scholarly journals Stellar Over-Densities in the Outer Halo of the Milky Way

2010 ◽  
Vol 27 (1) ◽  
pp. 45-55 ◽  
Author(s):  
Stefan C. Keller
Keyword(s):  
Surface Brightness ◽  
Dwarf Galaxy ◽  
Local Density ◽  
Spatial Scales ◽  
Sloan Digital Sky Survey ◽  
Tidal Disruption ◽  
Giant Stars ◽  
Sky Survey ◽  
Low Surface Brightness ◽  
Model Predictions

AbstractThis study presents a tomographic survey of a subset of the outer halo (10–40 kpc) drawn from the Sloan Digital Sky Survey Data Release 6. Halo substructure on spatial scales of >3 degrees is revealed as an excess in the local density of sub-giant stars. With an appropriate assumption of a model stellar isochrone it is possible for us to then derive distances to the sub-giant population. We describe three new candidate halo substructures; the 160- and 180-degree over-densities (at distances of 17 and 19 kpc respectively and radii of 1.3 and 1.5 kpc respectively) and an extended feature at 28 kpc that covers at least 162 deg2, the Virgo Equatorial Stream. In addition, we recover the Sagittarius dwarf galaxy (Sgr) leading-arm material and the Virgo Over-Density.The derived distances, together with the number of sub-giant stars associated with each substructure, enables us to derive the integrated luminosity for the features. The tenuous, low surface brightness of the features strongly suggests an origin from the tidal disruption of an accreted galaxy or galaxies. Given the dominance of the tidal debris of Sgr in this region of the sky we investigate if our observations can be accommodated by tidal disruption models for Sgr. The clear discordance between observations and model predictions for known Sgr features means it is difficult to tell unambiguously if the new substructures are related to Sgr or not. Radial velocities in the stellar over-densities will be critical in establishing their origins.

scholarly journals Tidal Remnants and Intergalactic H II Regions

2004 ◽  
Vol 217 ◽  
pp. 486-491 ◽  
Author(s):  
Tom Oosterloo ◽  
Raffaella Morganti ◽  
Elaine M. Sadler ◽  
Annette Ferguson ◽  
Thijs van der Hulst ◽  
...  
Keyword(s):  
Star Formation ◽  
Surface Brightness ◽  
Small Scale ◽  
H Ii Regions ◽  
Tidal Disruption ◽  
Tidal Interactions ◽  
Sky Survey ◽  
Low Surface Brightness ◽  
Intergalactic Space ◽  
Star Formation Regions

We report the discovery of two small intergalactic H II regions in the loose group of galaxies around the field elliptical NGC 1490. The H II regions are located at least 100 kpc from any optical galaxy but are associated with a number of large H I clouds that are lying along an arc 500 kpc in length and that have no optical counterpart on the Digital Sky Survey. The sum of the H I masses of the clouds is almost 1010M⊙ and the largest H I cloud is about 100 kpc in size. Deep optical imaging reveals a very low surface brightness counterpart to this largest H I cloud, making this one of the H I richest optical galaxies known (MHI/LV ~ 200). Spectroscopy of the H II regions indicates that the abundance in these H II regions is only slightly sub-solar, excluding a primordial origin of the H I clouds. The H I clouds are perhaps remnants resulting from the tidal disruption of a reasonably sized galaxy, probably quite some time ago, by the loose group to which NGC 1490 belongs. Alternatively, they are remnants of the merger that created the field elliptical NGC 1490. The isolated H II regions show that star formation on a very small scale can occur in intergalactic space in gas drawn from galaxies by tidal interactions. Many such intergalactic small star formation regions may exist near tidally interacting galaxies.

scholarly journals The IAC stripe82 legacy project

2016 ◽  
Vol 11 (S321) ◽  
pp. 266-266
Author(s):  
Javier Román ◽  
Juergen Fliri ◽  
Ignacio Trujillo
Keyword(s):  
Surface Brightness ◽  
Dwarf Galaxies ◽  
Sloan Digital Sky Survey ◽  
Diffuse Light ◽  
Imaging Data ◽  
Data Set ◽  
Unique Possibility ◽  
Sky Survey ◽  
Low Surface Brightness

AbstractWe present new deep co-adds of data taken within Stripe 82 of the Sloan Digital Sky Survey (SDSS), especially stacked to reach the faintest surface brightness limits of this data set. Our reduction puts special emphasis on preserving the characteristics of the background (sky + diffuse light) in the input images using a non-aggressive sky subtraction strategy, resulting in an exquisite quality on extremely faint structures. The IAC Stripe 82 co-adds offer a rather unique possibility to study the low surface brightness Universe like stellar haloes and disc truncations, low surface brightness, tidal galactic interactions, extremely faint dwarf galaxies, intra-cluster light or diffuse light from galactic dust. The imaging data is publicly available at http://www.iac.es/proyecto/stripe82/.

Evolution of bulgeless low surface brightness galaxies

2015 ◽  
Vol 11 (S319) ◽  
pp. 138-138
Author(s):  
X. Shao ◽  
F. Hammer ◽  
Y. B. Yang ◽  
Y. C. Liang
Keyword(s):  
Surface Brightness ◽  
Large Scale ◽  
Stellar Population ◽  
Young Stars ◽  
Sloan Digital Sky Survey ◽  
Limited Sample ◽  
Sky Survey ◽  
Low Surface Brightness ◽  
Low Surface Brightness Galaxies ◽  
Lsb Galaxies

AbstractBased on the Sloan Digital Sky Survey DR 7, we investigate the environment, morphology, and stellar population of bulgeless low surface-brightness (LSB) galaxies in a volume-limited sample with redshift ranging from 0.024 to 0.04 and Mr ≤ −18.8. We find that, for bulgeless galaxies, the surface brightness does not depend on the environment. Irregular LSB galaxies have more young stars and are more metal-poor than regular LSB galaxies. These results suggest that the evolution of LSB galaxies may be driven by their dynamics, including mergers rather than by their large-scale environment.

scholarly journals The Halos and Environments of Nearby Galaxies (HERON) Survey

2016 ◽  
Vol 11 (S321) ◽  
pp. 186-189 ◽  
Author(s):  
R. Michael Rich ◽  
Noah Brosch ◽  
James Bullock ◽  
Andreas Burkert ◽  
Michelle Collins ◽  
...  
Keyword(s):  
Star Formation ◽  
Surface Brightness ◽  
Spiral Galaxies ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
General Survey ◽  
Tidal Disruption ◽  
Local Volume ◽  
Low Surface Brightness ◽  
Nearby Galaxies

AbstractWe have used dedicated 0.7m telescopes in California and Israel to image the halos of ~ 200 galaxies in the Local Volume to 29 mag/sq arcsec, the sample mainly drawn from the 2MASS Large Galaxy Atlas (LGA). We supplement the LGA sample with dwarf galaxies and more distant giant ellipticals. Low surface brightness halos exceeding 50 kpc in diameter are found only in galaxies more luminous than L*, and classic interaction signatures are relatively infrequent. Halo diameter is correlated with total galaxy luminosity. Extended low surface brightness halos are present even in galaxies as faint as MV = - 18. Edge-on galaxies with boxy bulges tend to lack extended spheroidal halos, while those with large classical bulges exhibit extended round halos, supporting the notions that boxy or barlike bulges originate from disks. Most face-on spiral galaxies present features that appear to be irregular extensions of spiral arms, although rare cases show smooth boundaries with no sign of star formation. Although we serendipitously discovered a dwarf galaxy undergoing tidal disruption in the halo of NGC 4449, we found no comparable examples in our general survey. A search for similar examples in the Local Volume identified hcc087, a tidally disrupting dwarf galaxy in the Hercules Cluster, but we do not confirm an anomalously large half-light radius reported for the dwarf VCC 1661.

scholarly journals Low Surface Brightness Galaxies in the Sloan Digital Sky Survey. I. Search Method and Test Sample

2004 ◽  
Vol 127 (2) ◽  
pp. 704-727 ◽  
Author(s):  
Alexei Y. Kniazev ◽  
Eva K. Grebel ◽  
Simon A. Pustilnik ◽  
Alexander G. Pramskij ◽  
Tamara F. Kniazeva ◽  
...  
Keyword(s):  
Surface Brightness ◽  
Test Sample ◽  
Search Method ◽  
Sloan Digital Sky Survey ◽  
Sky Survey ◽  
Low Surface Brightness ◽  
Low Surface Brightness Galaxies

scholarly journals The Leo-I group: new dwarf galaxy and ultra diffuse galaxy candidates

2018 ◽  
Vol 615 ◽  
pp. A105 ◽  
Author(s):  
Oliver Müller ◽  
Helmut Jerjen ◽  
Bruno Binggeli
Keyword(s):  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Structural Parameters ◽  
Sloan Digital Sky Survey ◽  
Current Standard ◽  
Groups Of Galaxies ◽  
Galaxy Type ◽  
Sky Survey ◽  
Low Surface Brightness ◽  
Image Enhancing

Context. The study of dwarf galaxies and their environments provides crucial test beds for predictions of cosmological models and insights into the structure formation on small cosmological scales. In recent years, many problems on the scale of groups of galaxies has challenged the current standard model of cosmology. Aims. Our aim is to increase the sample of known galaxies in the Leo-I group, which contains the M 96 subgroup and the Leo Triplet. This galaxy aggregate is located at the edge of the Local Volume at a mean distance of 10.7 Mpc. Methods. We employed image enhancing techniques to search for low surface brightness objects in publicly available gr images taken by the Sloan Digital Sky Survey within 500 square degrees around the Leo-I group. Once detected, we performed surface photometry and compared their structural parameters to other known dwarf galaxies in the nearby universe. Results. We found 36 new dwarf galaxy candidates within the search area. Their morphology and structural parameters resemble known dwarfs in other groups. Among the candidates five or six galaxies are considered as ultra diffuse galaxy candidates. If confirmed, they would be some of the closest examples of this galaxy type. We assessed the luminosity function of the Leo-I group and find it to be considerably rich in dwarf galaxies, with twice the number of galaxies as the Local Group at a limiting magnitude of MV = −10 and a steeper faint-end slope.

scholarly journals Stellar Population Analysis on a Large Sample of Low Surface Brightness Galaxies

2012 ◽  
Vol 8 (S292) ◽  
pp. 154-154 ◽  
Author(s):  
Xiaoyan Chen ◽  
Ali Luo ◽  
Yanchun Liang
Keyword(s):  
Surface Brightness ◽  
Stellar Population ◽  
Population Analysis ◽  
Sloan Digital Sky Survey ◽  
Large Sample ◽  
Central Surface ◽  
Sky Survey ◽  
Low Surface Brightness ◽  
Galaxy Sample ◽  
Low Surface Brightness Galaxies

AbstractWe study the stellar populations of a large sample of nearly face-on disk Low Surface Brightness Galaxies (LSBGs), with B-band central surface brightness μ0(B) > 22 mag arcsec−2, selected from the Sloan Digital Sky Survey Data Release 4 (SDSS-DR4) main galaxy sample (similar to Zhong et al. 2008; Liang et al. 2010).

scholarly journals Linking Clustering Properties and the Evolution of Low Surface Brightness Galaxies

2007 ◽  
Vol 3 (S244) ◽  
pp. 274-278
Author(s):  
Dominik J. Bomans ◽  
S. Dominik Rosenbaum
Keyword(s):  
Galaxy Evolution ◽  
Surface Brightness ◽  
Large Scale ◽  
High Surface ◽  
Sloan Digital Sky Survey ◽  
Dark Matter Halo ◽  
Sky Survey ◽  
Low Surface Brightness ◽  
Low Surface Brightness Galaxies ◽  
Lsb Galaxies

AbstractThe reasons for the presence of two branches of galaxy evolution, one producing high surface brightness disks and one creating low surface brightness disks, is still unknown. Possible are the imprint of the properties of the dark matter halo, as well as evolutionary effects. In this paper we present an analysis of the clustering properties of LSB and HSB galaxies using the Sloan Digital Sky Survey. We show that LSB galaxies reside in regions of lower galaxy density than HSB galaxies on all scales between 0.8 and 8 Mpc, from scales of galaxy pairs to filaments of the Large Scale Structure. This implies a probable scenario of LSB galaxies preferentially forming as a result of local peaks in the large-scale valleys of the primordial density distribution.

scholarly journals The haloes and environments of nearby galaxies (HERON) – I. Imaging, sample characteristics, and envelope diameters

2019 ◽  
Vol 490 (2) ◽  
pp. 1539-1569 ◽  
Author(s):  
R Michael Rich ◽  
Aleksandr Mosenkov ◽  
Henry Lee-Saunders ◽  
Andreas Koch ◽  
John Kormendy ◽  
...  
Keyword(s):  
Surface Brightness ◽  
Dwarf Galaxy ◽  
Sky Survey ◽  
Low Surface Brightness ◽  
Magnitude Diagram ◽  
The Galaxy ◽  
Nearby Galaxies ◽  
Sample Characteristics ◽  
S0 Galaxies ◽  
Red Sequence

ABSTRACT We use a dedicated 0.7-m telescope to image the haloes of 119 galaxies in the Local Volume to μr ∼ 28–30 mag arcsec−2. The sample is primarily from the Two Micron All Sky Survey Large Galaxy Atlas (Jarrett et al. 2003) and extended to include nearby dwarf galaxies and more distant giant ellipticals, and spans fully the galaxy colour–magnitude diagram including the blue cloud and red sequence. We present an initial overview, including deep images of our galaxies. Our observations reproduce previously reported low surface brightness structures, including extended plumes in M 51, and a newly discovered tidally extended dwarf galaxy in NGC 7331. Low surface brightness structures, or ‘envelopes’, exceeding 50 kpc in diameter are found mostly in galaxies with MV < −20.5, and classic interaction signatures are infrequent. Defining a halo diameter at the surface brightness 28 mag arcsec−2, we find that halo diameter is correlated with total galaxy luminosity. Extended signatures of interaction are found throughout the galaxy colour–magnitude diagram without preference for the red or blue sequences, or the green valley. Large envelopes may be found throughout the colour–magnitude diagram with some preference for the bright end of the red sequence. Spiral and S0 galaxies have broadly similar sizes, but ellipticals extend to notably greater diameters, reaching 150 kpc. We propose that the extended envelopes of disc galaxies are dominated by an extension of the disc population rather than by a classical Population II halo.

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