Actively Star Forming Elliptical Galaxies at Low Redshifts in the Sloan Digital Sky Survey

Using spatially resolved spectroscopy, we investigated the characteristics and different modes of formation of stars in elliptical galaxies. We identified an unusual population of 59 star-forming elliptical (SF-E) galaxies in SDSS-MaNGA, our primary sample. To identify these rare star-forming ellipticals, we combined GSWLC-A2 containing outputs of stellar population synthesis models with morphological results from the deep-learning catalogue and resolved and integrated proper...

E+A galaxies are characterized as a galaxy with strong Balmer absorption lines but without any [OII] or H$\alpha$ emission lines. The existence of strong Balmer absorption lines means that E+A galaxies have experienced a starburst within the last $<$1-1.5 gigayear. However, the lack of [OII] or H$\alpha$ emission lines indicates that E+A galaxies do not have any on-going star formation. Therefore, E+A galaxies are interpreted as a post-starburst galaxy. Morphologically, E+A...

We study the evolution of elliptical galaxies at z >~ 1 on the basis of a sample of 247 Extremely Red Objects (EROs) with R-Ks >= 3.35 (AB) and Ks <= 22.1 (AB) constructed from BVRi'z'JHKs multicolor data of a 114 arcmin2 area in the Subaru/XMM Deep Survey Field. By fitting template spectra of old ellipticals (OEs) and young, dusty starbursts (DSs) to the multicolor data, we classify EROs into these two classes and estimate their redshifts. We find that 58% of the EROs in our...

We present the results of 11 elliptical galaxies with strong nebular emission lines during our study of star formation history along the Hubble sequence. After removing the dilution from the underlying old stellar populations by use of stellar population synthesis model, we derive the accurate fluxes of all emission lines for these objects, which are later classified with emission line ratios into one Seyfert 2, six LINERs and four HII galaxies. We also identify one HII galax...

We measure the star formation rates (SFRs) of massive ($M_{\star}>10^{10.1}M_{\odot}$) early-type galaxies (ETGs) in a sample of 11 high-redshift ($1.0 < z < 1.5$) galaxy clusters drawn from the IRAC Shallow Cluster Survey (ISCS). We identify ETGs visually from Hubble Space Telescope imaging and select likely cluster members as having either an appropriate spectroscopic redshift or red sequence color. Mid-infrared SFRs are measured using Spitzer 24 $\mu$m data for isolated cl...

We simulate the growth of large-scale structure in the universe using a N-body code. By combining these simulations with a Monte-Carlo method, we generate galaxy distributions at present that reproduces the observed morphology-density relation, with most ellipticals concentrated in the densest regions. By "tying" each galaxy to its nearest particle, we trace the trajectory of that galaxy back in time. This enables us to reconstruct the distribution of galaxies at high redshif...

This paper looks for any correlation between the internal dynamics of elliptical galaxies and the relatively mild nuclear activity found in many such systems. We show that there is such a relation in the sense that the active ellipticals tend to be significantly less rotationally supported than their inactive cousins. The correlation can partly be related to the galaxies' luminosities: the brightest galaxies tend to be more active and less rotationally supported. However, eve...

We report new observations of atomic and molecular gas in a volume limited sample of elliptical galaxies. Combining the elliptical sample with an earlier and similar lenticular one, we show that cool gas detection rates are very similar among low luminosity E and SO galaxies but are much higher among luminous S0s. Using the combined sample we revisit the correlation between cool gas mass and blue luminosity which emerged from our lenticular survey, finding strong support for ...

We take advantage of the largest high-resolution simulation of cosmic structure growth ever carried out -- the Millennium Simulation of the concordance LambdaCDM cosmogony -- to study how the star formation histories, ages and metallicities of elliptical galaxies depend on environment and on stellar mass. We concentrate on a galaxy formation model which is tuned to fit the joint luminosity/colour/morphology distribution of low redshift galaxies. Massive ellipticals in this mo...

We present an analysis of the neutral hydrogen and stellar populations of elliptical galaxies in the Tal et al. (2009) sample. Our aim is to test their conclusion that the continuing assembly of these galaxies at z~0 is essentially gas-free and not accompanied by significant star formation. In order to do so, we make use of HI data and line-strength indices available in the literature. We look for direct and indirect evidence of the presence of cold gas during the recent asse...