اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدInternal Kinematics and Stellar Populations of the Poststarburst+AGN Galaxy SDSS J230743.41+152558.4
180
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We present the first 3D spectroscopic observations of a nearby HI detected poststarburst, or E+A, galaxy, SDSS J230743.41+152558.4, obtained with the VIMOS IFU spectrograph at ESO VLT. Using the NBursts full spectral fitting technique, we derive maps of stellar kinematics, age, and metallicity out to 2-3 half-light radii. Our analysis reveals a large-scale rapidly rotating disc (v_circ = 300km/s) with a positive age gradient (0.6 to 1.5 Gyr), and a very metal-rich central region ([Fe/H]=+0.25 dex). If a merger or interaction is responsible for triggering the starburst, the presence of this undisturbed disc suggests a minor merger with a gas-rich satellite as the most plausible option, rather than a disruptive major merger. We find spectroscopic evidence for the presence of a LINER or AGN. This is an important clue to the feedback mechanism that truncated the starburst. The presently observed quiescent phase may well be a temporary episode in the galaxys life. SDSS J230743.41+152558.4 is gas-rich and may restart forming stars, again becoming blue before finally settling at the red sequence.
قيم البحث
اقرأ أيضاً
We investigate the effects of Active Galactic Nuclei (AGN) on the gas kinematics of their host galaxies, using MaNGA data for a sample of 62 AGN hosts and 109 control galaxies (inactive galaxies). We compare orientation of the line of nodes (kinemati
c Position Angle - PA) measured from the gas and stellar velocity fields for the two samples. We found that AGN hosts and control galaxies display similar kinematic PA offsets between gas and stars. However, we note that AGN have larger fractional velocity dispersion $sigma$ differences between gas and stars [$sigma_{frac}=(sigma_{rm gas}-sigma_{stars})/sigma_{rm stars}$] when compared to their controls, as obtained from the velocity dispersion values of the central (nuclear) pixel (2.5 diameter). The AGN have a median value of $sigma_{rm frac}$ of $<sigma_{frac}>_{rm AGN}=0.04$, while the the median value for the control galaxies is $<sigma_{frac}>_{rm CTR}=-0.23$. 75% of the AGN show $sigma_{frac}>-0.13$, while 75% of the normal galaxies show $sigma_{rm frac}<-0.04$, thus we suggest that the parameter $sigma_{rm frac}$ can be used as an indicative of AGN activity. We find a correlation between the [OIII]$lambda$5007 luminosity and $sigma_{frac}$ for our sample. Our main conclusion is that the AGN already observed with MaNGA are not powerful enough to produce important outflows at galactic scales, but at 1-2 kpc scales, AGN feedback signatures are always present on their host galaxies.
Based on MaNGA integral field unit (IFU) spectroscopy we search 60 AGN candidates, which have stellar masses $M_{star}leqslant5times10^{9}$$M_{odot}$ and show AGN ionization signatures in the BPT diagram. For these AGN candidates, we derive the spati
ally resolved stellar population with the stellar population synthesis code STARLIGHT and measure the gradients of the mean stellar age and metallicity. We find that the gradients of mean stellar age (metallicity) of individual AGN-host dwarfs are diverse in 0-0.5 Re, 0.5-1 Re and 0-1 Re. However, the overall behavior of the mean stellar age (metallicity) profiles tend to be flat, as the median values of the gradients are close to zero. We further study the overall behavior of the mean stellar age (metallicity) by plotting the co-added radial profiles for the AGN sample and compare with a control sample with similar stellar mass. We find that the median values of light-weighted mean stellar ages of AGN sample are as old as 2-3 ~Gyr within 2 Re,which are about 4-7 times older than those of the control sample. Meanwhile, most of the AGN candidates are low-level AGNs, as only eight sources have L[OIII]>$10^{39.5}$~erg~s$^{-1}$. Hence, the AGNs in dwarf galaxies might accelerate the evolution of galaxies by accelerating the consumption of the gas, resulting in an overall quenching of the dwarf galaxies, and the AGNs also become weak due to the lack of gas. The median values of mass-weighted mean stellar age of both samples within 2 $Re$ are similar and as old as about 10~Gyr, indicating that the stellar mass is mainly contributed by old stellar populations.The gradients of co-added mean stellar metallicity for both samples tend to be negative but close to zero, and the similar mean stellar metallicity profiles for both samples indicate that the chemical evolution of the host galaxy is not strongly influenced by the AGN.
NGC 7582 is defined as a Starburst/AGN galaxy, since its optical and X-Ray spectra reveal both characteristics. In this work, we show the results of a stellar population modeling in a datacube taken with the Gemini South telescope. We found that $sim
$ 90% of the light in the field of view is emitted by stars that are less than 1 billion years old. A strong burst occurred about $sim$ 6 million years ago and has nearly solar metallicity. We also found a Wolf-Rayet cluster.
We present the results of a detailed study of the central part of the Seyfert galaxy Mkn 938. Observational data were obtained with the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences using integral-field spe
ctrograph MPFS and a scanning Fabry--Perot interferometer. Mkn 938 is interesting for being a result of a merger of two gas-rich galaxies, and we observe the final stage of this interaction accompanied with an extremely powerful burst of star formation and nuclear activity. Our analysis of the kinematics of gas and stars revealed the presence of gas outflow in the circumnuclear region Mkn 938 with velocities ranging from -370 to -480 km/s, and allowed us for the first time to map the high-velocity galactic wind in NaD absorption line on large spatial scale in this galaxy.
We present Bayesian AGN Decomposition Analysis for SDSS Spectra (BADASS), an open source spectral analysis code designed for automatic detailed deconvolution of AGN and host galaxy spectra, implemented in Python, and designed for the next generation
of large scale surveys. BADASS simultaneously fits all spectral components, including power-law continuum, stellar line-of-sight velocity distribution, FeII emission, as well as forbidden (narrow), permitted (broad), and outflow emission line features, all performed using Markov Chain Monte Carlo to obtain robust uncertainties and autocorrelation analysis to assess parameter convergence. BADASS utilizes multiprocessing for batch fitting large samples of spectra while efficiently managing memory and computation resources and is currently being used in a cluster environment to fit thousands of SDSS spectra. We use BADASS to perform a correlation analysis of 63 SDSS type 1 AGNs with evidence of strong non-gravitational outflow kinematics in the [OIII]$lambda5007$ emission feature. We confirm findings from previous studies that show the core of the [OIII] profile is a suitable surrogate for stellar velocity dispersion $sigma_*$, however there is evidence that the core experiences broadening that scales with outflow velocity. We find sufficient evidence that $sigma_*$, [OIII] core dispersion, and the non-gravitational outflow dispersion of the [OIII] profile form a plane whose fit results in a scatter of $sim0.1$ dex. Finally, we discuss the implications, caveats, and recommendations when using the [OIII] dispersion as a surrogate for $sigma_*$ for the $M_{rm{BH}}-sigma_*$ relation.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
