Abstract
To date, the proposed observation of young stellar objects (YSOs) in the Galactic center still raises the question of where and how these objects could have formed due to the violent ...vicinity of Sgr A*. Here, we report the multiwavelength detection of a highly dynamic YSO close to Sgr A* that might be a member of the IRS 13 cluster. We observe the beforehand known coreless bow-shock source X3 in the near- and mid-infrared (NIR/MIR) with SINFONI (VLT), NACO (VLT), ISAAC (VLT), VISIR (VLT), SHARP (NTT), and NIRCAM2 (KECK). In the radio domain, we use CO continuum and H30
α
ALMA observations to identify system components at different temperatures and locations concerning the central stellar source. It is suggested that these radio/submillimeter observations in combination with the NIR Br
γ
line can be associated with a protoplanetary disk of the YSO, which is consistent with manifold VISIR observations that reveal complex molecules and elements such as PAH, S
iv
, Ne
ii
, and Ar
iii
in a dense and compact region. Based on the photometric multiwavelength analysis, we infer the mass of
15
−
5
+
10
M
⊙
for the YSO with a related age of a few 10
4
yr. Due to this age estimate and the required relaxation timescales for high-mass stars, this finding is an indication of ongoing star formation in the inner parsec. The proper motion and 3D distance imply a relation between X3 and IRS 13. We argue that IRS 13 may serve as a birthplace for young stars that are ejected due to the evaporation of the cluster.
Aims. We characterise the properties of stars, dust, and gas and their spatial distribution in the central region of the Seyfert 2 galaxy NGC 1068. Method. Our study is based on near-infrared (YJH, ...0.95−1.650 μm, R = 350) long-slit spectroscopy observations of the central region of NGC 1068 with a 0.4″ spatial resolution. We decomposed the observed continuum emission into three components: hot dust, stars, and scattered light from the central engine. We measured their contributions at various distances from the nucleus. We also measured fluxes and Doppler shifts for the emission lines in our spectrum to probe the physical conditions of the narrow line region. Results. Dust and stars are the main sources of continuum emission, but scattered light from the central engine has also been detected in the very central region. Together, these three components reproduce the observed continuum well. The dust emission is compatible with a 830 K blackbody. It has only been detected in the very central region and is not spatially resolved. The stellar content is ubiquitous. It harbours a 250 pc cusp centred around the nucleus, over-imposed on a young stellar background. The spectrum of the cusp is consistent with a 120 Myr old single stellar population. Finally, the emission lines exhibit a significant Doppler shift that is consistent with a radial outflow from the nucleus in a biconical structure. The Fe II behaviour strongly differs from other lines, indicating that it arises from a different structure.
Abstract
Several publications highlight the importance of the observations of bow shocks to learn more about the surrounding interstellar medium and radiation field. We revisit the most prominent ...dusty and gaseous bow shock source, X7, close to the supermassive black hole, Sgr A*, using multiwavelength analysis. For the purpose of this study, we use Spectrograph for Integral Field Observations in the Near Infrared (SINFONI) (
H
+
K
-band) and NACO
L
′- and
M
′-band) data sets between 2002 and 2018 with additional COMIC/ADONIS+RASOIR (
L
′-band)
7
7
COME-ON-PLUS Infrared Camera/Adaptive Optics Near Infrared System + Renouveau de l’Analyseur de Surface d’Onde InfraRouge
data of 1999. By analyzing the line maps of SINFONI, we identify a velocity of ∼200 km s
−1
from the tip to the tail. Furthermore, a combination of the multiwavelength data of NACO and SINFONI in the
H
-,
K
-,
L
′-, and
M
′-bands results in a two-component blackbody fit that implies that X7 is a dust-enshrouded stellar object. The observed ongoing elongation and orientation of X7 in the Br
γ
line maps and the NACO
L
′-band continuum indicate a wind arising at the position of Sgr A* or at the IRS16 complex. Observations after 2010 show that the dust and the gas shell seems to be decoupled in the projection from its stellar source S50. The data also implies that the tail of X7 thermally heats up due to the presence of S50. The gas emission at the tip is excited because of the related forward scattering (Mie scattering), which will continue to influence the shape of X7 in the near future. In addition, we find excited Fe
iii
lines, which together with the recently analyzed dusty sources and the Br
γ
-bar underline the uniqueness of this source.
The adaptive optics system for the second-generation VLT-interferometer (VLTI) instrument GRAVITY consists of a novel cryogenic near-infrared wavefront sensor to be installed at each of the four unit ...telescopes of the Very Large Telescope (VLT). Feeding the GRAVITY wavefront sensor with light in the 1.4 to 2.4 micrometer band, while suppressing laser light originating from the GRAVITY metrology system, custom-built optical components are required. In this paper, we present the development of a quantitative near-infrared point diffraction interferometric characterization technique, which allows measuring the transmitted wavefront error of the silicon entrance windows of the wavefront sensor cryostat. The technique can be readily applied to quantitative phase measurements in the near-infrared regime. Moreover, by employing a slightly off-axis optical setup, the proposed method can optimize the required spatial resolution and enable real time measurement capabilities. The feasibility of the proposed setup is demonstrated, followed by theoretical analysis and experimental results. Our experimental results show that the phase error repeatability in the nanometer regime can be achieved.
We present near-infrared interferometric data on the Seyfert 2 galaxy NGC 1068, obtained with the GRAVITY instrument on the European Southern Observatory Very Large Telescope Interferometer. The ...extensive baseline coverage from 5 to 60 M λ allowed us to reconstruct a continuum image of the nucleus with an unrivaled 0.2 pc resolution in the K -band. We find a thin ring-like structure of emission with a radius r = 0.24 ± 0.03 pc, inclination i = 70 ± 5°, position angle PA = −50 ± 4°, and h / r < 0.14, which we associate with the dust sublimation region. The observed morphology is inconsistent with the expected signatures of a geometrically and optically thick torus. Instead, the infrared emission shows a striking resemblance to the 22 GHz maser disc, which suggests they share a common region of origin. The near-infrared spectral energy distribution indicates a bolometric luminosity of (0.4–4.7) × 10 45 erg s −1 , behind a large A K ≈ 5.5 ( A V ≈ 90) screen of extinction that also appears to contribute significantly to obscuring the broad line region.
Context. Active galactic nuclei (AGNs) are very luminous galaxies from the ultraviolet (UV) to the far infrared (FIR). To study regions near the core, which are dominated by dust, IR is the perfect ...spectral range because of the lower optical depth of the dust. However, these galaxies are usually distant, and the structures near the core are faint compared to the central source. High resolution and high contrast are mandatory to study the inner structures of AGNs and better understand the interaction between the central core and its surroundings. Aims: Our goal is to propose an explanation for the coronal lines in our spectra of NGC 1068 at a far distance (few tens of parsec) from the central source inside wave-like structures that we call nodules. Methods: NGC 1068 was observed with NaCo at ESO/VLT, using long-slit spectroscopy at 2.2 mum and 3.5 mum. Reduced spectra were compared to the output of Cloudy, using various ionizing continua: the continuum of the central source, young stars, and radiative shocks caused by the jet. Results: For the first time, thanks to the resolution provided by NaCo, near-IR coronal emission can be precisely associated to structures observable in the IR broad-band images. We found that coronal lines observed in the nodules cannot be caused by photoionization by the central source but are instead caused by a local jet-induced ionizing continuum. In addition, studying the Brackett-gamma line (Brgamma) and CO 2-0 band head, we deduced a star density within the four nodules (~800 000 stars) compatible with super star cluster (hereafter SSC) models.
PDF
