اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدThe continuum radio emission from the Sy 1.5 galaxy NGC 5033
131
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We present new continuum VLA observations of the nearby Sy 1.5 galaxy NGC 5033, made at 4.9 and 8.4 GHz on 8 April 2003. Combined with VLA archival observations at 1.4 and 4.9 GHz made on 7 August 1993, 29 August 1999, and 31 October 1999, we sample the galaxy radio emission at scales ranging from the nuclear regions (<~ 100 pc) to the outer regions of the disk (~ 40 kpc). The high-resolution VLA images show a core-jet structure for the Sy 1.5 nucleus. While the core has a moderately steep non-thermal radio spectrum (S_ u ~ u^alpha; alpha_{1.5}^{4.9} approx -0.4), the inner kpc region shows a steeper spectrum (alpha_{1.5}^{8.4} approx -0.9). This latter spectrum is typical of galaxies where energy losses are high, indicating that the escape rate of cosmic ray electrons in NGC 5033 is low. The nucleus contributes little to the total 1.4 GHz radio power of NGC 5033 and, based on the radio to far-infrared (FIR) relation, it appears that the radio and far-infrared emission from NGC 5033 are dominated by a starburst that during the last 10 Myr produced stars at a rate of ~2.8 M_sun/yr, yielding a supernova (type Ib/c and II) rate of 0.045 #/yr. This supernova rate corresponds to about 1 SN event every 22 yr. Finally, from our deep 8.4 GHz VLA-D image, we suggest the existence of a radio spur in NGC 5033, which could have been due to a hot superbubble formed as a consequence of sequential supernova explosions occurring during the lifetime of a giant molecular cloud.
قيم البحث
اقرأ أيضاً
We analyze 3.5 resolution, high sensitivity radio continuum images of the nearby spiral galaxy NGC 4258 at 6 and 20 cm derived from multiple observations used to monitor the radio supernova SN 1981K (Van Dyk et al. 1992, [ApJ, 396, 1995]). Seven brig
ht H II region and five supernova remnant candidates are identified. Extinctions to the H II regions are estimated for the first time from a comparison of radio flux densities to new optical fluxes derived from H-alpha observations by Dutil & Roy (1999, [ApJ, 516, 62]). The bright end of the H II region luminosity function is established at each wavelength. The luminosity functions are best fit by power laws consistent with the shape of previously published radio and optical luminosity functions for a number of galaxies. The supernova remnants are all about 2--3 times the radio luminosity of Cas A. In addition, the galaxys nucleus is shown to have been variable over the SN 1981K monitoring period. The spectral index (alpha) distribution of the anomalous radio arms is investigated and found to be relatively uniform at alpha = -0.65 +/- 0.10.
Here we present an analysis of spectro-polarimetric observations of type 1.5 AGN Mrk 6, performed with 6m telescope SAO RAN in 12 epochs (2010 -- 2013). Additionally, the inter-stellar mater (ISM) polarization has been observed and its contribution t
o the AGN spectral polarization is taken into account. We measured Stokes parameters and determined the polarization parameters in 12 spectra with and without correction for the ISM polarization. We estimated the time lag between the unpolarized and polarized continuum flux variation of about ~2 days, that indicates a compact scattering region which contributes to the polarized continuum variability. The polarization in H{alpha} is complex, showing three prominent components in the BLR, one redshifted around +3000 km/s that corresponds to the red shoulder in H{alpha}, and two blue-shifted around -2000 km/s and -6000 km/s. We found that the ISM polarization has a very significant influence on the measured AGN polarization parameters. After correcting the observations for the ISM polarization we were able to detect the Keplerian motion in the BLR. We give a new method for the black hole mass estimation using spectro-polarimetric observation in the line profile, finding the black hole mass in Mrk 6 of $M_{BH} sim 1.53 cdot 10^8 M_{odot}$, that is in a good agreement with reverberation estimates.
We present VLA maps of the Seyfert 2 galaxy NGC 7319 at 3.6, 6, and 20 cm. Sub-arcsecond resolution is achieved at 3.6 and 6 cm. The radio emission exhibits a triple structure on a scale of ~4 (1.7 kpc). All three components have steep spectra, consi
stent with synchrotron radiation. We have also analyzed an HST archival, broad-band red image, which contains structure related to the radio components. In particular, a V-shaped feature in the HST image some 3.7 (1.6 kpc) southwest of the nucleus is associated with highly blueshifted emission lines seen in ground-based spectra. We interpret the V-shaped feature as emission from gas compressed by the bow shock driven by the outwardly moving radio plasmoid.
The recent detection by the Fermi gamma-ray space telescope of high-energy gamma-rays from the radio galaxy NGC 1275 makes the observation of the very high energy (VHE: E > 100 GeV) part of its broadband spectrum particularly interesting, especially
for the understanding of active galactic nuclei (AGN) with misaligned multi-structured jets. The radio galaxy NGC 1275 was recently observed by VERITAS at energies above 100 GeV for about 8 hours. No VHE gamma-ray emission was detected by VERITAS from NGC 1275. A 99% confidence level upper limit of 2.1% of the Crab Nebula flux level is obtained at the decorrelation energy of approximately 340 GeV, corresponding to 19% of the power-law extrapolation of the Fermi Large Area Telescope (LAT) result.
Galaxies which strongly deviate from the radio-far IR correlation are of great importance for studies of galaxy evolution as they may be tracing early, short-lived stages of starbursts and active galactic nuclei (AGNs). The most extreme FIR-excess ga
laxy NGC1377 has long been interpreted as a young dusty starburst, but millimeter observations of CO lines revealed a powerful collimated molecular outflow which cannot be explained by star formation alone. We present new radio observations at 1.5 and 10 GHz obtained with the Jansky Very Large Array (JVLA) and Chandra X-ray observations towards NGC1377. The observations are compared to synthetic starburst models to constrain the properties of the central energy source. We obtained the first detection of the cm radio continuum and X-ray emission in NGC1377. We find that the radio emission is distributed in two components, one on the nucleus and another offset by 4$$.5 to the South-West. We confirm the extreme FIR-excess of the galaxy, with a $q_mathrm{FIR}simeq$4.2, which deviates by more than 7-$sigma$ from the radio-FIR correlation. Soft X-ray emission is detected on the off-nucleus component. From the radio emission we estimate for a young ($<10$ Myr) starburst a star formation rate SFR$<$0.1 M$_odot$ yr$^{-1}$. Such a SFR is not sufficient to power the observed IR luminosity and to drive the CO outflow. We find that a young starburst cannot reproduce all the observed properties of the nucleus of NGC1377. We suggest that the galaxy may be harboring a radio-quiet, obscured AGN of 10$^6$M$_odot$, accreting at near-Eddington rates. We speculate that the off-nucleus component may be tracing an hot-spot in the AGN jet.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
