Population ◽  
Line Of Sight ◽  
Mass Ratio ◽  
Thick Disc ◽  
Novel Technique ◽  
The Galaxy ◽  
Depth Study ◽  
Formation And Evolution ◽  
Disc Galaxies ◽  
Disc Formation

ABSTRACT Galactic discs are known to have a complex multilayer structure. An in-depth study of the stellar population properties of the thin and thick components can elucidate the formation and evolution of disc galaxies. Even though thick discs are ubiquitous, their origin is still debated. Here we probe the thick disc formation scenarios by investigating NGC 7572, an enormous edge-on galaxy having R25 ≈ 25 kpc and Vrot ≈ 370 km s−1, which substantially exceeds the Milky Way size and mass. We analysed DECaLS archival imaging and found that the disc of NGC 7572 contains two flaring stellar discs (a thin and a thick disc) with similar radial scales. We collected deep long-slit spectroscopic data using the 6 m Russian BTA telescope and analysed them with a novel technique. We first reconstructed a non-parametric stellar line-of-sight velocity distribution along the radius of the galaxy and then fitted it with two kinematic components accounting for the orbital distribution of stars in thin and thick discs. The old thick disc turned out to be 2.7 times as massive as the intermediate-age thin component, 1.6 × 1011 M⊙ versus 5.9 × 1010 M⊙, which is very unusual. The different duration of the formation epochs evidenced by the [Mg/Fe] values of +0.3 and +0.15 dex for the thick and thin discs respectively, their kinematics, and the mass ratio suggest that in NGC 7572 we observe a rapidly formed very massive thick disc and an underdeveloped thin disc, whose growth ended prematurely due to the exhaustion of the cold gas likely because of environmental effects.

scholarly journals NGC 474 as viewed with KCWI: diagnosing a shell galaxy

2020 ◽  
Vol 497 (1) ◽  
pp. 626-631 ◽  
Author(s):  
Adebusola B Alabi ◽  
Anna Ferré-Mateu ◽  
Duncan A Forbes ◽  
Aaron J Romanowsky ◽  
Jean P Brodie
Keyword(s):  
Galaxy Formation ◽  
Surface Brightness ◽  
Stellar Population ◽  
Shell System ◽  
Satellite Galaxy ◽  
Galaxy Formation And Evolution ◽  
Low Surface Brightness ◽  
The Galaxy ◽  
Formation And Evolution ◽  
Star Formation Histories

ABSTRACT We present new spectra obtained using Keck/KCWI and perform kinematics and stellar population analyses of the shell galaxy NGC 474, from both the galaxy centre and a region from the outer shell. We show that both regions have similarly extended star formation histories although with different stellar population properties. The central region of NGC 474 is dominated by intermediate-aged stars (8.3 ± 0.3 Gyr) with subsolar metallicity ([Z/H] = −0.24 ± 0.07 dex) while the observed shell region, which hosts a substantial population of younger stars, has a mean luminosity-weighted age of 4.0 ± 0.5 Gyr with solar metallicities ([Z/H] = −0.03 ± 0.09 dex). Our results are consistent with a scenario in which NGC 474 experienced a major to intermediate merger with a log$(M_*/\rm M_\odot) \sim 10$ mass satellite galaxy at least ${\sim}2$ Gyr ago which produced its shell system. This work shows that the direct spectroscopic study of low-surface brightness stellar features, such as shells, is now feasible and opens up a new window to understanding galaxy formation and evolution.

scholarly journals Past, Present, and Future of the Scaling Relations of Galaxies and Active Galactic Nuclei

2021 ◽  
Vol 8 ◽  
Author(s):  
Mauro D’Onofrio ◽  
Paola Marziani ◽  
Cesare Chiosi
Keyword(s):  
Active Galactic Nuclei ◽  
Galaxy Formation ◽  
Galactic Nuclei ◽  
Scaling Relations ◽  
Short History ◽  
Physical Mechanisms ◽  
Galaxy Formation And Evolution ◽  
The Galaxy ◽  
History Of ◽  
Formation And Evolution

We review the properties of the established Scaling Relations (SRs) of galaxies and active galactic nuclei (AGN), focusing on their origin and expected evolution back in time, providing a short history of the most important progresses obtained up to now and discussing the possible future studies. We also try to connect the observed SRs with the physical mechanisms behind them, examining to what extent current models reproduce the observational data. The emerging picture clarifies the complexity intrinsic to the galaxy formation and evolution process as well as the basic uncertainties still affecting our knowledge of the AGN phenomenon. At the same time, however, it suggests that the detailed analysis of the SRs can profitably contribute to our understanding of galaxies and AGN.

scholarly journals Kinematics of Planetary Nebulae in M51's Tidal Tail

2003 ◽  
Vol 209 ◽  
pp. 633-634
Author(s):  
John J. Feldmeier ◽  
J. Christopher Mihos ◽  
Patrick R. Durrell ◽  
Robin Ciardullo ◽  
George H. Jacoby
Keyword(s):  
Surface Brightness ◽  
Numerical Models ◽  
Planetary Nebulae ◽  
Tidal Tail ◽  
Low Surface Brightness ◽  
Galaxy Interaction ◽  
Self Consistent ◽  
The Galaxy ◽  
Interacting Systems ◽  
Kinematic Properties

The galaxy pair NGC 5194/95 (M51) is one of the closest and best known interacting systems. Despite its notoriety, however, many of its features are not well studied. Extending westward from NGC 5195 is a low surface brightness tidal tail, which can only be seen in deep broadband exposures. Our previous [O III] λ5007 planetary nebulae (PN) survey of M51 recovered this tidal tail, and presented us with a opportunity to study the kinematics of a galaxy interaction in progress. We report the results of a spectroscopy survey of the PN, aimed at determining their kinematic properties. We then use these data to constrain new self-consistent numerical models of the system.

scholarly journals The Ghosts of Galaxies: Tidal Debris in Clusters

2004 ◽  
Vol 217 ◽  
pp. 70-76
Author(s):  
Michael D. Gregg ◽  
Michael J. West
Keyword(s):  
Globular Clusters ◽  
Surface Brightness ◽  
Large Scale ◽  
Dwarf Galaxies ◽  
Cluster Formation ◽  
X Ray ◽  
Cluster Evolution ◽  
Low Surface Brightness ◽  
Intergalactic Space ◽  
Formation And Evolution

Gravitational interactions in rich clusters can strip material from the outer parts of galaxies or even completely disrupt entire systems, giving rise to large scale, low surface brightness ghostly features stretching across intergalactic space. The nearby Coma and Centaurus clusters both have striking examples of galaxy ghosts, in the form of 100 kpc-long plumes of intergalactic debris. By searching HST archival images, we have found numerous other examples of galaxy ghosts in rich clusters at low redshift, evidence that galaxy destruction and recycling are ubiquitous, important in cluster formation and evolution, and continue to mold clusters at the present epoch. Many ghosts appear in X-ray bright clusters, perhaps signaling a connection with energetic subcluster mergers.The fate of such material has important ramifications for cluster evolution. Our new HST WFPC2 V & I images of a portion of the Centaurus plume reveal that it contains an excess of discrete objects with −12 < MV < −6, consistent with being globular clusters or smaller dwarf galaxies. This tidally liberated material is being recycled directly into the intracluster population of stars, dwarf galaxies, globular clusters, and gas, which may have been built largely from a multitude of similar events over the life of the cluster.

The Hi Neighborhoods Around STARBIRDS

2018 ◽  
Vol 14 (S344) ◽  
pp. 280-282
Author(s):  
Megan C. Johnson ◽  
Kristen B. W. McQuinn ◽  
John Cannon ◽  
Charlotte Martinkus ◽  
Evan Skillman ◽  
...  
Keyword(s):  
Star Formation ◽  
Surface Brightness ◽  
Spiral Galaxies ◽  
Dwarf Galaxies ◽  
Neutral Hydrogen ◽  
Tidal Interactions ◽  
Low Surface Brightness ◽  
The Galaxy ◽  
Green Bank Telescope ◽  
Intense Star Formation

AbstractStarbursts are finite periods of intense star formation (SF) that can dramatically impact the evolutionary state of a galaxy. Recent results suggest that starbursts in dwarf galaxies last longer and are distributed over more of the galaxy than previously thought, with star formation efficiencies (SFEs) comparable to spiral galaxies, much higher than those typical of non-bursting dwarfs. This difference might be explainable if the starburst mode is externally triggered by gravitational interactions with other nearby systems. We present new, sensitive neutral hydrogen observations of 18 starburst dwarf galaxies, which are part of the STARburst IRregular Dwarf Survey (STARBIRDS) and each were mapped with the Green Bank Telescope (GBT) and/or Parkes Telescope in order to study the low surface brightness gas distributions, a common tracer for tidal interactions.

scholarly journals The Low Surface Brightness Galaxy HIPASS1126-72

1999 ◽  
Vol 171 ◽  
pp. 204-206
Author(s):  
Virginia Kilborn ◽  
Erwin de Blok ◽  
Lister Staveley-Smith ◽  
Rachel Webster
Keyword(s):  
Surface Brightness ◽  
Neutral Hydrogen ◽  
Sky Survey ◽  
Low Surface Brightness ◽  
The Galaxy

AbstractThe low surface brightness galaxy HIPASS1126-72 was detected in the HI Parkes All Sky Survey (HIPASS). The galaxy was previously listed in the Southern Galaxy Catalogue under the name SGC1124.87221. This galaxy represents a class of galaxies that we will readily detect in the HIPASS survey, which have low surface brightness in the optical, but are easily detectable in neutral hydrogen.

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