Intergalactic Medium Emission Observations With the Cosmic Web Imager. I. The Circum-Qso Medium of Qso 1549+19, and Evidence for a Filamentary Gas Inflow

Abstract

The Palomar Cosmic Web Imager (PCWI), an integral field spectrograph designed to detect and map low surface brightness emission, has obtained imaging spectroscopic maps of Lyα from the circum-QSO medium (CQM) of QSO HS1549+19 at redshift z=2.843. Extensive extended emission is detected from the CQM, consistent with fluorescent and pumped Lyα produced by the ionizing and Lyα continuum of the QSO. Many features present in PCWI spectral images match those detected in narrow-band images. Filamentary structures with narrow line profiles are detected in several cases as long as 250-400 kpc. One of these is centered at a velocity redshifted with respect to the systemic velocity, and displays a spatially collimated and kinematically cold line profile increasing in velocity width approaching the QSO. This suggests that the filament gas is infalling onto the QSO, perhaps in a cold accretion flow. Because of the strong ionizing flux, the neutral column density is low, typically N(HI )  10 12 − 10 15 cm −2 , and the line center optical depth is also low (typically τ 0 < 10 ), insufficient to display well-separated double peak emission characteristic of higher line optical depths. With a simple ionization and cloud model we can very roughly estimate the total gas mass ( log M gas = 12.5 ± 0.5 ) and the total ( log M tot = 13.3 ± 0.5 ). We can also calculate a kinematic mass from the total line profile ( 2 × 10 13 M  ), which agrees with the mass estimated from the gas emission. The intensity-binned spectrum of the CQM shows a progression in kinematic properties consistent with heirarchical structure formation.

UBIQUITOUS GIANT Lyα NEBULAE AROUND THE BRIGHTEST QUASARS AT z ∼ 3.5 REVEALED WITH MUSE∗

“…The typical detection rate of giant nebulae (i.e., with projected sizes larger than 100 pkpc) around radio-quiet quasars in these NB surveys is less than 10% considering both deep LRIS/Keck data (S. Cantalupo et al 2016, in preparation) and shallower surveys using GMOS (Arrigoni Battaia et al 2016). This low detection rate is also found by other independent surveys using broader NB filters on LRIS/Keck (Martin et al 2014).…”

“…This result seems to be in stark contrast with previous narrow-band and spectroscopic surveys for bright radio-quiet quasars at highredshift. These studies have found detection rates of giant nebula less than 10% using NB imaging at < < z 2 3 (Cantalupo et al 2014;Martin et al 2014;Hennawi et al 2015;Arrigoni Battaia et al 2016), while spectroscopic surveys at any redshift have found exclusively smaller nebulae (<60 pkpc) and only in about 50% of the cases (North et al 2012;Fathivavsari et al 2015). Because all these surveys-including our MUSE observations-reached a similar depth, the origin of this discrepancy must be searched for somewhere else.…”

“…The three giant nebulae discovered hitherto with NB imaging (Cantalupo et al 2014;Martin et al 2014;Hennawi et al 2015) are all characterized by bright extended emission with surface brightness values larger than 10 −17 erg s −1 cm −2 arcsec −2 , a value that is easily reachable within 1 hr of integration time with MUSE. Therefore, for this exploratory survey (094.A-0396, 095.A-0708, 096.A-0345), we use a total exposure time of 1 hr for each quasar split into 4×900 s exposures.…”

“…To date, the two giant nebulae detected by Cantalupo et al (2014; the "Slug" Nebula) and Hennawi et al (2015; the "Jackpot" Nebula) and the extended emission reported by Martin et al (2014) are the only radio-quiet a Ly nebulae with sizes significantly larger than 100 pkpc. Other NB surveys (e.g., Hu et al 1991;Arrigoni Battaia et al 2016) and spectroscopic observations (e.g., Christensen et al 2006;North et al 2012;Herenz et al 2015) have either not detected any extended emission at all or detected emission on much smaller scales (50-60 pkpc), which was found in about 50% of the cases.…”

“…Filter losses could be particularly relevant for kinematically narrow nebulae while broader nebulae, such as radio-loud systems, would be less affected. Long-slit spectroscopic surveys, on the other hand, can only cover a small part of the area around the quasars (i.e., they suffer from slit losses) and all giant nebulae discovered so far are clearly asymmetric (Cantalupo et al 2014;Martin et al 2014;Hennawi et al 2015). Moreover, in order to discover faint and extended nebulosities, it is necessary to properly remove the point-spread function (PSF) associated with the hyper-luminous quasars, a task that is particularly difficult for some instruments (e.g., LRIS/Keck) and in general for NB imaging (PSF losses).…”