- ID:
- ivo://CDS.VizieR/J/ApJ/818/182
- Title:
- Early-type galaxies at z<0.04 star formation rates
- Short Name:
- J/ApJ/818/182
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We address the relation between star formation and active galactic nucleus (AGN) activity in a sample of 231 nearby (0.0002<z<0.0358) early-type galaxies by carrying out a multi-wavelength study using archival observations in the UV, IR, and radio. Our results indicate that early-type galaxies in the current epoch are rarely powerful AGNs, with P<10^22^W/Hz for a majority of the galaxies. Only massive galaxies are capable of hosting powerful radio sources while less massive galaxies are hosts to lower radio power sources. Evidence of ongoing star formation is seen in approximately 7% of the sample. The star formation rate (SFR) of these galaxies is less than 0.1M_{sun}_/yr. They also tend to be radio faint (P<10^22^W/Hz). There is a nearly equal fraction of star-forming galaxies in radio faint (P<10^22^W/Hz) and radio bright galaxies (P>=10^22^W/Hz) suggesting that both star formation and radio mode feedback are constrained to be very low in our sample. We notice that our galaxy sample and the Brightest Cluster Galaxies follow similar trends in radio power versus SFR. This may be produced if both radio power and SFR are related to stellar mass.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/127/2484
- Title:
- Early-type galaxies color evolution
- Short Name:
- J/AJ/127/2484
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the color evolution of elliptical and S0 galaxies in six clusters of galaxies inside the redshift range 0.78<z<1.27. For each cluster, we used imaging from the Hubble Space Telescope (HST) to determine morphological types of the galaxies. These types were determined both by an automated technique and from visual inspection. We performed simulations to determine the accuracy of the automated classifications and found a success rate of ~75% at m(L*) or brighter magnitudes for most of our HST imaging data with the fraction of late-type galaxies identified as early-type galaxies to be ~10% at m(L*) to ~20% at m(L*+2). From ground-based optical and near-infrared imaging, we measured the zero point and scatter in the color-magnitude relation of the elliptical and S0 galaxy populations, which we combine with the sample of Stanford et al. (1998ApJ...492..461S), yielding a sample of cluster early-type galaxies that span a look-back time of almost 9Gyr from the present.
- ID:
- ivo://CDS.VizieR/J/A+A/636/A8
- Title:
- Early type galaxies g-r colour fits maps
- Short Name:
- J/A+A/636/A8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations of neutral hydrogen (HI) and molecular gas show that 50% of all nearby early-type galaxies (ETGs) contain some cold gas. Molecular gas is always found in small gas discs in the central region of the galaxy, while neutral hydrogen is often distributed in a low-column density disc or ring typically extending well beyond the stellar body. Dust is frequently found in ETGs as well. The goal of our study is to understand the link between dust and cold gas in nearby ETGs as a function of HI content. We analyse deep optical g-r images obtained with the MegaCam camera at the Canada-France-Hawaii Telescope for a sample of 21 HI-rich and 41 HI-poor ETGs. We find that all HI- rich galaxies contain dust seen as absorption. Moreover, in 57 percent of these HI-rich galaxies, the dust is distributed in a large-scale spiral pattern. Although the dust detection rate is relatively high in the HI-poor galaxies (59 percent), most of these systems exhibit simpler dust morphologies without any evidence of spiral structures. We find that the HI-rich galaxies possess more complex dust morphology extending to almost two times larger radii than HI-poor objects. We measured the dust content of the galaxies from the optical colour excess and find that HI-rich galaxies contain six times more dust (in mass) than HI-poor ones. In order to maintain the dust structures in the galaxies, continuous gas accretion is needed, and the substantial HI gas reservoirs in the outer regions of ETGs can satisfy this need for a long time. We find that there is a good correspondence between the observed masses of the gas and dust, and it is also clear that dust is present in regions further than 3 Reff. Our findings indicate an essential relation between the presence of cold gas and dust in ETGs and offer a way to study the interstellar medium in more detail than what is possible with. HI observations.
- ID:
- ivo://CDS.VizieR/J/ApJ/706/158
- Title:
- Early-type galaxies in PEARS
- Short Name:
- J/ApJ/706/158
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using Hubble Space Telescope (HST)/Advanced Camera for Surveys (ACS) slitless grism spectra from the PEARS program, we study the stellar populations of morphologically selected early-type galaxies in the GOODS North and South fields. The sample - extracted from a visual classification of the (v2.0) HST/ACS images and restricted to redshifts z>0.4 - comprises 228 galaxies (i_F775W_<24mag, AB) out to z<~1.3 over 320arcmin^2^, with a median redshift z_M_=0.75. This work significantly increases our previous sample from the GRAPES survey in the HUDF (18 galaxies over ~11arcmin^2^). The grism data allow us to separate the sample into "red" and "blue" spectra, with the latter comprising 15% of the total. Three different grids of models parameterizing the star formation history are used to fit the low-resolution spectra.
- ID:
- ivo://CDS.VizieR/J/A+A/496/683
- Title:
- Early-type galaxies in the Centaurus cluster
- Short Name:
- J/A+A/496/683
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse the properties of the early-type dwarf galaxy population in the Centaurus cluster. We investigate the galaxy luminosity function, galaxy scaling relations down to M_V_=-10mag. On deep VLT/FORS1 V- and I-band images of the central part of the cluster, we identify cluster dwarf-galaxy candidates using both morphological and surface brightness selection criteria. The candidates' total magnitudes and central surface brightnesses are derived from the analysis of their surface brightness profiles.
- ID:
- ivo://CDS.VizieR/J/A+A/526/A72
- Title:
- Early-type galaxies in the EGS
- Short Name:
- J/A+A/526/A72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The fundamental plane links the structural properties of early-type galaxies such as its surface brightness and effective radius with its dynamics. The study of the fundamental plane evolution therefore has important implications for models of galaxy formation and evolution. This work aims to identify signs of evolution of early-type galaxies through the study of parameter correlations such as the fundamental plane, the Kormendy, and the Faber-Jackson relations, using a sample of 135 field galaxies extracted from the Extended Groth Strip in the redshift range 0.2<z<1.2.
- ID:
- ivo://CDS.VizieR/J/MNRAS/406/382
- Title:
- Early-type galaxies in the SDSS Stripe82
- Short Name:
- J/MNRAS/406/382
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the properties of "peculiar" early-type galaxies (ETGs) in the local Universe that show (faint) morphological signatures of recent interactions such as tidal tails, shells and dust lanes. Standard-depth (~51s exposure) multicolour galaxy images from the Sloan Digital Sky Survey (SDSS) are combined with the significantly (~2mag) deeper monochromatic images from the public SDSS Stripe82 (-50{deg}<{alpha}<59{deg}, -1.25{deg}<{delta}<1.25{deg}) to extract, through careful visual inspection, a robust sample of nearby (z<0.05), luminous (M_r_<-20.5) ETGs, including a subset of ~70 peculiar systems. ~18% of ETGs exhibit signs of disturbed morphologies (e.g. shells), while ~7% show evidence of dust lanes and patches. An analysis of optical emission-line ratios indicates that the fraction of peculiar ETGs that are Seyferts or LINERs (19.4%) is twice the corresponding values in their relaxed counterparts (10.1%). LINER-like emission is the dominant type of nebular activity in all ETG classes, plausibly driven by stellar photoionization associated with recent star formation. An analysis of ultraviolet-optical colours indicates that, regardless of the luminosity range being considered, the fraction of peculiar ETGs that have experienced star formation in the last Gyr is a factor of ~1.5 higher than that in their relaxed counterparts. The spectrophotometric results strongly suggest that the interactions that produce the morphological peculiarities also induce low-level recent star formation which, based on the recent literature, are likely to contribute a few per cent of the stellar mass over the last ~1Gyr. Peculiar ETGs preferentially inhabit low-density environments (outskirts of clusters, groups or the field), either due to high peculiar velocities in clusters making merging unlikely or because shell systems are disrupted through frequent interactions within a cluster crossing time.
- ID:
- ivo://CDS.VizieR/J/MNRAS/445/630
- Title:
- Early-type galaxies in Ursa Major cluster
- Short Name:
- J/MNRAS/445/630
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using SDSS-DR7 and NASA/IPAC Extragalactic Database spectroscopic data, we identify 166 galaxies as members of the Ursa Major cluster with M_r_<-13.5mag. We morphological classify all galaxies by means of carefully inspecting g-, r-, i-band colour and monochromatic images. We show that the Ursa Major cluster is dominated by late-type galaxies, but also contains a significant number of early-type galaxies, particularly in the dwarf regime. We present further evidence for the existence of several subgroups in the cluster, consistent with previous findings. The early-type fraction is found to correlate with the mass of the subgroup. We also investigate environmental effects by comparing the properties of the Ursa Major early-type dwarf galaxies to those of the Virgo cluster. In contrast to the Virgo, the red sequence of the Ursa Major cluster is only sparsely populated in the optical and ultraviolet colour-magnitude relations. It also shows a statistically significant gap between -18<M_r_<-17mag, i.e. the Ursa Major cluster lacks early-type dwarf galaxies at the bright end of their luminosity function. We discover that the majority of early-type dwarf galaxies in the Ursa Major cluster have blue cores with hints of recent or ongoing star formation. We suggest that gravitational tidal interactions can trigger central blue star-forming regions in early-type dwarfs. After that, star formation would only fade completely when the galaxies experience ram-pressure stripping or harassment, both of which are nearly absent in the Ursa Major cluster.
- ID:
- ivo://CDS.VizieR/J/MNRAS/327/1004
- Title:
- Early-type galaxy parameters
- Short Name:
- J/MNRAS/327/1004
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We perform a series of comparisons between distance-independent photometric and spectroscopic properties used in the surface brightness fluctuation (SBF) and fundamental plane (FP) methods of early-type galaxy distance estimation. The data are taken from two recent surveys: the SBF Survey of Galaxy Distances and the Streaming Motions of Abell Clusters (SMAC) FP survey. We derive a relation between (V-I)0 colour and Mg2 index using nearly 200 galaxies and discuss implications for Galactic extinction estimates and early-type galaxy stellar populations.
- ID:
- ivo://CDS.VizieR/J/A+A/373/608
- Title:
- Early-type stars towards the Galactic Center. II.
- Short Name:
- J/A+A/373/608
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We are searching for early-type stars towards the Galactic centre which are potentially young objects situated within the inner few kiloparsecs of the disk. Photographic photometry from the UK Schmidt Telescope has been used to identify the bluest candidates in nineteen Schmidt fields (centred close to the Galactic centre). We have previously obtained FLAIR low dispersion spectroscopy for three of these fields to estimate spectral types and here we present spectroscopy for an additional seven fields. Combining the results for all ten fields, 56 stars were initially classified as early-B type. Estimates of the equivalent widths of their Balmer and He I lines have been used to estimate atmospheric parameters and 32 targets have effective temperatures greater than or equal to 17000K (corresponding to a spectral type of B3 or earlier). The spectra of seven of these targets also have absorption lines due to O II and Si III and can be reliably classified as early-B type. Additionally 78 stars have estimated effective temperatures between 11000 and 16000K with a further 50 objects identified as late-B (or early-A) type. All but two of the early B-type candidates have magnitudes in the range 12.0<=V<=16.0, and our best estimates of their distance suggest that they could be close to (i.e. R_g_<3kpc), or even beyond the Galactic centre.
