We report the discovery of 4 strong gravitational lensing systems by visual inspections of the Sloan Digital Sky Survey images of galaxy clusters in Data Release 6 (SDSS DR6). Two of the four systems show Einstein r...We report the discovery of 4 strong gravitational lensing systems by visual inspections of the Sloan Digital Sky Survey images of galaxy clusters in Data Release 6 (SDSS DR6). Two of the four systems show Einstein rings while the others show tangen- tial giant arcs. These arcs or rings have large angular separations (〉 8″) from the bright central galaxies and show bluer color compared with the red cluster galaxies. In addition, we found 5 probable and 4 possible lenses by galaxy clusters.展开更多
We investigate two classes of conditions for galaxy quenching at 0.510^10 M⊙)have much higher stellar mass surface densities within the central 1 kpc(∑1)and smaller sizes than star-forming galaxies in the same stell...We investigate two classes of conditions for galaxy quenching at 0.510^10 M⊙)have much higher stellar mass surface densities within the central 1 kpc(∑1)and smaller sizes than star-forming galaxies in the same stellar mass range.In addition,the quiescent fractions significantly increase with the increase of∑1 regardless of whether galaxies are centrals or satellites.In contrast,we find that the overall lower-mass quiescent galaxies(M*<~10^10M⊙)have slightly higher E1 and comparable sizes compared to starforming galaxies of the same mass and at the same redshift.At z<1.5,satellites have higher halo masses and larger quiescent fractions than those of centrals at a given∑1(stellar mass).Our findings indicate that the significant growth of the galaxy cores is closely related to the quenching of massive galaxies since z^2.5,while the environmental effect plays an important role in the quenching of low-mass galaxies at z≤1.5.展开更多
We select a large volume-limited sample of low surface brightness galax- ies (LSBGs, 2021) to investigate in detail their statistical properties and their dif- ferences from high surface brightness galaxies (HSBGs,...We select a large volume-limited sample of low surface brightness galax- ies (LSBGs, 2021) to investigate in detail their statistical properties and their dif- ferences from high surface brightness galaxies (HSBGs, 3639). The distributions of stellar masses of LSBGs and HSBGs are nearly the same and they have the same me- dian values. Thus this volume-limited sample has good completeness and is further removed from the effect of stellar masses on their other properties when we compare LSBGs to HSBGs. We found that LSBGs tend to have lower stellar metallicities and lower effective dust attenuations, indicating that they have lower dust than HSBGs. The LSBGs have relatively higher stellar mass-to-light ratios, higher gas fractions, lower star forming rates (SFRs), and lower specific SFRs than HSBGs. Moreover, with the decreasing surface brightness, gas fraction increases, but the SFRs and spe- cific SFRs decrease rapidly for the sample galaxies. This could mean that the star formation histories between LSBGs and HSBGs are different, and HSBGs may have stronger star forming activities than LSBGs.展开更多
Two-dimensional bulge/disk light decomposition with GIM2D in both the r- and g-bands has been applied to a sample of 129 early-type galaxies brighter than 13.5 magnitude in the r-band, selected from the Sloan Digital ...Two-dimensional bulge/disk light decomposition with GIM2D in both the r- and g-bands has been applied to a sample of 129 early-type galaxies brighter than 13.5 magnitude in the r-band, selected from the Sloan Digital Sky Survey Data Release 2. Intensity-weighted Fourier coefficient (α4/α) was also derived for each sample galaxy. Our analysis shows that there are correlations between bulge-to-total light ratio (B/T) with bulge Sersic index nB and between bulge and disk scale sizes. Isophotal shape parameter (α4/α) is not correlated with BIT and riB. Both bulge and disk components satisfy a color-magnitude relation. The space Fundamental Plane analysis shows that galaxies with larger B/T tend to lie tighter and closer to the line of k1 + k2 = 8 (the so-called "zone of avoidance") than the galaxies with smaller B/T. It indicates that existence of the disk component may lead to scatter of the distribution on the Fundamental Plane. Our analysis also shows that k1 + k2 correlates with (g-r) color and B/T, but does not correlate with (α4/α) for early-type galaxies. The fitted parameters and other retrieved parameters used in this paper for all sample galaxies are available online.展开更多
We present an efficient spherical parameterization approach aimed at simultaneously reducing area and angle dis-tortions. We generate the final spherical mapping by independently establishing two hemisphere parameteri...We present an efficient spherical parameterization approach aimed at simultaneously reducing area and angle dis-tortions. We generate the final spherical mapping by independently establishing two hemisphere parameterizations. The essence of the approach is to reduce spherical parameterization to a planar problem using symmetry analysis of 3D meshes. Experiments and comparisons were undertaken with various non-trivial 3D models, which revealed that our approach is efficient and robust. In particular, our method produces almost isometric parameterizations for the objects close to the sphere.展开更多
基金supported by the National Natural Science Foundation of China (NSFC, Nos.10521001, 10773016 and 10833003)the National KeyBasic Research Science Foundation of China (2007CB815403).
文摘We report the discovery of 4 strong gravitational lensing systems by visual inspections of the Sloan Digital Sky Survey images of galaxy clusters in Data Release 6 (SDSS DR6). Two of the four systems show Einstein rings while the others show tangen- tial giant arcs. These arcs or rings have large angular separations (〉 8″) from the bright central galaxies and show bluer color compared with the red cluster galaxies. In addition, we found 5 probable and 4 possible lenses by galaxy clusters.
基金the National Key Research and Development Program of China(No.2017YFA0402703)the National Natural Science Foundation of China(Nos.11733002 and 11573017)。
文摘We investigate two classes of conditions for galaxy quenching at 0.510^10 M⊙)have much higher stellar mass surface densities within the central 1 kpc(∑1)and smaller sizes than star-forming galaxies in the same stellar mass range.In addition,the quiescent fractions significantly increase with the increase of∑1 regardless of whether galaxies are centrals or satellites.In contrast,we find that the overall lower-mass quiescent galaxies(M*<~10^10M⊙)have slightly higher E1 and comparable sizes compared to starforming galaxies of the same mass and at the same redshift.At z<1.5,satellites have higher halo masses and larger quiescent fractions than those of centrals at a given∑1(stellar mass).Our findings indicate that the significant growth of the galaxy cores is closely related to the quenching of massive galaxies since z^2.5,while the environmental effect plays an important role in the quenching of low-mass galaxies at z≤1.5.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10933001, 10973006, 10973015 and 10673002)the National Basic Research Program of China (973 Program+1 种基金 Nos. 2007CB815404 and 2007CB815406)the Young Researcher Grant of National Astronomical Observatories, Chinese Academy of Sciences
文摘We select a large volume-limited sample of low surface brightness galax- ies (LSBGs, 2021) to investigate in detail their statistical properties and their dif- ferences from high surface brightness galaxies (HSBGs, 3639). The distributions of stellar masses of LSBGs and HSBGs are nearly the same and they have the same me- dian values. Thus this volume-limited sample has good completeness and is further removed from the effect of stellar masses on their other properties when we compare LSBGs to HSBGs. We found that LSBGs tend to have lower stellar metallicities and lower effective dust attenuations, indicating that they have lower dust than HSBGs. The LSBGs have relatively higher stellar mass-to-light ratios, higher gas fractions, lower star forming rates (SFRs), and lower specific SFRs than HSBGs. Moreover, with the decreasing surface brightness, gas fraction increases, but the SFRs and spe- cific SFRs decrease rapidly for the sample galaxies. This could mean that the star formation histories between LSBGs and HSBGs are different, and HSBGs may have stronger star forming activities than LSBGs.
基金the National Natural Science Foundation of China
文摘Two-dimensional bulge/disk light decomposition with GIM2D in both the r- and g-bands has been applied to a sample of 129 early-type galaxies brighter than 13.5 magnitude in the r-band, selected from the Sloan Digital Sky Survey Data Release 2. Intensity-weighted Fourier coefficient (α4/α) was also derived for each sample galaxy. Our analysis shows that there are correlations between bulge-to-total light ratio (B/T) with bulge Sersic index nB and between bulge and disk scale sizes. Isophotal shape parameter (α4/α) is not correlated with BIT and riB. Both bulge and disk components satisfy a color-magnitude relation. The space Fundamental Plane analysis shows that galaxies with larger B/T tend to lie tighter and closer to the line of k1 + k2 = 8 (the so-called "zone of avoidance") than the galaxies with smaller B/T. It indicates that existence of the disk component may lead to scatter of the distribution on the Fundamental Plane. Our analysis also shows that k1 + k2 correlates with (g-r) color and B/T, but does not correlate with (α4/α) for early-type galaxies. The fitted parameters and other retrieved parameters used in this paper for all sample galaxies are available online.
基金Project supported by the National Natural Science Foundation of China (Nos. 60673006 and 60533060)the Program for New Century Excellent Talents in University (No. NCET-05-0275), Chinathe IDeA Network of Biomedical Research Excellence Grant (No. 5P20RR01647206) from National Institutes of Health (NIH), USA
文摘We present an efficient spherical parameterization approach aimed at simultaneously reducing area and angle dis-tortions. We generate the final spherical mapping by independently establishing two hemisphere parameterizations. The essence of the approach is to reduce spherical parameterization to a planar problem using symmetry analysis of 3D meshes. Experiments and comparisons were undertaken with various non-trivial 3D models, which revealed that our approach is efficient and robust. In particular, our method produces almost isometric parameterizations for the objects close to the sphere.