Related papers: Anomalous Surface Brightness Fluctuations in NGC 4…
We searched for X-ray serendipitous sources in over 370 Swift-XRT fields centered on gamma ray bursts detected between 2004 and 2008 and observed with total exposures ranging from 10 ks to over 1 Ms. This defines the Swift Serendipitous…
We present a joint analysis of the power spectra of density fluctuations from three independent cosmological redshift surveys; the PSCz galaxy catalog, the APM galaxy cluster catalog and the Abell/ACO cluster catalog. Over the range 0.03 <=…
We present I-band Surface Brightness Fluctuations (SBF) measurements for 16 early type galaxies (3 giants, 13 dwarfs) in the central region of the Hydra cluster, based on deep photometric data in 7 fields obtained with VLT FORS1. From the…
There is a well-known discrepancy in the distance estimation for M60, a giant elliptical galaxy in Virgo: the planetary nebula luminosity function (PNLF) distance moduli for this galaxy are, on average, $~0.4$ mag smaller than the values…
We have analysed the magnitudes, kinematics and positions of a complete sample of 320 PNs in the elliptical galaxy NGC 4697. We show (i) that the PNs in NGC 4697 do not constitute a single population that is a fair tracer of the…
We report on radio and X-ray observations of the only known repeating Fast Radio Burst (FRB) source, FRB 121102. We have detected six additional radio bursts from this source: five with the Green Bank Telescope at 2 GHz, and one at 1.4 GHz…
We present here the analysis of about 19,500 new star hours of low ecliptic latitude observations (|b| < 20 deg) obtained by the Hubble Space Telescope's FGS over a time span of more than nine years; which is an addition to the 12,000 star…
We study the two galaxies NGC4621 and NGC4374 in the Virgo cluster to derive their distances and stellar population properties. The targets have hosted three type Ia Supernova events allowing to investigate the correlations between the…
This paper presents optical and H-alpha imaging for a large sample of LSB galaxies selected from the PSS-II catalogs (Schombert et. al 1992). As noted in previous work, LSB galaxies span a range of luminosities (-10 > M_V > -20) and sizes…
We have used the Marano1 field observations with ISOPHOT at 170 $\mu$m to search for the Cosmic Far-InfraRed Background fluctuations. This field is part of the FIRBACK project (Puget et al., 1999a). For the first time, fluctuations due to…
AGN are known to account for a major portion, if not all, of the cosmic X-ray background radiation. The dominant sharp spectral feature in their spectra is the 6.4 keV fluorescent line of iron, which may contribute to as much as ~ 5-10 % of…
We present the results of a new epoch of a long-term photometric monitoring of the variable planetary nebula IC~4997. The integral $UBV$ light curves display a continuing brightening of 0.$^{m}15$ in $V$, a slight rise (<0.$^{m}1$) in $B$,…
We combine deep K-band (Keck) with V- and I-band (NTT) observations of two high-Galactic latitude fields, surveying a total of ~2 sq. arcmin. The K-band galaxy counts continue to rise above K=22, reaching surface densities of few x 10^5 per…
It is well known that the bright and remote Galactic globular cluster NGC2419 has a very peculiar structure. In particular its half-light radius is significantly larger than that of ordinary globular clusters of similar luminosity, being as…
The 143 galaxies with secure redshifts (median z = 0.62) from the 1415+52 field of the Canada-France Redshift Survey have been imaged at CFHT with median seeing of 0.67 arcseconds. Structural parameters have been derived by fitting…
The dispersion measure-redshift relation of fast radio bursts (FRBs) provides a valuable cosmological probe for constraining the Hubble constant, offering an independent measurement that could help resolve the ongoing Hubble tension. In…
We present a spectral variability study of the ultraluminous X-ray source NGC 4490 ULX-8 based on 14 Chandra, 6 XMM-Newton and 19 Swift-XRT observations obtained between 2000 and 2024. The X-ray spectra are modelled using absorbed power-law…
We investigate how the propagation of an astrophysical gravitational wave background (AGWB) is modified over cosmological volumes when considering theories beyond general relativity of the type Horndeski gravity. We first deduce an…
The discovery of a fast radio burst (FRB) in our galaxy associated with a magnetar (neutron star with strong magnetic field) has provided a critical piece of information to help us finally understand these enigmatic transients. We show that…
We present the observed H$\alpha$ flux and derived star formation rates (SFRs) for a fall sample of low$-$surface$-$brightness galaxies (LSBGs). The sample is selected from the fall sky region of the 40$\%$ ALFALFA {\ion{H}{1}} survey $-$…