- ID:
- ivo://CDS.VizieR/J/MNRAS/421/2982
- Title:
- Optical and UV colors of Coma galaxies
- Short Name:
- J/MNRAS/421/2982
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present and analyse optical and ultraviolet (UV) colours for passive and optically-red Coma cluster galaxies for which we have spectroscopic age and element abundance estimates. Our sample of 150 objects covers a wide range in mass, from giant ellipticals down to the bright end of the dwarf-galaxy regime. Galaxies with ongoing star formation have been removed using strict H{alpha} emission-line criteria. We focus on the colours FUV-i, NUV-i, FUV-NUV, u*-g and g-i. We find that all of these colours are correlated with both luminosity and velocity dispersion at the >5{sigma} level, with FUV-i and FUV-NUV becoming bluer with increasing 'mass' while the other colours become redder. We perform a purely empirical analysis to assess what fraction of the variation in each colour can be accounted for by variations in the average stellar populations, as traced by the optical spectra.
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- ID:
- ivo://CDS.VizieR/J/ApJ/883/94
- Title:
- Optical and UV follow-up of 1ES 1927+654
- Short Name:
- J/ApJ/883/94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the sudden optical and ultraviolet (UV) brightening of 1ES1927+654, which until now was known as a narrow-line active galactic nucleus (AGN). 1ES 1927+654 was part of the small and peculiar class of "true Type-2" AGNs that lack broad emission lines and line-of-sight obscuration. Our high-cadence spectroscopic monitoring captures the appearance of a blue, featureless continuum, followed several weeks later by the appearance of broad Balmer emission lines. This timescale is generally consistent with the expected light travel time between the central engine and the broadline emission region in (persistent) broadline AGN. Hubble Space Telescope spectroscopy reveals no evidence for broad UV emission lines (e.g., CIV{lambda}1549, CIII]{lambda}1909, MgII{lambda}2798), probably owing to dust in the broadline emission region. To the best of our knowledge, this is the first case where the lag between the change in continuum and in broadline emission of a "changing look" AGN has been temporally resolved. The nature and timescales of the photometric and spectral evolution disfavor both a change in line-of-sight obscuration and a change of the overall rate of gas inflow as driving the drastic spectral transformations seen in this AGN. Although the peak luminosity and timescales are consistent with those of tidal disruption events seen in inactive galaxies, the spectral properties are not. The X-ray emission displays a markedly different behavior, with frequent flares on timescales of hours to days, and will be presented in a companion publication.
- ID:
- ivo://CDS.VizieR/J/AJ/151/125
- Title:
- Optical and UV photometry of SN 2013dy
- Short Name:
- J/AJ/151/125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Extensive and independent observations of Type Ia supernova (SNIa) SN2013dy are presented, including a larger set of UBVRI photometry and optical spectra from a few days before the peak brightness to ~200days after explosion, and ultraviolet (UV) photometry spanning from t~-10days to t~+15days refers to the B band maximum. The peak brightness (i.e., M_B_=-19.65+/-0.40mag; L_max_=[1.95+/-0.55]*10^43^/ergs) and the mass of synthesized ^56^Ni (i.e., M(^56^Ni)=0.90+/-0.26M_{Sun}_) are calculated, and they conform to the expectation for an SNIa with a slow decline rate (i.e., {Delta}m_15_(B)=0.90+/-0.03mag). However, the near infrared (NIR) brightness of this SN (i.e., M_H_=-17.33+/-0.30mag) is at least 1.0mag fainter than usual. Besides, spectroscopy classification reveals that SN2013dy resides on the border of "core normal" and "shallow silicon" subclasses in the Branch et al. classification scheme, or on the border of the "normal velocity" SNeIa and 91T/99aa-like events in the Wang et al. system. These suggest that SN2013dy is a slow-declining SNIa located on the transitional region of nominal spectroscopic subclasses and might not be a typical normal sample of SNeIa.
- ID:
- ivo://CDS.VizieR/J/ApJ/833/149
- Title:
- Opt/NIR obs. of M31N 2008-12a 2015 eruption
- Short Name:
- J/ApJ/833/149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Andromeda Galaxy recurrent nova M31N 2008-12a had been observed in eruption 10 times, including yearly eruptions from 2008 to 2014. With a measured recurrence period of P_rec_=351+/-13days (we believe the true value to be half of this) and a white dwarf very close to the Chandrasekhar limit, M31N 2008-12a has become the leading pre-explosion supernova type Ia progenitor candidate. Following multi-wavelength follow-up observations of the 2013 and 2014 eruptions, we initiated a campaign to ensure early detection of the predicted 2015 eruption, which triggered ambitious ground- and space-based follow-up programs. In this paper we present the 2015 detection, visible to near-infrared photometry and visible spectroscopy, and ultraviolet and X-ray observations from the Swift observatory. The LCOGT 2m (Hawaii) discovered the 2015 eruption, estimated to have commenced at August 28.28+/-0.12UT. The 2013-2015 eruptions are remarkably similar at all wavelengths. New early spectroscopic observations reveal short-lived emission from material with velocities ~13000km/s, possibly collimated outflows. Photometric and spectroscopic observations of the eruption provide strong evidence supporting a red giant donor. An apparently stochastic variability during the early supersoft X-ray phase was comparable in amplitude and duration to past eruptions, but the 2013 and 2015 eruptions show evidence of a brief flux dip during this phase. The multi-eruption Swift/XRT spectra show tentative evidence of high-ionization emission lines above a high-temperature continuum. Following Henze+ (2015A&A...582L...8H), the updated recurrence period based on all known eruptions is P_rec_=174+/-10days, and we expect the next eruption of M31N 2008-12a to occur around 2016 mid-September.
- 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/817/1
- Title:
- Palomar/MSU and SDSS-DR7 M dwarfs with GALEX obs.
- Short Name:
- J/ApJ/817/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of Galaxy Evolution Explorer Near-UV (NUV) and Far-UV (FUV) photometry for the Palomar/MSU and SDSS DR7 spectroscopic M dwarf catalogs. The catalog contains NUV measurements matched to 577 spectroscopically confirmed M dwarfs and FUV measurements matched to 150 spectroscopically confirmed M dwarfs. Using these data, we find that NUV and FUV luminosities strongly correlate with H{alpha} emission, a typical indicator of magnetic activity in M dwarfs. We also examine the fraction of M dwarfs with varying degrees of strong line emission at NUV wavelengths. Our results indicate that the frequency of M dwarf NUV emission peaks at intermediate spectral types, with at least ~30% of young M4-M5 dwarfs having some level of activity. For mid-type M dwarfs, we show that NUV emission decreases with distance from the Galactic plane, a proxy for stellar age. Our complete matched source catalog is available online.
- ID:
- ivo://CDS.VizieR/J/MNRAS/462/L11
- Title:
- Passive spiral galaxy cand. multi-phot.
- Short Name:
- J/MNRAS/462/L11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have identified a population of passive spiral galaxies from photometry and integral field spectroscopy. We selected z<0.035 spiral galaxies that have WISE colours consistent with little mid-infrared emission from warm dust. Matched aperture photometry of 51 spiral galaxies in ultraviolet, optical and mid-infrared show these galaxies have colours consistent with passive galaxies. Six galaxies form a spectroscopic pilot study and were observed using the Wide-Field Spectrograph (WiFeS) to check for signs of nebular emission from star formation. We see no evidence of substantial nebular emission found in previous red spiral samples. These six galaxies possess absorption line spectra with 4000{AA} breaks consistent with an average luminosity-weighted age of 2.3Gyr. Our photometric and IFU spectroscopic observations confirm the existence of a population of local passive spiral galaxies, implying that transformation into early-type morphologies is not required for the quenching of star formation.
- ID:
- ivo://CDS.VizieR/J/ApJ/742/3
- Title:
- Photometric catalogs for ECDF-S and CDF-N
- Short Name:
- J/ApJ/742/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of deep multiwavelength data for z~0.3-3 starburst galaxies selected by their 70um emission in the Extended-Chandra Deep Field-South and Extended Groth Strip. We identify active galactic nuclei (AGNs) in these infrared sources through their X-ray emission and quantify the fraction that host an AGN. Lastly, we investigate the ratio between the supermassive black hole accretion rate (inferred from the AGN X-ray luminosity) and the bulge growth rate of the host galaxy (approximated as the SFR) and find that, for sources with detected AGNs and star formation (and neglecting systems with low star formation rates to which our data are insensitive), this ratio in distant starbursts agrees well with that expected from the local scaling relation assuming the black holes and bulges grew at the same epoch. These results imply that black holes and bulges grow together during periods of vigorous star formation and AGN activity.
- ID:
- ivo://CDS.VizieR/J/A+A/584/A44
- Title:
- Photometric classification of QSO from RCS-2
- Short Name:
- J/A+A/584/A44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new quasar candidate catalogs from the Red-Sequence Cluster Survey 2 (RCS-2), identified solely from photometric information using a Random Forest algorithm. The algorithm is trained using a well-defined SDSS spectroscopic sample of quasars and stars. The algorithm identifies putative quasars from broadband magnitudes (g, r, i, z) and colors. Exploiting NUV GALEX measurements for a subset of the objects, we refine the classifier by adding new information. An additional subset of the data with WISE W1 and W2 bands is also studied. Upon analyzing 542,897 RCS-2 point sources, the algorithm identified 21,501 quasar candidates, with a training-set-derived precision of 89.5% and recall of 88.4%. These performance metrics improve for the GALEX subset; 6530 quasar candidates are identified from 16898 sources, with a precision and recall respectively of 97.0% and 97.5%. Algorithm performance is further improved when WISE data are included, with precision and recall increasing to 99.3% and 99.1% respectively for 21834 quasar candidates from 242902 sources. After merging these samples and removing duplicates, we obtain 38257 candidates.
- ID:
- ivo://CDS.VizieR/J/MNRAS/449/1876
- Title:
- Photometric observations of SN PTF11iqb
- Short Name:
- J/MNRAS/449/1876
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The supernova (SN) PTF11iqb was initially classified as a Type IIn event caught very early after explosion. It showed narrow Wolf-Rayet (WR) spectral features on day 2 (as in SN 1998S and SN 2013cu), but the narrow emission weakened quickly and the spectrum morphed to resemble Types II-L and II-P. At late times, H{alpha} exhibited a complex, multipeaked profile reminiscent of SN 1998S. In terms of spectroscopic evolution, we find that PTF11iqb was a near twin of SN 1998S, although with somewhat weaker interaction with circumstellar material (CSM) at early times, and stronger interaction at late times. We interpret the spectral changes as caused by early interaction with asymmetric CSM that is quickly (by day 20) enveloped by the expanding SN ejecta photosphere, but then revealed again after the end of the plateau when the photosphere recedes. The light curve can be matched with a simple model for CSM interaction (with a mass-loss rate of roughly 10^-4^ M_{sun}_/yr) added to the light curve of a normal SN II-P. The underlying plateau requires a progenitor with an extended hydrogen envelope like a red supergiant at the moment of explosion, consistent with the slow wind speed (<80 km/s) inferred from narrow H{alpha} emission. The cool supergiant progenitor is significant because PTF11iqb showed WR features in its early spectrum - meaning that the presence of such WR features does not necessarily indicate a WR-like progenitor. Overall, PTF11iqb bridges SNe IIn with weaker pre-SN mass-loss seen in SNe II-L and II-P, implying a continuum between these types.