- ID:
- ivo://CDS.VizieR/J/ApJS/191/124
- Title:
- Optical spectroscopy of ECDF-S X-ray sources
- Short Name:
- J/ApJS/191/124
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a program to acquire high-quality optical spectra of X-ray sources detected in the Extended-Chandra Deep Field-South (E-CDF-S) and its central 2Ms area. New spectroscopic redshifts, up to z=4, are measured for 283 counterparts to Chandra sources with deep exposures (t~2-9hr per pointing) using multi-slit facilities on both VLT (VIMOS) and Keck (DEIMOS), thus bringing the total number of spectroscopically identified X-ray sources to over 500 in this survey field. Since our new spectroscopic identifications are mainly associated with X-ray sources in the shallower 250ks coverage, we provide a comprehensive catalog of X-ray sources detected in the E-CDF-S including the optical and near-infrared counterparts, determined by a likelihood routine, and redshifts (both spectroscopic and photometric), that incorporate published spectroscopic catalogs, thus resulting in a final sample with a high fraction (80%) of X-ray sources having secure identifications. Our redshift catalog includes 17 type-2 QSOs at 1<~z<~3.5. Based on our deepest (9 hr) VLT/VIMOS observation, we identify "elusive" optically faint galaxies (Rmag~25) at z~2-3 based upon the detection of interstellar absorption lines (e.g., OII+SiIV, CII], CIV).
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- ID:
- ivo://CDS.VizieR/J/ApJ/854/145
- Title:
- Opt. photometry & NIR spectroscopy of Wolf 1130
- Short Name:
- J/ApJ/854/145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Following the discovery of the T8 subdwarf WISE J200520.38+542433.9 (Wolf 1130C), which has a proper motion in common with a binary (Wolf 1130AB) consisting of an M subdwarf and a white dwarf, we set out to learn more about the old binary in the system. We find that the A and B components of Wolf 1130 are tidally locked, which is revealed by the coherence of more than a year of V-band photometry phase-folded to the derived orbital period of 0.4967 days. Forty new high-resolution, near-infrared spectra obtained with the Immersion Grating Infrared Spectrometer (IGRINS) provide radial velocities and a projected rotational velocity (vsini) of 14.7+/-0.7km/s for the M subdwarf. In tandem with a Gaia parallax-derived radius and verified tidal locking, we calculate an inclination of i=29{deg}+/-2{deg}. From the single-lined orbital solution and the inclination we derive an absolute mass for the unseen primary (1.24_-0.15_^+0.19^M_{sun}_). Its non-detection between 0.2 and 2.5{mu}m implies that it is an old (>3.7Gyr) and cool (T_eff_<7000K) ONe white dwarf. This is the first ultramassive white dwarf within 25pc. The evolution of Wolf 1130AB into a cataclysmic variable is inevitable, making it a potential SN Ia progenitor. The formation of a triple system with a primary mass >100 times the tertiary mass and the survival of the system through the common-envelope phase, where ~80% of the system mass was lost, is remarkable. Our analysis of Wolf 1130 allows us to infer its formation and evolutionary history, which has unique implications for understanding low-mass star and brown dwarf formation around intermediate-mass stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/872/42
- Title:
- Opt. spectroscopy of redback ms pulsar binaries
- Short Name:
- J/ApJ/872/42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first optical spectroscopy of five confirmed (or strong candidate) redback millisecond pulsar binaries, obtaining complete radial velocity curves for each companion star. The properties of these millisecond pulsar binaries with low-mass, hydrogen-rich companions are discussed in the context of the 14 confirmed and 10 candidate field redbacks. We find that the neutron stars in redbacks have a median mass of 1.78+/-0.09M_{sun}_ with a dispersion of {sigma}=0.21+/-0.09. Neutron stars with masses in excess of 2M_{sun}_ are consistent with, but not firmly demanded by, current observations. Redback companions have median masses of 0.36+/-0.04M_{sun}_ with a scatter of {sigma}=0.15+/-0.04M_{sun}_, and a tail possibly extending up to 0.7-0.9M_{sun}_. Candidate redbacks tend to have higher companion masses than confirmed redbacks, suggesting a possible selection bias against the detection of radio pulsations in these more massive candidate systems. The distribution of companion masses between redbacks and the less massive black widows continues to be strongly bimodal, which is an important constraint on evolutionary models for these systems. Among redbacks, the median efficiency of converting the pulsar spin-down energy to {gamma}-ray luminosity is ~10%.
- ID:
- ivo://CDS.VizieR/J/ApJ/873/92
- Title:
- Opt. & UV evolution of the TDE iPTF15af
- Short Name:
- J/ApJ/873/92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multiwavelength observations of the tidal disruption event (TDE) iPTF15af, discovered by the intermediate Palomar Transient Factory survey at redshift z=0.07897. The optical and ultraviolet (UV) light curves of the transient show a slow decay over 5 months, in agreement with previous optically discovered TDEs. It also has a comparable blackbody peak luminosity of L_peak_~1.5x10^44^erg/s. The inferred temperature from the optical and UV data shows a value of (3-5)x10^4^K. The transient is not detected in X-rays up to L_X_<3x10^42^erg/s within the first 5 months after discovery. The optical spectra exhibit two distinct broad emission lines in the HeII region, and at later times also H{alpha} emission. Additionally, emission from [NIII] and [OIII] is detected, likely produced by the Bowen fluorescence effect. UV spectra reveal broad emission and absorption lines associated with high-ionization states of NV, CIV, SiIV, and possibly PV. These features, analogous to those of broad absorption line quasars (BAL QSOs), require an absorber with column densities N_H_>10^23^cm^-2^. This optically thick gas would also explain the nondetection in soft X-rays. The profile of the absorption lines with the highest column density material at the largest velocity is opposite that of BAL QSOs. We suggest that radiation pressure generated by the TDE flare at early times could have provided the initial acceleration mechanism for this gas. Spectral UV line monitoring of future TDEs could test this proposal.
- ID:
- ivo://CDS.VizieR/J/ApJ/809/91
- Title:
- Outflows in sodium excess objects
- Short Name:
- J/ApJ/809/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Van Dokkum and Conroy (2010Natur.468..940V) revisited the unexpectedly strong NaI lines at 8200{AA} found in some giant elliptical galaxies and interpreted them as evidence for an unusually bottom-heavy initial mass function. Jeong et al. (2013, J/ApJS/208/7) later found a large population of galaxies showing equally extraordinary Na D doublet absorption lines at 5900{AA} (Na D excess objects: NEOs) and showed that their origins can be different for different types of galaxies. While a Na D excess seems to be related to the interstellar medium (ISM) in late-type galaxies, smooth-looking early-type NEOs show little or no dust extinction and hence no compelling signs of ISM contributions. To further test this finding, we measured the Doppler components in the Na D lines. We hypothesized that the ISM would have a better (albeit not definite) chance of showing a blueshift Doppler departure from the bulk of the stellar population due to outflow caused by either star formation or AGN activities. Many of the late-type NEOs clearly show blueshift in their Na D lines, which is consistent with the former interpretation that the Na D excess found in them is related to gas outflow caused by star formation. On the contrary, smooth-looking early-type NEOs do not show any notable Doppler components, which is also consistent with the interpretation of Jeong et al. that the Na D excess in early-type NEOs is likely not related to ISM activities but is purely stellar in origin.
- ID:
- ivo://CDS.VizieR/J/ApJ/735/71
- Title:
- Oxygen abundances in outlying HII regions
- Short Name:
- J/ApJ/735/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a search for outlying HII regions in the extended gaseous outskirts of nearby (D<40Mpc) galaxies and subsequent multi-slit spectroscopy used to obtain the HII region nebular oxygen abundances. The galaxies in our sample have extended HI disks and/or interaction-related HI features that extend well beyond their primary stellar components. We report oxygen abundance gradients out to 2.5 times the optical radius for these galaxies which span a range of morphologies and masses. We analyze the underlying stellar and neutral HI gas distributions in the vicinity of the HII regions to understand the physical processes that give rise to the observed metal distributions in galaxies. These measurements, for the first time, convincingly show flat abundance distributions out to large radii in a wide variety of systems and have broad implications for galaxy chemodynamical evolution.
- ID:
- ivo://CDS.VizieR/J/AJ/141/120
- Title:
- P Cygni H{alpha} measurements
- Short Name:
- J/AJ/141/120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- P Cygni is a prototype of the luminous blue variables (or S Doradus variables), and the star displays photometric and emission line variability on a timescale of years (known as the "short S Doradus-phase" variations). Here we present new high-resolution H{alpha} spectroscopy of P Cyg that we combine with earlier spectra and concurrent V-band photometry to document the emission and continuum flux variations over a 24 year time span.
- ID:
- ivo://CDS.VizieR/J/AJ/135/1624
- Title:
- PEARS emission-line galaxies
- Short Name:
- J/AJ/135/1624
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Hubble Space Telescope Advanced Camera for Surveys grism Probing Evolution And Reionization Spectroscopically (PEARS) survey provides a large dataset of low-resolution spectra from thousands of galaxies in the GOODS north and south fields. One important subset of objects in these data is emission-line galaxies (ELGs), and we have investigated several different methods aimed at systematically selecting these galaxies. Here, we present a new methodology and results of a search for these ELGs in the PEARS observations of the Hubble Ultra Deep Field (HUDF) using a 2D detection method that utilizes the observation that many emission lines originate from clumpy knots within galaxies. This 2D line-finding method proves to be useful in detecting emission lines from compact knots within galaxies that might not otherwise be detected using more traditional 1D line-finding techniques.
- ID:
- ivo://CDS.VizieR/J/AJ/141/64
- Title:
- PEARS emission-line galaxies spectroscopy
- Short Name:
- J/AJ/141/64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present spectroscopy of 76 emission-line galaxies (ELGs) in Chandra Deep Field South taken with the LDSS3 spectrograph on the Magellan Telescope. These galaxies are selected because they have emission lines with the Advanced Camera for Surveys (ACS) grism data in the Hubble Space Telescope Probing Evolution and Reionization Spectroscopically (PEARS) grism Survey. The ACS grism spectra cover the wavelength range 6000-9700{AA} and most PEARS grism redshifts are based on a single emission line + photometric redshifts from broadband colors; the Magellan spectra cover a wavelength range from 4000{AA} to 9000{AA} and provide a check on redshifts derived from PEARS data.
- ID:
- ivo://CDS.VizieR/J/MNRAS/325/1002
- Title:
- Photometric and redshift catalog of 581 galaxies
- Short Name:
- J/MNRAS/325/1002
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- File table1 contains names, positions, b_jori_ magnitudes, magnitude errors, redshifts, redshift errors, [OII]3727 emission-line fluxes (where detected) and identification codes for 485 early-type galaxies displaying consistent data quality suitable for statistical analyses. File table2 contains names, positions, b_jori_ magnitudes, magnitude errors, redshifts and redshift errors for 96 early-type galaxies displaying inconsistent data quality, unsuitable for statistical analyses.