- ID:
- ivo://CDS.VizieR/J/ApJ/900/58
- Title:
- Opt-IR LC compilation of DES Stripe 82 quasars
- Short Name:
- J/ApJ/900/58
- Date:
- 11 Mar 2022 15:16:31
- Publisher:
- CDS
- Description:
- The size of the dust torus in active galactic nuclei (AGNs) and their high-luminosity counterparts, quasars, can be inferred from the time delay between UV/optical accretion disk continuum variability and the response in the mid-infrared (MIR) torus emission. This dust reverberation mapping (RM) technique has been successfully applied to ~70 z<~0.3 AGNs and quasars. Here we present first results of our dust RM program for distant quasars covered in the Sloan Digital Sky Survey Stripe 82 region combining ~20yr ground-based optical light curves with 10yr MIR light curves from the WISE satellite. We measure a high-fidelity lag between W1 band (3.4{mu}m) and g band for 587 quasars over 0.3<~z<~2 (<z>~0.8) and two orders of magnitude in quasar luminosity. They tightly follow (intrinsic scatter ~0.17dex in lag) the IR lag-luminosity relation observed for z<0.3 AGNs, revealing a remarkable size-luminosity relation for the dust torus over more than four decades in AGN luminosity, with little dependence on additional quasar properties such as Eddington ratio and variability amplitude. This study motivates further investigations in the utility of dust RM for cosmology and strongly endorses a compelling science case for the combined 10yr Vera C. Rubin Observatory Legacy Survey of Space and Time (optical) and 5yr Nancy Grace Roman Space Telescope 2{mu}m light curves in a deep survey for low-redshift AGN dust RM with much lower luminosities and shorter, measurable IR lags. The compiled optical and MIR light curves for 7384 quasars in our parent sample are made public with this work.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/159/259
- Title:
- Opt-NIR light curve of the quasar 3C 273
- Short Name:
- J/AJ/159/259
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We monitored the z=0.158 quasar 3C273 between 2015 and 2019 in the optical (BVrz) and near-infrared (JHK) with the aim to perform dust reverberation mapping. Accounting for host galaxy and accretion disk contributions, we obtained pure dust light curves in JHK. Cross correlations between the V-band and the dust light curves yield an average rest-frame delay for the hot dust of {tau}cent~410days. This is a factor of two shorter than that expected from the the dust ring radius R_x_~900lt-day reported from interferometric studies. The dust covering factor (CF) is about 8%, much smaller than that predicted from the half covering angle of 45{deg} found for active galactic nuclei (AGNs). We analyze the asymmetric shape of the correlation functions and explore whether an inclined biconical bowl-shaped dust torus geometry could bring these findings ({tau}cent, Rx and CF) into a consistent picture. The hot varying dust emission originates from the edge of the bowl rim with a small covering angle 40{deg}<{theta}<45{deg}, and we see only the near side of the biconus. Such a dust gloriole with R_x_= 900{+/-}200lt-day and an inclination 12{deg} matches the data remarkably well. Comparing the results of 3C273 with literature for less luminous AGN, we find a lag-luminosity relation {tau}{prop}L{alpha} with {alpha}=0.33-0.40, flatter than the widely adopted relation with {alpha}~0.5. We address several explanations for the new lag-luminosity relation.
- ID:
- ivo://CDS.VizieR/J/ApJ/866/83
- Title:
- Opt/NIR obs. of 1FGLJ1417.7-4407 neutron star bin.
- Short Name:
- J/ApJ/866/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Fermi {gamma}-ray source 1FGL J1417.7-4407 (J1417) is a compact X-ray binary with a neutron star primary and a red giant companion in a ~5.4 days orbit. This initial conclusion, based on optical and X-ray data, was confirmed when a 2.66ms radio pulsar was found at the same location (and with the same orbital properties) as the optical/X-ray source. However, these initial studies found conflicting evidence about the accretion state and other properties of the binary. We present new optical, radio, and X-ray observations of J1417 that allow us to better understand this unusual system. We show that one of the main pieces of evidence previously put forward for an accretion disk-the complex morphology of the persistent H{alpha} emission line-can be better explained by the presence of a strong, magnetically driven stellar wind from the secondary and its interaction with the pulsar wind. The radio spectral index derived from VLA/ATCA observations is broadly consistent with that expected from a millisecond pulsar, further disfavoring an accretion disk scenario. X-ray observations show evidence for a double-peaked orbital light curve, similar to that observed in some redback millisecond pulsar binaries and likely due to an intrabinary shock. Refined optical light-curve fitting gives a distance of 3.1+/-0.6kpc, confirmed by a Gaia DR2 parallax measurement. At this distance the X-ray luminosity of J1417 is (1.0_-0.3_^+0.4^)x10^33^erg/s, which is more luminous than all known redback systems in the rotational-powered pulsar state, perhaps due to the wind from the giant companion. The unusual phenomenology of this system and its differing evolutionary path from redback millisecond pulsar binaries points to a new eclipsing pulsar "spider" subclass that is a possible progenitor of normal field millisecond pulsar binaries.
- 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/877/29
- Title:
- Opt & NIR SMARTS/ANDICAM photometry for DQ Tau
- Short Name:
- J/ApJ/877/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multiepoch optical and near-infrared (NIR) photometry and spectroscopy of the spectroscopic binary T Tauri star DQ Tau. The photometric monitoring, obtained using SMARTS ANDICAM, recovers the previously seen correlation between optical flux and the 15.8d binary orbital period, with blue flux peaks occurring close to most observed periastron passages. For the first time, we find an even more consistent correlation between orbital period and NIR brightness and color. The onset of pulse events in the NIR precedes those in the optical by a few days, on average, with the rise usually starting near apastron orbital phase. We further obtained five epochs of spectroscopy using Infrared Telescope Facility (IRTF) SpeX, with a wavelength range of 0.8-5{mu}m, and derived spectra of the infrared excess emission. The shape and strength of the excess varies with time, with cooler and weaker characteristic dust emission (T~1100-1300K) over most of the binary orbit, and stronger/warmer dust emission (T~1600K, indicative of dust sublimation) just before periastron passage. We suggest that our results are broadly consistent with predictions of simulations of disk structure and accretion flows around close binaries, with the varying dust emission possibly tracing the evolution of accretion streams falling inward through a circumbinary disk cavity and feeding the accretion pulses traced by the optical photometry and NIR emission lines. However, our results also show more complicated behavior that is not fully explained by this simple picture, and will require further observations and modeling to fully interpret.
- ID:
- ivo://CDS.VizieR/J/ApJS/238/37
- Title:
- Opt. & NIR spectral atlas of 16 2MASS NIR-red AGNs
- Short Name:
- J/ApJS/238/37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present medium-resolution spectra (R~2000-4000) at 0.4-1.0{mu}m and 0.7-2.5{mu}m of 16 active galactic nuclei (AGNs) selected with red color in the near-infrared (NIR) of J-K>2.0mag at z~0.3. We fit the H{beta}, H{alpha}, P{beta}, and P{alpha} lines from these spectra to obtain their luminosities and line widths. We derive the E(B-V) color excess values of the NIR-red AGNs using two methods, one based on the line-luminosity ratios and another based on the continuum slopes. The two E(B-V) values agree with each other at rms dispersion ~0.249. About half of the NIR-red AGNs have g'-K<5 magnitude, and we find that these NIR-red, but blue in optical-NIR AGNs, have E(B-V)~0, suggesting that a significant fraction of the NIR color-selected red AGNs are unobscured or only mildly obscured. After correcting for the dust extinction, we estimate the black hole (BH) masses and the bolometric luminosities of the NIR-red AGNs using the Paschen lines to calculate their Eddington ratios ({lambda}Edd). The median Eddington ratios of nine NIR-red AGNs (log({lambda}_Edd_~-0.654+/-0.176) are only mildly higher than those of unobscured type 1 AGNs (log({lambda}_Edd_~-0.961+/-0.008). Moreover, we find that the MBH-{sigma}* relation for three NIR-red AGNs is consistent with that of unobscured type 1 AGNs at similar redshift. These results suggest that the NIR-red color selection alone is not effective at picking up dusty, intermediate-stage AGNs.
- 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/ApJS/247/46
- Title:
- Opt. photometry of SMUDGes ultra-diffuse galaxies
- Short Name:
- J/ApJS/247/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first systematic study of the stellar populations of ultra-diffuse galaxies (UDGs) in the field, integrating the large area search and characterization of UDGs by the SMUDGes survey with the twelve-band optical photometry of the S-PLUS survey. Based on Bayesian modeling of the optical colors of UDGs, we determine the ages, metallicities, and stellar masses of 100 UDGs distributed in an area of ~330deg^2^ in the Stripe 82 region. We find that the stellar masses and metallicities of field UDGs are similar to those observed in clusters and follow the trends previously defined in studies of dwarf and giant galaxies. However, field UDGs have younger luminosity- weighted ages than do UDGs in clusters. We interpret this result to mean that field UDGs have more extended star formation histories, including some that continue to form stars at low levels to the present time. Finally, we examine stellar population scaling relations that show that UDGs are, as a population, similar to other low surface brightness galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/889/L30
- Title:
- Opt. spectra of the interstellar object 2I/Borisov
- Short Name:
- J/ApJ/889/L30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 2I/Borisov is the first-ever observed interstellar comet (and the second detected interstellar object (ISO)). It was discovered on 2019 August 30 and has a heliocentric orbital eccentricity of ~3.35, corresponding to a hyperbolic orbit that is unbound to the Sun. Given that it is an ISO, it is of interest to compare its properties-such as composition and activity-with the comets in our solar system. This study reports low-resolution optical spectra of 2I/Borisov. The spectra were obtained by the MDM Observatory Hiltner 2.4m telescope/Ohio State Multi-Object Spectrograph (on 2019 October 31.5 and November 4.5, UT). The wavelength coverage spanned from 3700 to 9200{AA}. The dust continuum reflectance spectra of 2I/Borisov show that the spectral slope is steeper in the blue end of the spectrum (compared to the red). The spectra of 2I/Borisov clearly show CN emission at 3880{AA}, as well as C2 emission at both 4750 and 5150{AA}. Using a Haser model to covert the observed fluxes into estimates for the molecular production rates, we find Q(CN)=2.4+/-0.2x10^24^s^-1^, and Q(C_2_)=(5.5+/-0.4)x10^23^s^-1^ at the heliocentric distance of 2.145au. Our Q(CN) estimate is consistent with contemporaneous observations, and the Q(C_2_) estimate is generally below the upper limits of previous studies. We derived the ratio Q(C_2_)/Q(CN)=0.2+/-0.1, which indicates that 2I/Borisov is depleted in carbon-chain species, but is not empty. This feature is not rare for the comets in our solar system, especially in the class of Jupiter-family comets.
- ID:
- ivo://CDS.VizieR/J/ApJ/889/L38
- Title:
- Opt. spectroscopic investigations of 2I/Borisov
- Short Name:
- J/ApJ/889/L38
- Date:
- 17 Jan 2022 00:14:14
- Publisher:
- CDS
- Description:
- The composition of comets in the solar system comes in multiple groups thought to encode information about their formation in different regions of the outer protosolar disk. The recent discovery of the second interstellar object, 2I/Borisov, allows for spectroscopic investigations into its gas content and a preliminary classification of it within the solar system comet taxonomies to test the applicability of planetesimal formation models to other stellar systems. We present spectroscopic and imaging observations from 2019 September 20 through October 26 from the Bok, MMT telescope (formerly the Multiple Mirror Telescope, Mount Hopkins, Arizona), and Large Binocular Telescopes. We identify CN in the comet's spectrum and set precise upper limits on the abundance of C_2_ on all dates in October. We use a Haser model to convert our integrated fluxes to production rates and find Q(CN)=(1.1-1.9)*10^24^mols/s increasing over 2019 October 1 to 26, consistent with contemporaneous observations. We set our lowest upper limit on a C_2_ production rate, Q(C_2_)<1.6*10^23^mols/s on 2019 October 10. The measured upper limit ratio for that date Q(C_2_)/Q(CN)<0.1 indicates that 2I/Borisov is strongly in the (carbon-chain) "depleted" taxonomic group if there is any C_2_ production at all. Most "depleted" comets are Jupiter-family comets (JFCs), perhaps indicating a similarity in formation conditions between the most depleted of the JFCs and 2I/Borisov. More work is needed to understand the applicability of our knowledge of solar system comet taxonomies onto interstellar objects and we discuss future work that could help to clarify the usefulness of the approach.
