The bright BL Lac object TXS 0506+056 is the most likely counterpart of the IceCube neutrino event EHE 170922A. The lack of this redshift prevents a comprehensive understanding of the modeling of the ...source. We present high signal-to-noise optical spectroscopy, in the range 4100-9000 , obtained at the 10.4 m Gran Telescopio Canarias. The spectrum is characterized by a power-law continuum and is marked by faint interstellar features. In the regions unaffected by these features, we found three very weak (EW ∼ 0.1 ) emission lines that we identify with O ii 3727 , O iii 5007 , and N ii 6583 , yielding the redshift z = 0.3365 0.0010.
ABSTRACT
We investigate the spectroscopic optical properties of gamma-ray sources detected with high significance above 50 GeV in the Third Catalog of Hard Fermi-LAT Sources and that are good ...candidates as TeV emitters. We focus on the 91 sources that are labelled by the Fermi team as BL Lac (BLL) objects or blazar candidates of uncertain type (BCUs), are in the Northern hemisphere, and are with unknown or uncertain redshift. We report here on GTC (Gran Telescopio Canarias) spectra (in the spectral range 4100–7750 Å) of 13 BCUs and 42 BLL objects. We are able to classify the observed targets as BLL objects and each source is briefly discussed. The spectra allowed us to determine the redshift of 25 objects on the basis of emission and/or absorption lines, finding 0.05 < z < 0.91. Most of the emission lines detected are due to forbidden transition of O iii and N ii. The observed line luminosity is found to be lower than that of quasi-stellar objects (QSOs) at similar continuum and could be reconciled with the line–continuum luminosity relationship of QSOs if a significant beaming factor is assumed. Moreover, for five sources we found intervening absorption lines that allow to set a spectroscopic lower limit of the redshift. For the remaining 25 sources, for which the spectra are lineless, a lower limit to z is given, assuming that the host galaxies are giant ellipticals.
This paper documents the policy context of renewable energy production in the European Union. The research adopts a choice experiment approach to investigate households' WTP for these renewable ...energy technologies in the UK. The micro-generation technologies comprise solar photovoltaic, micro-wind, solar thermal, heat pumps, and biomass boilers and pellet stoves. The study compares the results from conditional and mixed logit models, which estimate the distribution of utility coefficients and then derives WTP values as a ratio of the attribute coefficient to the price coefficient, with a model in which the WTP distribution is estimated directly from utility in the money space. The results suggest that whilst renewable energy adoption is significantly valued by households, this value is not sufficiently large, for the vast majority of households, to cover the higher capital costs of micro-generation energy technologies.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
4.
On the Redshift of TeV BL Lac Objects Paiano, Simona; Landoni, Marco; Falomo, Renato ...
The Astrophysical journal,
03/2017, Volume:
837, Issue:
2
Journal Article
Peer reviewed
Open access
We report results of a spectroscopic campaign carried out at the 10 m Gran Telescopio Canarias for a sample of 22 BL Lac objects detected (or candidates) at TeV energies, aiming to determine or ...constrain their redshift. This is of fundamental importance for the interpretation of their emission models and for population studies and is also mandatory for studying the interaction of high-energy photons with the extragalactic background light using TeV sources. Optical spectra with high signal-to-noise ratios in the range 4250-10000 Å were obtained to search for faint emission or absorption lines from both the host galaxy and the nucleus. We determine a new redshift for PKS 1424+240 (z = 0.604) and a tentative one for 1ES 0033+595 (z = 0.467). We are able to set new spectroscopic redshift lower limits for three other sources on the basis of Mg ii and Ca ii intervening absorption features: BZB J1243+3627 (z > 0.483), BZB J1540+8155 (z > 0.672), and BZB 0J2323+4210 (z > 0.267). We confirm previous redshift estimates for four blazars: S3 0218+357 (z = 0.944), 1ES 1215+303 (z = 0.129), W Comae (z = 0.102), and MS 1221.8+2452 (z = 0.218). For the remaining targets, in seven cases (S2 0109+22, 3C 66A, VER J0521+211, S4 0954+65, BZB J1120+4214, S3 1227+25, BZB J2323+4210), we do not validate the proposed redshift. Finally, for all sources of still-unknown redshift, we set a lower limit based on the minimum equivalent width of absorption features expected from the host galaxy.
We report on optical spectroscopy obtained at the 10.4 m Gran Telescopio Canarias of 28 Fermi γ-ray sources that completes the study of a sample of 60 targets of unidentified objects for which the ...detection of an X-ray and/or radio source inside the 3FGL error box is available. The observations aim to characterize the nature and measure the redshift of these sources. For all optical counterparts, the observations allow us to establish their active galactic nucleus nature. In particular, we found 24 BL Lac objects, one quasar, one narrow line Seyfert 1, and two objects showing spectral features typical of Seyfert 2 galaxies. For most of these, we determine a spectroscopic redshift, while for five we can set lower limits based on the lack of stellar features from the host galaxy. The global properties of the full sample are briefly discussed.
We compare two approaches for estimating the distribution of consumers' willingness to pay (WTP) in discrete choice models. The usual procedure is to estimate the distribution of the utility ...coefficients and then derive the distribution of WTP, which is the ratio of coefficients. The alternative is to estimate the distribution of WTP directly. We apply both approaches to data on site choice in the Alps. We find that the alternative approach fits the data better, reduces the incidence of exceedingly large estimated WTP values, and provides the analyst with greater control in specifying and testing the distribution of WTP.
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BFBNIB, FZAB, GIS, IJS, INZLJ, IZUM, KILJ, NLZOH, NMLJ, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK, ZRSKP
Abstract Following the high activity of the γ -ray Fermi source 4FGL J0449.1+1121 (PKS 0446+112), possibly associated with a IceCube neutrino event IC-240105A, we obtained optical spectroscopy with ...the Gran Telescopio Canarias of the counterpart. We detect a clear emission line at 3830 Å identified as Ly α that confirms the redshift of source at z = 2.153. Comparing with previous spectroscopy, we find an increase of the continuum by a factor ∼10, and a significant decrease of the C iv 1550 emission line flux by a factor ∼5. This produces a dramatic drop of the equivalent width from ∼20 to 0.8 Å, which is suggestive of a very high jet activity. The full width half maximum of the emission lines are midway (1000–2000 km s −1 ) between those typical of the broad and narrow regions of quasars. Based on this, the source classification is intermediate between flat spectrum radio quasar and BL Lac object.
The destination choices of individual recreationalists are dependent on the spatial distribution of sites and attractions. An important issue in destination choice modelling is how to account for the ...effects of cumulative attraction from multiple sites and hierarchical processing of potential destinations. This study is concerned with recreational visits to beaches on the Coromandel Peninsula of New Zealand. Each beach has a different combination of attractions with potentially complex substitution patterns. We find that an Agglomerating and Competing Destination Choice model, with differentiated accessibility parameters for each attribute, offers the best fit. It is flexible enough to model different levels of substitutability for different attraction types, yet is tractable in estimation. We compare response predictions of different models for two site-specific changes - closure of a campground and construction of a sea wall. Allowing for more complex substitution patterns results in different predictions for visitation in the wider area.
•The beach destination choices of domestic tourists in New Zealand are analysed.•The spatial distribution of beach amenities is an important consideration in choice.•We include complement and substitute accessibility parameters for each attribute.•The implications of two site changes are compared for different models.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
A key assumption of stated preference methods is that individuals have well-formed preferences that are robust over time. Both the discovered and constructed preference perspectives imply this is not ...necessarily the case. There can be a large situational component to expressed preferences that add to the uncertainty of sampling error. Most non-market valuation studies only collect data from one point in time so the degree of temporal variability cannot be tested. Test-retest studies that provide data from two points in time generally find significant differences in preference structure and willingness-to-pay (WTP). In this study we test stability of WTP for beach erosion management using a fully ranked discrete choice experiment survey with not one but two retests over a six month period. We find that stability does not improve with the additional repetition as the preference discovery hypothesis implies it might. WTP confidence intervals overlap but the models are significantly different at each point in time, even after allowing for variation in choice error. Either the survey did not facilitate sufficient preference discovery or preferences were reconstructed. However, respondents with high scores of self-reported certainty in their choices in the first survey had significantly more stable WTP estimates.
•We repeat a choice experiment three times in six months with the same individuals.•Tests reject joint parameter equality and mean WTP equality.•Consistency does not improve in second retest.•Respondents with high self-reported certainty do have stable WTP.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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