相关论文: Active galactic nuclei in four metal-poor dwarf em…

We present broad-band V and I imaging and long-slit spectroscopy in the optical range 3600-7500A of the dwarf irregular galaxy HS 1442+4250. The oxygen abundance 12+log(O/H)=7.63+/-0.02 (Z=Zsun/19) in the brightest H II region of HS…

We present 65 Sloan Digital Sky Survey (SDSS) spectra of 62 star-forming galaxies with oxygen abundances 12 + logO/H ~ 7.5-8.4. Redshifts of selected galaxies are in the range z~0.36-0.70. This allows us to detect the redshifted MgII…

We have collected an heterogeneous sample of galaxies at redshifts 0.001<z<3.35 with the aim of exploring the evolution of the physical parameters and of the element abundances calculated by modelling the observed spectra. The evolution…

We present ASCA X-ray results on two S0 galaxies, NGC 3065 and NGC 4203. In both galaxies, we detected hard X-ray emission from a point-like source at the nucleus. Single power law model having a photon index of 1.8 well described the…

We present observations of a peculiar Lyman alpha-emitting galaxy at redshift 3.344, discovered in a deep, blind spectroscopic survey for faint Lyman alpha emitters with the Magellan II telescope in the Hubble Ultra Deep Field (HUDF). The…

Multi-wavelength observations of active galactic nuclei (AGNs) often reveal various time scales of variability. Among these phenomena, "changing-look AGNs" are extreme cases where broad emission lines become faint/bright or even…

Properties of the cold interstellar medium of low-metallicity galaxies are not well-known due to the faintness and extremely small scale on which emission is expected. We present deep ALMA band 6 (230GHz) observations of the nearby,…

We present a sample of 930 intermediate-mass black hole (IMBH) active galactic nuclei (AGNs) with black hole masses of $M_\mathrm{BH} \leqslant 2 \times 10^{6}$ M$_{\odot}$, uniformly selected from the Seventeenth Data Release of the Sloan…

We assemble a broad-band spectral energy distribution (SED) ranging from optical to mid-infrared of nearby active galactic nuclei at $z < 0.4$. SED fitting analysis is performed using semi-empirical templates derived from Palomar-Green…

We have investigated the broad-line Balmer decrements (Halpha/Hbeta) for a large, homogeneous sample of Seyfert 1 galaxies and QSOs using spectroscopic data obtained in the Sloan Digital Sky Survey. The sample, drawn from the Fourth Data…

We consider the techniques to distinguish normal star forming (NSF) galaxies and active galactic nuclei (AGN) hosts using optical spectra. The observational data base is a set of 20000 galaxies extracted from the Sloan Digital Sky Survey,…

We report the detection of ubiquitous powerful nuclear outflows in massive (> 10^11 Msun) z~2 star-forming galaxies (SFGs), which are plausibly driven by an Active Galactic Nucleus (AGN). The sample consists of the eight most massive SFGs…

(abridged) We present long-slit spectroscopy with the 3.6m ESO telescope of eight HII regions in seven star-forming (SF) dwarf galaxies, discovered in SDSS DR4 and 6dFGRS. In addition, we use SDSS imaging data to study the photometric…

A fraction of active galactic nuclei do not show the classical Seyfert-type signatures in their optical spectra, i.e. they are optically "elusive". X-ray observations are an optimal tool to identify this class of objects. We combine new…

We present a sample of four emission-line galaxies at $z=6.11-6.35$ that were serendipitously discovered using the commissioning data for the JWST/NIRCam wide-field slitless spectroscopy (WFSS) mode. One of them (at $z=6.11$) has been…

We study zCOSMOS-bright optical spectra for 609 Spitzer/MIPS 24 micron-selected galaxies with S(24um)> 0.30 mJy and I<22.5 (AB mag) over 1.5 sq. deg. of the COSMOS field. From emission-line diagnostics we find that: 1) star-formation rates…

(Abridged) We have searched for nuclear radio emission from a statistically complete sample of 40 Sc galaxies within 30 Mpc that are optically classified as star-forming objects, in order to determine whether weak AGNs might be present.…

Recent studies on dwarf galaxies reveal that some of them harbor a massive black hole (BH), which is believed to have a similar mass of the Supermassive BH "seeds" at early times. The origin and growth of the primitive BHs are still open…

We have conducted a high-resolution spectroscopic study using Spitzer of 18 bulgeless (Sd/Sdm) galaxies that show no definitive signatures of nuclear activity in their optical spectra. This is the first systematic mid-IR search for weak or…

We analyze X-ray spectra of heavily obscured (N_H > 10^{24} cm^{-2}) active galaxies obtained with Chandra, concentrating on the iron K alpha fluorescence line. We measure very large equivalent widths in most cases, up to 5 keV in the most…