We derive the average mass profile of elliptical galaxies from the ensemble of 161 strong gravitational lens systems selected from several surveys, assuming that the mass profile scales with the ...stellar mass and effective radius of each lensing galaxy. The total mass profile is well fitted by a power law ρ(r) ∝ r
γ with best-fitting slope γ = −2.11 ± 0.05. The decomposition of the total mass profile into stellar and dark matter distributions is difficult due to a fundamental degeneracy between the stellar initial mass function (IMF) and the dark matter fraction f
DM. We demonstrate that this IMF-f
DM degeneracy can be broken by adding direct stellar mass fraction measurements by quasar microlensing observations. Our best-fitting model prefers the Salpeter IMF over the Chabrier IMF and a smaller central dark matter fraction than that predicted by adiabatic contraction models.
We present ground-based and Swift photometric and spectroscopic observations of the candidate tidal disruption event (TDE) ASASSN-14li, found at the centre of PGC 043234 (d ... 90 Mpc) by the All-Sky ...Automated Survey for SuperNovae (ASAS-SN). The source had a peak bolometric luminosity of ... and a total integrated energy of ... erg radiated over the ~6 months of observations presented. The UV/optical emission of the source is well fitted by a blackbody with roughly constant temperature of T ... 35,000 K, while the luminosity declines by roughly a factor of 16 over this time. The optical/UV luminosity decline is broadly consistent with an exponential decline, ..., with t0 ... 60 d. ASASSN-14li also exhibits soft X-ray emission comparable in luminosity to the optical and UV emission but declining at a slower rate, and the X-ray emission now dominates. Spectra of the source show broad Balmer and helium lines in emission as well as strong blue continuum emission at all epochs. We use the discoveries of ASASSN-14li and ASASSN-14ae to estimate the TDE rate implied by ASAS-SN, finding an average rate of ... per galaxy with a 90 per cent confidence interval of ... per galaxy. ASAS-SN found roughly 1 TDE for every 70 Type Ia supernovae in 2014, a rate that is much higher than that of other surveys. (ProQuest: ... denotes formulae/symbols omitted.)
In the present-day universe, supermassive black hole masses (M sub(BH)) appear to be strongly correlated with their galaxy's bulge luminosity, among other properties. In this study we explore the ...analogous relationship between M sub(BH), derived using the virial method, and the stellar R-band bulge luminosity (L sub(R)) or stellar bulge mass (M*) at epochs of 1 z 4.5, using a sample of 31 gravitationally lensed AGNs and 20 nonlensed AGNs. At redshifts z > 1.7 (10-12 Gyr ago), we find that the observed M sub(BH)-L sub(R) relation is nearly the same (to within 60.3 mag) as it is today. When the observed L sub(R) are corrected for luminosity evolution, this means that the black holes grew in mass faster than their hosts, with the M sub(BH)/M* mass ratio being a factor of 4 super(-1 +2) times larger at z > 1.7 than it is today. By the redshift range 1 z 1.7 (8-10 Gyr ago), the M sub(BH)/M* ratio is at most 2 times higher than today, but it may be consistent with no evolution. Combining the results, we conclude that the ratio M sub(BH)/M* rises with look-back time, although it may saturate at -6 times the local value. Scenarios in which moderately luminous quasar hosts at z 1.7 were fully formed bulges that passively faded to the present epoch are ruled out.
We use single-epoch spectroscopy of three gravitationally lensed quasars, HE 0435-1223, WFI 2033-4723, and HE 2149-2745, to study their inner structure (broad-line region BLR and continuum source). ...We detect microlensing-induced magnification in the wings of the broad emission lines of two of the systems (HE 0435-1223 and WFI 2033-4723). In the case of WFI 2033-4723, microlensing affects two "bumps" in the spectra that are almost symmetrically arranged on the blue (coincident with an Al iii emission line) and red wings of C iii. These match the typical double-peaked profile that follows from disk kinematics. The presence of microlensing in the wings of the emission lines indicates the existence of two different regions in the BLR: a relatively small one with kinematics possibly related to an accretion disk, and another one that is substantially more extended and insensitive to microlensing. There is good agreement between the estimated size of the region affected by microlensing in the emission lines, lt-day (red wing of C iv in HE 0435-1223) and lt-day (C iii bumps in WFI 2033-4723), and the sizes inferred from the continuum emission, lt-day (HE 0435-1223) and lt-day (WFI 2033-4723). For HE 2149-2745 we measure an accretion disk size lt-day. The estimates of p, the exponent of the size versus wavelength ( ), are 1.2 0.6, 0.8 0.2, and 0.4 0.3 for HE 0435-1223, WFI 2033-4723, and HE 2149-2745, respectively. In conclusion, the continuum microlensing amplitude in the three quasars and chromaticity in WFI 2033-4723 and HE 2149-2745 are below expectations for the thin-disk model. The disks are larger and their temperature gradients are flatter than predicted by this model.
We study the broad emission lines in a sample of 11 gravitationally lensed quasars with at least two epochs of observation to identify intrinsic variability and to disentangle it from microlensing. ...To improve our statistical significance and emphasize trends, we also include 15 lens systems with single-epoch spectra. Mg ii and C iii emission lines are only weakly affected by microlensing, but C iv shows strong microlensing in some cases, even for regions of the line core, presumably associated with small projected velocities. However, excluding the strongly microlensed cases, there is a strikingly good match, on average, between the red wings of the C iv and C iii profiles. Analysis of these results supports the existence of two regions in the broad-line region (BLR), one that is insensitive to microlensing (of size 50 lt-day and kinematics not confined to a plane) and another that shows up only when it is magnified by microlensing (of size of a few light-days, comparable to the accretion disk). Both regions can contribute in different proportions to the emission lines of different species and, within each line profile, to different velocity bins, all of which complicates detailed studies of the BLR based on microlensing size estimates. The strength of the microlensing indicates that some spectral features that make up the pseudo-continuum, such as the shelf-like feature at λ1610 or several Fe iii blends, may in part arise from an inner region of the accretion disk. In the case of Fe ii, microlensing is strong in some blends but not in others. This opens up interesting possibilities to study quasar accretion disk kinematics. Intrinsic variability seems to affect the same features prone to microlensing, with similar frequency and amplitude, but does not induce outstanding profile asymmetries. We measure intrinsic variability ( 20%) of the wings with respect to the cores in the C iv, C iii, and Mg ii lines consistent with reverberation mapping studies.
Here, we summarize the properties of MEarth data gathered so far, emphasizing the challenges they present for transit detection. We address these challenges with a new framework to detect shallow ...exoplanet transits in wiggly and irregularly spaced light curves. Our Method for Including Starspots and Systematics in the Marginalized Probability of a Lone Eclipse (MISS MarPLE) uses a computationally efficient semi-Bayesian approach to explore the vast probability space spanned by the many parameters of this model, naturally incorporating the uncertainties in these parameters into its evaluation of candidate events. We show how to combine individual transits processed by MISS MarPLE into periodic transiting planet candidates and compare our results to the popular box-fitting least-squares method with simulations. By applying MISS MarPLE to observations from the MEarth Project, we demonstrate the utility of this framework for robustly assessing the false alarm probability of transit signals in real data.
ASASSN-15lh: A highly super-luminous supernova Dong, Subo; Shappee, B. J.; Prieto, J. L. ...
Science (American Association for the Advancement of Science),
01/2016, Letnik:
351, Številka:
6270
Journal Article
Recenzirano
Odprti dostop
We report the discovery of ASASSN-15lh (SN 2015L), which we interpret as the most luminous supernova yet found. At redshift z = 0.2326, ASASSN-15lh reached an absolute magnitude of Mu,AB = −23.5 ± ...0.1 and bolometric luminosity Lbol = (2.2 ± 0.2) × 10⁴⁵ ergs s⁻¹, which is more than twice as luminous as any previously known supernova. It has several major features characteristic of the hydrogen-poor super-luminous supernovae (SLSNe-l), whose energy sources and progenitors are currently poorly understood. In contrast to most previously known SLSNe-l that reside in star-forming dwarf galaxies, ASASSN-15lh appears to be hosted by a luminous galaxy (MK ≈ −25.5) with little star formation. In the 4 months since first detection, ASASSN-15lh radiated (1.1 ± 0.2) × 10⁵² ergs, challenging the magnetar model for its engine.
Abstract
We present new light curves for the four bright images of the five image cluster-lensed quasar gravitational lens system SDSS J1004+4112. The light curves span 14.5 yr and allow the ...measurement of the time delay between the trailing bright quasar image D and the leading image C. When we fit all four light curves simultaneously and combine the models using the Bayesian information criterion, we find a time delay of Δ
t
DC
= 2458.47 ± 1.02 days (6.73 yr), the longest ever measured for a gravitational lens. For the other two independent time delays we obtain Δ
t
BC
= 782.20 ± 0.43 days (2.14 yr) and Δ
t
AC
= 825.23 ± 0.46 days (2.26 yr), in agreement with previous results. The information criterion is needed to weight the results for light curve models with different polynomial orders for the intrinsic variability and the effects of differential microlensing. The results using the Akaike information criterion are slightly different, but, in practice, the absolute delay errors are all dominated by the ∼4% cosmic variance in the delays rather than the statistical or systematic measurement uncertainties. Despite the lens being a cluster, the quasar images show slow differential variability due to microlensing at the level of a few tenths of a magnitude.
We present 13 seasons of R-band photometry of the quadruply lensed quasar WFI 2033-4723 from the 1.3 m SMARTS telescope at CTIO and the 1.2 m Euler Swiss Telescope at La Silla, in which we detect ...microlensing variability of ∼0.2 mag on a timescale of ∼6 years. Using a Bayesian Monte Carlo technique, we analyze the microlensing signal to obtain a measurement of the size of this system's accretion disk of at λrest = 2481 , assuming a 60° inclination angle. We confirm previous measurements of the BC and AB time delays, and we obtain a tentative measurement of the delay between the closely spaced A1 and A2 images of days. We conclude with an update to the Quasar Accretion Disk Size-Black Hole Mass Relation, in which we confirm that the accretion disk size predictions from simple thin disk theory are too small.
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