- ID:
- ivo://CDS.VizieR/J/ApJ/693/1484
- Title:
- Early optical afterglow catalog
- Short Name:
- J/ApJ/693/1484
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multicolor optical observations of long-duration {gamma}-ray bursts (GRBs) made over a three-year period with the robotic Palomar 60 inch telescope (P60). Our sample consists of all 29 events discovered by Swift for which P60 began observations less than 1hr after the burst trigger. We were able to recover 80% of the optical afterglows from this prompt sample, and we attribute this high efficiency to our red coverage. Like Melandri et al. (2008, Cat. J/ApJ/686/1209), we find that a significant fraction (~50%) of Swift events show a suppression of the optical flux with regard to the X-ray emission (the so-called "dark" bursts). Our multicolor photometry demonstrates this is likely due in large part to extinction in the host galaxy. We argue that previous studies, by selecting only the brightest and best-sampled optical afterglows, have significantly underestimated the amount of dust present in typical GRB environments.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/444/2571
- Title:
- Early-Tyoe Galaxies in SDSS and GALEX
- Short Name:
- J/MNRAS/444/2571
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the Hernandez-Perez and Bruzual stellar population synthesis models to study the role of interacting binary pairs as progenitors of extreme horizontal branch (EHB) stars. We assemble a sample of 3417 early-type galaxies observed both in the optical (SDSS-DR8) and the UV (GALEX-GR6). The galaxies in our sample can be classified according to their position in the colour-colour diagram as UV-weak or red-sequence galaxies (~48%), UV-strong or UVX galaxies (~9%), and recent star-forming galaxies (~43%). Analysing this sample using the models for various choices of basic model parameters, we conclude that (a) the UVr colours of UV-weak and UV-strong galaxies are reproduced by the models as long as the fraction of binary stars is at least 15%. (b) Higher metallicity models (Z=0.02 and 0.03) reproduce the colours of UV-weak and UV-strong galaxies better than lower Z models. The Z=0.03 model is slightly bluer than the Z=0.02 model in the UV-strong region, indicating a weak relationship between UVX and Z. (c) The strength of UVX increases with age in the model population. This is at variance with the results of other models that include binary stars as progenitors of EHB stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/401/257
- Title:
- Early-type binaries on main sequence
- Short Name:
- J/MNRAS/401/257
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We showed in a preceding paper based on an analysis of the observed rates of apsidal motion that synchronization in early-type eclipsing binaries continues on the main sequence, and the observed synchronization times, t_syn_, agree with the Zahn's theory (1977A&A....57..383Z) and are inconsistent with the shorter time-scale proposed by Tassoul (1987ApJ...322..856T, 1988ApJ...324L..71T). It follows from this that circularization in early-type binaries must also proceed in accordance with the Zahn's theory because the circularization times, t_circ_, in both theories are rather tightly related to tsyn via relation t_circ_~{alpha}t_syn_, where {alpha} is the orbital-to-axial momentum ratio.
- ID:
- ivo://CDS.VizieR/J/A+A/463/503
- Title:
- Early-type dwarf galaxies in Fornax cluster
- Short Name:
- J/A+A/463/503
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse the photometric properties of the early-type Fornax cluster dwarf galaxy population, based on a wide field imaging study of the central cluster area in V and I. We used the instrument/telescope combination IMACS/Magellan at Las Campanas Observatory. We create a fiducial sample of Fornax cluster dwarf ellipticals (dEs) in the following three steps: (1) To verify cluster membership, we measured I-band surface brightness fluctuation (SBF) distances to candidate dEs; (2) We re-assessed morphological classifications for candidate dEs too faint for SBF detection; and (3) We searched for new candidate dEs in the size-luminosity regime close to the resolution limit of previous surveys. (1) We confirm cluster membership for 28 candidate dEs in the range -16.6<M_V_<-10.1mag by means of SBF distances. We find no SBF background galaxy. (2) Of 51 further candidate dEs in the range -13.2<M_V_<-8.6mag, 2/3 are confirmed as probable cluster members by morphological re-assessment, while 1/3 are re-classified as probable background objects. (3) We find 12 new dE candidates in the range -12.3<M_V_<-8.8mag. The surface brightness-magnitude relation defined by the resulting fiducial dE sample shows that Fornax dEs are about 40% larger than Local Group dEs. The Fornax dE sample furthermore defines a colour-magnitude relation that appears slightly shallower than that of Local Group dEs. The early-type dwarf galaxy luminosity function in Fornax has a faint end slope alpha=-1.1+/- 0.1.
- ID:
- ivo://CDS.VizieR/J/ApJ/810/61
- Title:
- Early-type EBs with intermediate orbital periods
- Short Name:
- J/ApJ/810/61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze 221 eclipsing binaries (EBs) in the Large Magellanic Cloud with B-type main-sequence (MS) primaries (M_1_~4-14 M_{sun}_) and orbital periods P=20-50 days that were photometrically monitored by the Optical Gravitational Lensing Experiment. We utilize our three-stage automated pipeline to (1) classify all 221 EBs, (2) fit physical models to the light curves of 130 detached well-defined EBs from which unique parameters can be determined, and (3) recover the intrinsic binary statistics by correcting for selection effects. We uncover two statistically significant trends with age. First, younger EBs tend to reside in dustier environments with larger photometric extinctions, an empirical relation that can be implemented when modeling stellar populations. Second, younger EBs generally have large eccentricities. This demonstrates that massive binaries at moderate orbital periods are born with a Maxwellian "thermal" orbital velocity distribution, which indicates they formed via dynamical interactions. In addition, the age-eccentricity anticorrelation provides a direct constraint for tidal evolution in highly eccentric binaries containing hot MS stars with radiative envelopes. The intrinsic fraction of B-type MS stars with stellar companions q=M_2_/M_1_>0.2 and orbital periods P=20-50 days is (7+/-2)%. We find early-type binaries at P=20-50 days are weighted significantly toward small mass ratios q~0.2-0.3, which is different than the results from previous observations of closer binaries with P<20 days. This indicates that early-type binaries at slightly wider orbital separations have experienced substantially less competitive accretion and coevolution during their formation in the circumbinary disk.
- ID:
- ivo://CDS.VizieR/J/AJ/128/1990
- Title:
- Early-type field galaxies at z~0.75
- Short Name:
- J/AJ/128/1990
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We measure the luminosity function of morphologically selected E/S0 galaxies from z=0.5 to 1.0 using deep high-resolution Advanced Camera for Surveys (ACS) imaging data. Our analysis covers an area of 48arcmin^2^ (8 times the area of the Hubble Deep Field North) and extends 2mag deeper (I~24 mag) than was possible in the Deep Groth Strip Survey (DGSS). Our fields were observed as part of the ACS Guaranteed Time Observations.
- 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.
- 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.
