Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userA panchromatic spatially resolved study of the inner 500 pc of NGC 1052 - I: Stellar population
60
0
0.0
(
0
)
Added by
Luis Gabriel Dahmer Hahn
Publication date
2018
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
We map optical and near-infrared (NIR) stellar population properties of the inner 320$times$535pc$^2$ of the elliptical galaxy NGC1052. The optical and NIR spectra were obtained using the Gemini Integral Field Units of the GMOS instrument and NIFS, respectively. By performing stellar population synthesis in the optical alone, we find that this region of the galaxy is dominated by old (t$>$10Gyr) stellar populations. Using the NIR, we find the nucleus to be dominated by old stellar populations, and a circumnuclear ring with younger ($sim$2.5Gyr) stars. We also combined the optical and NIR datacubes and performed a panchromatic spatially resolved stellar population synthesis, which resulted in a dominance of older stellar populations, in agreement with optical results. We argue that the technique of combining optical and NIR data might be useful to isolate the contribution of stellar population ages with strong NIR absorption bands. We also derive the stellar kinematics and find that the stellar motions are dominated by a high ($sim$240km$cdot$s$^{-1}$) velocity dispersion in the nucleus, with stars also rotating around the center. Lastly, we measure the absorption bands, both in the optical and in the NIR, and find a nuclear drop in their equivalent widths. The favored explanation for this drop is a featureless continuum emission from the low luminosity active galactic nucleus.
rate research
Read More
We map the optical and near-infrared (NIR) emission-line flux distributions and kinematics of the inner 320$times$535pc$^2$ of the elliptical galaxy NGC1052. The integral field spectra were obtained with the Gemini Telescope using the GMOS-IFU and NIFS instruments, with angular resolutions of 088 and 01 in the optical and NIR, respectively. We detect five kinematic components: (1 and 2) Two spatially unresolved components, being a broad line region visible in H$alpha$, with a FWHM of $sim$3200km s$^{-1}$ and an intermediate-broad component seen in the [OIII]$lambda lambda$4959,5007 doublet; (3) an extended intermediate-width component with 280<FWHM<450km s$^{-1}$ and centroid velocities up to 400km s$^{-1}$, which dominates the flux in our data, attributed either to a bipolar outflow related to the jets, rotation in an eccentric disc or a combination of a disc and large-scale gas bubbles; (4 and 5) two narrow (FWHM<150km s$^{-1}$) components, one visible in [OIII], and one visible in the other emission lines, extending beyond the field-of-view of our data, which is attributed to large-scale shocks. Our results suggest that the ionization within the observed field of view cannot be explained by a single mechanism, with photoionization being the dominant mechanism in the nucleus with a combination of shocks and photoionization responsible for the extended ionization.
We present the first VLBI detection of HCN molecular absorption in the nearby active galactic nucleus NGC 1052. Utilizing the 1 milliarcsecond resolution achieved by the Korean VLBI Network, we have spatially resolved the HCN absorption against a double-sided nuclear jet structure. Two velocity features of HCN absorption are detected significantly at the radial velocity of 1656 and 1719 km/s, redshifted by 149 and 212 km/s with respect to the systemic velocity of the galaxy. The column density of the HCN molecule is estimated to be 10^{15}-10^{16} cm^{-2}, assuming the excitation temperature of 100-230 K. The absorption features show high optical depth localized on the receding jet side, where the free-free absorption occurred due to the circumnuclear torus. The size of the foreground absorbing molecular gas is estimated to be on approximately one-parsec scales, which agrees well with the approximate size of the circumnuclear torus. HCN absorbing gas is likely to be several clumps smaller than 0.1 parsec inside the circumnuclear torus. The redshifted velocities of the HCN absorption features imply that HCN absorbing gas traces ongoing infall motion inside the circumnuclear torus onto the central engine.
By combining high-resolution (HST-WFPC2) and wide-field ground based (2.2m ESO-WFI) and space (GALEX) observations, we have collected a multi-wavelength photometric data base (ranging from the far UV to the near infrared) of the galactic globular cluster NGC1904 (M79). The sample covers the entire cluster extension, from the very central regions up to the tidal radius. In the present paper such a data set is used to study the BSS population and its radial distribution. A total number of 39 bright ($m_{218}le 19.5$) BSS has been detected, and they have been found to be highly segregated in the cluster core. No significant upturn in the BSS frequency has been observed in the outskirts of NGC 1904, in contrast to other clusters (M 3, 47 Tuc, NGC 6752, M 5) studied with the same technique. Such evidences, coupled with the large radius of avoidance estimated for NGC 1904 ($r_{avoid}sim 30$ core radii), indicate that the vast majority of the cluster heavy stars (binaries) has already sunk to the core. Accordingly, extensive dynamical simulations suggest that BSS formed by mass transfer activity in primordial binaries evolving in isolation in the cluster outskirts represent only a negligible (0--10%) fraction of the overall population.
The so-called ultra-diffuse galaxy NGC~1052-DF2 was announced to be a galaxy lacking dark matter based on a spectroscopic study of its constituent globular clusters. Here we present the first spectroscopic analysis of the stellar body of this galaxy using the MUSE integral-field spectrograph at the (ESO) Very Large Telescope. The MUSE datacube simultaneously provides DF2s stellar velocity field and systemic velocities for seven globular clusters (GCs). We further discovered three planetary nebulae (PNe) that are likely part of this galaxy. While five of the clusters had velocities measured in the literature, we were able to confirm the membership of two more candidates through precise radial velocity measurements, which increases the measured specific frequency of GCs in DF2. The mean velocity of the diffuse stellar body, 1792.9$^{-1.8}_{+1.4}$~kms, is consistent with the mean globular cluster velocity. We detect a weak but significant velocity gradient within the stellar body, with a kinematic axis close to the photometric major-axis, making it a prolate-like rotator. We estimate a velocity dispersion from the clusters and PNe of $sigma_{mathrm{int}}=10.6^{+3.9}_{-2.3}$~kms. The velocity dispersion $sigma_{rm{DF2}star}$(re) for the stellar body within one effective radius is $10.8^{-4.0}_{+3.2}$~kms. Considering various sources of systemic uncertainties this central value varies between 5 and 13~kms, and we conservatively report a 95% confidence upper limit to the dispersion within one re of 21~kms. We provide updated mass estimates based on these dispersions corresponding to the different distances to NGC~1052-DF2 that have been reported in the recent literature.
Based upon the kinematics of ten globular clusters, it has recently been claimed that the ultra-diffuse galaxy, NCD 1052-DF2, lacks a significant quantity of dark matter. Dynamical analyses have generally assumed that this galaxy is pressure supported, with the relatively small velocity dispersion of the globular cluster population indicating the deficit of dark matter. However, the presence of a significant rotation of the globular cluster population could substantially modify this conclusion. Here we present the discovery of such a signature of rotation in the kinematics of NGC 1052-DF2s globular clusters, with a velocity amplitude of $sim12.44^{+4.40}_{-5.16}$ km/s, which, through Bayesian model comparison, represents a marginally better fit to the available kinematic data; note that this rotation is distinct from, and approximately perpendicular to, the recently identified rotation of the stellar component of NGC 1052-DF2. Assuming this truly represents an underlying rotation, it is shown that the determined mass depends upon the inclination of the rotational component and, with a moderate inclination, the resultant mass to light ratio can exceed $M/Lsim10$.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
