Is there any evidence that ionised outflows quench star formation in type 1 quasars at z<1?

The aim of this paper is to test the basic model of negative AGN feedback. According to this model, once the central black hole accretes at the Eddington limit and reaches a certain critical mass, AGN driven outflows blow out gas, suppressing star formation in the host galaxy and self-regulating black hole growth. We consider a sample of 224 quasars selected from the SDSS at z<1 observed in the infrared band by Herschel. We evaluate the star formation rate in relation to several outflow signatures traced by the [OIII]4959,5007 and [OII]3726,3729 emission lines in about half of the sample with high quality spectra. Most of the quasars show asymmetric and broad wings in [OIII], which we interpret as outflow signatures. We separate the quasars in two groups, ``weakly'' and ``strongly'' outflowing, using three different criteria. When we compare the mean star formation rate in five redshift bins in the two groups, we find that the SFRs are comparable or slightly larger in the strongly outflowing quasars. We estimate the stellar mass from SED fitting and the quasars are distributed along the star formation main sequence, although with a large scatter. The scatter from this relation is uncorrelated with respect to the kinematic properties of the outflow. Moreover, for quasars dominated in the infrared by starburst or by AGN emission, we do not find any correlation between the star formation rate and the velocity of the outflow, a trend previously reported in the literature for pure starburst galaxies. We conclude that the basic AGN negative feedback scenario seems not to agree with our results. Although we use a large sample of quasars, we did not find any evidence that the star formation rate is suppressed in the presence of AGN driven outflows on large scale. A possibility is that feedback is effective over much longer timescales than those of single episodes of quasar activity.Comment: 18 pages, new version that implements the suggestions of the referee and matches the AA published versio

Ionospheric response to the corotating interaction region-driven geomagnetic storm of October 2002

Unlike the geomagnetic storms produced by coronal mass ejections (CMEs), the storms generated by corotating interaction regions (CIRs) are not manifested by dramatic enhancements of the ring current. The CIR-driven storms are however capable of producing other phenomena typical for the magnetic storms such as relativistic particle acceleration, enhanced magnetospheric convection and ionospheric heating. This paper examines ionospheric plasma anomalies produced by a CIR-driven storm in the middle- and high-latitude ionosphere with a specific focus on the polar cap region. The moderate magnetic storm which took place on 14–17 October 2002 has been used as an example of the CIR-driven event. Four-dimensional tomographic reconstructions of the ionospheric plasma density using measurements of the total electron content along ray paths of GPS signals allow us to reveal the large-scale structure of storm-induced ionospheric anomalies. The tomographic reconstructions are compared with the data obtained by digital ionosonde located at Eureka station near the geomagnetic north pole. The morphology and dynamics of the observed ionospheric anomalies is compared qualitatively to the ionospheric anomalies produced by major CME-driven storms. It is demonstrated that the CIR-driven storm of October 2002 was able to produce ionospheric anomalies comparable to those produced by CME-driven storms of much greater Dst magnitude. This study represents an important step in linking the tomographic GPS reconstructions with the data from ground-based network of digital ionosondes

Metallicity evolution, metallicity gradients and gas fractions at z~3.4

We used near-infrared integral field spectroscopic observations from the AMAZE and LSD programs to constrain the metallicity in a sample of 40 star forming galaxies at 3<z<5 (most of which at z~3.4). We measure metallicities by exploiting strong emission line diagnostics. We found that a significant fraction of star-forming galaxies at z~3.4 deviate from the Fundamental Metallicity Relation (FMR), with a metallicity up to a factor of ten lower than expected according to the FMR. This deviation does not correlate with the dynamical properties of the galaxy or with the presence of interactions. To investigate the origin of the metallicity deviations in more detail, we also infer information on the gas content, by inverting the Schmidt-Kennicutt relation. In agreement with recent CO observational data, we found that, in contrast with the steeply rising trend at 0<z<2, the gas fraction in massive galaxies remains constant, with indication of a marginal decline, at 2<z<3.5. When combined with the metallicity information, we infer that to explain both the low metallicity and gas content in z~3.4 galaxies, both prominent outflows and massive pristine gas inflows are needed. In ten galaxies we can also spatially resolve the metallicity distribution. We found that the metallicity generally anticorrelates with the distribution of star formation and with the gas surface density. We discuss these findings in terms of pristine gas inflows towards the center, and outflows of metal rich gas from the center toward the external regions. (Abridged)Comment: Replaced to match the published versio

Dayside Ionospheric Superfountain

The Dayside Ionospheric Super-fountain modified SAMI2 code predicts the uplift, given storm-time electric fields, of the dayside near-equatorial ionosphere to heights of over 800 kilometers during magnetic storm intervals. This software is a simple 2D code developed over many years at the Naval Research Laboratory, and has importance relating to accuracy of GPS positioning, and for satellite drag

The supernova rate in local galaxy clusters

We report a measurement of the supernova (SN) rates (Ia and core-collapse) in galaxy clusters based on the 136 SNe of the sample described in Cappellaro et al. (1999) and Mannucci et al. (2005). Early-type cluster galaxies show a type Ia SN rate (0.066 SNuM) similar to that obtained by Sharon et al. (2007) and more than 3 times larger than that in field early-type galaxies (0.019 SNuM). This difference has a 98% statistical confidence level. We examine many possible observational biases which could affect the rate determination, and conclude that none of them is likely to significantly alter the results. We investigate how the rate is related to several properties of the parent galaxies, and find that cluster membership, morphology and radio power all affect the SN rate, while galaxy mass has no measurable effect. The increased rate may be due to galaxy interactions in clusters, inducing either the formation of young stars or a different evolution of the progenitor binary systems. We present the first measurement of the core-collapse SN rate in cluster late-type galaxies, which turns out to be comparable to the rate in field galaxies. This suggests that no large systematic difference in the initial mass function exists between the two environments.Comment: MNRAS, revised version after referee's comment

Primary prostatic adenocarcinoma in a domestic short-haired cat

An 8-years-old, domestic short-haired cat was presented for constipation and symptoms referable to the lower urinary tract. A solid mass located in the caudal area of the abdomen was palpated. Abdominal ultrasonography, positive-contrast retrograde urethrocystography and total body computed tomography showed the presence of a prostatic neoformation occupying almost completely the pelvic cavity. The neoformation displaced dorsolaterally the descending colon and completely englobed the prostatic urethra, without apparent involvement of the urethral lumen. Histopathologic examination revealed a prostatic carcinoma. Neoplastic cells showed a moderate to intense cytoplasmatic expression of AE1/AE3, while no expression of cytokeratin 7 and Uroplakin III was observed. Topographical, histological and immunohistochemical findings were consistent with a diagnosis of primary adenocarcinoma of the prostate body

Strongly star-forming rotating disks in a complex merging system at z = 4,7 as revealed by ALMA

We performed a kinematical analysis of the [CII] line emission of the BR 1202-0725 system at z~4,7 using ALMA observations. The most prominent sources of this system are a quasar and a submillimeter galaxy, separated by a projected distance of about 24 kpc and characterized by very high SFR, higher than 1000 Msun/yr. However, the ALMA observations reveal that these galaxies apparently have undisturbed rotating disks, which is at variance with the commonly accepted scenario in which strong star formation activity is induced by a major merger. We also detected faint components which, after spectral deblending, were spatially resolved from the main QSO and SMG emissions. The relative velocities and positions of these components are compatible with orbital motions within the gravitational potentials generated by the QSO host galaxy and the SMG, suggesting that they are smaller galaxies in interaction or gas clouds in accretion flows of tidal streams. We did not find any clear spectral evidence for outflows caused by AGN or stellar feedback. This suggests that the high star formation rates might be induced by interactions or minor mergers with these companions, which do not affect the large-scale kinematics of the disks, however. Our kinematical analysis also indicates that the QSO and the SMG have similar Mdyn, mostly in the form of molecular gas, and that the QSO host galaxy and the SMG are seen close to face-on with slightly different disk inclinations: the QSO host galaxy is seen almost face-on (i~15), while the SMG is seen at higher inclinations (i~25). Finally, the ratio between the black hole mass of the QSO, obtained from XShooter spectroscopy, and the Mdyn of the host galaxy is similar to value found in very massive local galaxies, suggesting that the evolution of black hole galaxy relations is probably better studied with dynamical than with stellar host galaxy masses.Comment: Accepted for publication in Astronomy and Astrophysic

Dense, Fe-rich Ejecta in Supernova Remnants DEM L238 and DEM L249: A New Class of Type Ia Supernova?

We present observations of two LMC supernova remnants (SNRs), DEM L238 and DEM L249, with the Chandra and XMM-Newton X-ray satellites. Bright central emission, surrounded by a faint shell, is present in both remnants. The central emission has an entirely thermal spectrum dominated by strong Fe L-shell lines, with the deduced Fe abundance in excess of solar and not consistent with the LMC abundance. This Fe overabundance leads to the conclusion that DEM L238 and DEM L249 are remnants of thermonuclear (Type Ia) explosions. The shell emission originates in gas swept up and heated by the blast wave. A standard Sedov analysis implies about 50 solar masses in both swept-up shells, SNR ages between 10,000 and 15,000 yr, low (< 0.05 cm^-3) preshock densities, and subluminous explosions with energies of 3x10^50 ergs. The central Fe-rich supernova ejecta are close to collisional ionization equilibrium. Their presence is unexpected, because standard Type Ia SNR models predict faint ejecta emission with short ionization ages. Both SNRs belong to a previously unrecognized class of Type Ia SNRs characterized by bright interior emission. Denser than expected ejecta and/or a dense circumstellar medium around the progenitors are required to explain the presence of Fe-rich ejecta in these SNRs. Substantial amounts of circumstellar gas are more likely to be present in explosions of more massive Type Ia progenitors. DEM L238, DEM L249, and similar SNRs could be remnants of ``prompt'' Type Ia explosions with young (~100 Myr old) progenitors.Comment: 24 pages, 8 figures, ApJ, in pres

Oxygen ion uplift and satellite drag effects during the 30 October 2003 daytime superfountain event

International audienceThe prompt penetration of interplanetary electric fields (IEFs) to the dayside low-latitude ionosphere during the first ~2 h of a superstorm is estimated and applied to a modified NRL SAMI2 code for the 30 October 2003 event. In our simulations, the dayside ionospheric O+ is convected to higher altitudes (~600 km) and higher latitudes (~±25° to 30°), forming highly displaced equatorial ionospheric anomaly (EIA) peaks. This feature plus others are consistent with previously published CHAMP electron (TEC) measurements and with the dayside superfountain model. The rapid upward motion of the O+ ions causes neutral oxygen (O) uplift due to ion-neutral drag. It is estimated that above ~400 km altitude the O densities within the displaced EIAs can be increased substantially over quiet time values. The latter feature will cause increased drag for low-altitude satellites. This newly predicted phenomenon is expected to be typical for superstorm/IEF events

Helium and Iron in X-ray galaxy clusters

I discuss the role of the sedimentation of helium in galaxy cluster cores on the observed X-ray properties and present a history of the metal accumulation in the ICM, with new calculations with respect to my previous work following the recent evidence of a bi-modal distribution of the delay time in Supernovae Type Ia.Comment: 6 pages. To appear in the Proceedings of "Heating vs. Cooling in Galaxies and Clusters of Galaxies", August 2006, Garching (Germany