We investigate the presence of extended ionized outflows in 18 luminous type 2 AGNs (11 quasars and 7 high-luminosity Seyfert 2s) at 0.3 < z < 0.6 based on VLT-FORS2 spectroscopy. We infer typical ...lower limits on the radial sizes of the outflows R
o ≳ several × 100 pc and upper limits R
o ≲ 1–2 kpc. Our results are inconsistent with related studies which suggest that large scale (R
o ∼ several-15 kpc) are ubiquitous in QSO2. We study the possible causes of discrepancy and propose that seeing smearing is the cause of the large inferred sizes. The implications in our understanding of the feedback phenomenon are important since the mass M
o (through the density), mass injection
$\skew3\dot{M}_{\rm o}$
and energy injection
$\dot{E}_{\rm o}$
rates of the outflows become highly uncertain. One conclusion seems unavoidable: M
o,
$\skew3\dot{M}_{\rm o}$
and
$\dot{E}_{\rm o}$
are modest or low compared with previous estimations. We obtain typically M
o ≲ (0.4–22) × 106 M⊙ (median 1.1 × 106 M⊙) assuming n = 1000 cm−3. These are ∼102–104 times lower than values reported in the literature. Even under the most favourable assumptions, we obtain
$\skew3\dot{M}_{\rm o}\lesssim$
10 M⊙ yr−1 in general, 100–1000 times lower than claimed in related studies. Although the uncertainties are large, it is probable that these are lower than typical star-forming rates. In conclusion, no evidence is found supporting that typical outflows can affect the interstellar medium of the host galaxies across spatial scales ≳ 1–2 kpc.
We have identified ionized outflows in the narrow-line region of all but one Sloan Digital Sky Survey type 2 quasars (QSO2) at z≲0.1 (20/21, detection rate 95 per cent), implying that this is a ...ubiquitous phenomenon in this object class also at the lowest z. The outflowing gas has high densities (n
e≳1000 cm−3) and covers a region the size of a few kpc. This implies ionized outflow masses M
outf ∼ (0.3–2.4) × 106 M⊙ and mass outflow rates Ṁ< few M⊙ yr−1. The triggering mechanism of the outflows is related to the nuclear activity. The QSO2 can be classified into two groups according to the behaviour and properties of the outflowing gas. QSO2 in Group 1 (5/20 objects) show the most extreme turbulence; they have on average higher radio luminosities and higher excess of radio emission. QSO2 in Group 2 (15/20 objects) show less extreme turbulence; they have lower radio luminosities and, on average, lower or no radio excess. We propose that two competing outflow mechanisms are at work: radio jets and accretion disc winds. Radio jet induced outflows are dominant in Group 1, while disc winds dominate in Group 2. We find that the radio jet mode is capable of producing more extreme outflows. To test this interpretation, we predict that (1) high resolution radio imaging will reveal the presence of jets in Group 1 QSO2; (2) the morphology of their extended ionized nebulae must be more highly collimated and kinematically perturbed.
ABSTRACT We present deep imaging observations of activated asteroid P/2016 G1 (PANSTARRS) using the 10.4 m Gran Telescopio Canarias (GTC) from 2016 late April to early June. The images are best ...interpreted as the result of a relatively short-duration event with an onset of about 350 − 30 + 10 days before perihelion (i.e., around 2016 February 10), starting sharply and decreasing with 24 − 7 + 10 days (HWHM). The results of the modeling imply that the emission of ∼1.7 × 107 kg of dust, if composed of particles of 1 m to 1 cm in radius, is distributed following a power law of index −3 and having a geometric albedo of 0.15. A detailed fitting of a conspicuous westward feature in the head of the comet-like object indicates that a significant fraction of the dust was ejected along a privileged direction right at the beginning of the event, which suggests that the parent body has possibly suffered an impact followed by a partial or total disruption. From the limiting magnitude reachable with the instrumental setup, and assuming a geometric albedo of 0.15 for the parent body, an upper limit for the size of possible fragment debris of ∼50 m in radius is derived.
We observed the hot Jupiter HAT-P-32b (also known as HAT-P-32Ab) to determine its optical transmission spectrum by measuring the wavelength-dependent, planet-to-star radius ratios in the region ...between 518-918 nm. We used the OSIRIS instrument at the Gran Telescopio CANARIAS (GTC) in long-slit spectroscopy mode, placing HAT-P-32 and a reference star in the same slit and obtaining a time series of spectra covering two transit events. Using the best quality data set, we were able to yield 20 narrowband transit light curves, with each passband spanning a 20 nm wide interval. After removal of all systematic noise signals and light curve modeling, the uncertainties for the resulting radius ratios lie between 337 and 972 ppm. The radius ratios show little variation with wavelength, suggesting a high altitude cloud layer masking any atmospheric features. Alternatively, a strong depletion in alkali metals or a much smaller than expected planetary atmospheric scale height could be responsible for the lack of atmospheric features. Our result of a flat transmission spectrum is consistent with a previous ground-based study of the optical spectrum of this planet. This agreement between independent results demonstrates that ground-based measurements of exoplanet atmospheres can give reliable and reproducible results despite the fact that the data often is heavily affected by systematic noise as long as the noise source is well understood and properly corrected. We also extract an optical spectrum of the M-dwarf companion HAT-P-32B. Using PHOENIX stellar atmosphere models we determine an effective temperature of T sub(eff)= 3187 super(+60) sub(-71) K, which is slightly colder than previous studies relying only on broadband infrared data.
DUST LOSS FROM ACTIVATED ASTEROID P/2015 X6 Moreno, F.; Licandro, J.; Cabrera-Lavers, A. ...
Astrophysical journal/The Astrophysical journal,
08/2016, Letnik:
826, Številka:
2
Journal Article, Web Resource
Recenzirano
Odprti dostop
ABSTRACT We present observations and dust tail models of activated asteroid P/2015 X6 from deep imaging data acquired at the 10.4 m Gran Telescopio Canarias (GTC) from 2015 mid-December to 2016 late ...January. The results of the modeling indicate that the asteroid has undergone sustained dust loss over a period of two months or longer. The dust parameters, derived from multidimensional fits of the available images, are compatible with either ice sublimation or rotational instability processes. An impulsive event, as might be associated with an impact with another body, is less likely. A power-law distribution of particles, with minimum and maximum radii of 1 m and 1 cm and a power index of −3.3, is found to be consistent with the observations. Depending on the model of ejection velocity adopted, the particle velocities are found to be in the range of 0.3-10 m s−1. The activation time was between 18 and 26 days before discovery. The total mass ejected from that time to the most recent observation is in the range 5-9 × 106 kg. No dust features giving indication of past activity earlier than the activation time have been observed.
A large-scale three-dimensional model of Galactic extinction is presented based on the Galactic dust distribution model of CITE. The extinction AV to any point within the Galactic disk can be quickly ...deduced using a set of three-dimensional Cartesian grids. Extinctions from the model are compared to empirical extinction measures, including lines-of-sight in and near the Galactic plane using optical and NIR extinction measures; in particular we show how extinction can be derived from NIR color-magnitude diagrams in the Galactic plane to a distance of 8 kiloparsec.
ABSTRACT
HiPERCAM is a portable, quintuple-beam optical imager that saw first light on the 10.4-m Gran Telescopio Canarias (GTC) in 2018. The instrument uses re-imaging optics and four dichroic ...beamsplitters to record $u_{\rm s}\, g_{\rm s}\, r_{\rm s}\, i_{\rm s}\, z_{\rm s}$ (320–1060 nm) images simultaneously on its five CCD cameras, each of 3.1-arcmin (diagonal) field of view. The detectors in HiPERCAM are frame-transfer devices cooled thermo-electrically to 183 K, thereby allowing both long-exposure, deep imaging of faint targets, as well as high-speed (over 1000 windowed frames per second) imaging of rapidly varying targets. A comparison-star pick-off system in the telescope focal plane increases the effective field of view to 6.7 arcmin for differential photometry. Combining HiPERCAM with the world’s largest optical telescope enables the detection of astronomical sources to gs ∼ 23 in 1 s and gs ∼ 28 in 1 h. In this paper, we describe the scientific motivation behind HiPERCAM, present its design, report on its measured performance, and outline some planned enhancements.
In this work, we use long-slit spectroscopy observations of a transit event of the close-in orbiting planet WASP-43b (Msubp=2.034 Msub Jup, Rsubp=1.036 RsubJup in an effort to detect its atmosphere. ...We used the Gran Telescopio Canarias (GTC) instrument OSIRIS to obtain long-slit spectra in the optical range 520-1040 nm of the planetary host star WASP-43 and of a reference star during a full primary transit event and four partial transit observations. We measure a mean planet-to-star radius ratio in the white light curve of 0.15988sub -0 .00145sup +0 .00133. Using broadband filters, we detect the color signature of WASP-43. We present a tentative detection in the planet-to-star radius ratio around the Na I doublet (lambda 588.9, 589.5 nm) when compared to the nearby continuum at the 2.9sigma level. As previous results, this hints to the orbital decay of this planet although a timing analysis over several years needs to be made to confirm this.
We present deep imaging observations, orbital dynamics, and dust-tail model analyses of the double-component asteroid P/2016 J1 (J1-A and J1-B). The observations were acquired at the Gran Telescopio ...Canarias (GTC) and the Canada-France-Hawaii Telescope (CFHT) from mid-March to late July of 2016. A statistical analysis of backward-in-time integrations of the orbits of a large sample of clone objects of P/2016 J1-A and J1-B shows that the minimum separation between them occurred most likely ∼2300 days prior to the current perihelion passage, i.e., during the previous orbit near perihelion. This closest approach was probably linked to a fragmentation event of their parent body. Monte Carlo dust-tail models show that those two components became active simultaneously ∼250 days before the current perihelion, with comparable maximum loss rates of ∼0.7 and ∼0.5 kg s−1, and total ejected masses of 8 × 106 and 6 × 106 kg for fragments J1-A and J1-B, respectively. Consequently, the fragmentation event and the present dust activity are unrelated. The simultaneous activation times of the two components and the fact that the activity lasted 6-9 months or longer, strongly indicate ice sublimation as the most likely mechanism involved in the dust emission process.
ABSTRACT
We report detection of PSR B0656+14 with the Gran Telescopio Canarias in narrow optical F657, F754, F802, and F902 and near-infrared JHKs bands. The pulsar detection in the Ks band extends ...its spectrum to 2.2 $\mu$m and confirms its flux increase towards the infrared. We also present a thorough analysis of the optical spectrum obtained by us with the VLT. For a consistency check, we revised the pulsar near-infrared and narrow-band photometry obtained with the HST. We find no narrow spectral lines in the optical spectrum. We compile available near-infrared-optical-UV and archival 0.3–20 keV X-ray data and perform a self-consistent analysis of the rotation phase-integrated spectrum of the pulsar using unified spectral models. The spectrum is best fitted by the four-component model including two blackbodies, describing the thermal emission from the neutron star surface and its hot polar cap, the broken power law, originating from the pulsar magnetosphere, and an absorption line near ∼0.5 keV detected previously. The fit provides better constraints on the model parameters than using only a single spectral domain. The derived surface temperature is $T_{NS}^{\infty } = 7.9(3)\times 10^5$ K. The intrinsic radius (7.8–9.9 km) of the emitting region is smaller than a typical neutron star radius (13 km) and suggests a non-uniform temperature distribution over the star surface. In contrast, the derived radius of the hot polar cap is about twice as large as the ‘canonical’ one. The spectrum of the non-thermal emission steepens from the optical to X-rays and has a break near 0.1 keV. The X-ray data suggest the presence of another absorption line near 0.3 keV.
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